Expressions: Move GEL into core as expressions (#29072)

* comes from grafana/gel-app
* remove transform plugin code
* move __expr__ and -100 constants to expr pkg
* set OrgID on request plugin context
* use gtime for resample duration
* in resample, rename "rule" to "window", use gtime for duration, parse duration before exec
* remove gel entry from plugins-bundled/external.json
which creates an empty array for plugins

go.mod

@@ -86,6 +86,7 @@ require (
 	golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9
 	golang.org/x/sys v0.0.0-20201022201747-fb209a7c41cd // indirect
 	golang.org/x/tools v0.0.0-20201023150057-2f4fa188d925 // indirect
+	gonum.org/v1/gonum v0.6.0
 	google.golang.org/api v0.33.0
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/genproto v0.0.0-20201022181438-0ff5f38871d5 // indirect

go.sum

@@ -1338,6 +1338,7 @@ golang.org/x/exp v0.0.0-20191227195350-da58074b4299/go.mod h1:2RIsYlXP63K8oxa1u0
 golang.org/x/exp v0.0.0-20200119233911-0405dc783f0a/go.mod h1:2RIsYlXP63K8oxa1u096TMicItID8zy7Y6sNkU49FU4=
 golang.org/x/exp v0.0.0-20200207192155-f17229e696bd/go.mod h1:J/WKrq2StrnmMY6+EHIKF9dgMWnmCNThgcyBT1FY9mM=
 golang.org/x/exp v0.0.0-20200224162631-6cc2880d07d6/go.mod h1:3jZMyOhIsHpP37uCMkUooju7aAi5cS1Q23tOzKc+0MU=
+golang.org/x/exp v0.0.0-20200331195152-e8c3332aa8e5 h1:FR+oGxGfbQu1d+jglI3rCkjAjUnhRSZcUxr+DqlDLNo=
 golang.org/x/exp v0.0.0-20200331195152-e8c3332aa8e5/go.mod h1:4M0jN8W1tt0AVLNr8HDosyJCDCDuyL9N9+3m7wDWgKw=
 golang.org/x/image v0.0.0-20180708004352-c73c2afc3b81/go.mod h1:ux5Hcp/YLpHSI86hEcLt0YII63i6oz57MZXIpbrjZUs=
 golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
@@ -1623,8 +1624,10 @@ golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1N
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gonum.org/v1/gonum v0.0.0-20180816165407-929014505bf4/go.mod h1:Y+Yx5eoAFn32cQvJDxZx5Dpnq+c3wtXuadVZAcxbbBo=
 gonum.org/v1/gonum v0.0.0-20181121035319-3f7ecaa7e8ca/go.mod h1:Y+Yx5eoAFn32cQvJDxZx5Dpnq+c3wtXuadVZAcxbbBo=
+gonum.org/v1/gonum v0.6.0 h1:DJy6UzXbahnGUf1ujUNkh/NEtK14qMo2nvlBPs4U5yw=
 gonum.org/v1/gonum v0.6.0/go.mod h1:9mxDZsDKxgMAuccQkewq682L+0eCu4dCN2yonUJTCLU=
 gonum.org/v1/netlib v0.0.0-20181029234149-ec6d1f5cefe6/go.mod h1:wa6Ws7BG/ESfp6dHfk7C6KdzKA7wR7u/rKwOGE66zvw=
+gonum.org/v1/netlib v0.0.0-20190313105609-8cb42192e0e0 h1:OE9mWmgKkjJyEmDAAtGMPjXu+YNeGvK9VTSHY6+Qihc=
 gonum.org/v1/netlib v0.0.0-20190313105609-8cb42192e0e0/go.mod h1:wa6Ws7BG/ESfp6dHfk7C6KdzKA7wR7u/rKwOGE66zvw=
 gonum.org/v1/plot v0.0.0-20190515093506-e2840ee46a6b/go.mod h1:Wt8AAjI+ypCyYX3nZBvf6cAIx93T+c/OS2HFAYskSZc=
 google.golang.org/api v0.3.1/go.mod h1:6wY9I6uQWHQ8EM57III9mq/AjF+i8G65rmVagqKMtkk=

pkg/api/metrics.go

@@ -5,8 +5,8 @@ import (
 	"errors"
 	"sort"
 
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/grafana/grafana/pkg/models"
-	"github.com/grafana/grafana/pkg/plugins"
 
 	"github.com/grafana/grafana/pkg/api/dtos"
 	"github.com/grafana/grafana/pkg/bus"
@@ -29,13 +29,13 @@ func (hs *HTTPServer) QueryMetricsV2(c *models.ReqContext, reqDto dtos.MetricReq
 		User:      c.SignedInUser,
 	}
 
-	expr := false
+	hasExpr := false
 	var ds *models.DataSource
 	for i, query := range reqDto.Queries {
 		hs.log.Debug("Processing metrics query", "query", query)
 		name := query.Get("datasource").MustString("")
-		if name == "__expr__" {
+		if name == expr.DatasourceName {
-			expr = true
+			hasExpr = true
 		}
 
 		datasourceID, err := query.Get("datasourceId").Int64()
@@ -44,7 +44,7 @@ func (hs *HTTPServer) QueryMetricsV2(c *models.ReqContext, reqDto dtos.MetricReq
 			return Error(400, "Query missing data source ID", nil)
 		}
 
-		if i == 0 && !expr {
+		if i == 0 && !hasExpr {
 			ds, err = hs.DatasourceCache.GetDatasource(datasourceID, c.SignedInUser, c.SkipCache)
 			if err != nil {
 				hs.log.Debug("Encountered error getting data source", "err", err)
@@ -70,7 +70,7 @@ func (hs *HTTPServer) QueryMetricsV2(c *models.ReqContext, reqDto dtos.MetricReq
 
 	var resp *tsdb.Response
 	var err error
-	if !expr {
+	if !hasExpr {
 		resp, err = tsdb.HandleRequest(c.Req.Context(), ds, request)
 		if err != nil {
 			return Error(500, "Metric request error", err)
@@ -80,7 +80,7 @@ func (hs *HTTPServer) QueryMetricsV2(c *models.ReqContext, reqDto dtos.MetricReq
 			return Error(404, "Expressions feature toggle is not enabled", nil)
 		}
 
-		resp, err = plugins.Transform.Transform(c.Req.Context(), request)
+		resp, err = expr.WrapTransformData(c.Req.Context(), request)
 		if err != nil {
 			return Error(500, "Transform request error", err)
 		}

pkg/expr/commands.go

@@ -0,0 +1,263 @@
+package expr
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana/pkg/components/gtime"
+	"github.com/grafana/grafana/pkg/expr/mathexp"
+)
+
+// Command is an interface for all expression commands.
+type Command interface {
+	NeedsVars() []string
+	Execute(c context.Context, vars mathexp.Vars) (mathexp.Results, error)
+}
+
+// MathCommand is a command for a math expression such as "1 + $GA / 2"
+type MathCommand struct {
+	RawExpression string
+	Expression    *mathexp.Expr
+}
+
+// NewMathCommand creates a new MathCommand. It will return an error
+// if there is an error parsing expr.
+func NewMathCommand(expr string) (*MathCommand, error) {
+	parsedExpr, err := mathexp.New(expr)
+	if err != nil {
+		return nil, err
+	}
+	return &MathCommand{
+		RawExpression: expr,
+		Expression:    parsedExpr,
+	}, nil
+}
+
+// UnmarshalMathCommand creates a MathCommand from Grafana's frontend query.
+func UnmarshalMathCommand(rn *rawNode) (*MathCommand, error) {
+	rawExpr, ok := rn.Query["expression"]
+	if !ok {
+		return nil, fmt.Errorf("math command for refId %v is missing an expression", rn.RefID)
+	}
+	exprString, ok := rawExpr.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected math command for refId %v expression to be a string, got %T", rn.RefID, rawExpr)
+	}
+
+	gm, err := NewMathCommand(exprString)
+	if err != nil {
+		return nil, fmt.Errorf("invalid math command type in '%v': %v", rn.RefID, err)
+	}
+	return gm, nil
+}
+
+// NeedsVars returns the variable names (refIds) that are dependencies
+// to execute the command and allows the command to fulfill the Command interface.
+func (gm *MathCommand) NeedsVars() []string {
+	return gm.Expression.VarNames
+}
+
+// Execute runs the command and returns the results or an error if the command
+// failed to execute.
+func (gm *MathCommand) Execute(ctx context.Context, vars mathexp.Vars) (mathexp.Results, error) {
+	return gm.Expression.Execute(vars)
+}
+
+// ReduceCommand is an expression command for reduction of a timeseries such as a min, mean, or max.
+type ReduceCommand struct {
+	Reducer     string
+	VarToReduce string
+}
+
+// NewReduceCommand creates a new ReduceCMD.
+func NewReduceCommand(reducer, varToReduce string) *ReduceCommand {
+	// TODO: validate reducer here, before execution
+	return &ReduceCommand{
+		Reducer:     reducer,
+		VarToReduce: varToReduce,
+	}
+}
+
+// UnmarshalReduceCommand creates a MathCMD from Grafana's frontend query.
+func UnmarshalReduceCommand(rn *rawNode) (*ReduceCommand, error) {
+	rawVar, ok := rn.Query["expression"]
+	if !ok {
+		return nil, fmt.Errorf("no variable specified to reduce for refId %v", rn.RefID)
+	}
+	varToReduce, ok := rawVar.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected reduce variable to be a string, got %T for refId %v", rawVar, rn.RefID)
+	}
+	varToReduce = strings.TrimPrefix(varToReduce, "$")
+
+	rawReducer, ok := rn.Query["reducer"]
+	if !ok {
+		return nil, fmt.Errorf("no reducer specified for refId %v", rn.RefID)
+	}
+	redFunc, ok := rawReducer.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected reducer to be a string, got %T for refId %v", rawReducer, rn.RefID)
+	}
+
+	return NewReduceCommand(redFunc, varToReduce), nil
+}
+
+// NeedsVars returns the variable names (refIds) that are dependencies
+// to execute the command and allows the command to fulfill the Command interface.
+func (gr *ReduceCommand) NeedsVars() []string {
+	return []string{gr.VarToReduce}
+}
+
+// Execute runs the command and returns the results or an error if the command
+// failed to execute.
+func (gr *ReduceCommand) Execute(ctx context.Context, vars mathexp.Vars) (mathexp.Results, error) {
+	newRes := mathexp.Results{}
+	for _, val := range vars[gr.VarToReduce].Values {
+		series, ok := val.(mathexp.Series)
+		if !ok {
+			return newRes, fmt.Errorf("can only reduce type series, got type %v", val.Type())
+		}
+		num, err := series.Reduce(gr.Reducer)
+		if err != nil {
+			return newRes, err
+		}
+		newRes.Values = append(newRes.Values, num)
+	}
+	return newRes, nil
+}
+
+// ResampleCommand is an expression command for resampling of a timeseries.
+type ResampleCommand struct {
+	Window        time.Duration
+	VarToResample string
+	Downsampler   string
+	Upsampler     string
+	TimeRange     backend.TimeRange
+}
+
+// NewResampleCommand creates a new ResampleCMD.
+func NewResampleCommand(rawWindow, varToResample string, downsampler string, upsampler string, tr backend.TimeRange) (*ResampleCommand, error) {
+	// TODO: validate reducer here, before execution
+	window, err := gtime.ParseDuration(rawWindow)
+	if err != nil {
+		return nil, fmt.Errorf(`failed to parse resample "window" duration field %q: %w`, window, err)
+	}
+	return &ResampleCommand{
+		Window:        window,
+		VarToResample: varToResample,
+		Downsampler:   downsampler,
+		Upsampler:     upsampler,
+		TimeRange:     tr,
+	}, nil
+}
+
+// UnmarshalResampleCommand creates a ResampleCMD from Grafana's frontend query.
+func UnmarshalResampleCommand(rn *rawNode) (*ResampleCommand, error) {
+	rawVar, ok := rn.Query["expression"]
+	if !ok {
+		return nil, fmt.Errorf("no variable to resample for refId %v", rn.RefID)
+	}
+	varToReduce, ok := rawVar.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected resample input variable to be type string, but got type %T for refId %v", rawVar, rn.RefID)
+	}
+	varToReduce = strings.TrimPrefix(varToReduce, "$")
+	varToResample := varToReduce
+
+	rawWindow, ok := rn.Query["window"]
+	if !ok {
+		return nil, fmt.Errorf("no time duration specified for the window in resample command for refId %v", rn.RefID)
+	}
+	window, ok := rawWindow.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected resample window to be a string, got %T for refId %v", rawWindow, rn.RefID)
+	}
+
+	rawDownsampler, ok := rn.Query["downsampler"]
+	if !ok {
+		return nil, fmt.Errorf("no downsampler function specified in resample command for refId %v", rn.RefID)
+	}
+	downsampler, ok := rawDownsampler.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected resample downsampler to be a string, got type %T for refId %v", downsampler, rn.RefID)
+	}
+
+	rawUpsampler, ok := rn.Query["upsampler"]
+	if !ok {
+		return nil, fmt.Errorf("no downsampler specified in resample command for refId %v", rn.RefID)
+	}
+	upsampler, ok := rawUpsampler.(string)
+	if !ok {
+		return nil, fmt.Errorf("expected resample downsampler to be a string, got type %T for refId %v", upsampler, rn.RefID)
+	}
+
+	return NewResampleCommand(window, varToResample, downsampler, upsampler, rn.TimeRange)
+}
+
+// NeedsVars returns the variable names (refIds) that are dependencies
+// to execute the command and allows the command to fulfill the Command interface.
+func (gr *ResampleCommand) NeedsVars() []string {
+	return []string{gr.VarToResample}
+}
+
+// Execute runs the command and returns the results or an error if the command
+// failed to execute.
+func (gr *ResampleCommand) Execute(ctx context.Context, vars mathexp.Vars) (mathexp.Results, error) {
+	newRes := mathexp.Results{}
+	for _, val := range vars[gr.VarToResample].Values {
+		series, ok := val.(mathexp.Series)
+		if !ok {
+			return newRes, fmt.Errorf("can only resample type series, got type %v", val.Type())
+		}
+		num, err := series.Resample(gr.Window, gr.Downsampler, gr.Upsampler, gr.TimeRange)
+		if err != nil {
+			return newRes, err
+		}
+		newRes.Values = append(newRes.Values, num)
+	}
+	return newRes, nil
+}
+
+// CommandType is the type of the expression command.
+type CommandType int
+
+const (
+	// TypeUnknown is the CMDType for an unrecognized expression type.
+	TypeUnknown CommandType = iota
+	// TypeMath is the CMDType for a math expression.
+	TypeMath
+	// TypeReduce is the CMDType for a reduction expression.
+	TypeReduce
+	// TypeResample is the CMDType for a resampling expression.
+	TypeResample
+)
+
+func (gt CommandType) String() string {
+	switch gt {
+	case TypeMath:
+		return "math"
+	case TypeReduce:
+		return "reduce"
+	case TypeResample:
+		return "resample"
+	default:
+		return "unknown"
+	}
+}
+
+// ParseCommandType returns a CommandType from its string representation.
+func ParseCommandType(s string) (CommandType, error) {
+	switch s {
+	case "math":
+		return TypeMath, nil
+	case "reduce":
+		return TypeReduce, nil
+	case "resample":
+		return TypeResample, nil
+	default:
+		return TypeUnknown, fmt.Errorf("'%v' is not a recognized expression type", s)
+	}
+}

pkg/expr/graph.go

@@ -0,0 +1,183 @@
+package expr
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana/pkg/expr/mathexp"
+
+	"gonum.org/v1/gonum/graph"
+	"gonum.org/v1/gonum/graph/simple"
+	"gonum.org/v1/gonum/graph/topo"
+)
+
+// NodeType is the type of a DPNode. Currently either a expression command or datasource query.
+type NodeType int
+
+const (
+	// TypeCMDNode is a NodeType for expression commands.
+	TypeCMDNode NodeType = iota
+	// TypeDatasourceNode is a NodeType for datasource queries.
+	TypeDatasourceNode
+)
+
+// Node is a node in a Data Pipeline. Node is either a expression command or a datasource query.
+type Node interface {
+	ID() int64 // ID() allows the gonum graph node interface to be fulfilled
+	NodeType() NodeType
+	RefID() string
+	Execute(c context.Context, vars mathexp.Vars) (mathexp.Results, error)
+	String() string
+}
+
+// DataPipeline is an ordered set of nodes returned from DPGraph processing.
+type DataPipeline []Node
+
+// execute runs all the command/datasource requests in the pipeline return a
+// map of the refId of the of each command
+func (dp *DataPipeline) execute(c context.Context) (mathexp.Vars, error) {
+	vars := make(mathexp.Vars)
+	for _, node := range *dp {
+		res, err := node.Execute(c, vars)
+		if err != nil {
+			return nil, err
+		}
+
+		vars[node.RefID()] = res
+	}
+	return vars, nil
+}
+
+// BuildPipeline builds a graph of the nodes, and returns the nodes in an
+// executable order.
+func buildPipeline(queries []backend.DataQuery) (DataPipeline, error) {
+	graph, err := buildDependencyGraph(queries)
+	if err != nil {
+		return nil, err
+	}
+
+	nodes, err := buildExecutionOrder(graph)
+	if err != nil {
+		return nil, err
+	}
+
+	return nodes, nil
+}
+
+// buildDependencyGraph returns a dependency graph for a set of queries.
+func buildDependencyGraph(queries []backend.DataQuery) (*simple.DirectedGraph, error) {
+	graph, err := buildGraph(queries)
+	if err != nil {
+		return nil, err
+	}
+
+	registry := buildNodeRegistry(graph)
+
+	if err := buildGraphEdges(graph, registry); err != nil {
+		return nil, err
+	}
+
+	return graph, nil
+}
+
+// buildExecutionOrder returns a sequence of nodes ordered by dependency.
+func buildExecutionOrder(graph *simple.DirectedGraph) ([]Node, error) {
+	sortedNodes, err := topo.Sort(graph)
+	if err != nil {
+		return nil, err
+	}
+
+	nodes := make([]Node, len(sortedNodes))
+	for i, v := range sortedNodes {
+		nodes[i] = v.(Node)
+	}
+
+	return nodes, nil
+}
+
+// buildNodeRegistry returns a lookup table for reference IDs to respective node.
+func buildNodeRegistry(g *simple.DirectedGraph) map[string]Node {
+	res := make(map[string]Node)
+
+	nodeIt := g.Nodes()
+
+	for nodeIt.Next() {
+		if dpNode, ok := nodeIt.Node().(Node); ok {
+			res[dpNode.RefID()] = dpNode
+		}
+	}
+
+	return res
+}
+
+// buildGraph creates a new graph populated with nodes for every query.
+func buildGraph(queries []backend.DataQuery) (*simple.DirectedGraph, error) {
+	dp := simple.NewDirectedGraph()
+
+	for _, query := range queries {
+		rawQueryProp := make(map[string]interface{})
+		err := json.Unmarshal(query.JSON, &rawQueryProp)
+		if err != nil {
+			return nil, err
+		}
+		rn := &rawNode{
+			Query:     rawQueryProp,
+			RefID:     query.RefID,
+			TimeRange: query.TimeRange,
+			QueryType: query.QueryType,
+		}
+
+		dsName, err := rn.GetDatasourceName()
+		if err != nil {
+			return nil, err
+		}
+
+		var node graph.Node
+		switch dsName {
+		case DatasourceName:
+			node, err = buildCMDNode(dp, rn)
+		default: // If it's not an expression query, it's a data source query.
+			node, err = buildDSNode(dp, rn)
+		}
+		if err != nil {
+			return nil, err
+		}
+		dp.AddNode(node)
+	}
+	return dp, nil
+}
+
+// buildGraphEdges generates graph edges based on each node's dependencies.
+func buildGraphEdges(dp *simple.DirectedGraph, registry map[string]Node) error {
+	nodeIt := dp.Nodes()
+
+	for nodeIt.Next() {
+		node := nodeIt.Node().(Node)
+
+		if node.NodeType() != TypeCMDNode {
+			// datasource node, nothing to do for now. Although if we want expression results to be
+			// used as datasource query params some day this will need change
+			continue
+		}
+
+		cmdNode := node.(*CMDNode)
+
+		for _, neededVar := range cmdNode.Command.NeedsVars() {
+			neededNode, ok := registry[neededVar]
+			if !ok {
+				return fmt.Errorf("unable to find dependent node '%v'", neededVar)
+			}
+
+			if neededNode.ID() == cmdNode.ID() {
+				return fmt.Errorf("can not add self referencing node for var '%v' ", neededVar)
+			}
+
+			edge := dp.NewEdge(neededNode, cmdNode)
+
+			dp.SetEdge(edge)
+		}
+	}
+	return nil
+}

