_content/js/playground.js - website - Git at Google

 // 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.

 /*
 In the absence of any formal way to specify interfaces in JavaScript,
 here's a skeleton implementation of a playground transport.

         function Transport() {
                 // Set up any transport state (eg, make a websocket connection).
                 return {
                         Run: function(body, output, options) {
                                 // Compile and run the program 'body' with 'options'.
 				// Call the 'output' callback to display program output.
                                 return {
                                         Kill: function() {
                                                 // Kill the running program.
                                         }
                                 };
                         }
                 };
         }

 	// The output callback is called multiple times, and each time it is
 	// passed an object of this form.
         var write = {
                 Kind: 'string', // 'start', 'stdout', 'stderr', 'end', 'system'
                 Body: 'string'  // content of write or end status message
         }

 	// The first call must be of Kind 'start' with no body.
 	// Subsequent calls may be of Kind 'stdout' or 'stderr'
 	// and must have a non-null Body string.
 	// The final call should be of Kind 'end' with an optional
 	// Body string, signifying a failure ("killed", for example),
 	// or be of Kind 'system'.

 	// The output callback must be of this form.
 	// See PlaygroundOutput (below) for an implementation.
         function outputCallback(write) {
         }
 */

 // HTTPTransport is the default transport.
 // enableVet enables running vet if a program was compiled and ran successfully.
 // If vet returned any errors, display them before the output of a program.
 function HTTPTransport(enableVet) {
   'use strict';

   function playback(output, data) {
     // Backwards compatibility: default values do not affect the output.
     var events = data.Events || [];
     var errors = data.Errors || '';
     var vetErrors = data.VetErrors || '';
     var status = data.Status || 0;
     var isTest = data.IsTest || false;
     var testsFailed = data.TestsFailed || 0;

     var timeout;
     output({ Kind: 'start' });
     if (vetErrors !== '') {
       output({ Kind: 'stderr', Body: vetErrors });
       output({ Kind: 'system', Body: '\nGo vet failed.\n\n' });
     }
     function next() {
       if (!events || events.length === 0) {
         if (isTest) {
           if (testsFailed > 0) {
             output({
               Kind: 'system',
               Body:
                 '\n' +
                 testsFailed +
                 ' test' +
                 (testsFailed > 1 ? 's' : '') +
                 ' failed.',
             });
           } else {
             output({ Kind: 'system', Body: '\nAll tests passed.' });
           }
         } else {
           if (status > 0) {
             output({ Kind: 'end', Body: 'status ' + status + '.' });
           } else {
             if (errors !== '') {
               // errors are displayed only in the case of timeout.
               output({ Kind: 'end', Body: errors + '.' });
             } else {
               output({ Kind: 'end' });
             }
           }
         }
         return;
       }
       var e = events.shift();
       if (e.Delay === 0) {
         output({ Kind: e.Kind, Body: e.Message });
         next();
         return;
       }
       timeout = setTimeout(function() {
         output({ Kind: e.Kind, Body: e.Message });
         next();
       }, e.Delay / 1000000);
     }
     next();
     return {
       Stop: function() {
         clearTimeout(timeout);
       },
     };
   }

   function error(output, msg) {
     output({ Kind: 'start' });
     output({ Kind: 'stderr', Body: msg });
     output({ Kind: 'end' });
   }

   function buildFailed(output, msg) {
     output({ Kind: 'start' });
     output({ Kind: 'stderr', Body: msg });
     output({ Kind: 'system', Body: '\nGo build failed.' });
   }

