opentofu/terraform/graph_walk.go
Martin Atkins c937c06a03 terraform: ugly huge change to weave in new HCL2-oriented types
Due to how deeply the configuration types go into Terraform Core, there
isn't a great way to switch out to HCL2 gradually. As a consequence, this
huge commit gets us from the old state to a _compilable_ new state, but
does not yet attempt to fix any tests and has a number of known missing
parts and bugs. We will continue to iterate on this in forthcoming
commits, heading back towards passing tests and making Terraform
fully-functional again.

The three main goals here are:
- Use the configuration models from the "configs" package instead of the
  older models in the "config" package, which is now deprecated and
  preserved only to help us write our migration tool.
- Do expression inspection and evaluation using the functionality of the
  new "lang" package, instead of the Interpolator type and related
  functionality in the main "terraform" package.
- Represent addresses of various objects using types in the addrs package,
  rather than hand-constructed strings. This is not critical to support
  the above, but was a big help during the implementation of these other
  points since it made it much more explicit what kind of address is
  expected in each context.

Since our new packages are built to accommodate some future planned
features that are not yet implemented (e.g. the "for_each" argument on
resources, "count"/"for_each" on modules), and since there's still a fair
amount of functionality still using old-style APIs, there is a moderate
amount of shimming here to connect new assumptions with old, hopefully in
a way that makes it easier to find and eliminate these shims later.

I apologize in advance to the person who inevitably just found this huge
commit while spelunking through the commit history.
2018-10-16 18:46:46 -07:00

63 lines
2.4 KiB
Go

package terraform
import (
"github.com/hashicorp/terraform/addrs"
"github.com/hashicorp/terraform/dag"
"github.com/hashicorp/terraform/tfdiags"
)
// GraphWalker is an interface that can be implemented that when used
// with Graph.Walk will invoke the given callbacks under certain events.
type GraphWalker interface {
EnterPath(addrs.ModuleInstance) EvalContext
ExitPath(addrs.ModuleInstance)
EnterVertex(dag.Vertex)
ExitVertex(dag.Vertex, tfdiags.Diagnostics)
EnterEvalTree(dag.Vertex, EvalNode) EvalNode
ExitEvalTree(dag.Vertex, interface{}, error) tfdiags.Diagnostics
}
// GrpahWalkerPanicwrapper can be optionally implemented to catch panics
// that occur while walking the graph. This is not generally recommended
// since panics should crash Terraform and result in a bug report. However,
// this is particularly useful for situations like the shadow graph where
// you don't ever want to cause a panic.
type GraphWalkerPanicwrapper interface {
GraphWalker
// Panic is called when a panic occurs. This will halt the panic from
// propogating so if the walker wants it to crash still it should panic
// again. This is called from within a defer so runtime/debug.Stack can
// be used to get the stack trace of the panic.
Panic(dag.Vertex, interface{})
}
// GraphWalkerPanicwrap wraps an existing Graphwalker to wrap and swallow
// the panics. This doesn't lose the panics since the panics are still
// returned as errors as part of a graph walk.
func GraphWalkerPanicwrap(w GraphWalker) GraphWalkerPanicwrapper {
return &graphWalkerPanicwrapper{
GraphWalker: w,
}
}
type graphWalkerPanicwrapper struct {
GraphWalker
}
func (graphWalkerPanicwrapper) Panic(dag.Vertex, interface{}) {}
// NullGraphWalker is a GraphWalker implementation that does nothing.
// This can be embedded within other GraphWalker implementations for easily
// implementing all the required functions.
type NullGraphWalker struct{}
func (NullGraphWalker) EnterPath(addrs.ModuleInstance) EvalContext { return new(MockEvalContext) }
func (NullGraphWalker) ExitPath(addrs.ModuleInstance) {}
func (NullGraphWalker) EnterVertex(dag.Vertex) {}
func (NullGraphWalker) ExitVertex(dag.Vertex, tfdiags.Diagnostics) {}
func (NullGraphWalker) EnterEvalTree(v dag.Vertex, n EvalNode) EvalNode { return n }
func (NullGraphWalker) ExitEvalTree(dag.Vertex, interface{}, error) tfdiags.Diagnostics {
return nil
}