pkg/expr/mathexp/exp.go

@@ -0,0 +1,536 @@
+package mathexp
+
+import (
+	"fmt"
+	"math"
+	"reflect"
+	"runtime"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/expr/mathexp/parse"
+)
+
+// Expr holds a parsed math command expression.
+type Expr struct {
+	*parse.Tree
+}
+
+// State embeds a parsed Expr with variables and their results
+// so the expression can act on them.
+type State struct {
+	*Expr
+	Vars Vars
+	// Could hold more properties that change behavior around:
+	//  - Unions (How many result A and many Result B in case A + B are joined)
+	//  - NaN/Null behavior
+}
+
+// Vars holds the results of datasource queries or other expression commands.
+type Vars map[string]Results
+
+// New creates a new expression tree
+func New(expr string, funcs ...map[string]parse.Func) (*Expr, error) {
+	funcs = append(funcs, builtins)
+	t, err := parse.Parse(expr, funcs...)
+	if err != nil {
+		return nil, err
+	}
+	e := &Expr{
+		Tree: t,
+	}
+	return e, nil
+}
+
+// Execute applies a parse expression to the context and executes it
+func (e *Expr) Execute(vars Vars) (r Results, err error) {
+	s := &State{
+		Expr: e,
+		Vars: vars,
+	}
+	return e.executeState(s)
+}
+
+func (e *Expr) executeState(s *State) (r Results, err error) {
+	defer errRecover(&err, s)
+	r, err = s.walk(e.Tree.Root)
+	return
+}
+
+// errRecover is the handler that turns panics into returns from the top
+// level of Parse.
+func errRecover(errp *error, s *State) {
+	e := recover()
+	if e != nil {
+		switch err := e.(type) {
+		case runtime.Error:
+			panic(e)
+		case error:
+			*errp = err
+		default:
+			panic(e)
+		}
+	}
+}
+
+// walk is the top level function to walk a parsed expression
+// with its associate variables
+func (e *State) walk(node parse.Node) (res Results, err error) {
+	switch node := node.(type) {
+	case *parse.ScalarNode:
+		res = NewScalarResults(&node.Float64)
+	case *parse.VarNode:
+		res = e.Vars[node.Name]
+	case *parse.BinaryNode:
+		res, err = e.walkBinary(node)
+	case *parse.UnaryNode:
+		res, err = e.walkUnary(node)
+	case *parse.FuncNode:
+		res, err = e.walkFunc(node)
+	default:
+		return res, fmt.Errorf("expr: can not walk node type: %s", node.Type())
+	}
+	return
+}
+
+func (e *State) walkUnary(node *parse.UnaryNode) (Results, error) {
+	a, err := e.walk(node.Arg)
+	if err != nil {
+		return Results{}, err
+	}
+	newResults := Results{}
+	for _, val := range a.Values {
+		var newVal Value
+		switch rt := val.(type) {
+		case Scalar:
+			newVal = NewScalar(nil)
+			f := rt.GetFloat64Value()
+			if f != nil {
+				newF, err := unaryOp(node.OpStr, *f)
+				if err != nil {
+					return newResults, err
+				}
+				newVal = NewScalar(&newF)
+			}
+		case Number:
+			newVal, err = unaryNumber(rt, node.OpStr)
+		case Series:
+			newVal, err = unarySeries(rt, node.OpStr)
+		default:
+			return newResults, fmt.Errorf("can not perform a unary operation on type %v", rt.Type())
+		}
+		if err != nil {
+			return newResults, err
+		}
+		newResults.Values = append(newResults.Values, newVal)
+	}
+	return newResults, nil
+}
+
+func unarySeries(s Series, op string) (Series, error) {
+	newSeries := NewSeries(s.GetName(), s.GetLabels(), s.TimeIdx, s.TimeIsNullable, s.ValueIdx, s.ValueIsNullabe, s.Len())
+	for i := 0; i < s.Len(); i++ {
+		t, f := s.GetPoint(i)
+		if f == nil {
+			if err := newSeries.SetPoint(i, t, nil); err != nil {
+				return newSeries, err
+			}
+			continue
+		}
+		newF, err := unaryOp(op, *f)
+		if err != nil {
+			return newSeries, err
+		}
+		if err := newSeries.SetPoint(i, t, &newF); err != nil {
+			return newSeries, err
+		}
+	}
+	return newSeries, nil
+}
+
+func unaryNumber(n Number, op string) (Number, error) {
+	newNumber := NewNumber(n.GetName(), n.GetLabels())
+
+	f := n.GetFloat64Value()
+	if f != nil {
+		newF, err := unaryOp(op, *f)
+		if err != nil {
+			return newNumber, err
+		}
+		newNumber.SetValue(&newF)
+	}
+	return newNumber, nil
+}
+
+// unaryOp performs a unary operation on a float.
+func unaryOp(op string, a float64) (r float64, err error) {
+	if math.IsNaN(a) {
+		return math.NaN(), nil
+	}
+	switch op {
+	case "!":
+		if a == 0 {
+			r = 1
+		} else {
+			r = 0
+		}
+	case "-":
+		r = -a
+	default:
+		return r, fmt.Errorf("expr: unknown unary operator %s", op)
+	}
+	return
+}
+
+// Union holds to Values from Two sets where their labels are compatible (TODO: define compatible).
+// This is a intermediate container for Binary operations such (e.g. A + B).
+type Union struct {
+	Labels data.Labels
+	A, B   Value
+}
+
+// union creates Union objects based on the Labels attached to each Series or Number
+// within a collection of Series or Numbers. The Unions are used with binary
+// operations. The labels of the Union will the taken from result with a greater
+// number of tags.
+func union(aResults, bResults Results) []*Union {
+	unions := []*Union{}
+	if len(aResults.Values) == 0 || len(bResults.Values) == 0 {
+		return unions
+	}
+	for _, a := range aResults.Values {
+		for _, b := range bResults.Values {
+			var labels data.Labels
+			aLabels := a.GetLabels()
+			bLabels := b.GetLabels()
+			switch {
+			case aLabels.Equals(bLabels) || len(aLabels) == 0 || len(bLabels) == 0:
+				l := aLabels
+				if len(aLabels) == 0 {
+					l = bLabels
+				}
+				labels = l
+			case len(aLabels) == len(bLabels):
+				continue // invalid union, drop for now
+			case aLabels.Contains(bLabels):
+				labels = aLabels
+			case bLabels.Contains(aLabels):
+				labels = bLabels
+			default:
+				continue
+			}
+			u := &Union{
+				Labels: labels,
+				A:      a,
+				B:      b,
+			}
+			unions = append(unions, u)
+		}
+	}
+	if len(unions) == 0 && len(aResults.Values) == 1 && len(bResults.Values) == 1 {
+		// In the case of only 1 thing on each side of the operator, we combine them
+		// and strip the tags.
+		// This isn't ideal for understanding behavior, but will make more stuff work when
+		// combining different datasources without munging.
+		// This choice is highly questionable in the long term.
+		unions = append(unions, &Union{
+			A: aResults.Values[0],
+			B: bResults.Values[0],
+		})
+	}
+	return unions
+}
+
+func (e *State) walkBinary(node *parse.BinaryNode) (Results, error) {
+	res := Results{Values{}}
+	ar, err := e.walk(node.Args[0])
+	if err != nil {
+		return res, err
+	}
+	br, err := e.walk(node.Args[1])
+	if err != nil {
+		return res, err
+	}
+	unions := union(ar, br)
+	for _, uni := range unions {
+		name := uni.Labels.String()
+		var value Value
+		switch at := uni.A.(type) {
+		case Scalar:
+			aFloat := at.GetFloat64Value()
+			switch bt := uni.B.(type) {
+			// Scalar op Scalar
+			case Scalar:
+				bFloat := bt.GetFloat64Value()
+				if aFloat == nil || bFloat == nil {
+					value = NewScalar(nil)
+					break
+				}
+				f := math.NaN()
+				if aFloat != nil && bFloat != nil {
+					f, err = binaryOp(node.OpStr, *aFloat, *bFloat)
+					if err != nil {
+						return res, err
+					}
+				}
+				value = NewScalar(&f)
+			// Scalar op Scalar
+			case Number:
+				value, err = biScalarNumber(name, uni.Labels, node.OpStr, bt, aFloat, false)
+			// Scalar op Series
+			case Series:
+				value, err = biSeriesNumber(name, uni.Labels, node.OpStr, bt, aFloat, false)
+			default:
+				return res, fmt.Errorf("not implemented: binary %v on %T and %T", node.OpStr, uni.A, uni.B)
+			}
+		case Series:
+			switch bt := uni.B.(type) {
+			// Series Op Scalar
+			case Scalar:
+				bFloat := bt.GetFloat64Value()
+				value, err = biSeriesNumber(name, uni.Labels, node.OpStr, at, bFloat, true)
+			// case Series Op Number
+			case Number:
+				bFloat := bt.GetFloat64Value()
+				value, err = biSeriesNumber(name, uni.Labels, node.OpStr, at, bFloat, true)
+			// case Series op Series
+			case Series:
+				value, err = biSeriesSeries(name, uni.Labels, node.OpStr, at, bt)
+			default:
+				return res, fmt.Errorf("not implemented: binary %v on %T and %T", node.OpStr, uni.A, uni.B)
+			}
+		case Number:
+			aFloat := at.GetFloat64Value()
+			switch bt := uni.B.(type) {
+			case Scalar:
+				bFloat := bt.GetFloat64Value()
+				value, err = biScalarNumber(name, uni.Labels, node.OpStr, at, bFloat, true)
+			case Number:
+				bFloat := bt.GetFloat64Value()
+				value, err = biScalarNumber(name, uni.Labels, node.OpStr, at, bFloat, true)
+			case Series:
+				value, err = biSeriesNumber(name, uni.Labels, node.OpStr, bt, aFloat, false)
+			default:
+				return res, fmt.Errorf("not implemented: binary %v on %T and %T", node.OpStr, uni.A, uni.B)
+			}
+		default:
+			return res, fmt.Errorf("not implemented: binary %v on %T and %T", node.OpStr, uni.A, uni.B)
+		}
+		if err != nil {
+			return res, err
+		}
+		res.Values = append(res.Values, value)
+	}
+	return res, nil
+}
+
+// binaryOp performs a binary operations (e.g. A+B or A>B) on two
+// float values
+// nolint:gocyclo
+func binaryOp(op string, a, b float64) (r float64, err error) {
+	// Test short circuit before NaN.
+	switch op {
+	case "||":
+		if a != 0 {
+			return 1, nil
+		}
+	case "&&":
+		if a == 0 {
+			return 0, nil
+		}
+	}
+	if math.IsNaN(a) || math.IsNaN(b) {
+		return math.NaN(), nil
+	}
+	switch op {
+	case "+":
+		r = a + b
+	case "*":
+		r = a * b
+	case "-":
+		r = a - b
+	case "/":
+		r = a / b
+	case "**":
+		r = math.Pow(a, b)
+	case "%":
+		r = math.Mod(a, b)
+	case "==":
+		if a == b {
+			r = 1
+		} else {
+			r = 0
+		}
+	case ">":
+		if a > b {
+			r = 1
+		} else {
+			r = 0
+		}
+	case "!=":
+		if a != b {
+			r = 1
+		} else {
+			r = 0
+		}
+	case "<":
+		if a < b {
+			r = 1
+		} else {
+			r = 0
+		}
+	case ">=":
+		if a >= b {
+			r = 1
+		} else {
+			r = 0
+		}
+	case "<=":
+		if a <= b {
+			r = 1
+		} else {
+			r = 0
+		}
+	case "||":
+		if a != 0 || b != 0 {
+			r = 1
+		} else {
+			r = 0
+		}
+	case "&&":
+		if a != 0 && b != 0 {
+			r = 1
+		} else {
+			r = 0
+		}
+	default:
+		return r, fmt.Errorf("expr: unknown operator %s", op)
+	}
+	return r, nil
+}
+
+func biScalarNumber(name string, labels data.Labels, op string, number Number, scalarVal *float64, numberFirst bool) (Number, error) {
+	newNumber := NewNumber(name, labels)
+	f := number.GetFloat64Value()
+	if f == nil || scalarVal == nil {
+		newNumber.SetValue(nil)
+		return newNumber, nil
+	}
+	nF := math.NaN()
+	var err error
+	if numberFirst {
+		nF, err = binaryOp(op, *f, *scalarVal)
+	} else {
+		nF, err = binaryOp(op, *scalarVal, *f)
+	}
+	if err != nil {
+		return newNumber, err
+	}
+	newNumber.SetValue(&nF)
+	return newNumber, nil
+}
+
+func biSeriesNumber(name string, labels data.Labels, op string, s Series, scalarVal *float64, seriesFirst bool) (Series, error) {
+	newSeries := NewSeries(name, labels, s.TimeIdx, s.TimeIsNullable, s.ValueIdx, s.ValueIsNullabe, s.Len())
+	var err error
+	for i := 0; i < s.Len(); i++ {
+		nF := math.NaN()
+		t, f := s.GetPoint(i)
+		if f == nil || scalarVal == nil {
+			if err := newSeries.SetPoint(i, t, nil); err != nil {
+				return newSeries, err
+			}
+			continue
+		}
+		if seriesFirst {
+			nF, err = binaryOp(op, *f, *scalarVal)
+		} else {
+			nF, err = binaryOp(op, *scalarVal, *f)
+		}
+		if err != nil {
+			return newSeries, err
+		}
+		if err := newSeries.SetPoint(i, t, &nF); err != nil {
+			return newSeries, err
+		}
+	}
+	return newSeries, nil
+}
+
+// ... if would you like some series with your series and then get some series, or is that enough series?
+// biSeriesSeries performs a the binary operation for each value in the two series where the times
+// are equal. If there are datapoints in A or B that do not share a time, they will be dropped.
+func biSeriesSeries(name string, labels data.Labels, op string, aSeries, bSeries Series) (Series, error) {
+	bPoints := make(map[time.Time]*float64)
+	for i := 0; i < bSeries.Len(); i++ {
+		t, f := bSeries.GetPoint(i)
+		if t != nil {
+			bPoints[*t] = f
+		}
+	}
+
+	newSeries := NewSeries(name, labels, aSeries.TimeIdx, aSeries.TimeIsNullable || bSeries.TimeIsNullable, aSeries.ValueIdx, aSeries.ValueIsNullabe || bSeries.ValueIsNullabe, 0)
+	for aIdx := 0; aIdx < aSeries.Len(); aIdx++ {
+		aTime, aF := aSeries.GetPoint(aIdx)
+		bF, ok := bPoints[*aTime]
+		if !ok {
+			continue
+		}
+		if aF == nil || bF == nil {
+			if err := newSeries.AppendPoint(aIdx, aTime, nil); err != nil {
+				return newSeries, err
+			}
+			continue
+		}
+		nF, err := binaryOp(op, *aF, *bF)
+		if err != nil {
+			return newSeries, err
+		}
+		if err := newSeries.AppendPoint(aIdx, aTime, &nF); err != nil {
+			return newSeries, err
+		}
+	}
+	return newSeries, nil
+}
+
+func (e *State) walkFunc(node *parse.FuncNode) (Results, error) {
+	var res Results
+	var err error
+	var in []reflect.Value
+	for _, a := range node.Args {
+		var v interface{}
+		switch t := a.(type) {
+		case *parse.StringNode:
+			v = t.Text
+		case *parse.VarNode:
+			v = e.Vars[t.Name]
+		case *parse.ScalarNode:
+			v = t.Float64
+		case *parse.FuncNode:
+			v, err = e.walkFunc(t)
+		case *parse.UnaryNode:
+			v, err = e.walkUnary(t)
+		case *parse.BinaryNode:
+			v, err = e.walkBinary(t)
+		default:
+			return res, fmt.Errorf("expr: unknown func arg type: %T", t)
+		}
+		if err != nil {
+			return res, err
+		}
+		in = append(in, reflect.ValueOf(v))
+	}
+
+	f := reflect.ValueOf(node.F.F)
+
+	fr := f.Call(append([]reflect.Value{reflect.ValueOf(e)}, in...))
+
+	res = fr[0].Interface().(Results)
+	if len(fr) > 1 && !fr[1].IsNil() {
+		err := fr[1].Interface().(error)
+		if err != nil {
+			return res, err
+		}
+	}
+	return res, nil
+}

pkg/expr/mathexp/exp_nan_null_val_test.go

@@ -0,0 +1,423 @@
+package mathexp
+
+import (
+	"math"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNaN(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		results   Results
+		willPanic bool
+	}{
+		{
+			name:      "unary !: Op Number(NaN) is NaN",
+			expr:      "! $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("", nil, NaN)}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   Results{[]Value{makeNumber("", nil, NaN)}},
+		},
+		{
+			name:      "unary -: Op Number(NaN) is NaN",
+			expr:      "! $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("", nil, NaN)}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   Results{[]Value{makeNumber("", nil, NaN)}},
+		},
+		{
+			name:      "binary: Scalar Op(Non-AND/OR) Number(NaN) is NaN",
+			expr:      "1 * $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("", nil, NaN)}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   Results{[]Value{makeNumber("", nil, NaN)}},
+		},
+		{
+			name:      "binary: Scalar Op(AND/OR) Number(NaN) is 0/1",
+			expr:      "1 || $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("", nil, NaN)}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   Results{[]Value{makeNumber("", nil, float64Pointer(1))}},
+		},
+		{
+			name: "binary: Scalar Op(Non-AND/OR) Series(with NaN value) is NaN)",
+			expr: "1 - $A",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("temp", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(2),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), NaN,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(-1),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), NaN,
+					}),
+				},
+			},
+		},
+		{
+			name: "binary: Number Op(Non-AND/OR) Series(with NaN value) is Series with NaN",
+			expr: "$A == $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("temp", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(2),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), NaN,
+						}),
+					},
+				},
+				"B": Results{[]Value{makeNumber("", nil, float64Pointer(0))}},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(0),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), NaN,
+					}),
+				},
+			},
+		},
+		{
+			name: "binary: Number(NaN) Op Series(with NaN value) is Series with NaN",
+			expr: "$A + $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("temp", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(2),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), NaN,
+						}),
+					},
+				},
+				"B": Results{[]Value{makeNumber("", nil, NaN)}},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), NaN,
+					}, nullTimeTP{
+						unixTimePointer(10, 0), NaN,
+					}),
+				},
+			},
+		},
+	}
+
+	opt := cmp.Comparer(func(x, y float64) bool {
+		return (math.IsNaN(x) && math.IsNaN(y)) || x == y
+	})
+	options := append([]cmp.Option{opt}, data.FrameTestCompareOptions()...)
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			testBlock := func() {
+				e, err := New(tt.expr)
+				tt.newErrIs(t, err)
+				if e != nil {
+					res, err := e.Execute(tt.vars)
+					tt.execErrIs(t, err)
+					if diff := cmp.Diff(res, tt.results, options...); diff != "" {
+						assert.FailNow(t, tt.name, diff)
+					}
+				}
+			}
+			if tt.willPanic {
+				assert.Panics(t, testBlock)
+			} else {
+				assert.NotPanics(t, testBlock)
+			}
+		})
+	}
+}
+
+func TestNullValues(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		results   Results
+		willPanic bool
+	}{
+		{
+			name:      "scalar: unary ! null(): is null",
+			expr:      "! null()",
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   NewScalarResults(nil),
+		},
+		{
+			name:      "scalar: binary null() + null(): is null",
+			expr:      "null() + null()",
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   NewScalarResults(nil),
+		},
+		{
+			name:      "scalar: binary 1 + null(): is null",
+			expr:      "1 + null()",
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results:   NewScalarResults(nil),
+		},
+		{
+			name: "series: unary with a null value in it has a null value in result",
+			expr: "- $A",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(1),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), nil,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(-1),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), nil,
+					}),
+				},
+			},
+		},
+		{
+			name: "series: binary with a null value in it has a null value in result",
+			expr: "$A - $A",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(1),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), nil,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(0),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), nil,
+					}),
+				},
+			},
+		},
+		{
+			name: "series and scalar: binary with a null value in it has a nil value in result",
+			expr: "$A - 1",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(1),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), nil,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(0),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), nil,
+					}),
+				},
+			},
+		},
+		{
+			name: "number: unary ! null number: is null",
+			expr: "! $A",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeNumber("", nil, nil),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeNumber("", nil, nil),
+				},
+			},
+		},
+		{
+			name: "number: binary null number and null number: is null",
+			expr: "$A + $A",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeNumber("", nil, nil),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeNumber("", nil, nil),
+				},
+			},
+		},
+		{
+			name: "number: binary non-null number and null number: is null",
+			expr: "$A * $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeNumber("", nil, nil),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeNumber("", nil, float64Pointer(1)),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeNumber("", nil, nil),
+				},
+			},
+		},
+		{
+			name: "number and series: binary non-null number and series with a null: is null",
+			expr: "$A * $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeNumber("", nil, float64Pointer(1)),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeSeriesNullableTime("", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(1),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), nil,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(1),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), nil,
+					}),
+				},
+			},
+		},
+		{
+			name: "number and series: binary null number and series with non-null and null: is null and null",
+			expr: "$A * $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeNumber("", nil, nil),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeSeriesNullableTime("", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(1),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), nil,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), nil,
+					}, nullTimeTP{
+						unixTimePointer(10, 0), nil,
+					}),
+				},
+			},
+		},
+	}
+
+	// go-cmp instead of testify assert is used to compare results here
+	// because it supports an option for NaN equality.
+	// https://github.com/stretchr/testify/pull/691#issuecomment-528457166
+	opt := cmp.Comparer(func(x, y float64) bool {
+		return (math.IsNaN(x) && math.IsNaN(y)) || x == y
+	})
+	options := append([]cmp.Option{opt}, data.FrameTestCompareOptions()...)
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			testBlock := func() {
+				e, err := New(tt.expr)
+				tt.newErrIs(t, err)
+				if e != nil {
+					res, err := e.Execute(tt.vars)
+					tt.execErrIs(t, err)
+					if diff := cmp.Diff(tt.results, res, options...); diff != "" {
+						t.Errorf("Result mismatch (-want +got):\n%s", diff)
+					}
+				}
+			}
+			if tt.willPanic {
+				assert.Panics(t, testBlock)
+			} else {
+				testBlock()
+			}
+		})
+	}
+}

pkg/expr/mathexp/exp_scalar_no_test.go

@@ -0,0 +1,144 @@
+package mathexp
+
+import (
+	"math"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestScalarExpr(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		resultIs  assert.ComparisonAssertionFunc
+		Results   Results
+	}{
+		{
+			name:      "a scalar",
+			expr:      "1",
+			vars:      Vars{},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			Results:   Results{[]Value{NewScalar(float64Pointer(1.0))}},
+		},
+		{
+			name:      "unary: scalar",
+			expr:      "! 1.2",
+			vars:      Vars{},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			Results:   Results{[]Value{NewScalar(float64Pointer(0.0))}},
+		},
+		{
+			name:      "binary: scalar Op scalar",
+			expr:      "1 + 1",
+			vars:      Vars{},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			Results:   Results{[]Value{NewScalar(float64Pointer(2.0))}},
+		},
+		{
+			name:      "binary: scalar Op scalar - divide by zero",
+			expr:      "1 / 0",
+			vars:      Vars{},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			Results:   Results{[]Value{NewScalar(float64Pointer(math.Inf(1)))}},
+		},
+		{
+			name:      "binary: scalar Op number",
+			expr:      "1 + $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("temp", nil, float64Pointer(2.0))}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			Results:   Results{[]Value{makeNumber("", nil, float64Pointer(3.0))}},
+		},
+		{
+			name:      "binary: number Op Scalar",
+			expr:      "$A - 3",
+			vars:      Vars{"A": Results{[]Value{makeNumber("temp", nil, float64Pointer(2.0))}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			Results:   Results{[]Value{makeNumber("", nil, float64Pointer(-1))}},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e, err := New(tt.expr)
+			tt.newErrIs(t, err)
+			if e != nil {
+				res, err := e.Execute(tt.vars)
+				tt.execErrIs(t, err)
+				tt.resultIs(t, tt.Results, res)
+			}
+		})
+	}
+}
+
+func TestNumberExpr(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		resultIs  assert.ComparisonAssertionFunc
+		results   Results
+		willPanic bool
+	}{
+		{
+			name:      "binary: number Op Scalar",
+			expr:      "$A / $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("temp", nil, float64Pointer(2.0))}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			results:   Results{[]Value{makeNumber("", nil, float64Pointer(1))}},
+		},
+		{
+			name:      "unary: number",
+			expr:      "- $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("temp", nil, float64Pointer(2.0))}}},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			results:   Results{[]Value{makeNumber("", nil, float64Pointer(-2.0))}},
+		},
+		{
+			name:      "binary: Scalar Op Number (Number will nil val) - currently Panics",
+			expr:      "1 + $A",
+			vars:      Vars{"A": Results{[]Value{makeNumber("", nil, nil)}}},
+			willPanic: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			testBlock := func() {
+				e, err := New(tt.expr)
+				tt.newErrIs(t, err)
+				if e != nil {
+					res, err := e.Execute(tt.vars)
+					tt.execErrIs(t, err)
+					tt.resultIs(t, tt.results, res)
+				}
+			}
+			if tt.willPanic {
+				assert.Panics(t, testBlock)
+			} else {
+				assert.NotPanics(t, testBlock)
+			}
+		})
+	}
+}