   var seq = 0;
   return {
     Run: function(body, output, options) {
       seq++;
       var cur = seq;
       var playing;
       $.ajax('/_/compile?backend=' + (options.backend || ''), {
         type: 'POST',
         data: { version: 2, body: body, withVet: enableVet },
         dataType: 'json',
         success: function(data) {
           if (seq != cur) return;
           if (!data) return;
           if (playing != null) playing.Stop();
           if (data.Errors) {
             if (data.Errors === 'process took too long') {
               // Playback the output that was captured before the timeout.
               playing = playback(output, data);
             } else {
               buildFailed(output, data.Errors);
             }
             return;
           }
           playing = playback(output, data);
         },
         error: function() {
           error(output, 'Error communicating with remote server.');
         },
       });
       return {
         Kill: function() {
           if (playing != null) playing.Stop();
           output({ Kind: 'end', Body: 'killed' });
         },
       };
     },
   };
 }

 function SocketTransport() {
   'use strict';

   var id = 0;
   var outputs = {};
   var started = {};
   var websocket;
   if (window.location.protocol == 'http:') {
     websocket = new WebSocket('ws://' + window.location.host + '/socket');
   } else if (window.location.protocol == 'https:') {
     websocket = new WebSocket('wss://' + window.location.host + '/socket');
   }

   websocket.onclose = function() {
     console.log('websocket connection closed');
   };

   websocket.onmessage = function(e) {
     var m = JSON.parse(e.data);
     var output = outputs[m.Id];
     if (output === null) return;
     if (!started[m.Id]) {
       output({ Kind: 'start' });
       started[m.Id] = true;
     }
     output({ Kind: m.Kind, Body: m.Body });
   };

   function send(m) {
     websocket.send(JSON.stringify(m));
   }

   return {
     Run: function(body, output, options) {
       var thisID = id + '';
       id++;
       outputs[thisID] = output;
       send({ Id: thisID, Kind: 'run', Body: body, Options: options });
       return {
         Kill: function() {
           send({ Id: thisID, Kind: 'kill' });
         },
       };
     },
   };
 }

 function PlaygroundOutput(el) {
   'use strict';

   return function(write) {
     if (write.Kind == 'start') {
       el.innerHTML = '';
       return;
     }

     var cl = 'system';
     if (write.Kind == 'stdout' || write.Kind == 'stderr') cl = write.Kind;

     var m = write.Body;
     if (write.Kind == 'end') {
       m = '\nProgram exited' + (m ? ': ' + m : '.');
     }

     if (m.indexOf('IMAGE:') === 0) {
       // TODO(adg): buffer all writes before creating image
       var url = 'data:image/png;base64,' + m.substr(6);
       var img = document.createElement('img');
       img.src = url;
       el.appendChild(img);
       return;
     }

     // ^L clears the screen.
     var s = m.split('\x0c');
     if (s.length > 1) {
       el.innerHTML = '';
       m = s.pop();
     }

     m = m.replace(/&/g, '&amp;');
     m = m.replace(/</g, '&lt;');
     m = m.replace(/>/g, '&gt;');

     var needScroll = el.scrollTop + el.offsetHeight == el.scrollHeight;

     var span = document.createElement('span');
     span.className = cl;
     span.innerHTML = m;
     el.appendChild(span);

     if (needScroll) el.scrollTop = el.scrollHeight - el.offsetHeight;
   };
 }

 (function() {
   function lineHighlight(error) {
     var regex = /prog.go:([0-9]+)/g;
     var r = regex.exec(error);
     while (r) {
       $('.lines div')
         .eq(r[1] - 1)
         .addClass('lineerror');
       r = regex.exec(error);
     }
   }
   function highlightOutput(wrappedOutput) {
     return function(write) {
       if (write.Body) lineHighlight(write.Body);
       wrappedOutput(write);
     };
   }
   function lineClear() {
     $('.lineerror').removeClass('lineerror');
   }

   // opts is an object with these keys
   //  codeEl - code editor element
   //  outputEl - program output element
   //  runEl - run button element
   //  fmtEl - fmt button element (optional)
   //  fmtImportEl - fmt "imports" checkbox element (optional)
   //  shareEl - share button element (optional)
   //  shareURLEl - share URL text input element (optional)
   //  shareRedirect - base URL to redirect to on share (optional)
   //  toysEl - toys select element (optional)
   //  enableHistory - enable using HTML5 history API (optional)
   //  transport - playground transport to use (default is HTTPTransport)
   //  enableShortcuts - whether to enable shortcuts (Ctrl+S/Cmd+S to save) (default is false)
   //  enableVet - enable running vet and displaying its errors
   function playground(opts) {
     var code = $(opts.codeEl);
     var transport = opts['transport'] || new HTTPTransport(opts['enableVet']);
     var running;

