godoc: support Playground examples on App Engine

Updates setup-godoc-app.bash to produce a working godoc app
by substituting the go1.0.x go/... packages with those from tip.

R=gri
CC=golang-dev
https://golang.org/cl/6587080

src/cmd/godoc/appinit.go

@@ -37,6 +37,7 @@ func init() {
 	*indexFiles = indexFilenames
 	*maxResults = 100    // reduce latency by limiting the number of fulltext search results
 	*indexThrottle = 0.3 // in case *indexFiles is empty (and thus the indexer is run)
+	*showPlayground = true
 
 	// read .zip file and set up file systems
 	const zipfile = zipFilename
@@ -51,6 +52,7 @@ func init() {
 	readTemplates()
 	initHandlers()
 	registerPublicHandlers(http.DefaultServeMux)
+	registerPlaygroundHandlers(http.DefaultServeMux)
 
 	// initialize default directory tree with corresponding timestamp.
 	initFSTree()

src/cmd/godoc/main.go

@@ -282,14 +282,7 @@ func main() {
 		}
 
 		registerPublicHandlers(http.DefaultServeMux)
-
-		playHandler := disabledHandler
-		if *showPlayground {
-			playHandler = bounceToPlayground
-		}
-		http.HandleFunc("/compile", playHandler)
-		http.HandleFunc("/share", playHandler)
-		http.HandleFunc("/fmt", playHandler)
+		registerPlaygroundHandlers(http.DefaultServeMux)
 
 		// Initialize default directory tree with corresponding timestamp.
 		// (Do it in a goroutine so that launch is quick.)
@@ -469,25 +462,3 @@ type httpWriter struct {
 
 func (w *httpWriter) Header() http.Header  { return w.h }
 func (w *httpWriter) WriteHeader(code int) { w.code = code }
-
-// bounceToPlayground forwards the request to play.golang.org.
-// TODO(adg): implement this stuff locally.
-func bounceToPlayground(w http.ResponseWriter, req *http.Request) {
-	defer req.Body.Close()
-	req.URL.Scheme = "http"
-	req.URL.Host = "play.golang.org"
-	resp, err := http.Post(req.URL.String(), req.Header.Get("Content-type"), req.Body)
-	if err != nil {
-		http.Error(w, err.Error(), 500)
-		return
-	}
-	w.WriteHeader(resp.StatusCode)
-	io.Copy(w, resp.Body)
-	resp.Body.Close()
-}
-
-// disabledHandler serves a 501 "Not Implemented" response.
-func disabledHandler(w http.ResponseWriter, r *http.Request) {
-	w.WriteHeader(http.StatusNotImplemented)
-	fmt.Fprint(w, "This functionality is not available via local godoc.")
-}

src/cmd/godoc/play-appengine.go

+// 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.
+
+// App Engine godoc Playground functionality.
+
+// +build appengine
+
+package main
+
+import (
+	"io"
+	"net/http"
+
+	"appengine"
+	"appengine/urlfetch"
+)
+
+func bounceToPlayground(w http.ResponseWriter, req *http.Request) {
+	c := appengine.NewContext(req)
+	client := urlfetch.Client(c)
+	url := playgroundBaseURL + req.URL.Path
+	defer req.Body.Close()
+	resp, err := client.Post(url, req.Header.Get("Content-type"), req.Body)
+	if err != nil {
+		http.Error(w, "Internal Server Error", 500)
+		c.Errorf("making POST request:", err)
+		return
+	}
+	defer resp.Body.Close()
+	if _, err := io.Copy(w, resp.Body); err != nil {
+		http.Error(w, "Internal Server Error", 500)
+		c.Errorf("making POST request:", err)
+	}
+}

src/cmd/godoc/play-local.go

+// 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.
+
+// Stand-alone godoc Playground functionality.
+
+// +build !appengine
+
+package main
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+)
+
+var playgroundScheme, playgroundHost string
+
+func init() {
+	u, err := url.Parse(playgroundBaseURL)
+	if err != nil {
+		panic(err)
+	}
+	playgroundScheme = u.Scheme
+	playgroundHost = u.Host
+}
+
+// bounceToPlayground forwards the request to play.golang.org.
+func bounceToPlayground(w http.ResponseWriter, req *http.Request) {
+	defer req.Body.Close()
+	req.URL.Scheme = playgroundScheme
+	req.URL.Host = playgroundHost
+	resp, err := http.Post(req.URL.String(), req.Header.Get("Content-type"), req.Body)
+	if err != nil {
+		http.Error(w, err.Error(), 500)
+		return
+	}
+	w.WriteHeader(resp.StatusCode)
+	io.Copy(w, resp.Body)
+	resp.Body.Close()
+}