pkg/expr/mathexp/exp_series_test.go

@@ -0,0 +1,383 @@
+package mathexp
+
+import (
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSeriesExpr(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		results   Results
+	}{
+		{
+			name:      "unary series",
+			expr:      "! ! $A",
+			vars:      aSeriesNullableTime,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{ // Not sure about preservering names...
+						unixTimePointer(5, 0), float64Pointer(1),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(1),
+					}),
+				},
+			},
+		},
+		{
+			name:      "binary scalar Op series",
+			expr:      "98 + $A",
+			vars:      aSeriesNullableTime,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{ // Not sure about preservering names...
+						unixTimePointer(5, 0), float64Pointer(100),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(99),
+					}),
+				},
+			},
+		},
+		{
+			name:      "binary series Op scalar",
+			expr:      "$A + 98",
+			vars:      aSeriesNullableTime,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{ // Not sure about preservering names...
+						unixTimePointer(5, 0), float64Pointer(100),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(99),
+					}),
+				},
+			},
+		},
+		{
+			name:      "series Op series",
+			expr:      "$A + $A",
+			vars:      aSeriesNullableTime,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{ // Not sure about preservering names...
+						unixTimePointer(5, 0), float64Pointer(4),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(2),
+					}),
+				},
+			},
+		},
+		{
+			name:      "series Op number",
+			expr:      "$A + $B",
+			vars:      aSeriesbNumber,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("id=1", data.Labels{"id": "1"}, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(9),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(8),
+					}),
+				},
+			},
+		},
+		{
+			name:      "number Op series",
+			expr:      "$B + $A",
+			vars:      aSeriesbNumber,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("id=1", data.Labels{"id": "1"}, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(9),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(8),
+					}),
+				},
+			},
+		},
+		{
+			name:      "series Op series with label union",
+			expr:      "$A * $B",
+			vars:      twoSeriesSets,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("sensor=a, turbine=1", data.Labels{"sensor": "a", "turbine": "1"}, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(6 * .5),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(8 * .2),
+					}),
+					makeSeriesNullableTime("sensor=b, turbine=1", data.Labels{"sensor": "b", "turbine": "1"}, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(10 * .5),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(16 * .2),
+					}),
+				},
+			},
+		},
+		// Length of resulting series is A when A + B. However, only points where the time matches
+		// for A and B are added to the result
+		{
+			name: "series Op series with sparse time join",
+			expr: "$A + $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("temp", data.Labels{}, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(1),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), float64Pointer(2),
+						}),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeSeriesNullableTime("efficiency", data.Labels{}, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(3),
+						}, nullTimeTP{
+							unixTimePointer(9, 0), float64Pointer(4),
+						}),
+					},
+				},
+			},
+
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{ // Not sure about preserving names...
+						unixTimePointer(5, 0), float64Pointer(4),
+					}),
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e, err := New(tt.expr)
+			tt.newErrIs(t, err)
+			if e != nil {
+				res, err := e.Execute(tt.vars)
+				tt.execErrIs(t, err)
+				if diff := cmp.Diff(tt.results, res, data.FrameTestCompareOptions()...); diff != "" {
+					t.Errorf("Result mismatch (-want +got):\n%s", diff)
+				}
+			}
+		})
+	}
+}
+
+func TestSeriesAlternateFormsExpr(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		results   Results
+	}{
+		{
+			name:      "unary series: non-nullable time",
+			expr:      "! ! $A",
+			vars:      aSeries,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeries("", nil, tp{ // Not sure about preservering names...
+						time.Unix(5, 0), float64Pointer(1),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(1),
+					}),
+				},
+			},
+		},
+		{
+			name:      "unary series: non-nullable time, time second",
+			expr:      "! ! $A",
+			vars:      aSeriesTimeSecond,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesTimeSecond("", nil, timeSecondTP{ // Not sure about preservering names...
+						float64Pointer(1), time.Unix(5, 0),
+					}, timeSecondTP{
+						float64Pointer(1), time.Unix(10, 0),
+					}),
+				},
+			},
+		},
+		{
+			name:      "unary series: non-nullable value",
+			expr:      "! ! $A",
+			vars:      aSeriesNoNull,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeNoNullSeries("", nil, noNullTP{ // Not sure about preservering names...
+						time.Unix(5, 0), 1,
+					}, noNullTP{
+						time.Unix(10, 0), 1,
+					}),
+				},
+			},
+		},
+		{
+			name: "series Op series: nullable and non-nullable time",
+			expr: "$A + $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeries("temp", data.Labels{}, tp{
+							time.Unix(5, 0), float64Pointer(1),
+						}, tp{
+							time.Unix(10, 0), float64Pointer(2),
+						}),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeSeriesNullableTime("efficiency", data.Labels{}, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(3),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), float64Pointer(4),
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(4),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(6),
+					}),
+				},
+			},
+		},
+		{
+			name: "series Op series: nullable (time second) and non-nullable time (time first)",
+			expr: "$B + $A", // takes order from first operator
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesTimeSecond("temp", data.Labels{}, timeSecondTP{
+							float64Pointer(1), time.Unix(5, 0),
+						}, timeSecondTP{
+							float64Pointer(2), time.Unix(10, 0),
+						}),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeSeriesNullableTime("efficiency", data.Labels{}, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(3),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), float64Pointer(4),
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(4),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(6),
+					}),
+				},
+			},
+		},
+		{
+			name: "series Op series: nullable and non-nullable values",
+			expr: "$A + $B",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeries("temp", data.Labels{}, tp{
+							time.Unix(5, 0), float64Pointer(1),
+						}, tp{
+							time.Unix(10, 0), float64Pointer(2),
+						}),
+					},
+				},
+				"B": Results{
+					[]Value{
+						makeNoNullSeries("efficiency", data.Labels{}, noNullTP{
+							time.Unix(5, 0), 3,
+						}, noNullTP{
+							time.Unix(10, 0), 4,
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeries("", nil, tp{
+						time.Unix(5, 0), float64Pointer(4),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(6),
+					}),
+				},
+			},
+		},
+		{
+			name:      "binary scalar Op series: non-nullable time second",
+			expr:      "98 + $A",
+			vars:      aSeriesTimeSecond,
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			results: Results{
+				[]Value{
+					makeSeriesTimeSecond("", nil, timeSecondTP{ // Not sure about preservering names...
+						float64Pointer(100), time.Unix(5, 0),
+					}, timeSecondTP{
+						float64Pointer(99), time.Unix(10, 0),
+					}),
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e, err := New(tt.expr)
+			tt.newErrIs(t, err)
+			if e != nil {
+				res, err := e.Execute(tt.vars)
+				tt.execErrIs(t, err)
+				if diff := cmp.Diff(tt.results, res, data.FrameTestCompareOptions()...); diff != "" {
+					t.Errorf("Result mismatch (-want +got):\n%s", diff)
+				}
+			}
+		})
+	}
+}

pkg/expr/mathexp/exp_test.go

@@ -0,0 +1,181 @@
+package mathexp
+
+import (
+	"math"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+)
+
+// Common Test Constructor Utils and Types
+type nullTimeTP struct {
+	t *time.Time
+	f *float64
+}
+
+type tp struct {
+	t time.Time
+	f *float64
+}
+
+type timeSecondTP struct {
+	f *float64
+	t time.Time
+}
+
+type noNullTP struct {
+	t time.Time
+	f float64
+}
+
+func makeSeriesNullableTime(name string, labels data.Labels, points ...nullTimeTP) Series {
+	newSeries := NewSeries(name, labels, 0, true, 1, true, len(points))
+	for idx, p := range points {
+		_ = newSeries.SetPoint(idx, p.t, p.f)
+	}
+	return newSeries
+}
+
+func makeSeries(name string, labels data.Labels, points ...tp) Series {
+	newSeries := NewSeries(name, labels, 0, false, 1, true, len(points))
+	for idx, p := range points {
+		err := newSeries.SetPoint(idx, &p.t, p.f)
+		if err != nil {
+			panic(err)
+		}
+	}
+	return newSeries
+}
+
+func makeNoNullSeries(name string, labels data.Labels, points ...noNullTP) Series {
+	newSeries := NewSeries(name, labels, 0, false, 1, false, len(points))
+	for idx, p := range points {
+		err := newSeries.SetPoint(idx, &p.t, &p.f)
+		if err != nil {
+			panic(err)
+		}
+	}
+	return newSeries
+}
+
+func makeSeriesTimeSecond(name string, labels data.Labels, points ...timeSecondTP) Series {
+	newSeries := NewSeries(name, labels, 1, false, 0, true, len(points))
+	for idx, p := range points {
+		err := newSeries.SetPoint(idx, &p.t, p.f)
+		if err != nil {
+			panic(err)
+		}
+	}
+	return newSeries
+}
+
+func makeNumber(name string, labels data.Labels, f *float64) Number {
+	newNumber := NewNumber(name, labels)
+	newNumber.SetValue(f)
+	return newNumber
+}
+
+func unixTimePointer(sec, nsec int64) *time.Time {
+	t := time.Unix(sec, nsec)
+	return &t
+}
+
+func float64Pointer(f float64) *float64 {
+	return &f
+}
+
+var aSeriesNullableTime = Vars{
+	"A": Results{
+		[]Value{
+			makeSeriesNullableTime("temp", nil, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(1),
+			}),
+		},
+	},
+}
+
+var aSeries = Vars{
+	"A": Results{
+		[]Value{
+			makeSeries("temp", nil, tp{
+				time.Unix(5, 0), float64Pointer(2),
+			}, tp{
+				time.Unix(10, 0), float64Pointer(1),
+			}),
+		},
+	},
+}
+
+var aSeriesTimeSecond = Vars{
+	"A": Results{
+		[]Value{
+			makeSeriesTimeSecond("temp", nil, timeSecondTP{
+				float64Pointer(2), time.Unix(5, 0),
+			}, timeSecondTP{
+				float64Pointer(1), time.Unix(10, 0),
+			}),
+		},
+	},
+}
+
+var aSeriesNoNull = Vars{
+	"A": Results{
+		[]Value{
+			makeNoNullSeries("temp", nil, noNullTP{
+				time.Unix(5, 0), 2,
+			}, noNullTP{
+				time.Unix(10, 0), 1,
+			}),
+		},
+	},
+}
+
+var aSeriesbNumber = Vars{
+	"A": Results{
+		[]Value{
+			makeSeriesNullableTime("temp", nil, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(1),
+			}),
+		},
+	},
+	"B": Results{
+		[]Value{
+			makeNumber("volt", data.Labels{"id": "1"}, float64Pointer(7)),
+		},
+	},
+}
+
+var twoSeriesSets = Vars{
+	"A": Results{
+		[]Value{
+			makeSeriesNullableTime("temp", data.Labels{"sensor": "a", "turbine": "1"}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(6),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(8),
+			}),
+			makeSeriesNullableTime("temp", data.Labels{"sensor": "b", "turbine": "1"}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(10),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(16),
+			}),
+		},
+	},
+	"B": Results{
+		[]Value{
+			makeSeriesNullableTime("efficiency", data.Labels{"turbine": "1"}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(.5),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(.2),
+			}),
+		},
+	},
+}
+
+// NaN is just to make the calls a little cleaner, the one
+// call is not for any sort of equality side effect in tests.
+// note: cmp.Equal must be used to test Equality for NaNs.
+var NaN = float64Pointer(math.NaN())

pkg/expr/mathexp/funcs.go

@@ -0,0 +1,112 @@
+package mathexp
+
+import (
+	"math"
+
+	"github.com/grafana/grafana/pkg/expr/mathexp/parse"
+)
+
+var builtins = map[string]parse.Func{
+	"abs": {
+		Args:          []parse.ReturnType{parse.TypeVariantSet},
+		VariantReturn: true,
+		F:             abs,
+	},
+	"log": {
+		Args:          []parse.ReturnType{parse.TypeVariantSet},
+		VariantReturn: true,
+		F:             log,
+	},
+	"nan": {
+		Return: parse.TypeScalar,
+		F:      nan,
+	},
+	"inf": {
+		Return: parse.TypeScalar,
+		F:      inf,
+	},
+	"null": {
+		Return: parse.TypeScalar,
+		F:      null,
+	},
+}
+
+// abs returns the absolute value for each result in NumberSet, SeriesSet, or Scalar
+func abs(e *State, varSet Results) (Results, error) {
+	newRes := Results{}
+	for _, res := range varSet.Values {
+		newVal, err := perFloat(res, math.Abs)
+		if err != nil {
+			return newRes, err
+		}
+		newRes.Values = append(newRes.Values, newVal)
+	}
+	return newRes, nil
+}
+
+// log returns the natural logarithm value for each result in NumberSet, SeriesSet, or Scalar
+func log(e *State, varSet Results) (Results, error) {
+	newRes := Results{}
+	for _, res := range varSet.Values {
+		newVal, err := perFloat(res, math.Log)
+		if err != nil {
+			return newRes, err
+		}
+		newRes.Values = append(newRes.Values, newVal)
+	}
+	return newRes, nil
+}
+
+// nan returns a scalar nan value
+func nan(e *State) Results {
+	aNaN := math.NaN()
+	return NewScalarResults(&aNaN)
+}
+
+// inf returns a scalar positive infinity value
+func inf(e *State) Results {
+	aInf := math.Inf(0)
+	return NewScalarResults(&aInf)
+}
+
+// null returns a null scalar value
+func null(e *State) Results {
+	return NewScalarResults(nil)
+}
+
+func perFloat(val Value, floatF func(x float64) float64) (Value, error) {
+	var newVal Value
+	switch val.Type() {
+	case parse.TypeNumberSet:
+		n := NewNumber(val.GetName(), val.GetLabels())
+		f := val.(Number).GetFloat64Value()
+		nF := math.NaN()
+		if f != nil {
+			nF = floatF(*f)
+		}
+		n.SetValue(&nF)
+		newVal = n
+	case parse.TypeScalar:
+		f := val.(Scalar).GetFloat64Value()
+		nF := math.NaN()
+		if f != nil {
+			nF = floatF(*f)
+		}
+		newVal = NewScalar(&nF)
+	case parse.TypeSeriesSet:
+		resSeries := val.(Series)
+		newSeries := NewSeries(resSeries.GetName(), resSeries.GetLabels(), resSeries.TimeIdx, resSeries.TimeIsNullable, resSeries.ValueIdx, resSeries.ValueIsNullabe, resSeries.Len())
+		for i := 0; i < resSeries.Len(); i++ {
+			t, f := resSeries.GetPoint(i)
+			nF := math.NaN()
+			if f != nil {
+				nF = floatF(*f)
+			}
+			if err := newSeries.SetPoint(i, t, &nF); err != nil {
+				return newSeries, err
+			}
+		}
+		newVal = newSeries
+	}
+	return newVal, nil
+}

pkg/expr/mathexp/funcs_test.go

@@ -0,0 +1,88 @@
+package mathexp
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFunc(t *testing.T) {
+	var tests = []struct {
+		name      string
+		expr      string
+		vars      Vars
+		newErrIs  assert.ErrorAssertionFunc
+		execErrIs assert.ErrorAssertionFunc
+		resultIs  assert.ComparisonAssertionFunc
+		results   Results
+	}{
+		{
+			name: "abs on number",
+			expr: "abs($A)",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeNumber("", nil, float64Pointer(-7)),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			results:   Results{[]Value{makeNumber("", nil, float64Pointer(7))}},
+		},
+		{
+			name:      "abs on scalar",
+			expr:      "abs(-1)",
+			vars:      Vars{},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			results:   Results{[]Value{NewScalar(float64Pointer(1.0))}},
+		},
+		{
+			name: "abs on series",
+			expr: "abs($A)",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("", nil, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(-2),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), float64Pointer(-1),
+						}),
+					},
+				},
+			},
+			newErrIs:  assert.NoError,
+			execErrIs: assert.NoError,
+			resultIs:  assert.Equal,
+			results: Results{
+				[]Value{
+					makeSeriesNullableTime("", nil, nullTimeTP{
+						unixTimePointer(5, 0), float64Pointer(2),
+					}, nullTimeTP{
+						unixTimePointer(10, 0), float64Pointer(1),
+					}),
+				},
+			},
+		},
+		{
+			name:     "abs on string - should error",
+			expr:     `abs("hi")`,
+			vars:     Vars{},
+			newErrIs: assert.Error,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			e, err := New(tt.expr)
+			tt.newErrIs(t, err)
+			if e != nil {
+				res, err := e.Execute(tt.vars)
+				tt.execErrIs(t, err)
+				tt.resultIs(t, tt.results, res)
+			}
+		})
+	}
+}

pkg/expr/mathexp/parse/lex.go

@@ -0,0 +1,337 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package parse
+
+import (
+	"fmt"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// item represents a token or text string returned from the scanner.
+type item struct {
+	typ itemType // The type of this item.
+	pos Pos      // The starting position, in bytes, of this item in the input string.
+	val string   // The value of this item.
+}
+
+func (i item) String() string {
+	switch {
+	case i.typ == itemEOF:
+		return "EOF"
+	case i.typ == itemError:
+		return i.val
+	case len(i.val) > 10:
+		return fmt.Sprintf("%.10q...", i.val)
+	}
+	return fmt.Sprintf("%q", i.val)
+}
+
+// itemType identifies the type of lex items.
+type itemType int
+
+const (
+	itemError itemType = iota // error occurred; value is text of error
+	itemEOF
+	itemNot       // '!'
+	itemAnd       // '&&'
+	itemOr        // '||'
+	itemGreater   // '>'
+	itemLess      // '<'
+	itemGreaterEq // '>='
+	itemLessEq    // '<='
+	itemEq        // '=='
+	itemNotEq     // '!='
+	itemPlus      // '+'
+	itemMinus     // '-'
+	itemMult      // '*'
+	itemDiv       // '/'
+	itemMod       // '%'
+	itemNumber    // simple number
+	itemComma
+	itemLeftParen
+	itemRightParen
+	itemString
+	itemFunc
+	itemVar // e.g. $A
+	itemPow // '**'
+)
+
+const eof = -1
+
+// stateFn represents the state of the scanner as a function that returns the next state.
+type stateFn func(*lexer) stateFn
+
+// lexer holds the state of the scanner.
+type lexer struct {
+	input   string    // the string being scanned
+	state   stateFn   // the next lexing function to enter
+	pos     Pos       // current position in the input
+	start   Pos       // start position of this item
+	width   Pos       // width of last rune read from input
+	lastPos Pos       // position of most recent item returned by nextItem
+	items   chan item // channel of scanned items
+}
+
+// next returns the next rune in the input.
+func (l *lexer) next() rune {
+	if int(l.pos) >= len(l.input) {
+		l.width = 0
+		return eof
+	}
+	r, w := utf8.DecodeRuneInString(l.input[l.pos:])
+	l.width = Pos(w)
+	l.pos += l.width
+	return r
+}
+
+// peek returns but does not consume the next rune in the input.
+// nolint:unused
+func (l *lexer) peek() rune {
+	r := l.next()
+	l.backup()
+	return r
+}
+
+// backup steps back one rune. Can only be called once per call of next.
+func (l *lexer) backup() {
+	l.pos -= l.width
+}
+
+// emit passes an item back to the client.
+func (l *lexer) emit(t itemType) {
+	l.items <- item{t, l.start, l.input[l.start:l.pos]}
+	l.start = l.pos
+}
+
+// accept consumes the next rune if it's from the valid set.
+func (l *lexer) accept(valid string) bool {
+	if strings.ContainsRune(valid, l.next()) {
+		return true
+	}
+	l.backup()
+	return false
+}
+
+// acceptRun consumes a run of runes from the valid set.
+func (l *lexer) acceptRun(valid string) {
+	for strings.ContainsRune(valid, l.next()) {
+	}
+	l.backup()
+}
+
+// ignore skips over the pending input before this point.
+func (l *lexer) ignore() {
+	l.start = l.pos
+}
+
+// lineNumber reports which line we're on, based on the position of
+// the previous item returned by nextItem. Doing it this way
+// means we don't have to worry about peek double counting.
+// nolint:unused
+func (l *lexer) lineNumber() int {
+	return 1 + strings.Count(l.input[:l.lastPos], "\n")
+}
+
+// errorf returns an error token and terminates the scan by passing
+// back a nil pointer that will be the next state, terminating l.nextItem.
+func (l *lexer) errorf(format string, args ...interface{}) stateFn {
+	l.items <- item{itemError, l.start, fmt.Sprintf(format, args...)}
+	return nil
+}
+
+// nextItem returns the next item from the input.
+func (l *lexer) nextItem() item {
+	item := <-l.items
+	l.lastPos = item.pos
+	return item
+}
+
+// lex creates a new scanner for the input string.
+func lex(input string) *lexer {
+	l := &lexer{
+		input: input,
+		items: make(chan item),
+	}
+	go l.run()
+	return l
+}
+
+// run runs the state machine for the lexer.
+func (l *lexer) run() {
+	for l.state = lexItem; l.state != nil; {
+		l.state = l.state(l)
+	}
+}
+
+// state functions
+
+func lexItem(l *lexer) stateFn {
+Loop:
+	for {
+		switch r := l.next(); {
+		case r == '$':
+			return lexVar
+		case isSymbol(r):
+			return lexSymbol
+		case isNumber(r):
+			l.backup()
+			return lexNumber
+		case unicode.IsLetter(r):
+			return lexFunc
+		case r == '(':
+			l.emit(itemLeftParen)
+		case r == ')':
+			l.emit(itemRightParen)
+		case r == '"':
+			return lexString
+		case r == ',':
+			l.emit(itemComma)
+		case isSpace(r):
+			l.ignore()
+		case r == eof:
+			l.emit(itemEOF)
+			break Loop
+		default:
+			return l.errorf("invalid character: %s", string(r))
+		}
+	}
+	return nil
+}
+
+// lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
+// isn't a perfect number scanner - for instance it accepts "." and "0x0.2"
+// and "089" - but when it's wrong the input is invalid and the parser (via
+// strconv) will notice.
+func lexNumber(l *lexer) stateFn {
+	if !l.scanNumber() {
+		return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
+	}
+	l.emit(itemNumber)
+	return lexItem
+}
+
+func (l *lexer) scanNumber() bool {
+	// Is it hex?
+	digits := "0123456789"
+	if l.accept("0") && l.accept("xX") {
+		digits = "0123456789abcdefABCDEF"
+	}
+	l.acceptRun(digits)
+	if l.accept(".") {
+		l.acceptRun(digits)
+	}
+	if l.accept("eE") {
+		l.accept("+-")
+		l.acceptRun("0123456789")
+	}
+	return true
+}
+
+const symbols = "!<>=&|+-*/%"
+
+func lexSymbol(l *lexer) stateFn {
+	l.acceptRun(symbols)
+	s := l.input[l.start:l.pos]
+	switch s {
+	case "!":
+		l.emit(itemNot)
+	case "&&":
+		l.emit(itemAnd)
+	case "||":
+		l.emit(itemOr)
+	case ">":
+		l.emit(itemGreater)
+	case "<":
+		l.emit(itemLess)
+	case ">=":
+		l.emit(itemGreaterEq)
+	case "<=":
+		l.emit(itemLessEq)
+	case "==":
+		l.emit(itemEq)
+	case "!=":
+		l.emit(itemNotEq)
+	case "+":
+		l.emit(itemPlus)
+	case "-":
+		l.emit(itemMinus)
+	case "*":
+		l.emit(itemMult)
+	case "**":
+		l.emit(itemPow)
+	case "/":
+		l.emit(itemDiv)
+	case "%":
+		l.emit(itemMod)
+	default:
+		l.emit(itemError)
+	}
+	return lexItem
+}
+
+func lexFunc(l *lexer) stateFn {
+	for {
+		switch r := l.next(); {
+		case unicode.IsLetter(r):
+			// absorb
+		default:
+			l.backup()
+			l.emit(itemFunc)
+			return lexItem
+		}
+	}
+}
+
+func lexVar(l *lexer) stateFn {
+	hasChar := false
+	for {
+		switch r := l.next(); {
+		case unicode.IsLetter(r):
+			hasChar = true
+			// absorb
+		default:
+			if !hasChar {
+				return l.errorf("incomplete variable")
+			}
+			l.backup()
+			l.emit(itemVar)
+			return lexItem
+		}
+	}
+}
+
+func lexString(l *lexer) stateFn {
+	for {
+		switch l.next() {
+		case '"':
+			l.emit(itemString)
+			return lexItem
+		case eof:
+			return l.errorf("unterminated string")
+		}
+	}
+}
+
+// isSpace reports whether r is a space character.
+func isSpace(r rune) bool {
+	return unicode.IsSpace(r)
+}
+
+// isVarchar should maybe be used in place of unicode is letter above,
+// but do not want to modify it at this time, so adding lint exception.
+// nolint:unused,deadcode
+func isVarchar(r rune) bool {
+	return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r)
+}
+
+func isSymbol(r rune) bool {
+	return strings.ContainsRune(symbols, r)
+}
+
+func isNumber(r rune) bool {
+	return unicode.IsDigit(r) || r == '.'
+}