     // autoindent helpers.
     function insertTabs(n) {
       // Without the n > 0 check, Safari cannot type a blank line at the bottom of a playground snippet.
       // See go.dev/issue/49794.
       if (n > 0) {
         document.execCommand('insertText', false, '\t'.repeat(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);
     }

     // NOTE(cbro): e is a jQuery event, not a DOM event.
     function handleSaveShortcut(e) {
       if (e.isDefaultPrevented()) return false;
       if (!e.metaKey && !e.ctrlKey) return false;
       if (e.key != 'S' && e.key != 's') return false;

       e.preventDefault();

       // Share and save
       share(function(url) {
         window.location.href = url + '.go?download=true';
       });

       return true;
     }

     function keyHandler(e) {
       if (opts.enableShortcuts && handleSaveShortcut(e)) return;

       if (e.keyCode == 9 && !e.ctrlKey) {
         // tab (but not ctrl-tab)
         insertTabs(1);
         e.preventDefault();
         return false;
       }
       if (e.keyCode == 13) {
         // enter
         if (e.shiftKey) {
           // +shift
           run();
           e.preventDefault();
           return false;
         }
         if (e.ctrlKey) {
           // +control
           fmt();
           e.preventDefault();
         } else {
           autoindent(e.target);
         }
       }
       return true;
     }
     code.unbind('keydown').bind('keydown', keyHandler);
     var outdiv = $(opts.outputEl).empty();
     var output = $('<pre/>').appendTo(outdiv);

     function body() {
       return $(opts.codeEl).val();
     }
     function setBody(text) {
       $(opts.codeEl).val(text);
     }
     function origin(href) {
       return ('' + href)
         .split('/')
         .slice(0, 3)
         .join('/');
     }

     var pushedPlay = window.location.pathname == '/play/';
     function inputChanged() {
       if (pushedPlay) {
         return;
       }
       pushedPlay = true;
       $(opts.shareURLEl).hide();
       $(opts.toysEl).show();
       var path = window.location.pathname;
       var i = path.indexOf('/play/');
       var p = path.substr(0, i+6);
       if (opts.versionEl !== null) {
         var v = $(opts.versionEl).val();
         if (v != '') {
           p += '?v=' + v;
         }
       }
       window.history.pushState(null, '', p);
     }
     function popState(e) {
       if (e === null) {
         return;
       }
       if (e && e.state && e.state.code) {
         setBody(e.state.code);
       }
     }
     var rewriteHistory = false;
     if (
       window.history &&
       window.history.pushState &&
       window.addEventListener &&
       opts.enableHistory
     ) {
       rewriteHistory = true;
       code[0].addEventListener('input', inputChanged);
       window.addEventListener('popstate', popState);
     }

     function backend() {
       if (!opts.versionEl) {
         return '';
       }
       var vers = $(opts.versionEl);
       if (!vers) {
         return '';
       }
       return vers.val();
     }

     function setError(error) {
       if (running) running.Kill();
       lineClear();
       lineHighlight(error);
       output
         .empty()
         .addClass('error')
         .text(error);
     }
     function loading() {
       lineClear();
       if (running) running.Kill();
       output.removeClass('error').text('Waiting for remote server...');
     }
     function runOnly() {
       loading();
       running = transport.Run(
         body(),
         highlightOutput(PlaygroundOutput(output[0])),
         {backend: backend()},
       );
     }

