gotour/goplay.go - tour - Git at Google

 // 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"
 	"fmt"
 	"http"
 	"template"
 )

 func init() {
 	http.HandleFunc("/compile", Compile)
 }

 // 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) {
 	out, err := compile(req)
 	if err != nil {
 		w.WriteHeader(404)
 		var s string
 		if out != nil {
 			s = string(out)
 		} else {
 			s = err.String()
 		}
 		output.Execute(w, s)
 		return
 	}

 	// write the output of x as the http response
 	if *htmlOutput {
 		w.Write(out)
 	} else if url, ok := isImage(out); ok {
 		fmt.Fprintf(w, `<img src="%s">`, url)
 	} else {
 		output.Execute(w, out)
 	}
 }

 func isImage(out []byte) (string, bool) {
 	out = bytes.TrimSpace(out)
 	if !bytes.HasPrefix(out, []byte("IMAGE:")) {
 		return "", false
 	}
 	out = out[6:]
 	for _, c := range out {
 		switch {
 		case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z', '0' <= c && c <= '9',
 			c == '+', c == '-', c == '/', c == '_', c == '=':
 		default:
 			println("bad", c)
 			return "", false
 		}
 	}
 	return "data:image/png;base64," + string(out), true
 }

 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: monospace; /* use the user's browser setting */
 	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(event) {
 	var e = window.event || 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 = function() { compileUpdate(req); }
 	req.open("POST", "/compile", true);
 	req.setRequestHeader("Content-Type", "text/plain; charset=utf-8");
 	req.send(prog);
 	document.getElementById("output").innerHTML = "running...";
 }

 function compileUpdate(req) {
 	if(req != xmlreq || !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(event);" 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")
 }
 `)
	// 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"
	"fmt"
	"http"
	"template"
	)

	func init() {
	http.HandleFunc("/compile", Compile)
	}

	// 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) {
	out, err := compile(req)
	if err != nil {
	w.WriteHeader(404)
	var s string
	if out != nil {
	s = string(out)
	} else {
	s = err.String()
	}
	output.Execute(w, s)
	return
	}

	// write the output of x as the http response
	if *htmlOutput {
	w.Write(out)
	} else if url, ok := isImage(out); ok {
	fmt.Fprintf(w, `<img src="%s">`, url)
	} else {
	output.Execute(w, out)
	}
	}

	func isImage(out []byte) (string, bool) {
	out = bytes.TrimSpace(out)
	if !bytes.HasPrefix(out, []byte("IMAGE:")) {
	return "", false
	}
	out = out[6:]
	for _, c := range out {
	switch {
	case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z', '0' <= c && c <= '9',
	c == '+', c == '-', c == '/', c == '_', c == '=':
	default:
	println("bad", c)
	return "", false
	}
	}
	return "data:image/png;base64," + string(out), true
	}

	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: monospace; /* use the user's browser setting */
	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(event) {
	var e = window.event \|\| 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 = function() { compileUpdate(req); }
	req.open("POST", "/compile", true);
	req.setRequestHeader("Content-Type", "text/plain; charset=utf-8");
	req.send(prog);
	document.getElementById("output").innerHTML = "running...";
	}

	function compileUpdate(req) {
	if(req != xmlreq \|\| !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(event);" onkeyup="autocompile();">«@\|html»</textarea>
	<div class="hints">
	(Shift-Enter to compile and run.)
	<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")
	}
	`)