pkg/expr/mathexp/parse/lex_test.go

@@ -0,0 +1,156 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package parse
+
+import (
+	"fmt"
+	"testing"
+)
+
+// Make the types prettyprint.
+var itemName = map[itemType]string{
+	itemError:      "error",
+	itemEOF:        "EOF",
+	itemNot:        "!",
+	itemAnd:        "&&",
+	itemOr:         "||",
+	itemGreater:    ">",
+	itemLess:       "<",
+	itemGreaterEq:  ">=",
+	itemLessEq:     "<=",
+	itemEq:         "==",
+	itemNotEq:      "!=",
+	itemPlus:       "+",
+	itemMinus:      "-",
+	itemMult:       "*",
+	itemDiv:        "/",
+	itemMod:        "%",
+	itemNumber:     "number",
+	itemComma:      ",",
+	itemLeftParen:  "(",
+	itemRightParen: ")",
+	itemString:     "string",
+	itemFunc:       "func",
+}
+
+func (i itemType) String() string {
+	s := itemName[i]
+	if s == "" {
+		return fmt.Sprintf("item%d", int(i))
+	}
+	return s
+}
+
+type lexTest struct {
+	name  string
+	input string
+	items []item
+}
+
+var (
+	tEOF   = item{itemEOF, 0, ""}
+	tLt    = item{itemLess, 0, "<"}
+	tGt    = item{itemGreater, 0, ">"}
+	tOr    = item{itemOr, 0, "||"}
+	tNot   = item{itemNot, 0, "!"}
+	tAnd   = item{itemAnd, 0, "&&"}
+	tLtEq  = item{itemLessEq, 0, "<="}
+	tGtEq  = item{itemGreaterEq, 0, ">="}
+	tNotEq = item{itemNotEq, 0, "!="}
+	tEq    = item{itemEq, 0, "=="}
+	tPlus  = item{itemPlus, 0, "+"}
+	tMinus = item{itemMinus, 0, "-"}
+	tMult  = item{itemMult, 0, "*"}
+	tDiv   = item{itemDiv, 0, "/"}
+	tMod   = item{itemMod, 0, "%"}
+)
+
+var lexTests = []lexTest{
+	{"empty", "", []item{tEOF}},
+	{"spaces", " \t\n", []item{tEOF}},
+	{"text", `"now is the time"`, []item{{itemString, 0, `"now is the time"`}, tEOF}},
+	{"operators", "! && || < > <= >= == != + - * / %", []item{
+		tNot,
+		tAnd,
+		tOr,
+		tLt,
+		tGt,
+		tLtEq,
+		tGtEq,
+		tEq,
+		tNotEq,
+		tPlus,
+		tMinus,
+		tMult,
+		tDiv,
+		tMod,
+		tEOF,
+	}},
+	{"numbers", "1 02 0x14 7.2 1e3 1.2e-4", []item{
+		{itemNumber, 0, "1"},
+		{itemNumber, 0, "02"},
+		{itemNumber, 0, "0x14"},
+		{itemNumber, 0, "7.2"},
+		{itemNumber, 0, "1e3"},
+		{itemNumber, 0, "1.2e-4"},
+		tEOF,
+	}},
+	{"number plus var", "1 + $A", []item{
+		{itemNumber, 0, "1"},
+		tPlus,
+		{itemVar, 0, "$A"},
+		tEOF,
+	}},
+	// errors
+	{"unclosed quote", "\"", []item{
+		{itemError, 0, "unterminated string"},
+	}},
+	{"single quote", "'single quote is invalid'", []item{
+		{itemError, 0, "invalid character: '"},
+	}},
+	{"invalid var", "$", []item{
+		{itemError, 0, "incomplete variable"},
+	}},
+}
+
+// collect gathers the emitted items into a slice.
+func collect(t *lexTest) (items []item) {
+	l := lex(t.input)
+	for {
+		item := l.nextItem()
+		items = append(items, item)
+		if item.typ == itemEOF || item.typ == itemError {
+			break
+		}
+	}
+	return
+}
+
+func equal(i1, i2 []item, checkPos bool) bool {
+	if len(i1) != len(i2) {
+		return false
+	}
+	for k := range i1 {
+		if i1[k].typ != i2[k].typ {
+			return false
+		}
+		if i1[k].val != i2[k].val {
+			return false
+		}
+		if checkPos && i1[k].pos != i2[k].pos {
+			return false
+		}
+	}
+	return true
+}
+
+func TestLex(t *testing.T) {
+	for i, test := range lexTests {
+		items := collect(&lexTests[i])
+		if !equal(items, test.items, false) {
+			t.Errorf("%s: got\n\t%+v\nexpected\n\t%v", test.name, items, test.items)
+		}
+	}
+}

pkg/expr/mathexp/parse/node.go

@@ -0,0 +1,422 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parse nodes.
+
+package parse
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// A Node is an element in the parse tree. The interface is trivial.
+// The interface contains an unexported method so that only
+// types local to this package can satisfy it.
+type Node interface {
+	Type() NodeType
+	String() string
+	StringAST() string
+	Position() Pos     // byte position of start of node in full original input string
+	Check(*Tree) error // performs type checking for itself and sub-nodes
+	Return() ReturnType
+
+	// Make sure only functions in this package can create Nodes.
+	unexported()
+}
+
+// NodeType identifies the type of a parse tree node.
+type NodeType int
+
+// Pos represents a byte position in the original input text from which
+// this template was parsed.
+type Pos int
+
+// Position returns the integer Position of p
+func (p Pos) Position() Pos {
+	return p
+}
+
+// unexported keeps Node implementations local to the package.
+// All implementations embed Pos, so this takes care of it.
+func (Pos) unexported() {
+}
+
+// Type returns itself and provides an easy default implementation
+// for embedding in a Node. Embedded in all non-trivial Nodes.
+func (t NodeType) Type() NodeType {
+	return t
+}
+
+const (
+	// NodeFunc is a function call.
+	NodeFunc NodeType = iota
+	// NodeBinary is a binary operator: math, logical, compare
+	NodeBinary
+	// NodeUnary is unary operator: !, -
+	NodeUnary
+	// NodeString is string constant.
+	NodeString
+	// NodeNumber is a numerical constant (Scalar).
+	NodeNumber
+	// NodeVar is variable: $A
+	NodeVar
+)
+
+// String returns the string representation of the NodeType
+func (t NodeType) String() string {
+	switch t {
+	case NodeFunc:
+		return "NodeFunc"
+	case NodeBinary:
+		return "NodeBinary"
+	case NodeUnary:
+		return "NodeUnary"
+	case NodeString:
+		return "NodeString"
+	case NodeNumber:
+		return "NodeNumber"
+	default:
+		return "NodeUnknown"
+	}
+}
+
+// Nodes.
+
+// VarNode holds a variable reference.
+type VarNode struct {
+	NodeType
+	Pos
+	Name string // Without the $
+	Text string // Raw
+}
+
+func newVar(pos Pos, name, text string) *VarNode {
+	return &VarNode{NodeType: NodeVar, Pos: pos, Name: name, Text: text}
+}
+
+// Type returns the Type of the VarNode so it fulfills the Node interface.
+func (n *VarNode) Type() NodeType { return NodeVar }
+
+// String returns the string representation of the VarNode so it fulfills the Node interface.
+func (n *VarNode) String() string { return n.Text }
+
+// StringAST returns the string representation of abstract syntax tree of the VarNode so it fulfills the Node interface.
+func (n *VarNode) StringAST() string { return n.String() }
+
+// Check performs parse time checking on the VarNode so it fulfills the Node interface.
+func (n *VarNode) Check(*Tree) error {
+	return nil
+}
+
+// Return returns the result type of the VarNode so it fulfills the Node interface.
+func (n *VarNode) Return() ReturnType {
+	return TypeSeriesSet // Vars are only time series for now I guess....
+}
+
+// FuncNode holds a function invocation.
+type FuncNode struct {
+	NodeType
+	Pos
+	Name   string
+	F      *Func
+	Args   []Node
+	Prefix string
+}
+
+func newFunc(pos Pos, name string, f Func) *FuncNode {
+	return &FuncNode{NodeType: NodeFunc, Pos: pos, Name: name, F: &f}
+}
+
+func (f *FuncNode) append(arg Node) {
+	f.Args = append(f.Args, arg)
+}
+
+// String returns the string representation of the FuncNode so it fulfills the Node interface.
+func (f *FuncNode) String() string {
+	s := f.Name + "("
+	for i, arg := range f.Args {
+		if i > 0 {
+			s += ", "
+		}
+		s += arg.String()
+	}
+	s += ")"
+	return s
+}
+
+// StringAST returns the string representation of abstract syntax tree of the FuncNode so it fulfills the Node interface.
+func (f *FuncNode) StringAST() string {
+	s := f.Name + "("
+	for i, arg := range f.Args {
+		if i > 0 {
+			s += ", "
+		}
+		s += arg.StringAST()
+	}
+	s += ")"
+	return s
+}
+
+// Check performs parse time checking on the FuncNode so it fulfills the Node interface.
+func (f *FuncNode) Check(t *Tree) error {
+	if len(f.Args) < len(f.F.Args) {
+		return fmt.Errorf("parse: not enough arguments for %s", f.Name)
+	} else if len(f.Args) > len(f.F.Args) {
+		return fmt.Errorf("parse: too many arguments for %s", f.Name)
+	}
+
+	for i, arg := range f.Args {
+		funcType := f.F.Args[i]
+		argType := arg.Return()
+		// if funcType == TypeNumberSet && argType == TypeScalar {
+		// 	argType = TypeNumberSet
+		// }
+		if funcType == TypeVariantSet {
+			if !(argType == TypeNumberSet || argType == TypeSeriesSet || argType == TypeScalar) {
+				return fmt.Errorf("parse: expected %v or %v for argument %v, got %v", TypeNumberSet, TypeSeriesSet, i, argType)
+			}
+		} else if funcType != argType {
+			return fmt.Errorf("parse: expected %v, got %v for argument %v (%v)", funcType, argType, i, arg.String())
+		}
+		if err := arg.Check(t); err != nil {
+			return err
+		}
+	}
+
+	if f.F.Check != nil {
+		return f.F.Check(t, f)
+	}
+	return nil
+}
+
+// Return returns the result type of the FuncNode so it fulfills the Node interface.
+func (f *FuncNode) Return() ReturnType {
+	return f.F.Return
+}
+
+// ScalarNode holds a number: signed or unsigned integer or float.
+// The value is parsed and stored under all the types that can represent the value.
+// This simulates in a small amount of code the behavior of Go's ideal constants.
+type ScalarNode struct {
+	NodeType
+	Pos
+	IsUint  bool    // Number has an unsigned integral value.
+	IsFloat bool    // Number has a floating-point value.
+	Uint64  uint64  // The unsigned integer value.
+	Float64 float64 // The floating-point value.
+	Text    string  // The original textual representation from the input.
+}
+
+func newNumber(pos Pos, text string) (*ScalarNode, error) {
+	n := &ScalarNode{NodeType: NodeNumber, Pos: pos, Text: text}
+	// Do integer test first so we get 0x123 etc.
+	u, err := strconv.ParseUint(text, 0, 64) // will fail for -0.
+	if err == nil {
+		n.IsUint = true
+		n.Uint64 = u
+	}
+	// If an integer extraction succeeded, promote the float.
+	if n.IsUint {
+		n.IsFloat = true
+		n.Float64 = float64(n.Uint64)
+	} else {
+		f, err := strconv.ParseFloat(text, 64)
+		if err == nil {
+			n.IsFloat = true
+			n.Float64 = f
+			// If a floating-point extraction succeeded, extract the int if needed.
+			if !n.IsUint && float64(uint64(f)) == f {
+				n.IsUint = true
+				n.Uint64 = uint64(f)
+			}
+		}
+	}
+	if !n.IsUint && !n.IsFloat {
+		return nil, fmt.Errorf("illegal number syntax: %q", text)
+	}
+	return n, nil
+}
+
+// String returns the string representation of the ScalarNode so it fulfills the Node interface.
+func (n *ScalarNode) String() string {
+	return n.Text
+}
+
+// StringAST returns the string representation of abstract syntax tree of the ScalarNode so it fulfills the Node interface.
+func (n *ScalarNode) StringAST() string {
+	return n.String()
+}
+
+// Check performs parse time checking on the ScalarNode so it fulfills the Node interface.
+func (n *ScalarNode) Check(*Tree) error {
+	return nil
+}
+
+// Return returns the result type of the ScalarNode so it fulfills the Node interface.
+func (n *ScalarNode) Return() ReturnType {
+	return TypeScalar
+}
+
+// StringNode holds a string constant. The value has been "unquoted".
+type StringNode struct {
+	NodeType
+	Pos
+	Quoted string // The original text of the string, with quotes.
+	Text   string // The string, after quote processing.
+}
+
+func newString(pos Pos, orig, text string) *StringNode {
+	return &StringNode{NodeType: NodeString, Pos: pos, Quoted: orig, Text: text}
+}
+
+// String returns the string representation of the StringNode so it fulfills the Node interface.
+func (s *StringNode) String() string {
+	return s.Quoted
+}
+
+// StringAST returns the string representation of abstract syntax tree of the StringNode so it fulfills the Node interface.
+func (s *StringNode) StringAST() string {
+	return s.String()
+}
+
+// Check performs parse time checking on the StringNode so it fulfills the Node interface.
+func (s *StringNode) Check(*Tree) error {
+	return nil
+}
+
+// Return returns the result type of the TypeString so it fulfills the Node interface.
+func (s *StringNode) Return() ReturnType {
+	return TypeString
+}
+
+// BinaryNode holds two arguments and an operator.
+type BinaryNode struct {
+	NodeType
+	Pos
+	Args     [2]Node
+	Operator item
+	OpStr    string
+}
+
+func newBinary(operator item, arg1, arg2 Node) *BinaryNode {
+	return &BinaryNode{NodeType: NodeBinary, Pos: operator.pos, Args: [2]Node{arg1, arg2}, Operator: operator, OpStr: operator.val}
+}
+
+// String returns the string representation of the BinaryNode so it fulfills the Node interface.
+func (b *BinaryNode) String() string {
+	return fmt.Sprintf("%s %s %s", b.Args[0], b.Operator.val, b.Args[1])
+}
+
+// StringAST returns the string representation of abstract syntax tree of the BinaryNode so it fulfills the Node interface.
+func (b *BinaryNode) StringAST() string {
+	return fmt.Sprintf("%s(%s, %s)", b.Operator.val, b.Args[0], b.Args[1])
+}
+
+// Check performs parse time checking on the BinaryNode so it fulfills the Node interface.
+func (b *BinaryNode) Check(t *Tree) error {
+	return nil
+}
+
+// Return returns the result type of the BinaryNode so it fulfills the Node interface.
+func (b *BinaryNode) Return() ReturnType {
+	t0 := b.Args[0].Return()
+	t1 := b.Args[1].Return()
+	if t1 > t0 {
+		return t1
+	}
+	return t0
+}
+
+// UnaryNode holds one argument and an operator.
+type UnaryNode struct {
+	NodeType
+	Pos
+	Arg      Node
+	Operator item
+	OpStr    string
+}
+
+func newUnary(operator item, arg Node) *UnaryNode {
+	return &UnaryNode{NodeType: NodeUnary, Pos: operator.pos, Arg: arg, Operator: operator, OpStr: operator.val}
+}
+
+// String returns the string representation of the UnaryNode so it fulfills the Node interface.
+func (u *UnaryNode) String() string {
+	return fmt.Sprintf("%s%s", u.Operator.val, u.Arg)
+}
+
+// StringAST returns the string representation of abstract syntax tree of the UnaryNode so it fulfills the Node interface.
+func (u *UnaryNode) StringAST() string {
+	return fmt.Sprintf("%s(%s)", u.Operator.val, u.Arg)
+}
+
+// Check performs parse time checking on the UnaryNode so it fulfills the Node interface.
+func (u *UnaryNode) Check(t *Tree) error {
+	switch rt := u.Arg.Return(); rt {
+	case TypeNumberSet, TypeSeriesSet, TypeScalar:
+		return u.Arg.Check(t)
+	default:
+		return fmt.Errorf(`parse: type error in %s, expected "number", got %s`, u, rt)
+	}
+}
+
+// Return returns the result type of the UnaryNode so it fulfills the Node interface.
+func (u *UnaryNode) Return() ReturnType {
+	return u.Arg.Return()
+}
+
+// Walk invokes f on n and sub-nodes of n.
+func Walk(n Node, f func(Node)) {
+	f(n)
+	switch n := n.(type) {
+	case *BinaryNode:
+		Walk(n.Args[0], f)
+		Walk(n.Args[1], f)
+	case *FuncNode:
+		for _, a := range n.Args {
+			Walk(a, f)
+		}
+	case *ScalarNode, *StringNode:
+		// Ignore since these node types have no sub nodes.
+	case *UnaryNode:
+		Walk(n.Arg, f)
+	default:
+		panic(fmt.Errorf("other type: %T", n))
+	}
+}
+
+// ReturnType represents the type that is returned from a node.
+type ReturnType int
+
+const (
+	// TypeString is a single string.
+	TypeString ReturnType = iota
+	// TypeScalar is a unlabled number constant.
+	TypeScalar
+	// TypeNumberSet is a collection of labelled numbers.
+	TypeNumberSet
+	// TypeSeriesSet is a collection of labelled time series.
+	TypeSeriesSet
+	// TypeVariantSet is a collection of the same type Number, Series, or Scalar.
+	TypeVariantSet
+)
+
+// String returns a string representation of the ReturnType.
+func (f ReturnType) String() string {
+	switch f {
+	case TypeNumberSet:
+		return "numberSet"
+	case TypeString:
+		return "string"
+	case TypeSeriesSet:
+		return "seriesSet"
+	case TypeScalar:
+		return "scalar"
+	case TypeVariantSet:
+		return "variant"
+	default:
+		return "unknown"
+	}
+}