     function fmtAnd(run) {
       loading();
       var data = { body: body() };
       data['imports'] = 'true';
       $.ajax('/_/fmt?backend='+backend(), {
         data: data,
         type: 'POST',
         dataType: 'json',
         success: function(data) {
           if (data.Error) {
             setError(data.Error);
           } else {
             setBody(data.Body);
             setError('');
           }
           run();
         },
         error: function() {
           setError('Error communicating with remote server.');
         },
       });
     }

     function loadShare(id) {
       $.ajax('/_/share?id='+id, {
         processData: false,
         type: 'GET',
         complete: function(xhr) {
           if(xhr.status != 200) {
             setBody('Cannot load shared snippet; try again.');
             return;
           }
           setBody(xhr.responseText);
         },
       })
     }

     function fmt() {
       fmtAnd(function(){});
     }

     function run() {
       fmtAnd(runOnly);
     }

     var shareURL; // jQuery element to show the shared URL.
     var sharing = false; // true if there is a pending request.
     var shareCallbacks = [];
     function share(opt_callback) {
       if (opt_callback) shareCallbacks.push(opt_callback);

       if (sharing) return;
       sharing = true;

       var errorMessages = {
         413: 'Snippet is too large to share.'
       };

       var sharingData = body();
       $.ajax('/_/share', {
         processData: false,
         data: sharingData,
         type: 'POST',
         contentType: 'text/plain; charset=utf-8',
         complete: function(xhr) {
           sharing = false;
           if (xhr.status != 200) {
             var alertMsg = errorMessages[xhr.status] ? errorMessages[xhr.status] : 'Server error; try again.';
             alert(alertMsg);
             return;
           }
           if (opts.shareRedirect) {
             window.location = opts.shareRedirect + xhr.responseText;
           }
           var path = '/play/p/' + xhr.responseText;
           if (opts.versionEl !== null && $(opts.versionEl).val() != "") {
             path += "?v=" + $(opts.versionEl).val();
           }
           var url = origin(window.location) + path;
           for (var i = 0; i < shareCallbacks.length; i++) {
             shareCallbacks[i](url);
           }
           shareCallbacks = [];

           if (shareURL) {
             shareURL
               .show()
               .val(url)
               .focus()
               .select();

             $(opts.toysEl).hide();
             if (rewriteHistory) {
               var historyData = { code: sharingData };
               window.history.pushState(historyData, '', path);
               pushedPlay = false;
             }
           }
         },
       });
     }

     $(opts.runEl).click(run);
     $(opts.fmtEl).click(fmt);

     if (
       opts.shareEl !== null &&
       (opts.shareURLEl !== null || opts.shareRedirect !== null)
     ) {
       if (opts.shareURLEl) {
         shareURL = $(opts.shareURLEl).hide();
       }
       $(opts.shareEl).click(function() {
         share();
       });
     }

     var path = window.location.pathname;
     var toyDisable = false;
     if (path.startsWith('/go.dev/')) {
       path = path.slice(7);
     }
     if (path.startsWith('/play/p/')) {
       var id = path.slice(8);
       id = id.replace(/\.go$/, "");
       loadShare(id);
       toyDisable = true;
     }

     if (opts.toysEl !== null) {
       $(opts.toysEl).bind('change', function() {
         if (toyDisable) {
           toyDisable = false;
           return;
         }
         var toy = $(this).val();
         $.ajax('/doc/play/' + toy, {
           processData: false,
           type: 'GET',
           complete: function(xhr) {
             if (xhr.status != 200) {
               alert('Server error; try again.');
               return;
             }
             setBody(xhr.responseText);
             if (toy.includes('-dev') && opts.versionEl !== null) {
               $(opts.versionEl).val('gotip');
             }
             run();
           },
         });
       });
     }

     if (opts.versionEl !== null) {
      var select = $(opts.versionEl);
       var v = (new URL(window.location)).searchParams.get('v');
       if (v !== null && v != "") {
       	select.val(v);
         if (select.val() != v) {
           select.append($('<option>', {value: v, text: 'Backend: ' + v}));
           select.val(v);
         }
       }
       if (opts.enableHistory) {
         select.bind('change', inputChanged);
       }
     }
   }

   window.playground = playground;
 })();
	// 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.

