repl: fix formatting of list and map values

The indent function was stripping out newlines, causing multi-element
lists and maps to be rendered incorrectly.

We were also not quoting strings in these nested structures, leading to
weird behavior if any expression punctuation or newlines were present in
these strings.

This part of Terraform will get a more serious overhaul as part of
switching to the new parser/interpreter implementation but this is a
tactical fix to make the results of this command more usable in the
short term.

repl/format.go

@@ -13,12 +13,15 @@ import (
 // The value must currently be a string, list, map, and any nested values
 // with those same types.
 func FormatResult(value interface{}) (string, error) {
-	return formatResult(value)
+	return formatResult(value, false)
 }
 
-func formatResult(value interface{}) (string, error) {
+func formatResult(value interface{}, nested bool) (string, error) {
 	switch output := value.(type) {
 	case string:
+		if nested {
+			return fmt.Sprintf("%q", output), nil
+		}
 		return output, nil
 	case []interface{}:
 		return formatListResult(output)
@@ -36,18 +39,14 @@ func formatListResult(value []interface{}) (string, error) {
 		outputBuf.WriteString("\n")
 	}
 
-	lastIdx := len(value) - 1
-	for i, v := range value {
-		raw, err := formatResult(v)
+	for _, v := range value {
+		raw, err := formatResult(v, true)
 		if err != nil {
 			return "", err
 		}
 
 		outputBuf.WriteString(indent(raw))
-		if lastIdx != i {
-			outputBuf.WriteString(",")
-		}
-		outputBuf.WriteString("\n")
+		outputBuf.WriteString(",\n")
 	}
 
 	outputBuf.WriteString("]")
@@ -69,12 +68,17 @@ func formatMapResult(value map[string]interface{}) (string, error) {
 
 	for _, k := range ks {
 		v := value[k]
-		raw, err := formatResult(v)
+		rawK, err := formatResult(k, true)
+		if err != nil {
+			return "", err
+		}
+		rawV, err := formatResult(v, true)
 		if err != nil {
 			return "", err
 		}
 
-		outputBuf.WriteString(indent(fmt.Sprintf("%s = %v\n", k, raw)))
+		outputBuf.WriteString(indent(fmt.Sprintf("%s = %s", rawK, rawV)))
+		outputBuf.WriteString("\n")
 	}
 
 	outputBuf.WriteString("}")
@@ -84,8 +88,13 @@ func formatMapResult(value map[string]interface{}) (string, error) {
 func indent(value string) string {
 	var outputBuf bytes.Buffer
 	s := bufio.NewScanner(strings.NewReader(value))
+	newline := false
 	for s.Scan() {
+		if newline {
+			outputBuf.WriteByte('\n')
+		}
 		outputBuf.WriteString("  " + s.Text())
+		newline = true
 	}
 
 	return outputBuf.String()