pkg/expr/mathexp/parse/parse.go

@@ -0,0 +1,353 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package parse builds parse trees for expressions as defined by expr. Clients
+// should use that package to construct expressions rather than this one, which
+// provides shared internal data structures not intended for general use.
+package parse
+
+import (
+	"fmt"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+// Tree is the representation of a single parsed expression.
+type Tree struct {
+	Text     string // text parsed to create the expression.
+	Root     Node   // top-level root of the tree, returns a number.
+	VarNames []string
+
+	funcs []map[string]Func
+
+	// Parsing only; cleared after parse.
+	lex       *lexer
+	token     [1]item // one-token lookahead for parser.
+	peekCount int
+}
+
+// Func holds the structure of a parsed function call.
+type Func struct {
+	Args          []ReturnType
+	Return        ReturnType
+	F             interface{}
+	VariantReturn bool
+	Check         func(*Tree, *FuncNode) error
+}
+
+// Parse returns a Tree, created by parsing the expression described in the
+// argument string. If an error is encountered, parsing stops and an empty Tree
+// is returned with the error.
+func Parse(text string, funcs ...map[string]Func) (t *Tree, err error) {
+	t = New()
+	t.Text = text
+	err = t.Parse(text, funcs...)
+	return
+}
+
+// next returns the next token.
+func (t *Tree) next() item {
+	if t.peekCount > 0 {
+		t.peekCount--
+	} else {
+		t.token[0] = t.lex.nextItem()
+	}
+	return t.token[t.peekCount]
+}
+
+// backup backs the input stream up one token.
+func (t *Tree) backup() {
+	t.peekCount++
+}
+
+// peek returns but does not consume the next token.
+func (t *Tree) peek() item {
+	if t.peekCount > 0 {
+		return t.token[t.peekCount-1]
+	}
+	t.peekCount = 1
+	t.token[0] = t.lex.nextItem()
+	return t.token[0]
+}
+
+// Parsing.
+
+// New allocates a new parse tree with the given name.
+func New(funcs ...map[string]Func) *Tree {
+	return &Tree{
+		funcs: funcs,
+	}
+}
+
+// errorf formats the error and terminates processing.
+func (t *Tree) errorf(format string, args ...interface{}) {
+	t.Root = nil
+	format = fmt.Sprintf("expr: %s", format)
+	panic(fmt.Errorf(format, args...))
+}
+
+// error terminates processing.
+func (t *Tree) error(err error) {
+	t.errorf("%s", err)
+}
+
+// expect consumes the next token and guarantees it has the required type.
+func (t *Tree) expect(expected itemType, context string) item {
+	token := t.next()
+	if token.typ != expected {
+		t.unexpected(token, context)
+	}
+	return token
+}
+
+// expectOneOf consumes the next token and guarantees it has one of the required types.
+// nolint:unused
+func (t *Tree) expectOneOf(expected1, expected2 itemType, context string) item {
+	token := t.next()
+	if token.typ != expected1 && token.typ != expected2 {
+		t.unexpected(token, context)
+	}
+	return token
+}
+
+// unexpected complains about the token and terminates processing.
+func (t *Tree) unexpected(token item, context string) {
+	t.errorf("unexpected %s in %s", token, context)
+}
+
+// recover is the handler that turns panics into returns from the top level of Parse.
+func (t *Tree) recover(errp *error) {
+	e := recover()
+	if e != nil {
+		if _, ok := e.(runtime.Error); ok {
+			panic(e)
+		}
+		if t != nil {
+			t.stopParse()
+		}
+		*errp = e.(error)
+	}
+}
+
+// startParse initializes the parser, using the lexer.
+func (t *Tree) startParse(funcs []map[string]Func, lex *lexer) {
+	t.Root = nil
+	t.lex = lex
+	t.funcs = funcs
+}
+
+// stopParse terminates parsing.
+func (t *Tree) stopParse() {
+	t.lex = nil
+}
+
+// Parse parses the expression definition string to construct a representation
+// of the expression for execution.
+func (t *Tree) Parse(text string, funcs ...map[string]Func) (err error) {
+	defer t.recover(&err)
+	t.startParse(funcs, lex(text))
+	t.Text = text
+	t.parse()
+	t.stopParse()
+	return nil
+}
+
+// parse is the top-level parser for an expression.
+// It runs to EOF.
+func (t *Tree) parse() {
+	t.Root = t.O()
+	t.expect(itemEOF, "root input")
+	if err := t.Root.Check(t); err != nil {
+		t.error(err)
+	}
+}
+
+/* Grammar:
+O -> A {"||" A}
+A -> C {"&&" C}
+C -> P {( "==" | "!=" | ">" | ">=" | "<" | "<=") P}
+P -> M {( "+" | "-" ) M}
+M -> E {( "*" | "/" ) F}
+E -> F {( "**" ) F}
+F -> v | "(" O ")" | "!" O | "-" O
+v -> number | func(..) | queryVar
+Func -> name "(" param {"," param} ")"
+param -> number | "string" | queryVar
+*/
+
+// expr:
+
+// O is A {"||" A} in the grammar.
+func (t *Tree) O() Node {
+	n := t.A()
+	for {
+		switch t.peek().typ {
+		case itemOr:
+			n = newBinary(t.next(), n, t.A())
+		default:
+			return n
+		}
+	}
+}
+
+// A is C {"&&" C} in the grammar.
+func (t *Tree) A() Node {
+	n := t.C()
+	for {
+		switch t.peek().typ {
+		case itemAnd:
+			n = newBinary(t.next(), n, t.C())
+		default:
+			return n
+		}
+	}
+}
+
+// C is C -> P {( "==" | "!=" | ">" | ">=" | "<" | "<=") P} in the grammar.
+func (t *Tree) C() Node {
+	n := t.P()
+	for {
+		switch t.peek().typ {
+		case itemEq, itemNotEq, itemGreater, itemGreaterEq, itemLess, itemLessEq:
+			n = newBinary(t.next(), n, t.P())
+		default:
+			return n
+		}
+	}
+}
+
+// P is  M {( "+" | "-" ) M} in the grammar.
+func (t *Tree) P() Node {
+	n := t.M()
+	for {
+		switch t.peek().typ {
+		case itemPlus, itemMinus:
+			n = newBinary(t.next(), n, t.M())
+		default:
+			return n
+		}
+	}
+}
+
+// M is E {( "*" | "/" ) F} in the grammar.
+func (t *Tree) M() Node {
+	n := t.E()
+	for {
+		switch t.peek().typ {
+		case itemMult, itemDiv, itemMod:
+			n = newBinary(t.next(), n, t.E())
+		default:
+			return n
+		}
+	}
+}
+
+// E is F {( "**" ) F} in the grammar.
+func (t *Tree) E() Node {
+	n := t.F()
+	for {
+		switch t.peek().typ {
+		case itemPow:
+			n = newBinary(t.next(), n, t.F())
+		default:
+			return n
+		}
+	}
+}
+
+// F is v | "(" O ")" | "!" O | "-" O in the grammar.
+func (t *Tree) F() Node {
+	switch token := t.peek(); token.typ {
+	case itemNumber, itemFunc, itemVar:
+		return t.v()
+	case itemNot, itemMinus:
+		return newUnary(t.next(), t.F())
+	case itemLeftParen:
+		t.next()
+		n := t.O()
+		t.expect(itemRightParen, "input: F()")
+		return n
+	default:
+		t.unexpected(token, "input: F()")
+	}
+	return nil
+}
+
+// V is number | func(..) | queryVar in the grammar.
+func (t *Tree) v() Node {
+	switch token := t.next(); token.typ {
+	case itemNumber:
+		n, err := newNumber(token.pos, token.val)
+		if err != nil {
+			t.error(err)
+		}
+		return n
+	case itemFunc:
+		t.backup()
+		return t.Func()
+	case itemVar:
+		t.backup()
+		return t.Var()
+	default:
+		t.unexpected(token, "input: v()")
+	}
+	return nil
+}
+
+// Var is queryVar in the grammar.
+func (t *Tree) Var() (v *VarNode) {
+	token := t.next()
+	varNoPrefix := strings.TrimPrefix(token.val, "$")
+	t.VarNames = append(t.VarNames, varNoPrefix)
+	return newVar(token.pos, varNoPrefix, token.val)
+}
+
+// Func parses a FuncNode.
+func (t *Tree) Func() (f *FuncNode) {
+	token := t.next()
+	funcv, ok := t.GetFunction(token.val)
+	if !ok {
+		t.errorf("non existent function %s", token.val)
+	}
+	f = newFunc(token.pos, token.val, funcv)
+	t.expect(itemLeftParen, "func")
+	for {
+		switch token = t.next(); token.typ {
+		default:
+			t.backup()
+			node := t.O()
+			f.append(node)
+			if len(f.Args) == 1 && f.F.VariantReturn {
+				f.F.Return = node.Return()
+			}
+		case itemString:
+			s, err := strconv.Unquote(token.val)
+			if err != nil {
+				t.errorf("Unquoting error: %s", err)
+			}
+			f.append(newString(token.pos, token.val, s))
+		case itemRightParen:
+			return
+		}
+	}
+}
+
+// GetFunction gets a parsed Func from the functions available on the tree's func property.
+func (t *Tree) GetFunction(name string) (v Func, ok bool) {
+	for _, funcMap := range t.funcs {
+		if funcMap == nil {
+			continue
+		}
+		if v, ok = funcMap[name]; ok {
+			return
+		}
+	}
+	return
+}
+
+// String returns a string representation of the parse tree.
+func (t *Tree) String() string {
+	return t.Root.String()
+}

pkg/expr/mathexp/reduce.go

@@ -0,0 +1,101 @@
+package mathexp
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+)
+
+func Sum(v *data.Field) *float64 {
+	var sum float64
+	for i := 0; i < v.Len(); i++ {
+		if f, ok := v.At(i).(*float64); ok {
+			if f == nil {
+				nan := math.NaN()
+				return &nan
+			}
+			sum += *f
+		}
+	}
+	return &sum
+}
+
+func Avg(v *data.Field) *float64 {
+	sum := Sum(v)
+	f := *sum / float64(v.Len())
+	return &f
+}
+
+func Min(fv *data.Field) *float64 {
+	var f float64
+	if fv.Len() == 0 {
+		nan := math.NaN()
+		return &nan
+	}
+	for i := 0; i < fv.Len(); i++ {
+		if v, ok := fv.At(i).(*float64); ok {
+			if v == nil {
+				nan := math.NaN()
+				return &nan
+			}
+			if i == 0 || *v < f {
+				f = *v
+			}
+		}
+	}
+	return &f
+}
+
+func Max(fv *data.Field) *float64 {
+	var f float64
+	if fv.Len() == 0 {
+		nan := math.NaN()
+		return &nan
+	}
+	for i := 0; i < fv.Len(); i++ {
+		if v, ok := fv.At(i).(*float64); ok {
+			if v == nil {
+				nan := math.NaN()
+				return &nan
+			}
+			if i == 0 || *v > f {
+				f = *v
+			}
+		}
+	}
+	return &f
+}
+
+func Count(fv *data.Field) *float64 {
+	f := float64(fv.Len())
+	return &f
+}
+
+// Reduce turns the Series into a Number based on the given reduction function
+func (s Series) Reduce(rFunc string) (Number, error) {
+	var l data.Labels
+	if s.GetLabels() != nil {
+		l = s.GetLabels().Copy()
+	}
+	number := NewNumber(fmt.Sprintf("%v_%v", rFunc, s.GetName()), l)
+	var f *float64
+	fVec := s.Frame.Fields[1]
+	switch rFunc {
+	case "sum":
+		f = Sum(fVec)
+	case "mean":
+		f = Avg(fVec)
+	case "min":
+		f = Min(fVec)
+	case "max":
+		f = Max(fVec)
+	case "count":
+		f = Count(fVec)
+	default:
+		return number, fmt.Errorf("reduction %v not implemented", rFunc)
+	}
+	number.SetValue(f)
+
+	return number, nil
+}

pkg/expr/mathexp/reduce_test.go

@@ -0,0 +1,240 @@
+package mathexp
+
+import (
+	"math"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/stretchr/testify/require"
+)
+
+var seriesWithNil = Vars{
+	"A": Results{
+		[]Value{
+			makeSeries("temp", nil, tp{
+				time.Unix(5, 0), float64Pointer(2),
+			}, tp{
+				time.Unix(10, 0), nil,
+			}),
+		},
+	},
+}
+
+var seriesEmpty = Vars{
+	"A": Results{
+		[]Value{
+			makeSeries("temp", nil),
+		},
+	},
+}
+
+func TestSeriesReduce(t *testing.T) {
+	var tests = []struct {
+		name        string
+		red         string
+		vars        Vars
+		varToReduce string
+		errIs       require.ErrorAssertionFunc
+		resultsIs   require.ComparisonAssertionFunc
+		results     Results
+	}{
+		{
+			name:        "foo reduction will error",
+			red:         "foo",
+			varToReduce: "A",
+			vars:        aSeriesNullableTime,
+			errIs:       require.Error,
+			resultsIs:   require.Equal,
+		},
+		{
+			name:        "sum series",
+			red:         "sum",
+			varToReduce: "A",
+			vars:        aSeriesNullableTime,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("sum_", nil, float64Pointer(3)),
+				},
+			},
+		},
+		{
+			name:        "sum series with a nil value",
+			red:         "sum",
+			varToReduce: "A",
+			vars:        seriesWithNil,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("sum_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "sum empty series",
+			red:         "sum",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("sum_", nil, float64Pointer(0)),
+				},
+			},
+		},
+		{
+			name:        "mean series with a nil value",
+			red:         "mean",
+			varToReduce: "A",
+			vars:        seriesWithNil,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("mean_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "mean empty series",
+			red:         "mean",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("mean_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "min series with a nil value",
+			red:         "min",
+			varToReduce: "A",
+			vars:        seriesWithNil,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("min_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "min empty series",
+			red:         "min",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("min_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "max series with a nil value",
+			red:         "max",
+			varToReduce: "A",
+			vars:        seriesWithNil,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("max_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "max empty series",
+			red:         "max",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("max_", nil, NaN),
+				},
+			},
+		},
+		{
+			name:        "mean series",
+			red:         "mean",
+			varToReduce: "A",
+			vars:        aSeriesNullableTime,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("mean_", nil, float64Pointer(1.5)),
+				},
+			},
+		},
+		{
+			name:        "count empty series",
+			red:         "count",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("count_", nil, float64Pointer(0)),
+				},
+			},
+		},
+		{
+			name:        "mean series with labels",
+			red:         "mean",
+			varToReduce: "A",
+			vars: Vars{
+				"A": Results{
+					[]Value{
+						makeSeriesNullableTime("temp", data.Labels{"host": "a"}, nullTimeTP{
+							unixTimePointer(5, 0), float64Pointer(2),
+						}, nullTimeTP{
+							unixTimePointer(10, 0), float64Pointer(1),
+						}),
+					},
+				},
+			},
+			errIs:     require.NoError,
+			resultsIs: require.Equal,
+			results: Results{
+				[]Value{
+					makeNumber("mean_", data.Labels{"host": "a"}, float64Pointer(1.5)),
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			results := Results{}
+			seriesSet := tt.vars[tt.varToReduce]
+			for _, series := range seriesSet.Values {
+				ns, err := series.Value().(*Series).Reduce(tt.red)
+				tt.errIs(t, err)
+				if err != nil {
+					return
+				}
+				results.Values = append(results.Values, ns)
+			}
+			opt := cmp.Comparer(func(x, y float64) bool {
+				return (math.IsNaN(x) && math.IsNaN(y)) || x == y
+			})
+			options := append([]cmp.Option{opt}, data.FrameTestCompareOptions()...)
+			if diff := cmp.Diff(tt.results, results, options...); diff != "" {
+				t.Errorf("Result mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}

pkg/expr/mathexp/resample.go

@@ -0,0 +1,83 @@
+package mathexp
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+)
+
+// Resample turns the Series into a Number based on the given reduction function
+func (s Series) Resample(interval time.Duration, downsampler string, upsampler string, tr backend.TimeRange) (Series, error) {
+	newSeriesLength := int(float64(tr.To.Sub(tr.From).Nanoseconds()) / float64(interval.Nanoseconds()))
+	if newSeriesLength <= 0 {
+		return s, fmt.Errorf("the series cannot be sampled further; the time range is shorter than the interval")
+	}
+	resampled := NewSeries(s.GetName(), s.GetLabels(), s.TimeIdx, s.TimeIsNullable, s.ValueIdx, s.ValueIsNullabe, newSeriesLength+1)
+	bookmark := 0
+	var lastSeen *float64
+	idx := 0
+	t := tr.From
+	for !t.After(tr.To) && idx <= newSeriesLength {
+		vals := make([]*float64, 0)
+		sIdx := bookmark
+		for {
+			if sIdx == s.Len() {
+				break
+			}
+			st, v := s.GetPoint(sIdx)
+			if st.After(t) {
+				break
+			}
+			bookmark++
+			sIdx++
+			lastSeen = v
+			vals = append(vals, v)
+		}
+		var value *float64
+		if len(vals) == 0 { // upsampling
+			switch upsampler {
+			case "pad":
+				if lastSeen != nil {
+					value = lastSeen
+				} else {
+					value = nil
+				}
+			case "backfilling":
+				if sIdx == s.Len() { // no vals left
+					value = nil
+				} else {
+					_, value = s.GetPoint(sIdx)
+				}
+			case "fillna":
+				value = nil
+			default:
+				return s, fmt.Errorf("upsampling %v not implemented", upsampler)
+			}
+		} else { // downsampling
+			fVec := data.NewField("", s.GetLabels(), vals)
+			var tmp *float64
+			switch downsampler {
+			case "sum":
+				tmp = Sum(fVec)
+			case "mean":
+				tmp = Avg(fVec)
+			case "min":
+				tmp = Min(fVec)
+			case "max":
+				tmp = Max(fVec)
+			default:
+				return s, fmt.Errorf("downsampling %v not implemented", downsampler)
+			}
+			value = tmp
+		}
+		tv := t // his is required otherwise all points keep the latest timestamp; anything better?
+		if err := resampled.SetPoint(idx, &tv, value); err != nil {
+			return resampled, err
+		}
+		t = t.Add(interval)
+		idx++
+	}
+	return resampled, nil
+}

pkg/expr/mathexp/resample_test.go

@@ -0,0 +1,260 @@
+package mathexp
+
+import (
+	"testing"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestResampleSeries(t *testing.T) {
+	var tests = []struct {
+		name             string
+		interval         time.Duration
+		downsampler      string
+		upsampler        string
+		timeRange        backend.TimeRange
+		seriesToResample Series
+		series           Series
+	}{
+		{
+			name:        "resample series: time range shorter than the rule interval",
+			interval:    time.Second * 5,
+			downsampler: "mean",
+			upsampler:   "fillna",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(4, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}),
+		},
+		{
+			name:        "resample series: invalid time range",
+			interval:    time.Second * 5,
+			downsampler: "mean",
+			upsampler:   "fillna",
+			timeRange: backend.TimeRange{
+				From: time.Unix(11, 0),
+				To:   time.Unix(0, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}),
+		},
+		{
+			name:        "resample series: downsampling (mean / pad)",
+			interval:    time.Second * 5,
+			downsampler: "mean",
+			upsampler:   "pad",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(16, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(9, 0), float64Pointer(2),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), nil,
+			}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(2.5),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(1.5),
+			}, nullTimeTP{
+				unixTimePointer(15, 0), float64Pointer(2),
+			}),
+		},
+		{
+			name:        "resample series: downsampling (max / fillna)",
+			interval:    time.Second * 5,
+			downsampler: "max",
+			upsampler:   "fillna",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(16, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(9, 0), float64Pointer(2),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), nil,
+			}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(15, 0), nil,
+			}),
+		},
+		{
+			name:        "resample series: downsampling (min / fillna)",
+			interval:    time.Second * 5,
+			downsampler: "min",
+			upsampler:   "fillna",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(16, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(9, 0), float64Pointer(2),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), nil,
+			}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(15, 0), nil,
+			}),
+		},
+		{
+			name:        "resample series: downsampling (sum / fillna)",
+			interval:    time.Second * 5,
+			downsampler: "sum",
+			upsampler:   "fillna",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(16, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(9, 0), float64Pointer(2),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), nil,
+			}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(5),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(15, 0), nil,
+			}),
+		},
+		{
+			name:        "resample series: downsampling (mean / fillna)",
+			interval:    time.Second * 5,
+			downsampler: "mean",
+			upsampler:   "fillna",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(16, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(9, 0), float64Pointer(2),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), nil,
+			}, nullTimeTP{
+				unixTimePointer(5, 0), float64Pointer(2.5),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(1.5),
+			}, nullTimeTP{
+				unixTimePointer(15, 0), nil,
+			}),
+		},
+		{
+			name:        "resample series: upsampling (mean / pad )",
+			interval:    time.Second * 2,
+			downsampler: "mean",
+			upsampler:   "pad",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(11, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), nil,
+			}, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(6, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(8, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), float64Pointer(1),
+			}),
+		},
+		{
+			name:        "resample series: upsampling (mean / backfilling )",
+			interval:    time.Second * 2,
+			downsampler: "mean",
+			upsampler:   "backfilling",
+			timeRange: backend.TimeRange{
+				From: time.Unix(0, 0),
+				To:   time.Unix(11, 0),
+			},
+			seriesToResample: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(7, 0), float64Pointer(1),
+			}),
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(0, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(4, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(6, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(8, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(10, 0), nil,
+			}),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			series, err := tt.seriesToResample.Resample(tt.interval, tt.downsampler, tt.upsampler, tt.timeRange)
+			if tt.series.Frame == nil {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				assert.Equal(t, tt.series, series)
+			}
+		})
+	}
+}