	/*
	In the absence of any formal way to specify interfaces in JavaScript,
	here's a skeleton implementation of a playground transport.

	function Transport() {
	// Set up any transport state (eg, make a websocket connection).
	return {
	Run: function(body, output, options) {
	// Compile and run the program 'body' with 'options'.
	// Call the 'output' callback to display program output.
	return {
	Kill: function() {
	// Kill the running program.
	}
	};
	}
	};
	}

	// The output callback is called multiple times, and each time it is
	// passed an object of this form.
	var write = {
	Kind: 'string', // 'start', 'stdout', 'stderr', 'end', 'system'
	Body: 'string' // content of write or end status message
	}

	// The first call must be of Kind 'start' with no body.
	// Subsequent calls may be of Kind 'stdout' or 'stderr'
	// and must have a non-null Body string.
	// The final call should be of Kind 'end' with an optional
	// Body string, signifying a failure ("killed", for example),
	// or be of Kind 'system'.

	// The output callback must be of this form.
	// See PlaygroundOutput (below) for an implementation.
	function outputCallback(write) {
	}
	*/

	// HTTPTransport is the default transport.
	// enableVet enables running vet if a program was compiled and ran successfully.
	// If vet returned any errors, display them before the output of a program.
	function HTTPTransport(enableVet) {
	'use strict';

	function playback(output, data) {
	// Backwards compatibility: default values do not affect the output.
	var events = data.Events \|\| [];
	var errors = data.Errors \|\| '';
	var vetErrors = data.VetErrors \|\| '';
	var status = data.Status \|\| 0;
	var isTest = data.IsTest \|\| false;
	var testsFailed = data.TestsFailed \|\| 0;

	var timeout;
	output({ Kind: 'start' });
	if (vetErrors !== '') {
	output({ Kind: 'stderr', Body: vetErrors });
	output({ Kind: 'system', Body: '\nGo vet failed.\n\n' });
	}
	function next() {
	if (!events \|\| events.length === 0) {
	if (isTest) {
	if (testsFailed > 0) {
	output({
	Kind: 'system',
	Body:
	'\n' +
	testsFailed +
	' test' +
	(testsFailed > 1 ? 's' : '') +
	' failed.',
	});
	} else {
	output({ Kind: 'system', Body: '\nAll tests passed.' });
	}
	} else {
	if (status > 0) {
	output({ Kind: 'end', Body: 'status ' + status + '.' });
	} else {
	if (errors !== '') {
	// errors are displayed only in the case of timeout.
	output({ Kind: 'end', Body: errors + '.' });
	} else {
	output({ Kind: 'end' });
	}
	}
	}
	return;
	}
	var e = events.shift();
	if (e.Delay === 0) {
	output({ Kind: e.Kind, Body: e.Message });
	next();
	return;
	}
	timeout = setTimeout(function() {
	output({ Kind: e.Kind, Body: e.Message });
	next();
	}, e.Delay / 1000000);
	}
	next();
	return {
	Stop: function() {
	clearTimeout(timeout);
	},
	};
	}

	function error(output, msg) {
	output({ Kind: 'start' });
	output({ Kind: 'stderr', Body: msg });
	output({ Kind: 'end' });
	}

	function buildFailed(output, msg) {
	output({ Kind: 'start' });
	output({ Kind: 'stderr', Body: msg });
	output({ Kind: 'system', Body: '\nGo build failed.' });
	}

	var seq = 0;
	return {
	Run: function(body, output, options) {
	seq++;
	var cur = seq;
	var playing;
	$.ajax('/_/compile?backend=' + (options.backend \|\| ''), {
	type: 'POST',
	data: { version: 2, body: body, withVet: enableVet },
	dataType: 'json',
	success: function(data) {
	if (seq != cur) return;
	if (!data) return;
	if (playing != null) playing.Stop();
	if (data.Errors) {
	if (data.Errors === 'process took too long') {
	// Playback the output that was captured before the timeout.
	playing = playback(output, data);
	} else {
	buildFailed(output, data.Errors);
	}
	return;
	}
	playing = playback(output, data);
	},
	error: function() {
	error(output, 'Error communicating with remote server.');
	},
	});
	return {
	Kill: function() {
	if (playing != null) playing.Stop();
	output({ Kind: 'end', Body: 'killed' });
	},
	};
	},
	};
	}