src/cmd/godoc/play.go

+// 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.
+
+// Common Playground functionality.
+
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/printer"
+	"go/token"
+	"net/http"
+)
+
+// The server that will service compile and share requests.
+const playgroundBaseURL = "http://play.golang.org"
+
+func registerPlaygroundHandlers(mux *http.ServeMux) {
+	if *showPlayground {
+		mux.HandleFunc("/compile", bounceToPlayground)
+		mux.HandleFunc("/share", bounceToPlayground)
+	} else {
+		mux.HandleFunc("/compile", disabledHandler)
+		mux.HandleFunc("/share", disabledHandler)
+	}
+	http.HandleFunc("/fmt", fmtHandler)
+}
+
+type fmtResponse struct {
+	Body  string
+	Error string
+}
+
+// fmtHandler takes a Go program in its "body" form value, formats it with
+// standard gofmt formatting, and writes a fmtResponse as a JSON object.
+func fmtHandler(w http.ResponseWriter, r *http.Request) {
+	resp := new(fmtResponse)
+	body, err := gofmt(r.FormValue("body"))
+	if err != nil {
+		resp.Error = err.Error()
+	} else {
+		resp.Body = body
+	}
+	json.NewEncoder(w).Encode(resp)
+}
+
+// gofmt takes a Go program, formats it using the standard Go formatting
+// rules, and returns it or an error.
+func gofmt(body string) (string, error) {
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "prog.go", body, parser.ParseComments)
+	if err != nil {
+		return "", err
+	}
+	ast.SortImports(fset, f)
+	var buf bytes.Buffer
+	err = printer.Fprint(&buf, fset, f)
+	if err != nil {
+		return "", err
+	}
+	return buf.String(), nil
+}
+
+// disabledHandler serves a 501 "Not Implemented" response.
+func disabledHandler(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusNotImplemented)
+	fmt.Fprint(w, "This functionality is not available via local godoc.")
+}

src/cmd/godoc/setup-godoc-app.bash

@@ -4,13 +4,14 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-# This script creates the .zip, index, and configuration files for running
-# godoc on app-engine.
+# This script creates a complete godoc app in $APPDIR.
+# It copies the cmd/godoc and src/pkg/go/... sources from GOROOT,
+# synthesizes an app.yaml file, and creates the .zip, index, and
+# configuration files.
 #
 # If an argument is provided it is assumed to be the app-engine godoc directory.
-# Without an argument, $APPDIR is used instead. If GOROOT is not set, the
-# current working directory is assumed to be $GOROOT. Various sanity checks
-# prevent accidents.
+# Without an argument, $APPDIR is used instead. If GOROOT is not set, "go env"
+# is consulted to find the $GOROOT.
 #
 # The script creates a .zip file representing the $GOROOT file system
 # and computes the correspondig search index files. These files are then
@@ -29,8 +30,8 @@ error() {
 
 getArgs() {
 	if [ -z $GOROOT ]; then
-		GOROOT=$(pwd)
-		echo "GOROOT not set, using cwd instead"
+		GOROOT=$(go env GOROOT)
+		echo "GOROOT not set explicitly, using $GOROOT instead"
 	fi
 	if [ -z $APPDIR ]; then
 		if [ $# == 0 ]; then
@@ -47,14 +48,8 @@ getArgs() {
 	if [ ! -x $GOROOT/bin/godoc ]; then
 		error "$GOROOT/bin/godoc does not exist or is not executable"
 	fi
-	if [ ! -d $APPDIR ]; then
-		error "$APPDIR is not a directory"
-	fi
-	if [ ! -e $APPDIR/app.yaml ]; then
-		error "$APPDIR is not an app-engine directory; missing file app.yaml"
-	fi
-	if [ ! -d $APPDIR/godoc ]; then
-		error "$APPDIR is missing directory godoc"
+	if [ -e $APPDIR ]; then
+		error "$APPDIR exists; check and remove it before trying again"
 	fi
 
 	# reporting
@@ -62,12 +57,32 @@ getArgs() {
 	echo "APPDIR = $APPDIR"
 }
 
-cleanup() {
-	echo "*** cleanup $APPDIR"
-	rm $APPDIR/$ZIPFILE
-	rm $APPDIR/$INDEXFILE
-	rm $APPDIR/$SPLITFILES*
-	rm $APPDIR/$CONFIGFILE
+copyGodoc() {
+	echo "*** copy $GOROOT/src/cmd/godoc to $APPDIR/godoc"
+	cp -r $GOROOT/src/cmd/godoc $APPDIR/godoc
+}
+
+copyGoPackages() {
+	echo "*** copy $GOROOT/src/pkg/go to $APPDIR/newgo and rewrite imports"
+	cp -r $GOROOT/src/pkg/go $APPDIR/newgo
+	find $APPDIR/newgo -type d -name testdata | xargs rm -r
+	gofiles=$(find $APPDIR -name '*.go')
+	sed -i '' 's_^\(."\)\(go/[a-z]*\)"$_\1new\2"_' $gofiles
+	sed -i '' 's_^\(import "\)\(go/[a-z]*\)"$_\1new\2"_' $gofiles
+}
+
+makeAppYaml() {
+	echo "*** make $APPDIR/app.yaml"
+	cat > $APPDIR/app.yaml <<EOF
+application: godoc
+version: 1
+runtime: go
+api_version: go1
+
+handlers:
+- url: /.*
+  script: _go_app
+EOF
 }
 
 makeZipfile() {
@@ -112,7 +127,11 @@ EOF
 }
 
 getArgs "$@"
-cleanup
+set -e
+mkdir $APPDIR
+copyGodoc
+copyGoPackages
+makeAppYaml
 makeZipfile
 makeIndexfile
 splitIndexfile