pkg/expr/mathexp/type_series.go

@@ -0,0 +1,199 @@
+package mathexp
+
+import (
+	"fmt"
+	"sort"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/expr/mathexp/parse"
+)
+
+// Series has time.Time and ...? *float64 fields.
+type Series struct {
+	Frame          *data.Frame
+	TimeIsNullable bool
+	TimeIdx        int
+	ValueIsNullabe bool
+	ValueIdx       int
+	// TODO:
+	// - Multiple Value Fields
+	// - Value can be different number types
+}
+
+// SeriesFromFrame validates that the dataframe can be considered a Series type
+// and populate meta information on Series about the frame.
+func SeriesFromFrame(frame *data.Frame) (s Series, err error) {
+	if len(frame.Fields) != 2 {
+		return s, fmt.Errorf("frame must have exactly two fields to be a series, has %v", len(frame.Fields))
+	}
+
+	foundTime := false
+	foundValue := false
+	for i, field := range frame.Fields {
+		switch field.Type() {
+		case data.FieldTypeTime:
+			s.TimeIdx = i
+			foundTime = true
+		case data.FieldTypeNullableTime:
+			s.TimeIsNullable = true
+			foundTime = true
+			s.TimeIdx = i
+		case data.FieldTypeFloat64:
+			foundValue = true
+			s.ValueIdx = i
+		case data.FieldTypeNullableFloat64:
+			s.ValueIsNullabe = true
+			foundValue = true
+			s.ValueIdx = i
+		}
+	}
+	if !foundTime {
+		return s, fmt.Errorf("no time column found in frame %v", frame.Name)
+	}
+	if !foundValue {
+		return s, fmt.Errorf("no float64 value column found in frame %v", frame.Name)
+	}
+	s.Frame = frame
+	return s, nil
+}
+
+// NewSeries returns a dataframe of type Series.
+func NewSeries(name string, labels data.Labels, timeIdx int, nullableTime bool, valueIdx int, nullableValue bool, size int) Series {
+	fields := make([]*data.Field, 2)
+
+	if nullableValue {
+		fields[valueIdx] = data.NewField(name, labels, make([]*float64, size))
+	} else {
+		fields[valueIdx] = data.NewField(name, labels, make([]float64, size))
+	}
+
+	if nullableTime {
+		fields[timeIdx] = data.NewField("Time", nil, make([]*time.Time, size))
+	} else {
+		fields[timeIdx] = data.NewField("Time", nil, make([]time.Time, size))
+	}
+
+	return Series{
+		Frame:          data.NewFrame("", fields...),
+		TimeIsNullable: nullableTime,
+		TimeIdx:        timeIdx,
+		ValueIsNullabe: nullableValue,
+		ValueIdx:       valueIdx,
+	}
+}
+
+// Type returns the Value type and allows it to fulfill the Value interface.
+func (s Series) Type() parse.ReturnType { return parse.TypeSeriesSet }
+
+// Value returns the actual value allows it to fulfill the Value interface.
+func (s Series) Value() interface{} { return &s }
+
+func (s Series) GetLabels() data.Labels { return s.Frame.Fields[s.ValueIdx].Labels }
+
+func (s Series) SetLabels(ls data.Labels) { s.Frame.Fields[s.ValueIdx].Labels = ls }
+
+func (s Series) GetName() string { return s.Frame.Name }
+
+// AsDataFrame returns the underlying *data.Frame.
+func (s Series) AsDataFrame() *data.Frame { return s.Frame }
+
+// GetPoint returns the time and value at the specified index.
+func (s Series) GetPoint(pointIdx int) (*time.Time, *float64) {
+	return s.GetTime(pointIdx), s.GetValue(pointIdx)
+}
+
+// SetPoint sets the time and value on the corresponding vectors at the specified index.
+func (s Series) SetPoint(pointIdx int, t *time.Time, f *float64) (err error) {
+	if s.TimeIsNullable {
+		s.Frame.Fields[s.TimeIdx].Set(pointIdx, t)
+	} else {
+		if t == nil {
+			return fmt.Errorf("can not set null time value on non-nullable time field for series name %v", s.Frame.Name)
+		}
+		s.Frame.Fields[s.TimeIdx].Set(pointIdx, *t)
+	}
+	if s.ValueIsNullabe {
+		s.Frame.Fields[s.ValueIdx].Set(pointIdx, f)
+	} else {
+		if f == nil {
+			return fmt.Errorf("can not set null float value on non-nullable float field for series name %v", s.Frame.Name)
+		}
+		s.Frame.Fields[s.ValueIdx].Set(pointIdx, *f)
+	}
+	return
+}
+
+// AppendPoint appends a point (time/value).
+func (s Series) AppendPoint(pointIdx int, t *time.Time, f *float64) (err error) {
+	if s.TimeIsNullable {
+		s.Frame.Fields[s.TimeIdx].Append(t)
+	} else {
+		if t == nil {
+			return fmt.Errorf("can not append null time value on non-nullable time field for series name %v", s.Frame.Name)
+		}
+		s.Frame.Fields[s.TimeIdx].Append(*t)
+	}
+	if s.ValueIsNullabe {
+		s.Frame.Fields[s.ValueIdx].Append(f)
+	} else {
+		if f == nil {
+			return fmt.Errorf("can not append null float value on non-nullable float field for series name %v", s.Frame.Name)
+		}
+		s.Frame.Fields[s.ValueIdx].Append(*f)
+	}
+	return
+}
+
+// Len returns the length of the series.
+func (s Series) Len() int {
+	return s.Frame.Fields[0].Len()
+}
+
+// GetTime returns the time at the specified index.
+func (s Series) GetTime(pointIdx int) *time.Time {
+	if s.TimeIsNullable {
+		return s.Frame.Fields[s.TimeIdx].At(pointIdx).(*time.Time)
+	}
+	t := s.Frame.Fields[s.TimeIdx].At(pointIdx).(time.Time)
+	return &t
+}
+
+// GetValue returns the float value at the specified index.
+func (s Series) GetValue(pointIdx int) *float64 {
+	if s.ValueIsNullabe {
+		return s.Frame.Fields[s.ValueIdx].At(pointIdx).(*float64)
+	}
+	f := s.Frame.Fields[s.ValueIdx].At(pointIdx).(float64)
+	return &f
+}
+
+// SortByTime sorts the series by the time from oldest to newest.
+// If desc is true, it will sort from newest to oldest.
+// If any time values are nil, it will panic.
+func (s Series) SortByTime(desc bool) {
+	if desc {
+		sort.Sort(sort.Reverse(SortSeriesByTime(s)))
+		return
+	}
+	sort.Sort(SortSeriesByTime(s))
+}
+
+// SortSeriesByTime allows a Series to be sorted by time
+// the sort interface will panic if any timestamps are null
+type SortSeriesByTime Series
+
+func (ss SortSeriesByTime) Len() int { return Series(ss).Len() }
+
+func (ss SortSeriesByTime) Swap(i, j int) {
+	iTimeVal, iFVal := Series(ss).GetPoint(i)
+	jTimeVal, jFVal := Series(ss).GetPoint(j)
+	_ = Series(ss).SetPoint(j, iTimeVal, iFVal)
+	_ = Series(ss).SetPoint(i, jTimeVal, jFVal)
+}
+
+func (ss SortSeriesByTime) Less(i, j int) bool {
+	iTimeVal := Series(ss).GetTime(i)
+	jTimeVal := Series(ss).GetTime(j)
+	return iTimeVal.Before(*jTimeVal)
+}

pkg/expr/mathexp/types.go

@@ -0,0 +1,112 @@
+package mathexp
+
+import (
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/expr/mathexp/parse"
+)
+
+// Results is a container for Value interfaces.
+type Results struct {
+	Values Values
+}
+
+// Values is a slice of Value interfaces
+type Values []Value
+
+// AsDataFrames returns each value as a slice of frames.
+func (vals Values) AsDataFrames(refID string) []*data.Frame {
+	frames := make([]*data.Frame, len(vals))
+	for i, v := range vals {
+		frames[i] = v.AsDataFrame()
+		frames[i].RefID = refID
+	}
+	return frames
+}
+
+// Value is the interface that holds different types such as a Scalar, Series, or Number.
+// all Value implementations should be a *data.Frame
+type Value interface {
+	Type() parse.ReturnType
+	Value() interface{}
+	GetLabels() data.Labels
+	SetLabels(data.Labels)
+	GetName() string
+	AsDataFrame() *data.Frame
+}
+
+// Scalar is the type that holds a single number constant.
+// Before returning from an expression it will be wrapped in a
+// data frame.
+type Scalar struct{ Frame *data.Frame }
+
+// Type returns the Value type and allows it to fulfill the Value interface.
+func (s Scalar) Type() parse.ReturnType { return parse.TypeScalar }
+
+// Value returns the actual value allows it to fulfill the Value interface.
+func (s Scalar) Value() interface{} { return s }
+
+func (s Scalar) GetLabels() data.Labels { return nil }
+
+func (s Scalar) SetLabels(ls data.Labels) {}
+
+func (s Scalar) GetName() string { return s.Frame.Name }
+
+// AsDataFrame returns the underlying *data.Frame.
+func (s Scalar) AsDataFrame() *data.Frame { return s.Frame }
+
+// NewScalar creates a Scalar holding value f.
+func NewScalar(f *float64) Scalar {
+	frame := data.NewFrame("",
+		data.NewField("Scalar", nil, []*float64{f}),
+	)
+	return Scalar{frame}
+}
+
+// NewScalarResults creates a Results holding a single Scalar
+func NewScalarResults(f *float64) Results {
+	return Results{
+		Values: []Value{NewScalar(f)},
+	}
+}
+
+// GetFloat64Value retrieves the single scalar value from the data
+func (s Scalar) GetFloat64Value() *float64 {
+	return s.Frame.At(0, 0).(*float64)
+}
+
+// Number hold a labelled single number values.
+type Number struct{ Frame *data.Frame }
+
+// Type returns the Value type and allows it to fulfill the Value interface.
+func (n Number) Type() parse.ReturnType { return parse.TypeNumberSet }
+
+// Value returns the actual value allows it to fulfill the Value interface.
+func (n Number) Value() interface{} { return &n }
+
+func (n Number) GetLabels() data.Labels { return n.Frame.Fields[0].Labels }
+
+func (n Number) SetLabels(ls data.Labels) { n.Frame.Fields[0].Labels = ls }
+
+func (n Number) GetName() string { return n.Frame.Name }
+
+// AsDataFrame returns the underlying *data.Frame.
+func (n Number) AsDataFrame() *data.Frame { return n.Frame }
+
+// SetValue sets the value of the Number to float64 pointer f
+func (n Number) SetValue(f *float64) {
+	n.Frame.Set(0, 0, f)
+}
+
+// GetFloat64Value retrieves the single scalar value from the data
+func (n Number) GetFloat64Value() *float64 {
+	return n.Frame.At(0, 0).(*float64)
+}
+
+// NewNumber returns a data that holds a float64Vector
+func NewNumber(name string, labels data.Labels) Number {
+	return Number{
+		data.NewFrame("",
+			data.NewField(name, labels, make([]*float64, 1)),
+		),
+	}
+}

pkg/expr/mathexp/types_test.go

@@ -0,0 +1,168 @@
+package mathexp
+
+import (
+	"testing"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSeriesSort(t *testing.T) {
+	var tests = []struct {
+		name           string
+		descending     bool
+		series         Series
+		sortedSeriesIs assert.ComparisonAssertionFunc
+		sortedSeries   Series
+		panics         assert.PanicTestFunc
+	}{
+		{
+			name:       "unordered series should sort by time ascending",
+			descending: false,
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(3, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(1, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}),
+			sortedSeriesIs: assert.Equal,
+			sortedSeries: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(1, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(3, 0), float64Pointer(3),
+			}),
+		},
+		{
+			name:       "unordered series should sort by time descending",
+			descending: true,
+			series: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(3, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(1, 0), float64Pointer(1),
+			}, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}),
+			sortedSeriesIs: assert.Equal,
+			sortedSeries: makeSeriesNullableTime("", nil, nullTimeTP{
+				unixTimePointer(3, 0), float64Pointer(3),
+			}, nullTimeTP{
+				unixTimePointer(2, 0), float64Pointer(2),
+			}, nullTimeTP{
+				unixTimePointer(1, 0), float64Pointer(1),
+			}),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tt.series.SortByTime(tt.descending)
+			tt.sortedSeriesIs(t, tt.series, tt.sortedSeries)
+		})
+	}
+}
+
+func TestSeriesFromFrame(t *testing.T) {
+	var tests = []struct {
+		name   string
+		frame  *data.Frame
+		errIs  assert.ErrorAssertionFunc
+		Is     assert.ComparisonAssertionFunc
+		Series Series
+	}{
+		{
+			name: "[]time, []float frame should convert",
+			frame: &data.Frame{
+				Name: "test",
+				Fields: []*data.Field{
+					data.NewField("time", nil, []time.Time{}),
+					data.NewField("value", nil, []float64{}),
+				},
+			},
+			errIs: assert.NoError,
+			Is:    assert.Equal,
+			Series: Series{
+				Frame: &data.Frame{
+					Name: "test",
+					Fields: []*data.Field{
+						data.NewField("time", nil, []time.Time{}),
+						data.NewField("value", nil, []float64{}),
+					},
+				},
+				TimeIdx:        0,
+				TimeIsNullable: false,
+				ValueIdx:       1,
+				ValueIsNullabe: false,
+			},
+		},
+		{
+			name: "[]*float, []*time frame should convert",
+			frame: &data.Frame{
+				Name: "test",
+				Fields: []*data.Field{
+					data.NewField("value", nil, []*float64{float64Pointer(5)}),
+					data.NewField("time", nil, []*time.Time{unixTimePointer(5, 0)}),
+				},
+			},
+			errIs: assert.NoError,
+			Is:    assert.Equal,
+			Series: Series{
+				Frame: &data.Frame{
+					Name: "test",
+					Fields: []*data.Field{
+						data.NewField("value", nil, []*float64{float64Pointer(5)}),
+						data.NewField("time", nil, []*time.Time{unixTimePointer(5, 0)}),
+					},
+				},
+				TimeIdx:        1,
+				TimeIsNullable: true,
+				ValueIdx:       0,
+				ValueIsNullabe: true,
+			},
+		},
+		{
+			name: "[]*time, []*time frame should error",
+			frame: &data.Frame{
+				Name: "test",
+				Fields: []*data.Field{
+					data.NewField("time", nil, []*time.Time{}),
+					data.NewField("time", nil, []*time.Time{}),
+				},
+			},
+			errIs: assert.Error,
+		},
+		{
+			name: "[]*float64, []float64 frame should error",
+			frame: &data.Frame{
+				Name: "test",
+				Fields: []*data.Field{
+					data.NewField("value", nil, []*float64{}),
+					data.NewField("value", nil, []*float64{}),
+				},
+			},
+			errIs: assert.Error,
+		},
+		{
+			name: "[]*float64 frame should error",
+			frame: &data.Frame{
+				Name: "test",
+				Fields: []*data.Field{
+					data.NewField("value", nil, []*float64{}),
+				},
+			},
+			errIs: assert.Error,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s, err := SeriesFromFrame(tt.frame)
+			tt.errIs(t, err)
+			if err == nil {
+				tt.Is(t, s, tt.Series)
+			}
+		})
+	}
+}

pkg/expr/mathexp/union_test.go

@@ -0,0 +1,244 @@
+package mathexp
+
+import (
+	"testing"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_union(t *testing.T) {
+	var tests = []struct {
+		name      string
+		aResults  Results
+		bResults  Results
+		unionsAre assert.ComparisonAssertionFunc
+		unions    []*Union
+	}{
+		{
+			name: "equal tags single union",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					Labels: data.Labels{"id": "1"},
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1"}),
+				},
+			},
+		},
+		{
+			name: "equal tags keys with no matching values will result in a union when len(A) == 1 && len(B) == 1",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "2"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					A: makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B: makeSeriesNullableTime("b", data.Labels{"id": "2"}),
+				},
+			},
+		},
+		{
+			name: "equal tags keys with no matching values will result in no unions when len(A) != 1 && len(B) != 1",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					makeSeriesNullableTime("q", data.Labels{"id": "3"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "2"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions:    []*Union{},
+		},
+		{
+			name:      "empty results will result in no unions",
+			aResults:  Results{},
+			bResults:  Results{},
+			unionsAre: assert.EqualValues,
+			unions:    []*Union{},
+		},
+		{
+			name: "incompatible tags of different length with will result in no unions when len(A) != 1 && len(B) != 1",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"ID": "1"}),
+					makeSeriesNullableTime("q", data.Labels{"ID": "3"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "red snapper"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions:    []*Union{},
+		},
+		{
+			name: "A is subset of B results in single union with Labels of B",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"}, // Union gets the labels that is not the subset
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+				},
+			},
+		},
+		{
+			name: "B is subset of A results in single union with Labels of A",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1", "fish": "herring"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"}, // Union gets the labels that is not the subset
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1", "fish": "herring"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1"}),
+				},
+			},
+		},
+		{
+			name: "single valued A is subset of many valued B, results in many union with Labels of B",
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+					makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "red snapper"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"},
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+				},
+				{
+					Labels: data.Labels{"id": "1", "fish": "red snapper"},
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "red snapper"}),
+				},
+			},
+		},
+		{
+			name: "A with different tags keys lengths to B makes 3 unions (with two unions have matching tags)",
+			// Is this the behavior we want? A result within the results will no longer
+			// be uniquely identifiable.
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					makeSeriesNullableTime("aa", data.Labels{"id": "1", "fish": "herring"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+					makeSeriesNullableTime("bb", data.Labels{"id": "1", "fish": "red snapper"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"},
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+				},
+				{
+					Labels: data.Labels{"id": "1", "fish": "red snapper"},
+					A:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					B:      makeSeriesNullableTime("bb", data.Labels{"id": "1", "fish": "red snapper"}),
+				},
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"},
+					A:      makeSeriesNullableTime("aa", data.Labels{"id": "1", "fish": "herring"}),
+					B:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+				},
+			},
+		},
+		{
+			name: "B with different tags keys lengths to A makes 3 unions (with two unions have matching tags)",
+			// Is this the behavior we want? A result within the results will no longer
+			// be uniquely identifiable.
+			aResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+					makeSeriesNullableTime("bb", data.Labels{"id": "1", "fish": "red snapper"}),
+				},
+			},
+			bResults: Results{
+				Values: Values{
+					makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+					makeSeriesNullableTime("aa", data.Labels{"id": "1", "fish": "herring"}),
+				},
+			},
+			unionsAre: assert.EqualValues,
+			unions: []*Union{
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"},
+					A:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+					B:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+				},
+				{
+					Labels: data.Labels{"id": "1", "fish": "herring"},
+					A:      makeSeriesNullableTime("b", data.Labels{"id": "1", "fish": "herring"}),
+					B:      makeSeriesNullableTime("aa", data.Labels{"id": "1", "fish": "herring"}),
+				},
+				{
+					Labels: data.Labels{"id": "1", "fish": "red snapper"},
+					A:      makeSeriesNullableTime("bb", data.Labels{"id": "1", "fish": "red snapper"}),
+					B:      makeSeriesNullableTime("a", data.Labels{"id": "1"}),
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			unions := union(tt.aResults, tt.bResults)
+			tt.unionsAre(t, tt.unions, unions)
+		})
+	}
+}