	function SocketTransport() {
	'use strict';

	var id = 0;
	var outputs = {};
	var started = {};
	var websocket;
	if (window.location.protocol == 'http:') {
	websocket = new WebSocket('ws://' + window.location.host + '/socket');
	} else if (window.location.protocol == 'https:') {
	websocket = new WebSocket('wss://' + window.location.host + '/socket');
	}

	websocket.onclose = function() {
	console.log('websocket connection closed');
	};

	websocket.onmessage = function(e) {
	var m = JSON.parse(e.data);
	var output = outputs[m.Id];
	if (output === null) return;
	if (!started[m.Id]) {
	output({ Kind: 'start' });
	started[m.Id] = true;
	}
	output({ Kind: m.Kind, Body: m.Body });
	};

	function send(m) {
	websocket.send(JSON.stringify(m));
	}

	return {
	Run: function(body, output, options) {
	var thisID = id + '';
	id++;
	outputs[thisID] = output;
	send({ Id: thisID, Kind: 'run', Body: body, Options: options });
	return {
	Kill: function() {
	send({ Id: thisID, Kind: 'kill' });
	},
	};
	},
	};
	}

	function PlaygroundOutput(el) {
	'use strict';

	return function(write) {
	if (write.Kind == 'start') {
	el.innerHTML = '';
	return;
	}

	var cl = 'system';
	if (write.Kind == 'stdout' \|\| write.Kind == 'stderr') cl = write.Kind;

	var m = write.Body;
	if (write.Kind == 'end') {
	m = '\nProgram exited' + (m ? ': ' + m : '.');
	}

	if (m.indexOf('IMAGE:') === 0) {
	// TODO(adg): buffer all writes before creating image
	var url = 'data:image/png;base64,' + m.substr(6);
	var img = document.createElement('img');
	img.src = url;
	el.appendChild(img);
	return;
	}

	// ^L clears the screen.
	var s = m.split('\x0c');
	if (s.length > 1) {
	el.innerHTML = '';
	m = s.pop();
	}

	m = m.replace(/&/g, '&');
	m = m.replace(/</g, '<');
	m = m.replace(/>/g, '>');

	var needScroll = el.scrollTop + el.offsetHeight == el.scrollHeight;

	var span = document.createElement('span');
	span.className = cl;
	span.innerHTML = m;
	el.appendChild(span);

	if (needScroll) el.scrollTop = el.scrollHeight - el.offsetHeight;
	};
	}

	(function() {
	function lineHighlight(error) {
	var regex = /prog.go:([0-9]+)/g;
	var r = regex.exec(error);
	while (r) {
	$('.lines div')
	.eq(r[1] - 1)
	.addClass('lineerror');
	r = regex.exec(error);
	}
	}
	function highlightOutput(wrappedOutput) {
	return function(write) {
	if (write.Body) lineHighlight(write.Body);
	wrappedOutput(write);
	};
	}
	function lineClear() {
	$('.lineerror').removeClass('lineerror');
	}

	// opts is an object with these keys
	// codeEl - code editor element
	// outputEl - program output element
	// runEl - run button element
	// fmtEl - fmt button element (optional)
	// fmtImportEl - fmt "imports" checkbox element (optional)
	// shareEl - share button element (optional)
	// shareURLEl - share URL text input element (optional)
	// shareRedirect - base URL to redirect to on share (optional)
	// toysEl - toys select element (optional)
	// enableHistory - enable using HTML5 history API (optional)
	// transport - playground transport to use (default is HTTPTransport)
	// enableShortcuts - whether to enable shortcuts (Ctrl+S/Cmd+S to save) (default is false)
	// enableVet - enable running vet and displaying its errors
	function playground(opts) {
	var code = $(opts.codeEl);
	var transport = opts['transport'] \|\| new HTTPTransport(opts['enableVet']);
	var running;

