go.tools/godoc/playground: copy playground package from go.talks

After this change is submitted the dependants on go.talks/pkg/playground
talks will be updated to use this one and the old package will be deleted.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/11759043

godoc/playground/appengine.go

@@ -0,0 +1,22 @@
+// Copyright 2012 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.
+
+// +build appengine
+
+package playground
+
+import (
+	"net/http"
+
+	"appengine"
+	"appengine/urlfetch"
+)
+
+func client(r *http.Request) *http.Client {
+	return urlfetch.Client(appengine.NewContext(r))
+}
+
+func report(r *http.Request, err error) {
+	appengine.NewContext(r).Errorf("%v", err)
+}

godoc/playground/common.go

@@ -0,0 +1,46 @@
+// Copyright 2013 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 playground registers HTTP handlers at "/compile" and "/share" that
+// proxy requests to the golang.org playground service.
+// This package may be used unaltered on App Engine.
+package playground
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+const baseURL = "http://play.golang.org"
+
+func init() {
+	http.HandleFunc("/compile", bounce)
+	http.HandleFunc("/share", bounce)
+}
+
+func bounce(w http.ResponseWriter, r *http.Request) {
+	b := new(bytes.Buffer)
+	if err := passThru(b, r); err != nil {
+		http.Error(w, "Server error.", http.StatusInternalServerError)
+		report(r, err)
+		return
+	}
+	io.Copy(w, b)
+}
+
+func passThru(w io.Writer, req *http.Request) error {
+	defer req.Body.Close()
+	url := baseURL + req.URL.Path
+	r, err := client(req).Post(url, req.Header.Get("Content-type"), req.Body)
+	if err != nil {
+		return fmt.Errorf("making POST request: %v", err)
+	}
+	defer r.Body.Close()
+	if _, err := io.Copy(w, r.Body); err != nil {
+		return fmt.Errorf("copying response Body: %v", err)
+	}
+	return nil
+}

godoc/playground/local.go

@@ -0,0 +1,20 @@
+// Copyright 2012 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.
+
+// +build !appengine
+
+package playground
+
+import (
+	"log"
+	"net/http"
+)
+
+func client(r *http.Request) *http.Client {
+	return http.DefaultClient
+}
+
+func report(r *http.Request, err error) {
+	log.Println(err)
+}