Generate return types

internal/funcs/0.12/funcgen/gen.go

@@ -5,34 +5,38 @@ import (
 	"log"
 	"os"
 	"text/template"
+
+	"github.com/zclconf/go-cty/cty"
+	"github.com/zclconf/go-cty/cty/function"
+	"github.com/zclconf/go-cty/cty/function/stdlib"
 )
 
-type function struct {
+type fun struct {
 	Name         string
 	InternalName string
-	ReturnType   string
+	Function     function.Function
 }
 
-var functions = []function{
+var functions = []fun{
 	{
 		Name:         "csvdecode",
 		InternalName: "CSVDecodeFunc",
-		ReturnType:   "cty.DynamicPseudoType",
+		Function:     stdlib.CSVDecodeFunc,
 	},
 	{
 		Name:         "formatdate",
 		InternalName: "FormatDateFunc",
-		ReturnType:   "cty.String",
+		Function:     stdlib.FormatDateFunc,
 	},
 	{
 		Name:         "jsondecode",
 		InternalName: "JSONDecodeFunc",
-		ReturnType:   "cty.DynamicPseudoType",
+		Function:     stdlib.JSONDecodeFunc,
 	},
 	{
 		Name:         "reverse",
 		InternalName: "ReverseListFunc",
-		ReturnType:   "cty.DynamicPseudoType",
+		Function:     stdlib.ReverseListFunc,
 	},
 }
 
@@ -65,20 +69,22 @@ func BaseFunctions() map[string]schema.FuncSignature {
 		"{{ .Name }}": {
 			Params:      stdlib.{{ .InternalName }}.Params(),
 			VarParam:    stdlib.{{ .InternalName }}.VarParam(),
-			ReturnTypes: {{ .ReturnType }}, // TODO use stdlib.FormatDateFunc.ReturnType(cty.DynamicPseudoType)
+			ReturnTypes: {{ getReturnType .Function }},
 			Description: stdlib.{{ .InternalName }}.Description(),
 		},	
 {{- end }}
 	}
 }
 `
-	tpl, err := template.New("output").Parse(outputTpl)
+	tpl, err := template.New("output").Funcs(template.FuncMap{
+		"getReturnType": getReturnType,
+	}).Parse(outputTpl)
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	type data struct {
-		Functions []function
+		Functions []fun
 	}
 
 	err = tpl.Execute(output, data{
@@ -88,3 +94,19 @@ func BaseFunctions() map[string]schema.FuncSignature {
 		log.Fatal(err)
 	}
 }
+
+func getReturnType(f function.Function) (string, error) {
+	args := make([]cty.Type, 0)
+	for _, param := range f.Params() {
+		args = append(args, param.Type)
+	}
+	if f.VarParam() != nil {
+		args = append(args, f.VarParam().Type)
+	}
+
+	returnType, err := f.ReturnType(args)
+	if err != nil {
+		return "", err
+	}
+	return returnType.GoString(), nil
+}