	// autoindent helpers.
	function insertTabs(n) {
	// Without the n > 0 check, Safari cannot type a blank line at the bottom of a playground snippet.
	// See go.dev/issue/49794.
	if (n > 0) {
	document.execCommand('insertText', false, '\t'.repeat(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);
	}

	// NOTE(cbro): e is a jQuery event, not a DOM event.
	function handleSaveShortcut(e) {
	if (e.isDefaultPrevented()) return false;
	if (!e.metaKey && !e.ctrlKey) return false;
	if (e.key != 'S' && e.key != 's') return false;

	e.preventDefault();

	// Share and save
	share(function(url) {
	window.location.href = url + '.go?download=true';
	});

	return true;
	}

	function keyHandler(e) {
	if (opts.enableShortcuts && handleSaveShortcut(e)) return;

	if (e.keyCode == 9 && !e.ctrlKey) {
	// tab (but not ctrl-tab)
	insertTabs(1);
	e.preventDefault();
	return false;
	}
	if (e.keyCode == 13) {
	// enter
	if (e.shiftKey) {
	// +shift
	run();
	e.preventDefault();
	return false;
	}
	if (e.ctrlKey) {
	// +control
	fmt();
	e.preventDefault();
	} else {
	autoindent(e.target);
	}
	}
	return true;
	}
	code.unbind('keydown').bind('keydown', keyHandler);
	var outdiv = $(opts.outputEl).empty();
	var output = $('<pre/>').appendTo(outdiv);

	function body() {
	return $(opts.codeEl).val();
	}
	function setBody(text) {
	$(opts.codeEl).val(text);
	}
	function origin(href) {
	return ('' + href)
	.split('/')
	.slice(0, 3)
	.join('/');
	}

	var pushedPlay = window.location.pathname == '/play/';
	function inputChanged() {
	if (pushedPlay) {
	return;
	}
	pushedPlay = true;
	$(opts.shareURLEl).hide();
	$(opts.toysEl).show();
	var path = window.location.pathname;
	var i = path.indexOf('/play/');
	var p = path.substr(0, i+6);
	if (opts.versionEl !== null) {
	var v = $(opts.versionEl).val();
	if (v != '') {
	p += '?v=' + v;
	}
	}
	window.history.pushState(null, '', p);
	}
	function popState(e) {
	if (e === null) {
	return;
	}
	if (e && e.state && e.state.code) {
	setBody(e.state.code);
	}
	}
	var rewriteHistory = false;
	if (
	window.history &&
	window.history.pushState &&
	window.addEventListener &&
	opts.enableHistory
	) {
	rewriteHistory = true;
	code[0].addEventListener('input', inputChanged);
	window.addEventListener('popstate', popState);
	}

	function backend() {
	if (!opts.versionEl) {
	return '';
	}
	var vers = $(opts.versionEl);
	if (!vers) {
	return '';
	}
	return vers.val();
	}

	function setError(error) {
	if (running) running.Kill();
	lineClear();
	lineHighlight(error);
	output
	.empty()
	.addClass('error')
	.text(error);
	}
	function loading() {
	lineClear();
	if (running) running.Kill();
	output.removeClass('error').text('Waiting for remote server...');
	}
	function runOnly() {
	loading();
	running = transport.Run(
	body(),
	highlightOutput(PlaygroundOutput(output[0])),
	{backend: backend()},
	);
	}

	function fmtAnd(run) {
	loading();
	var data = { body: body() };
	data['imports'] = 'true';
	$.ajax('/_/fmt?backend='+backend(), {
	data: data,
	type: 'POST',
	dataType: 'json',
	success: function(data) {
	if (data.Error) {
	setError(data.Error);
	} else {
	setBody(data.Body);
	setError('');
	}
	run();
	},
	error: function() {
	setError('Error communicating with remote server.');
	},
	});
	}

