misc: add goplay

R=rsc, r
CC=golang-dev
https://golang.org/cl/2473041

misc/goplay/Makefile

+# Copyright 2010 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.
+
+include ../../src/Make.inc
+
+TARG=goplay
+
+GOFILES=\
+	goplay.go\
+
+include ../../src/Make.cmd
+

misc/goplay/README

+See doc.go.

misc/goplay/doc.go

+// Copyright 2010 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.
+
+// Goplay is a web interface for experimenting with Go code.
+// It is similar to the Go Playground: http://golang.org/doc/play/
+// 
+// To use goplay, first build and install it:
+//   $ cd $GOROOT/misc/goplay
+//   $ gomake install
+// Then, run it:
+//   $ goplay
+// and load http://localhost:3999/ in a web browser.
+// 
+// You should see a Hello World program, which you can compile and run by
+// pressing shift-enter. There is also a "compile-on-keypress" feature that can
+// be enabled by checking a checkbox.
+// 
+// WARNING! CUIDADO! ACHTUNG! ATTENZIONE!
+// A note on security: anyone with access to the goplay web interface can run
+// arbitrary code on your computer. Goplay is not a sandbox, and has no other
+// security mechanisms. Do not deploy it in untrusted environments. 
+// By default, goplay listens only on localhost. This can be overridden with 
+// the -http parameter. Do so at your own risk.
+package documentation