pkg/expr/nodes.go

@@ -0,0 +1,358 @@
+package expr
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/expr/mathexp"
+
+	"gonum.org/v1/gonum/graph/simple"
+)
+
+// baseNode includes commmon properties used across DPNodes.
+type baseNode struct {
+	id    int64
+	refID string
+}
+
+type rawNode struct {
+	RefID     string `json:"refId"`
+	Query     map[string]interface{}
+	QueryType string
+	TimeRange backend.TimeRange
+}
+
+func (rn *rawNode) GetDatasourceName() (string, error) {
+	rawDs, ok := rn.Query["datasource"]
+	if !ok {
+		return "", fmt.Errorf("no datasource in query for refId %v", rn.RefID)
+	}
+	dsName, ok := rawDs.(string)
+	if !ok {
+		return "", fmt.Errorf("expted datasource identifier to be a string, got %T", rawDs)
+	}
+	return dsName, nil
+}
+
+func (rn *rawNode) GetCommandType() (c CommandType, err error) {
+	rawType, ok := rn.Query["type"]
+	if !ok {
+		return c, fmt.Errorf("no expression command type in query for refId %v", rn.RefID)
+	}
+	typeString, ok := rawType.(string)
+	if !ok {
+		return c, fmt.Errorf("expected expression command type to be a string, got type %T", rawType)
+	}
+	return ParseCommandType(typeString)
+}
+
+// String returns a string representation of the node. In particular for
+// %v formating in error messages.
+func (b *baseNode) String() string {
+	return b.refID
+}
+
+// CMDNode is a DPNode that holds an expression command.
+type CMDNode struct {
+	baseNode
+	CMDType CommandType
+	Command Command
+}
+
+// ID returns the id of the node so it can fulfill the gonum's graph Node interface.
+func (b *baseNode) ID() int64 {
+	return b.id
+}
+
+// RefID returns the refId of the node.
+func (b *baseNode) RefID() string {
+	return b.refID
+}
+
+// NodeType returns the data pipeline node type.
+func (gn *CMDNode) NodeType() NodeType {
+	return TypeCMDNode
+}
+
+// Execute runs the node and adds the results to vars. If the node requires
+// other nodes they must have already been executed and their results must
+// already by in vars.
+func (gn *CMDNode) Execute(ctx context.Context, vars mathexp.Vars) (mathexp.Results, error) {
+	return gn.Command.Execute(ctx, vars)
+}
+
+func buildCMDNode(dp *simple.DirectedGraph, rn *rawNode) (*CMDNode, error) {
+	commandType, err := rn.GetCommandType()
+	if err != nil {
+		return nil, fmt.Errorf("invalid expression command type in '%v'", rn.RefID)
+	}
+
+	node := &CMDNode{
+		baseNode: baseNode{
+			id:    dp.NewNode().ID(),
+			refID: rn.RefID,
+		},
+	}
+
+	switch commandType {
+	case TypeMath:
+		node.Command, err = UnmarshalMathCommand(rn)
+	case TypeReduce:
+		node.Command, err = UnmarshalReduceCommand(rn)
+	case TypeResample:
+		node.Command, err = UnmarshalResampleCommand(rn)
+	default:
+		return nil, fmt.Errorf("expression command type '%v' in '%v' not implemented", commandType, rn.RefID)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	return node, nil
+}
+
+const (
+	defaultIntervalMS = int64(64)
+	defaultMaxDP      = int64(5000)
+)
+
+// DSNode is a DPNode that holds a datasource request.
+type DSNode struct {
+	baseNode
+	query        json.RawMessage
+	datasourceID int64
+	orgID        int64
+	queryType    string
+	timeRange    backend.TimeRange
+	intervalMS   int64
+	maxDP        int64
+}
+
+// NodeType returns the data pipeline node type.
+func (dn *DSNode) NodeType() NodeType {
+	return TypeDatasourceNode
+}
+
+func buildDSNode(dp *simple.DirectedGraph, rn *rawNode) (*DSNode, error) {
+	encodedQuery, err := json.Marshal(rn.Query)
+	if err != nil {
+		return nil, err
+	}
+
+	dsNode := &DSNode{
+		baseNode: baseNode{
+			id:    dp.NewNode().ID(),
+			refID: rn.RefID,
+		},
+		query:      json.RawMessage(encodedQuery),
+		queryType:  rn.QueryType,
+		intervalMS: defaultIntervalMS,
+		maxDP:      defaultMaxDP,
+		timeRange:  rn.TimeRange,
+	}
+
+	rawDsID, ok := rn.Query["datasourceId"]
+	if !ok {
+		return nil, fmt.Errorf("no datasourceId in expression data source request for refId %v", rn.RefID)
+	}
+	floatDsID, ok := rawDsID.(float64)
+	if !ok {
+		return nil, fmt.Errorf("expected datasourceId to be a float64, got type %T for refId %v", rawDsID, rn.RefID)
+	}
+	dsNode.datasourceID = int64(floatDsID)
+
+	rawOrgID, ok := rn.Query["orgId"]
+	if !ok {
+		return nil, fmt.Errorf("no orgId in expression data source request command for refId %v", rn.RefID)
+	}
+	floatOrgID, ok := rawOrgID.(float64)
+	if !ok {
+		return nil, fmt.Errorf("expected orgId to be a float64, got type %T for refId %v", rawOrgID, rn.RefID)
+	}
+	dsNode.orgID = int64(floatOrgID)
+
+	var floatIntervalMS float64
+	if rawIntervalMS := rn.Query["intervalMs"]; ok {
+		if floatIntervalMS, ok = rawIntervalMS.(float64); !ok {
+			return nil, fmt.Errorf("expected intervalMs to be an float64, got type %T for refId %v", rawIntervalMS, rn.RefID)
+		}
+		dsNode.intervalMS = int64(floatIntervalMS)
+	}
+
+	var floatMaxDP float64
+	if rawMaxDP := rn.Query["maxDataPoints"]; ok {
+		if floatMaxDP, ok = rawMaxDP.(float64); !ok {
+			return nil, fmt.Errorf("expected maxDataPoints to be an float64, got type %T for refId %v", rawMaxDP, rn.RefID)
+		}
+		dsNode.maxDP = int64(floatMaxDP)
+	}
+
+	return dsNode, nil
+}
+
+// Execute runs the node and adds the results to vars. If the node requires
+// other nodes they must have already been executed and their results must
+// already by in vars.
+func (dn *DSNode) Execute(ctx context.Context, vars mathexp.Vars) (mathexp.Results, error) {
+	pc := backend.PluginContext{
+		OrgID: dn.orgID,
+		DataSourceInstanceSettings: &backend.DataSourceInstanceSettings{
+			ID: dn.datasourceID,
+		},
+	}
+
+	q := []backend.DataQuery{
+		{
+			RefID:         dn.refID,
+			MaxDataPoints: dn.maxDP,
+			Interval:      time.Duration(int64(time.Millisecond) * dn.intervalMS),
+			JSON:          dn.query,
+			TimeRange:     dn.timeRange,
+			QueryType:     dn.queryType,
+		},
+	}
+
+	resp, err := QueryData(ctx, &backend.QueryDataRequest{
+		PluginContext: pc,
+		Queries:       q,
+	})
+
+	if err != nil {
+		return mathexp.Results{}, err
+	}
+
+	vals := make([]mathexp.Value, 0)
+	for refID, qr := range resp.Responses {
+		if len(qr.Frames) == 1 {
+			frame := qr.Frames[0]
+			if frame.TimeSeriesSchema().Type == data.TimeSeriesTypeNot && isNumberTable(frame) {
+				backend.Logger.Debug("expression datasource query (numberSet)", "query", refID)
+				numberSet, err := extractNumberSet(frame)
+				if err != nil {
+					return mathexp.Results{}, err
+				}
+				for _, n := range numberSet {
+					vals = append(vals, n)
+				}
+
+				return mathexp.Results{
+					Values: vals,
+				}, nil
+			}
+		}
+
+		for _, frame := range qr.Frames {
+			backend.Logger.Debug("expression datasource query (seriesSet)", "query", refID)
+			series, err := WideToMany(frame)
+			if err != nil {
+				return mathexp.Results{}, err
+			}
+			for _, s := range series {
+				vals = append(vals, s)
+			}
+		}
+	}
+	return mathexp.Results{
+		Values: vals,
+	}, nil
+}
+
+func isNumberTable(frame *data.Frame) bool {
+	if frame == nil || frame.Fields == nil {
+		return false
+	}
+	numericCount := 0
+	stringCount := 0
+	otherCount := 0
+	for _, field := range frame.Fields {
+		fType := field.Type()
+		switch {
+		case fType.Numeric():
+			numericCount++
+		case fType == data.FieldTypeString || fType == data.FieldTypeNullableString:
+			stringCount++
+		default:
+			otherCount++
+		}
+	}
+	return numericCount == 1 && otherCount == 0
+}
+
+func extractNumberSet(frame *data.Frame) ([]mathexp.Number, error) {
+	numericField := 0
+	stringFieldIdxs := []int{}
+	stringFieldNames := []string{}
+	for i, field := range frame.Fields {
+		fType := field.Type()
+		switch {
+		case fType.Numeric():
+			numericField = i
+		case fType == data.FieldTypeString || fType == data.FieldTypeNullableString:
+			stringFieldIdxs = append(stringFieldIdxs, i)
+			stringFieldNames = append(stringFieldNames, field.Name)
+		}
+	}
+	numbers := make([]mathexp.Number, frame.Rows())
+
+	for rowIdx := 0; rowIdx < frame.Rows(); rowIdx++ {
+		val, _ := frame.FloatAt(numericField, rowIdx)
+		var labels data.Labels
+		for i := 0; i < len(stringFieldIdxs); i++ {
+			if i == 0 {
+				labels = make(data.Labels)
+			}
+			key := stringFieldNames[i] // TODO check for duplicate string column names
+			val, _ := frame.ConcreteAt(stringFieldIdxs[i], rowIdx)
+			labels[key] = val.(string) // TODO check assertion / return error
+		}
+
+		n := mathexp.NewNumber("", labels)
+		n.SetValue(&val)
+		numbers[rowIdx] = n
+	}
+	return numbers, nil
+}
+
+// WideToMany converts a data package wide type Frame to one or multiple Series. A series
+// is created for each value type column of wide frame.
+//
+// This might not be a good idea long term, but works now as an adapter/shim.
+func WideToMany(frame *data.Frame) ([]mathexp.Series, error) {
+	tsSchema := frame.TimeSeriesSchema()
+	if tsSchema.Type != data.TimeSeriesTypeWide {
+		return nil, fmt.Errorf("input data must be a wide series but got type %s (input refid)", tsSchema.Type)
+	}
+
+	if len(tsSchema.ValueIndices) == 1 {
+		s, err := mathexp.SeriesFromFrame(frame)
+		if err != nil {
+			return nil, err
+		}
+		return []mathexp.Series{s}, nil
+	}
+
+	series := []mathexp.Series{}
+	for _, valIdx := range tsSchema.ValueIndices {
+		l := frame.Rows()
+		f := data.NewFrameOfFieldTypes(frame.Name, l, frame.Fields[tsSchema.TimeIndex].Type(), frame.Fields[valIdx].Type())
+		f.Fields[0].Name = frame.Fields[tsSchema.TimeIndex].Name
+		f.Fields[1].Name = frame.Fields[valIdx].Name
+		if frame.Fields[valIdx].Labels != nil {
+			f.Fields[1].Labels = frame.Fields[valIdx].Labels.Copy()
+		}
+		for i := 0; i < l; i++ {
+			f.SetRow(i, frame.Fields[tsSchema.TimeIndex].CopyAt(i), frame.Fields[valIdx].CopyAt(i))
+		}
+		s, err := mathexp.SeriesFromFrame(f)
+		if err != nil {
+			return nil, err
+		}
+		series = append(series, s)
+	}
+
+	return series, nil
+}

pkg/expr/service.go

@@ -0,0 +1,39 @@
+package expr
+
+import (
+	"context"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+)
+
+// DatasourceName is the string constant used as the datasource name in requests
+// to identify it as an expression command.
+const DatasourceName = "__expr__"
+
+// DatasourceID is the fake datasource id used in requests to identify it as an
+// expression command.
+const DatasourceID = -100
+
+// Service is service representation for expression handling.
+type Service struct {
+}
+
+// BuildPipeline builds a pipeline from a request.
+func (s *Service) BuildPipeline(queries []backend.DataQuery) (DataPipeline, error) {
+	return buildPipeline(queries)
+}
+
+// ExecutePipeline executes an expression pipeline and returns all the results.
+func (s *Service) ExecutePipeline(ctx context.Context, pipeline DataPipeline) (*backend.QueryDataResponse, error) {
+	res := backend.NewQueryDataResponse()
+	vars, err := pipeline.execute(ctx)
+	if err != nil {
+		return nil, err
+	}
+	for refID, val := range vars {
+		res.Responses[refID] = backend.DataResponse{
+			Frames: val.Values.AsDataFrames(refID),
+		}
+	}
+	return res, nil
+}

pkg/expr/service_test.go

@@ -0,0 +1,111 @@
+package expr
+
+import (
+	"context"
+	"encoding/json"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+	"github.com/grafana/grafana/pkg/bus"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/tsdb"
+	"github.com/stretchr/testify/require"
+)
+
+func TestService(t *testing.T) {
+	dsDF := data.NewFrame("test",
+		data.NewField("time", nil, []*time.Time{utp(1)}),
+		data.NewField("value", nil, []*float64{fp(2)}))
+
+	registerEndPoint(dsDF)
+
+	s := Service{}
+
+	queries := []backend.DataQuery{
+		{
+			RefID: "A",
+			JSON:  json.RawMessage(`{ "datasource": "test", "datasourceId": 1, "orgId": 1, "intervalMs": 1000, "maxDataPoints": 1000 }`),
+		},
+		{
+			RefID: "B",
+			JSON:  json.RawMessage(`{ "datasource": "__expr__", "datasourceId": -100, "type": "math", "expression": "$A * 2" }`),
+		},
+	}
+
+	pl, err := s.BuildPipeline(queries)
+	require.NoError(t, err)
+
+	res, err := s.ExecutePipeline(context.Background(), pl)
+	require.NoError(t, err)
+
+	bDF := data.NewFrame("",
+		data.NewField("Time", nil, []*time.Time{utp(1)}),
+		data.NewField("", nil, []*float64{fp(4)}))
+	bDF.RefID = "B"
+
+	expect := &backend.QueryDataResponse{
+		Responses: backend.Responses{
+			"A": {
+				Frames: []*data.Frame{dsDF},
+			},
+			"B": {
+				Frames: []*data.Frame{bDF},
+			},
+		},
+	}
+
+	// Service currently doesn't care about order of datas in the return.
+	trans := cmp.Transformer("Sort", func(in []*data.Frame) []*data.Frame {
+		out := append([]*data.Frame(nil), in...) // Copy input to avoid mutating it
+		sort.SliceStable(out, func(i, j int) bool {
+			return out[i].RefID > out[j].RefID
+		})
+		return out
+	})
+	options := append([]cmp.Option{trans}, data.FrameTestCompareOptions()...)
+	if diff := cmp.Diff(expect, res, options...); diff != "" {
+		t.Errorf("Result mismatch (-want +got):\n%s", diff)
+	}
+}
+
+func utp(sec int64) *time.Time {
+	t := time.Unix(sec, 0)
+	return &t
+}
+
+func fp(f float64) *float64 {
+	return &f
+}
+
+type mockEndpoint struct {
+	Frames data.Frames
+}
+
+func (me *mockEndpoint) Query(ctx context.Context, ds *models.DataSource, query *tsdb.TsdbQuery) (*tsdb.Response, error) {
+	return &tsdb.Response{
+		Results: map[string]*tsdb.QueryResult{
+			"A": {
+				Dataframes: tsdb.NewDecodedDataFrames(me.Frames),
+			},
+		},
+	}, nil
+}
+
+func registerEndPoint(df ...*data.Frame) {
+	me := &mockEndpoint{
+		Frames: df,
+	}
+	endpoint := func(dsInfo *models.DataSource) (tsdb.TsdbQueryEndpoint, error) {
+		return me, nil
+	}
+
+	tsdb.RegisterTsdbQueryEndpoint("test", endpoint)
+	bus.AddHandler("test", func(query *models.GetDataSourceByIdQuery) error {
+		query.Result = &models.DataSource{Id: 1, OrgId: 1, Type: "test"}
+		return nil
+	})
+}

pkg/expr/transform.go

@@ -0,0 +1,211 @@
+package expr
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana/pkg/bus"
+	"github.com/grafana/grafana/pkg/components/simplejson"
+	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/tsdb"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func WrapTransformData(ctx context.Context, query *tsdb.TsdbQuery) (*tsdb.Response, error) {
+	sdkReq := &backend.QueryDataRequest{
+		PluginContext: backend.PluginContext{
+			OrgID: query.User.OrgId,
+		},
+		Queries: []backend.DataQuery{},
+	}
+
+	for _, q := range query.Queries {
+		modelJSON, err := q.Model.MarshalJSON()
+		if err != nil {
+			return nil, err
+		}
+		sdkReq.Queries = append(sdkReq.Queries, backend.DataQuery{
+			JSON:          modelJSON,
+			Interval:      time.Duration(q.IntervalMs) * time.Millisecond,
+			RefID:         q.RefId,
+			MaxDataPoints: q.MaxDataPoints,
+			QueryType:     q.QueryType,
+			TimeRange: backend.TimeRange{
+				From: query.TimeRange.GetFromAsTimeUTC(),
+				To:   query.TimeRange.GetToAsTimeUTC(),
+			},
+		})
+	}
+	pbRes, err := TransformData(ctx, sdkReq)
+	if err != nil {
+		return nil, err
+	}
+
+	tR := &tsdb.Response{
+		Results: make(map[string]*tsdb.QueryResult, len(pbRes.Responses)),
+	}
+	for refID, res := range pbRes.Responses {
+		tRes := &tsdb.QueryResult{
+			RefId:      refID,
+			Dataframes: tsdb.NewDecodedDataFrames(res.Frames),
+		}
+		// if len(res.JsonMeta) != 0 {
+		// 	tRes.Meta = simplejson.NewFromAny(res.JsonMeta)
+		// }
+		if res.Error != nil {
+			tRes.Error = res.Error
+			tRes.ErrorString = res.Error.Error()
+		}
+		tR.Results[refID] = tRes
+	}
+
+	return tR, nil
+}
+
+// TransformData takes Queries which are either expressions nodes
+// or are datasource requests.
+func TransformData(ctx context.Context, req *backend.QueryDataRequest) (*backend.QueryDataResponse, error) {
+	svc := Service{}
+	// Build the pipeline from the request, checking for ordering issues (e.g. loops)
+	// and parsing graph nodes from the queries.
+	pipeline, err := svc.BuildPipeline(req.Queries)
+	if err != nil {
+		return nil, status.Error(codes.InvalidArgument, err.Error())
+	}
+
+	// Execute the pipeline
+	responses, err := svc.ExecutePipeline(ctx, pipeline)
+	if err != nil {
+		return nil, status.Error(codes.Unknown, err.Error())
+	}
+
+	// Get which queries have the Hide property so they those queries' results
+	// can be excluded from the response.
+	hidden, err := hiddenRefIDs(req.Queries)
+	if err != nil {
+		return nil, status.Error((codes.Internal), err.Error())
+	}
+
+	if len(hidden) != 0 {
+		filteredRes := backend.NewQueryDataResponse()
+		for refID, res := range responses.Responses {
+			if _, ok := hidden[refID]; !ok {
+				filteredRes.Responses[refID] = res
+			}
+		}
+		responses = filteredRes
+	}
+
+	return responses, nil
+}
+
+func hiddenRefIDs(queries []backend.DataQuery) (map[string]struct{}, error) {
+	hidden := make(map[string]struct{})
+
+	for _, query := range queries {
+		hide := struct {
+			Hide bool `json:"hide"`
+		}{}
+
+		if err := json.Unmarshal(query.JSON, &hide); err != nil {
+			return nil, err
+		}
+
+		if hide.Hide {
+			hidden[query.RefID] = struct{}{}
+		}
+	}
+	return hidden, nil
+}
+
+// QueryData is called used to query datasources that are not expression commands, but are used
+// alongside expressions and/or are the input of an expression command.
+func QueryData(ctx context.Context, req *backend.QueryDataRequest) (*backend.QueryDataResponse, error) {
+	if len(req.Queries) == 0 {
+		return nil, fmt.Errorf("zero queries found in datasource request")
+	}
+
+	datasourceID := int64(0)
+
+	if req.PluginContext.DataSourceInstanceSettings != nil {
+		datasourceID = req.PluginContext.DataSourceInstanceSettings.ID
+	}
+
+	getDsInfo := &models.GetDataSourceByIdQuery{
+		OrgId: req.PluginContext.OrgID,
+		Id:    datasourceID,
+	}
+
+	if err := bus.Dispatch(getDsInfo); err != nil {
+		return nil, fmt.Errorf("could not find datasource: %w", err)
+	}
+
+	// Convert plugin-model (datasource) queries to tsdb queries
+	queries := make([]*tsdb.Query, len(req.Queries))
+	for i, query := range req.Queries {
+		sj, err := simplejson.NewJson(query.JSON)
+		if err != nil {
+			return nil, err
+		}
+		queries[i] = &tsdb.Query{
+			RefId:         query.RefID,
+			IntervalMs:    query.Interval.Microseconds(),
+			MaxDataPoints: query.MaxDataPoints,
+			QueryType:     query.QueryType,
+			DataSource:    getDsInfo.Result,
+			Model:         sj,
+		}
+	}
+
+	// For now take Time Range from first query.
+	timeRange := tsdb.NewTimeRange(strconv.FormatInt(req.Queries[0].TimeRange.From.Unix()*1000, 10), strconv.FormatInt(req.Queries[0].TimeRange.To.Unix()*1000, 10))
+
+	tQ := &tsdb.TsdbQuery{
+		TimeRange: timeRange,
+		Queries:   queries,
+	}
+
+	// Execute the converted queries
+	tsdbRes, err := tsdb.HandleRequest(ctx, getDsInfo.Result, tQ)
+	if err != nil {
+		return nil, err
+	}
+	// Convert tsdb results (map) to plugin-model/datasource (slice) results.
+	// Only error, tsdb.Series, and encoded Dataframes responses are mapped.
+	responses := make(map[string]backend.DataResponse, len(tsdbRes.Results))
+	for refID, res := range tsdbRes.Results {
+		pRes := backend.DataResponse{}
+		if res.Error != nil {
+			pRes.Error = res.Error
+		}
+
+		if res.Dataframes != nil {
+			decoded, err := res.Dataframes.Decoded()
+			if err != nil {
+				return nil, err
+			}
+			pRes.Frames = decoded
+			responses[refID] = pRes
+			continue
+		}
+
+		for _, series := range res.Series {
+			frame, err := tsdb.SeriesToFrame(series)
+			frame.RefID = refID
+			if err != nil {
+				return nil, err
+			}
+			pRes.Frames = append(pRes.Frames, frame)
+		}
+
+		responses[refID] = pRes
+	}
+	return &backend.QueryDataResponse{
+		Responses: responses,
+	}, nil
+}

pkg/plugins/backendplugin/grpcplugin/client.go

@@ -71,7 +71,6 @@ func getV2PluginSet() goplugin.PluginSet {
 		"diagnostics": &grpcplugin.DiagnosticsGRPCPlugin{},
 		"resource":    &grpcplugin.ResourceGRPCPlugin{},
 		"data":        &grpcplugin.DataGRPCPlugin{},
-		"transform":   &grpcplugin.TransformGRPCPlugin{},
 		"renderer":    &pluginextensionv2.RendererGRPCPlugin{},
 	}
 }
@@ -117,6 +116,5 @@ type LegacyClient struct {
 // Client client for communicating with a plugin using the current (v2) plugin protocol.
 type Client struct {
 	DataPlugin     grpcplugin.DataClient
-	TransformPlugin grpcplugin.TransformClient
 	RendererPlugin pluginextensionv2.RendererPlugin
 }

pkg/plugins/backendplugin/grpcplugin/client_v2.go

@@ -21,7 +21,6 @@ type clientV2 struct {
 	grpcplugin.DiagnosticsClient
 	grpcplugin.ResourceClient
 	grpcplugin.DataClient
-	grpcplugin.TransformClient
 	pluginextensionv2.RendererPlugin
 }
 
@@ -41,11 +40,6 @@ func newClientV2(descriptor PluginDescriptor, logger log.Logger, rpcClient plugi
 		return nil, err
 	}
 
-	rawTransform, err := rpcClient.Dispense("transform")
-	if err != nil {
-		return nil, err
-	}
-
 	rawRenderer, err := rpcClient.Dispense("renderer")
 	if err != nil {
 		return nil, err
@@ -70,12 +64,6 @@ func newClientV2(descriptor PluginDescriptor, logger log.Logger, rpcClient plugi
 		}
 	}
 
-	if rawTransform != nil {
-		if plugin, ok := rawTransform.(grpcplugin.TransformClient); ok {
-			c.TransformClient = instrumentTransformPlugin(plugin)
-		}
-	}
-
 	if rawRenderer != nil {
 		if plugin, ok := rawRenderer.(pluginextensionv2.RendererPlugin); ok {
 			c.RendererPlugin = plugin
@@ -85,7 +73,6 @@ func newClientV2(descriptor PluginDescriptor, logger log.Logger, rpcClient plugi
 	if descriptor.startFns.OnStart != nil {
 		client := &Client{
 			DataPlugin:     c.DataClient,
-			TransformPlugin: c.TransformClient,
 			RendererPlugin: c.RendererPlugin,
 		}
 		if err := descriptor.startFns.OnStart(descriptor.pluginID, client, logger); err != nil {
@@ -189,24 +176,3 @@ func instrumentDataClient(plugin grpcplugin.DataClient) grpcplugin.DataClient {
 		return resp, err
 	})
 }
-
-type transformPluginTransformDataFunc func(ctx context.Context, req *pluginv2.QueryDataRequest, callback grpcplugin.TransformDataCallBack) (*pluginv2.QueryDataResponse, error)
-
-func (fn transformPluginTransformDataFunc) TransformData(ctx context.Context, req *pluginv2.QueryDataRequest, callback grpcplugin.TransformDataCallBack) (*pluginv2.QueryDataResponse, error) {
-	return fn(ctx, req, callback)
-}
-
-func instrumentTransformPlugin(plugin grpcplugin.TransformClient) grpcplugin.TransformClient {
-	if plugin == nil {
-		return nil
-	}
-
-	return transformPluginTransformDataFunc(func(ctx context.Context, req *pluginv2.QueryDataRequest, callback grpcplugin.TransformDataCallBack) (*pluginv2.QueryDataResponse, error) {
-		var resp *pluginv2.QueryDataResponse
-		err := backendplugin.InstrumentTransformDataRequest(req.PluginContext.PluginId, func() (innerErr error) {
-			resp, innerErr = plugin.TransformData(ctx, req, callback)
-			return
-		})
-		return resp, err
-	})
-}

pkg/plugins/backendplugin/instrumentation.go

@@ -65,11 +65,6 @@ func InstrumentQueryDataRequest(pluginID string, fn func() error) error {
 	return instrumentPluginRequest(pluginID, "queryData", fn)
 }
 
-// InstrumentTransformDataRequest instruments success rate and latency of transform data request.
-func InstrumentTransformDataRequest(pluginID string, fn func() error) error {
-	return instrumentPluginRequest(pluginID, "transformData", fn)
-}
-
 // InstrumentQueryDataHandler wraps a backend.QueryDataHandler with instrumentation of success rate and latency.
 func InstrumentQueryDataHandler(handler backend.QueryDataHandler) backend.QueryDataHandler {
 	if handler == nil {

pkg/plugins/plugins.go

@@ -31,7 +31,6 @@ var (
 	Plugins      map[string]*PluginBase
 	PluginTypes  map[string]interface{}
 	Renderer     *RendererPlugin
-	Transform    *TransformPlugin
 