	function loadShare(id) {
	$.ajax('/_/share?id='+id, {
	processData: false,
	type: 'GET',
	complete: function(xhr) {
	if(xhr.status != 200) {
	setBody('Cannot load shared snippet; try again.');
	return;
	}
	setBody(xhr.responseText);
	},
	})
	}

	function fmt() {
	fmtAnd(function(){});
	}

	function run() {
	fmtAnd(runOnly);
	}

	var shareURL; // jQuery element to show the shared URL.
	var sharing = false; // true if there is a pending request.
	var shareCallbacks = [];
	function share(opt_callback) {
	if (opt_callback) shareCallbacks.push(opt_callback);

	if (sharing) return;
	sharing = true;

	var errorMessages = {
	413: 'Snippet is too large to share.'
	};

	var sharingData = body();
	$.ajax('/_/share', {
	processData: false,
	data: sharingData,
	type: 'POST',
	contentType: 'text/plain; charset=utf-8',
	complete: function(xhr) {
	sharing = false;
	if (xhr.status != 200) {
	var alertMsg = errorMessages[xhr.status] ? errorMessages[xhr.status] : 'Server error; try again.';
	alert(alertMsg);
	return;
	}
	if (opts.shareRedirect) {
	window.location = opts.shareRedirect + xhr.responseText;
	}
	var path = '/play/p/' + xhr.responseText;
	if (opts.versionEl !== null && $(opts.versionEl).val() != "") {
	path += "?v=" + $(opts.versionEl).val();
	}
	var url = origin(window.location) + path;
	for (var i = 0; i < shareCallbacks.length; i++) {
	shareCallbacks[i](url);
	}
	shareCallbacks = [];

	if (shareURL) {
	shareURL
	.show()
	.val(url)
	.focus()
	.select();

	$(opts.toysEl).hide();
	if (rewriteHistory) {
	var historyData = { code: sharingData };
	window.history.pushState(historyData, '', path);
	pushedPlay = false;
	}
	}
	},
	});
	}

	$(opts.runEl).click(run);
	$(opts.fmtEl).click(fmt);

	if (
	opts.shareEl !== null &&
	(opts.shareURLEl !== null \|\| opts.shareRedirect !== null)
	) {
	if (opts.shareURLEl) {
	shareURL = $(opts.shareURLEl).hide();
	}
	$(opts.shareEl).click(function() {
	share();
	});
	}

	var path = window.location.pathname;
	var toyDisable = false;
	if (path.startsWith('/go.dev/')) {
	path = path.slice(7);
	}
	if (path.startsWith('/play/p/')) {
	var id = path.slice(8);
	id = id.replace(/\.go$/, "");
	loadShare(id);
	toyDisable = true;
	}

	if (opts.toysEl !== null) {
	$(opts.toysEl).bind('change', function() {
	if (toyDisable) {
	toyDisable = false;
	return;
	}
	var toy = $(this).val();
	$.ajax('/doc/play/' + toy, {
	processData: false,
	type: 'GET',
	complete: function(xhr) {
	if (xhr.status != 200) {
	alert('Server error; try again.');
	return;
	}
	setBody(xhr.responseText);
	if (toy.includes('-dev') && opts.versionEl !== null) {
	$(opts.versionEl).val('gotip');
	}
	run();
	},
	});
	});
	}

	if (opts.versionEl !== null) {
	var select = $(opts.versionEl);
	var v = (new URL(window.location)).searchParams.get('v');
	if (v !== null && v != "") {
	select.val(v);
	if (select.val() != v) {
	select.append($('<option>', {value: v, text: 'Backend: ' + v}));
	select.val(v);
	}
	}
	if (opts.enableHistory) {
	select.bind('change', inputChanged);
	}
	}
	}

	window.playground = playground;
	})();