misc/goplay/goplay.go

+// Copyright 2010 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 main
+
+import (
+	"bytes"
+	"exec"
+	"flag"
+	"http"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"runtime"
+	"strconv"
+	"template"
+)
+
+var (
+	httpListen = flag.String("http", "127.0.0.1:3999", "host:port to listen on")
+	htmlOutput = flag.Bool("html", false, "render program output as HTML")
+)
+
+var (
+	// a source of numbers, for naming temporary files
+	uniq = make(chan int)
+	// the architecture-identifying character of the tool chain, 5, 6, or 8
+	archChar string
+)
+
+func main() {
+	flag.Parse()
+
+	// set archChar
+	switch runtime.GOARCH {
+	case "arm":
+		archChar = "5"
+	case "amd64":
+		archChar = "6"
+	case "386":
+		archChar = "8"
+	default:
+		log.Exitln("unrecognized GOARCH:", runtime.GOARCH)
+	}
+
+	// source of unique numbers
+	go func() {
+		for i := 0; ; i++ {
+			uniq <- i
+		}
+	}()
+
+	http.HandleFunc("/", FrontPage)
+	http.HandleFunc("/compile", Compile)
+	log.Exit(http.ListenAndServe(*httpListen, nil))
+}
+
+// FrontPage is an HTTP handler that renders the goplay interface. 
+// If a filename is supplied in the path component of the URI,
+// its contents will be put in the interface's text area.
+// Otherwise, the default "hello, world" program is displayed.
+func FrontPage(w http.ResponseWriter, req *http.Request) {
+	data, err := ioutil.ReadFile(req.URL.Path[1:])
+	if err != nil {
+		data = helloWorld
+	}
+	frontPage.Execute(data, w)
+}
+
+// Compile is an HTTP handler that reads Go source code from the request,
+// compiles and links the code (returning any errors), runs the program, 
+// and sends the program's output as the HTTP response.
+func Compile(w http.ResponseWriter, req *http.Request) {
+	// x is the base name for .go, .6, executable files
+	x := "/tmp/compile" + strconv.Itoa(<-uniq)
+
+	// write request Body to x.go
+	f, err := os.Open(x+".go", os.O_CREAT|os.O_WRONLY|os.O_TRUNC, 0666)
+	if err != nil {
+		error(w, nil, err)
+		return
+	}
+	defer os.Remove(x + ".go")
+	defer f.Close()
+	_, err = io.Copy(f, req.Body)
+	if err != nil {
+		error(w, nil, err)
+		return
+	}
+	f.Close()
+
+	// build x.go, creating x.6
+	out, err := run(archChar+"g", "-o", x+"."+archChar, x+".go")
+	defer os.Remove(x + "." + archChar)
+	if err != nil {
+		error(w, out, err)
+		return
+	}
+
+	// link x.6, creating x (the program binary)
+	out, err = run(archChar+"l", "-o", x, x+"."+archChar)
+	defer os.Remove(x)
+	if err != nil {
+		error(w, out, err)
+		return
+	}
+
+	// run x
+	out, err = run(x)
+	if err != nil {
+		error(w, out, err)
+	}
+
+	// write the output of x as the http response
+	if *htmlOutput {
+		w.Write(out)
+	} else {
+		output.Execute(out, w)
+	}
+}
+
+// error writes compile, link, or runtime errors to the HTTP connection.
+// The JavaScript interface uses the 404 status code to identify the error.
+func error(w http.ResponseWriter, out []byte, err os.Error) {
+	w.WriteHeader(404)
+	if out != nil {
+		output.Execute(out, w)
+	} else {
+		output.Execute(err.String(), w)
+	}
+}
+
+// run executes the specified command and returns its output and an error.
+func run(cmd ...string) ([]byte, os.Error) {
+	// find the specified binary
+	bin, err := exec.LookPath(cmd[0])
+	if err != nil {
+		// report binary as well as the error
+		return nil, os.NewError(cmd[0] + ": " + err.String())
+	}
+
+	// run the binary and read its combined stdout and stderr into a buffer
+	p, err := exec.Run(bin, cmd, os.Environ(), "", exec.DevNull, exec.Pipe, exec.MergeWithStdout)
+	if err != nil {
+		return nil, err
+	}
+	var buf bytes.Buffer
+	io.Copy(&buf, p.Stdout)
+	w, err := p.Wait(0)
+	p.Close()
+
+	// set the error return value if the program had a non-zero exit status
+	if !w.Exited() || w.ExitStatus() != 0 {
+		err = os.ErrorString("running " + cmd[0] + ": " + w.String())
+	}
+
+	return buf.Bytes(), err
+}
+
+var frontPage, output *template.Template // HTML templates
+
+func init() {
+	frontPage = template.New(nil)
+	frontPage.SetDelims("«", "»")
+	if err := frontPage.Parse(frontPageText); err != nil {
+		panic(err)
+	}
+	output = template.MustParse(outputText, nil)
+}
+
+var outputText = `<pre>{@|html}</pre>`
+
+var frontPageText = `<!doctype html>
+<html>
+<head>
+<style>
+pre, textarea {
+	font-family: Monaco, 'Courier New', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', monospace;
+	font-size: 100%;
+}
+.hints {
+	font-size: 0.8em;
+	text-align: right;
+}
+#edit, #output, #errors { width: 100%; text-align: left; }
+#edit { height: 500px; }
+#output { color: #00c; }
+#errors { color: #c00; }
+</style>
+<script>
+
+function insertTabs(n) {
+	// find the selection start and end
+	var cont  = document.getElementById("edit");
+	var start = cont.selectionStart;
+	var end   = cont.selectionEnd;
+	// split the textarea content into two, and insert n tabs
+	var v = cont.value;
+	var u = v.substr(0, start);
+	for (var i=0; i<n; i++) {
+		u += "\t";
+	}
+	u += v.substr(end);
+	// set revised content
+	cont.value = u;
+	// reset caret position after inserted tabs
+	cont.selectionStart = start+n;
+	cont.selectionEnd = start+n;
+}
+
+function autoindent(el) {
+	var curpos = el.selectionStart;
+	var tabs = 0;
+	while (curpos > 0) {
+		curpos--;
+		if (el.value[curpos] == "\t") {
+			tabs++;
+		} else if (tabs > 0 || el.value[curpos] == "\n") {
+			break;
+		}
+	}
+	setTimeout(function() {
+		insertTabs(tabs);
+	}, 1);
+}
+
+function keyHandler() {
+	var e = window.event;
+	if (e.keyCode == 9) { // tab
+		insertTabs(1);
+		e.preventDefault();
+		return false;
+	}
+	if (e.keyCode == 13) { // enter
+		if (e.shiftKey) { // +shift
+			compile(e.target);
+			e.preventDefault();
+			return false;
+		} else {
+			autoindent(e.target);
+		}
+	}
+	return true;
+}
+
+var xmlreq;
+
+function autocompile() {
+	if(!document.getElementById("autocompile").checked) {
+		return;
+	}
+	compile();
+}
+
+function compile() {
+	var prog = document.getElementById("edit").value;
+	var req = new XMLHttpRequest();
+	xmlreq = req;
+	req.onreadystatechange = compileUpdate;
+	req.open("POST", "/compile", true);
+	req.setRequestHeader("Content-Type", "text/plain; charset=utf-8");
+	req.send(prog);	
+}
+
+function compileUpdate() {
+	var req = xmlreq;
+	if(!req || req.readyState != 4) {
+		return;
+	}
+	if(req.status == 200) {
+		document.getElementById("output").innerHTML = req.responseText;
+		document.getElementById("errors").innerHTML = "";
+	} else {
+		document.getElementById("errors").innerHTML = req.responseText;
+		document.getElementById("output").innerHTML = "";
+	}
+}
+</script>
+</head>
+<body>
+<table width="100%"><tr><td width="60%" valign="top">
+<textarea autofocus="true" id="edit" spellcheck="false" onkeydown="keyHandler();" onkeyup="autocompile();">«@|html»</textarea>
+<div class="hints">
+(Shift-Enter to compile and run.)&nbsp;&nbsp;&nbsp;&nbsp;
+<input type="checkbox" id="autocompile" value="checked" /> Compile and run after each keystroke
+</div>
+<td width="3%">
+<td width="27%" align="right" valign="top">
+<div id="output"></div>
+</table>
+<div id="errors"></div>
+</body>
+</html>
+`
+
+var helloWorld = []byte(`package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("hello, world")
+}
+`)