generate plugin clients via template

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

plugins/pluginrpc-gen/template.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"strings"
+	"text/template"
+)
+
+func printArgs(args []arg) string {
+	var argStr []string
+	for _, arg := range args {
+		argStr = append(argStr, arg.String())
+	}
+	return strings.Join(argStr, ", ")
+}
+
+func marshalType(t string) string {
+	switch t {
+	case "error":
+		// convert error types to plain strings to ensure the values are encoded/decoded properly
+		return "string"
+	default:
+		return t
+	}
+}
+
+func isErr(t string) bool {
+	switch t {
+	case "error":
+		return true
+	default:
+		return false
+	}
+}
+
+// Need to use this helper due to issues with go-vet
+func buildTag(s string) string {
+	return "+build " + s
+}
+
+var templFuncs = template.FuncMap{
+	"printArgs":   printArgs,
+	"marshalType": marshalType,
+	"isErr":       isErr,
+	"lower":       strings.ToLower,
+	"title":       strings.Title,
+	"tag":         buildTag,
+}
+
+var generatedTempl = template.Must(template.New("rpc_cient").Funcs(templFuncs).Parse(`
+// generated code - DO NOT EDIT
+{{ range $k, $v := .BuildTags }}
+	// {{ tag $k }} {{ end }}
+
+package {{ .Name }}
+
+import "errors"
+
+type client interface{
+	Call(string, interface{}, interface{}) error
+}
+
+type {{ .InterfaceType }}Proxy struct {
+	client
+}
+
+{{ range .Functions }}
+	type {{ $.InterfaceType }}Proxy{{ .Name }}Request struct{
+		{{ range .Args }}
+			{{ title .Name }} {{ .ArgType }} {{ end }}
+	}
+
+	type {{ $.InterfaceType }}Proxy{{ .Name }}Response struct{
+		{{ range .Returns }}
+			{{ title .Name }} {{ marshalType .ArgType }} {{ end }}
+	}
+
+	func (pp *{{ $.InterfaceType }}Proxy) {{ .Name }}({{ printArgs .Args }}) ({{ printArgs .Returns }}) {
+		var(
+			req {{ $.InterfaceType }}Proxy{{ .Name }}Request
+			ret {{ $.InterfaceType }}Proxy{{ .Name }}Response
+		)
+		{{ range .Args }}
+			req.{{ title .Name }} = {{ lower .Name }} {{ end }}
+		if err = pp.Call("{{ $.RPCName }}.{{ .Name }}", req, &ret); err != nil {
+			return
+		}
+		{{ range $r := .Returns }}
+			{{ if isErr .ArgType }}
+				if ret.{{ title .Name }} != "" {
+					{{ lower .Name }} = errors.New(ret.{{ title .Name }})
+				} {{ end }}
+			{{ if isErr .ArgType | not }} {{ lower .Name }} = ret.{{ title .Name }} {{ end }} {{ end }}
+
+		return
+	}
+{{ end }}
+`))