 	GrafanaLatestVersion string
 	GrafanaHasUpdate     bool
@@ -82,7 +81,6 @@ func (pm *PluginManager) Init() error {
 		"datasource": DataSourcePlugin{},
 		"app":        AppPlugin{},
 		"renderer":   RendererPlugin{},
-		"transform":  TransformPlugin{},
 	}
 	pluginScanningErrors = map[string]*PluginError{}
 
@@ -357,16 +355,6 @@ func (s *PluginScanner) loadPlugin(pluginJSONFilePath string) error {
 		return errors.New("did not find type or id properties in plugin.json")
 	}
 
-	// The expressions feature toggle corresponds to transform plug-ins.
-	if pluginCommon.Type == "transform" {
-		isEnabled := s.cfg.IsExpressionsEnabled()
-		if !isEnabled {
-			s.log.Debug("Transform plugin is disabled since the expressions feature toggle is not enabled",
-				"pluginID", pluginCommon.Id)
-			return nil
-		}
-	}
-
 	pluginCommon.PluginDir = filepath.Dir(pluginJSONFilePath)
 	pluginCommon.Signature = getPluginSignatureState(s.log, &pluginCommon)
 
@@ -376,7 +364,7 @@ func (s *PluginScanner) loadPlugin(pluginJSONFilePath string) error {
 }
 
 func (*PluginScanner) IsBackendOnlyPlugin(pluginType string) bool {
-	return pluginType == "renderer" || pluginType == "transform"
+	return pluginType == "renderer"
 }
 
 // validateSignature validates a plugin's signature.

pkg/plugins/plugins_test.go

@@ -142,29 +142,6 @@ func TestPluginManager_Init(t *testing.T) {
 		assert.Empty(t, fm.registeredPlugins)
 	})
 
-	t.Run("Transform plugins should be loaded when expressions feature is on", func(t *testing.T) {
-		origPluginsPath := setting.PluginsPath
-		t.Cleanup(func() {
-			setting.PluginsPath = origPluginsPath
-		})
-		setting.PluginsPath = "testdata/behind-feature-flag"
-
-		fm := &fakeBackendPluginManager{}
-		pm := &PluginManager{
-			Cfg: &setting.Cfg{
-				FeatureToggles: map[string]bool{
-					"expressions": true,
-				},
-			},
-			BackendPluginManager: fm,
-		}
-		err := pm.Init()
-		require.NoError(t, err)
-
-		require.Empty(t, pm.scanningErrors)
-		assert.Equal(t, []string{"gel"}, fm.registeredPlugins)
-	})
-
 	t.Run("With nested plugin duplicating parent", func(t *testing.T) {
 		origPluginsPath := setting.PluginsPath
 		t.Cleanup(func() {

pkg/plugins/testdata/behind-feature-flag/gel/MANIFEST.txt

@@ -1,23 +0,0 @@
-
------BEGIN PGP SIGNED MESSAGE-----
-Hash: SHA512
-
-{
-  "plugin": "gel",
-  "version": "1.0.0",
-  "files": {
-    "plugin.json": "b9b3bb0dab3c4655a929a1e48a957466e3e2717992bdd29da27e5eed2fae090c"
-  },
-  "time": 1589274667427,
-  "keyId": "7e4d0c6a708866e7"
-}
------BEGIN PGP SIGNATURE-----
-Version: OpenPGP.js v4.10.1
-Comment: https://openpgpjs.org
-
-wqIEARMKAAYFAl66aCsACgkQfk0ManCIZufDMAIJAWoNVihI9ZSBpUpgXrzY
-XXsI3OmHuVpzrv6M6bk5jYdzY4SyzZmdw4CB51TIDJW9SnUajlXxWLXGYY+w
-B2rSYvuhAgkBlG9w5OV3jcyg/wfUrIcCO5XRHMydCg0hIOznClzuG0uWn3wm
-d4RT/ap1ezislQ/91zvhsLgAIztZlm3EsNBv7sI=
-=WPLw
------END PGP SIGNATURE-----

pkg/plugins/testdata/behind-feature-flag/gel/plugin.json

@@ -1,14 +0,0 @@
-{
-  "type": "transform",
-  "name": "GEL",
-  "id": "gel",
-  "backend": true,
-  "info": {
-    "description": "Test",
-    "version": "1.0.0",
-    "author": {
-      "name": "Grafana Labs",
-      "url": "https://grafana.com"
-    }
-  }
-}

pkg/plugins/transform_plugin.go

@@ -1,228 +0,0 @@
-package plugins
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"path/filepath"
-	"strconv"
-
-	sdkgrpcplugin "github.com/grafana/grafana-plugin-sdk-go/backend/grpcplugin"
-	"github.com/grafana/grafana-plugin-sdk-go/genproto/pluginv2"
-	"github.com/grafana/grafana/pkg/bus"
-	"github.com/grafana/grafana/pkg/components/simplejson"
-	"github.com/grafana/grafana/pkg/infra/log"
-	"github.com/grafana/grafana/pkg/models"
-	"github.com/grafana/grafana/pkg/plugins/backendplugin"
-	"github.com/grafana/grafana/pkg/plugins/backendplugin/grpcplugin"
-	"github.com/grafana/grafana/pkg/plugins/datasource/wrapper"
-	"github.com/grafana/grafana/pkg/tsdb"
-	"github.com/grafana/grafana/pkg/util/errutil"
-)
-
-type TransformPlugin struct {
-	PluginBase
-
-	Executable string `json:"executable,omitempty"`
-
-	*TransformWrapper
-}
-
-func (p *TransformPlugin) Load(decoder *json.Decoder, base *PluginBase, backendPluginManager backendplugin.Manager) error {
-	if err := decoder.Decode(p); err != nil {
-		return err
-	}
-
-	if err := p.registerPlugin(base); err != nil {
-		return err
-	}
-
-	cmd := ComposePluginStartCommand(p.Executable)
-	fullpath := filepath.Join(p.PluginDir, cmd)
-	factory := grpcplugin.NewBackendPlugin(p.Id, fullpath, grpcplugin.PluginStartFuncs{
-		OnStart: p.onPluginStart,
-	})
-	if err := backendPluginManager.Register(p.Id, factory); err != nil {
-		return errutil.Wrapf(err, "Failed to register backend plugin")
-	}
-
-	Transform = p
-
-	return nil
-}
-
-func (p *TransformPlugin) onPluginStart(pluginID string, client *grpcplugin.Client, logger log.Logger) error {
-	p.TransformWrapper = NewTransformWrapper(logger, client.TransformPlugin)
-
-	if client.DataPlugin != nil {
-		tsdb.RegisterTsdbQueryEndpoint(pluginID, func(dsInfo *models.DataSource) (tsdb.TsdbQueryEndpoint, error) {
-			return wrapper.NewDatasourcePluginWrapperV2(logger, p.Id, p.Type, client.DataPlugin), nil
-		})
-	}
-
-	return nil
-}
-
-// ...
-// Wrapper Code
-// ...
-
-func NewTransformWrapper(log log.Logger, plugin sdkgrpcplugin.TransformClient) *TransformWrapper {
-	return &TransformWrapper{plugin, log, &transformCallback{log}}
-}
-
-type TransformWrapper struct {
-	sdkgrpcplugin.TransformClient
-	logger   log.Logger
-	Callback *transformCallback
-}
-
-func (tw *TransformWrapper) Transform(ctx context.Context, query *tsdb.TsdbQuery) (*tsdb.Response, error) {
-	pbQuery := &pluginv2.QueryDataRequest{
-		PluginContext: &pluginv2.PluginContext{
-			// TODO: Things probably
-		},
-		Queries: []*pluginv2.DataQuery{},
-	}
-
-	for _, q := range query.Queries {
-		modelJSON, err := q.Model.MarshalJSON()
-		if err != nil {
-			return nil, err
-		}
-		pbQuery.Queries = append(pbQuery.Queries, &pluginv2.DataQuery{
-			Json:          modelJSON,
-			IntervalMS:    q.IntervalMs,
-			RefId:         q.RefId,
-			MaxDataPoints: q.MaxDataPoints,
-			QueryType:     q.QueryType,
-			TimeRange: &pluginv2.TimeRange{
-				ToEpochMS:   query.TimeRange.GetToAsMsEpoch(),
-				FromEpochMS: query.TimeRange.GetFromAsMsEpoch(),
-			},
-		})
-	}
-	pbRes, err := tw.TransformClient.TransformData(ctx, pbQuery, tw.Callback)
-	if err != nil {
-		return nil, err
-	}
-
-	tR := &tsdb.Response{
-		Results: make(map[string]*tsdb.QueryResult, len(pbRes.Responses)),
-	}
-	for refID, res := range pbRes.Responses {
-		tRes := &tsdb.QueryResult{
-			RefId:      refID,
-			Dataframes: tsdb.NewEncodedDataFrames(res.Frames),
-		}
-		if len(res.JsonMeta) != 0 {
-			tRes.Meta = simplejson.NewFromAny(res.JsonMeta)
-		}
-		if res.Error != "" {
-			tRes.Error = fmt.Errorf(res.Error)
-			tRes.ErrorString = res.Error
-		}
-		tR.Results[refID] = tRes
-	}
-
-	return tR, nil
-}
-
-type transformCallback struct {
-	logger log.Logger
-}
-
-func (s *transformCallback) QueryData(ctx context.Context, req *pluginv2.QueryDataRequest) (*pluginv2.QueryDataResponse, error) {
-	if len(req.Queries) == 0 {
-		return nil, fmt.Errorf("zero queries found in datasource request")
-	}
-
-	datasourceID := int64(0)
-
-	if req.PluginContext.DataSourceInstanceSettings != nil {
-		datasourceID = req.PluginContext.DataSourceInstanceSettings.Id
-	}
-
-	getDsInfo := &models.GetDataSourceByIdQuery{
-		OrgId: req.PluginContext.OrgId,
-		Id:    datasourceID,
-	}
-
-	if err := bus.Dispatch(getDsInfo); err != nil {
-		return nil, fmt.Errorf("could not find datasource: %w", err)
-	}
-
-	// Convert plugin-model (datasource) queries to tsdb queries
-	queries := make([]*tsdb.Query, len(req.Queries))
-	for i, query := range req.Queries {
-		sj, err := simplejson.NewJson(query.Json)
-		if err != nil {
-			return nil, err
-		}
-		queries[i] = &tsdb.Query{
-			RefId:         query.RefId,
-			IntervalMs:    query.IntervalMS,
-			MaxDataPoints: query.MaxDataPoints,
-			QueryType:     query.QueryType,
-			DataSource:    getDsInfo.Result,
-			Model:         sj,
-		}
-	}
-
-	// For now take Time Range from first query.
-	timeRange := tsdb.NewTimeRange(strconv.FormatInt(req.Queries[0].TimeRange.FromEpochMS, 10), strconv.FormatInt(req.Queries[0].TimeRange.ToEpochMS, 10))
-
-	tQ := &tsdb.TsdbQuery{
-		TimeRange: timeRange,
-		Queries:   queries,
-	}
-
-	// Execute the converted queries
-	tsdbRes, err := tsdb.HandleRequest(ctx, getDsInfo.Result, tQ)
-	if err != nil {
-		return nil, err
-	}
-	// Convert tsdb results (map) to plugin-model/datasource (slice) results.
-	// Only error, tsdb.Series, and encoded Dataframes responses are mapped.
-	responses := make(map[string]*pluginv2.DataResponse, len(tsdbRes.Results))
-	for refID, res := range tsdbRes.Results {
-		pRes := &pluginv2.DataResponse{}
-		if res.Error != nil {
-			pRes.Error = res.Error.Error()
-		}
-
-		if res.Dataframes != nil {
-			encoded, err := res.Dataframes.Encoded()
-			if err != nil {
-				return nil, err
-			}
-			pRes.Frames = encoded
-			responses[refID] = pRes
-			continue
-		}
-
-		for _, series := range res.Series {
-			frame, err := tsdb.SeriesToFrame(series)
-			frame.RefID = refID
-			if err != nil {
-				return nil, err
-			}
-			encFrame, err := frame.MarshalArrow()
-			if err != nil {
-				return nil, err
-			}
-			pRes.Frames = append(pRes.Frames, encFrame)
-		}
-		if res.Meta != nil {
-			b, err := res.Meta.MarshalJSON()
-			if err != nil {
-				s.logger.Error("failed to marshal json metadata", err)
-			}
-			pRes.JsonMeta = b
-		}
-		responses[refID] = pRes
-	}
-	return &pluginv2.QueryDataResponse{
-		Responses: responses,
-	}, nil
-}

pkg/services/ngalert/eval/alert_query.go

@@ -5,15 +5,13 @@ import (
 	"fmt"
 	"time"
 
-	"github.com/grafana/grafana-plugin-sdk-go/genproto/pluginv2"
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana/pkg/expr"
 )
 
 const defaultMaxDataPoints float64 = 100
 const defaultIntervalMS float64 = 1000
 
-// DefaultExprDatasourceID is the datasource identifier for expressions.:w
-const DefaultExprDatasourceID = -100
-
 // Duration is a type used for marshalling durations.
 type Duration time.Duration
 
@@ -51,10 +49,10 @@ func (rtr *RelativeTimeRange) isValid() bool {
 	return rtr.From > rtr.To
 }
 
-func (rtr *RelativeTimeRange) toTimeRange(now time.Time) *pluginv2.TimeRange {
+func (rtr *RelativeTimeRange) toTimeRange(now time.Time) backend.TimeRange {
-	return &pluginv2.TimeRange{
+	return backend.TimeRange{
-		FromEpochMS: now.Add(-time.Duration(rtr.From)).UnixNano() / 1e6,
+		From: now.Add(-time.Duration(rtr.From)),
-		ToEpochMS:   now.Add(-time.Duration(rtr.To)).UnixNano() / 1e6,
+		To:   now.Add(-time.Duration(rtr.To)),
 	}
 }
 
@@ -103,9 +101,9 @@ func (aq *AlertQuery) setDatasource() error {
 		return fmt.Errorf("failed to get datasource from query model")
 	}
 
-	if dsName == "__expr__" {
+	if dsName == expr.DatasourceName {
-		aq.DatasourceID = DefaultExprDatasourceID
+		aq.DatasourceID = expr.DatasourceID
-		aq.modelProps["datasourceId"] = DefaultExprDatasourceID
+		aq.modelProps["datasourceId"] = expr.DatasourceID
 		return nil
 	}
 
@@ -127,7 +125,7 @@ func (aq *AlertQuery) IsExpression() (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	return aq.DatasourceID == DefaultExprDatasourceID, nil
+	return aq.DatasourceID == expr.DatasourceID, nil
 }
 
 // setMaxDatapoints sets the model maxDataPoints if it's missing or invalid
@@ -194,6 +192,19 @@ func (aq *AlertQuery) getIntervalMS() (int64, error) {
 	return int64(intervalMs), nil
 }
 
+func (aq *AlertQuery) getIntervalDuration() (time.Duration, error) {
+	err := aq.setIntervalMS()
+	if err != nil {
+		return 0, err
+	}
+
+	intervalMs, ok := aq.modelProps["intervalMs"].(float64)
+	if !ok {
+		return 0, fmt.Errorf("failed to cast intervalMs to float64: %v", aq.modelProps["intervalMs"])
+	}
+	return time.Duration(intervalMs) * time.Millisecond, nil
+}
+
 // GetDatasource returns the query datasource identifier.
 func (aq *AlertQuery) GetDatasource() (int64, error) {
 	err := aq.setDatasource()

pkg/services/ngalert/eval/alert_query_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -32,8 +33,8 @@ func TestAlertQuery(t *testing.T) {
 				}`),
 			},
 			expectedIsExpression: true,
-			expectedDatasource:   "__expr__",
+			expectedDatasource:   expr.DatasourceName,
-			expectedDatasourceID: int64(DefaultExprDatasourceID),
+			expectedDatasourceID: int64(expr.DatasourceID),
 			expectedMaxPoints:    int64(defaultMaxDataPoints),
 			expectedIntervalMS:   int64(defaultIntervalMS),
 		},

pkg/services/ngalert/eval/eval.go

@@ -7,11 +7,10 @@ import (
 	"fmt"
 	"time"
 
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
 	"github.com/grafana/grafana-plugin-sdk-go/data"
-	"github.com/grafana/grafana-plugin-sdk-go/genproto/pluginv2"
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/grafana/grafana/pkg/models"
-	"github.com/grafana/grafana/pkg/plugins"
-	"github.com/grafana/grafana/pkg/tsdb"
 )
 
 // invalidEvalResultFormatError is an error for invalid format of the alert definition evaluation results.
@@ -99,11 +98,11 @@ func (c *Condition) Execute(ctx AlertExecCtx, fromStr, toStr string) (*Execution
 		return nil, fmt.Errorf("invalid conditions")
 	}
 
-	pbQuery := &pluginv2.QueryDataRequest{
+	queryDataReq := &backend.QueryDataRequest{
-		PluginContext: &pluginv2.PluginContext{
+		PluginContext: backend.PluginContext{
 			// TODO: Things probably
 		},
-		Queries: []*pluginv2.DataQuery{},
+		Queries: []backend.DataQuery{},
 	}
 
 	for i := range c.QueriesAndExpressions {
@@ -112,7 +111,7 @@ func (c *Condition) Execute(ctx AlertExecCtx, fromStr, toStr string) (*Execution
 		if err != nil {
 			return nil, fmt.Errorf("failed to get query model: %w", err)
 		}
-		intervalMS, err := q.getIntervalMS()
+		interval, err := q.getIntervalDuration()
 		if err != nil {
 			return nil, fmt.Errorf("failed to retrieve intervalMs from the model: %w", err)
 		}
@@ -122,18 +121,17 @@ func (c *Condition) Execute(ctx AlertExecCtx, fromStr, toStr string) (*Execution
 			return nil, fmt.Errorf("failed to retrieve maxDatapoints from the model: %w", err)
 		}
 
-		pbQuery.Queries = append(pbQuery.Queries, &pluginv2.DataQuery{
+		queryDataReq.Queries = append(queryDataReq.Queries, backend.DataQuery{
-			Json:          model,
+			JSON:          model,
-			IntervalMS:    intervalMS,
+			Interval:      interval,
-			RefId:         q.RefID,
+			RefID:         q.RefID,
 			MaxDataPoints: maxDatapoints,
 			QueryType:     q.QueryType,
 			TimeRange:     q.RelativeTimeRange.toTimeRange(time.Now()),
 		})
 	}
 
-	tw := plugins.Transform
+	pbRes, err := expr.TransformData(ctx.Ctx, queryDataReq)
-	pbRes, err := tw.TransformClient.TransformData(ctx.Ctx, pbQuery, tw.Callback)
 	if err != nil {
 		return &result, err
 	}
@@ -142,12 +140,7 @@ func (c *Condition) Execute(ctx AlertExecCtx, fromStr, toStr string) (*Execution
 		if refID != c.RefID {
 			continue
 		}
-		df := tsdb.NewEncodedDataFrames(res.Frames)
+		result.Results = res.Frames
-		result.Results, err = df.Decoded()
-		if err != nil {
-			result.Error = err
-			return &result, err
-		}
 	}
 
 	if len(result.Results) == 0 {

pkg/services/ngalert/validator.go

@@ -3,8 +3,8 @@ package ngalert
 import (
 	"fmt"
 
+	"github.com/grafana/grafana/pkg/expr"
 	"github.com/grafana/grafana/pkg/models"
-	"github.com/grafana/grafana/pkg/services/ngalert/eval"
 )
 
 // validateAlertDefinition validates that the alert definition contains at least one alert query
@@ -20,7 +20,7 @@ func (ng *AlertNG) validateAlertDefinition(alertDefinition *AlertDefinition, sig
 			return err
 		}
 
-		if datasourceID == eval.DefaultExprDatasourceID {
+		if datasourceID == expr.DatasourceID {
 			return nil
 		}
 

pkg/tsdb/sqleng/sql_engine.go

@@ -55,8 +55,8 @@ var engineCache = engineCacheType{
 
 var sqlIntervalCalculator = tsdb.NewIntervalCalculator(nil)
 
-//nolint:gocritic
 // NewXormEngine is an xorm.Engine factory, that can be stubbed by tests.
+//nolint:gocritic
 var NewXormEngine = func(driverName string, connectionString string) (*xorm.Engine, error) {
 	return xorm.NewEngine(driverName, connectionString)
 }

plugins-bundled/external.json

@@ -1,9 +1,3 @@
 {
-  "plugins": [
+  "plugins": []
-    {
-      "name": "gel",
-      "version": "0.6.0",
-      "checksum": "eeab73565b0f167d3d576dc6da86d53419bff5bbb2ea927fae1cc2fe4b52f55f"
-    }
-  ]
 }

public/app/features/expressions/ExpressionQueryEditor.tsx

@@ -97,7 +97,7 @@ export class ExpressionQueryEditor extends PureComponent<Props, State> {
     const { query, onChange } = this.props;
     onChange({
       ...query,
-      rule: item.value!,
+      window: item.value!,
     });
   };
 
@@ -109,11 +109,11 @@ export class ExpressionQueryEditor extends PureComponent<Props, State> {
     });
   };
 
-  onRuleChange = (evt: ChangeEvent<any>) => {
+  onWindowChange = (evt: ChangeEvent<any>) => {
     const { query, onChange } = this.props;
     onChange({
       ...query,
-      rule: evt.target.value,
+      window: evt.target.value,
     });
   };
 
@@ -150,7 +150,7 @@ export class ExpressionQueryEditor extends PureComponent<Props, State> {
               <Input onChange={this.onExpressionChange} value={query.expression} width={25} />
             </InlineField>
             <InlineField label="Window">
-              <Input onChange={this.onRuleChange} value={query.rule} width={25} />
+              <Input onChange={this.onWindowChange} value={query.window} width={25} />
             </InlineField>
             <InlineField label="Downsample">
               <Select options={downsamplingTypes} value={downsampler} onChange={this.onSelectDownsampler} width={25} />

public/app/features/expressions/types.ts

@@ -14,7 +14,7 @@ export interface ExpressionQuery extends DataQuery {
   type: GELQueryType;
   reducer?: string;
   expression?: string;
-  rule?: string;
+  window?: string;
   downsampler?: string;
   upsampler?: string;
 }