examples/rails_app-2.3.4/public/javascripts/ajax_pull/ajax_pull.js

   1 // ref: http://rubyforge.org/pipermail/mongrel-users/2007-July/003747.html
   2 // ry dahl <ry@tinyclouds.org>
   3 // Don't Poll. Pull!
   4 // version 0.1
   5 Ajax.Pull = Class.create();
   6
   7 Ajax.Pull.prototype = Object.extend(Ajax.Request.prototype, {
   8   initialize: function(url, options) {
   9     this.handler = options.handler;
  10     this.frequency = options.frequency || 0.5;
  11     options['method'] = options['method'] || 'get';
  12     this.setOptions(options);
  13     this.transport = Ajax.getTransport();
  14
  15     this.request(url);
  16     this.startPuller();
  17   },
  18
  19   startPuller: function() {
  20     this.pullPointer = 0;
  21     this.puller = new PeriodicalExecuter(this.pull.bind(this), this.frequency);
  22   },
  23
  24   pull: function() {
  25     if(this.transport.readyState < 3) {
  26       return; // not receiving yet
  27     } else if (this._complete) {
  28       this.puller.stop(); // this is our last pull
  29     }
  30
  31     var slice = this.transport.responseText.slice(this.pullPointer);
  32
  33     (this.options.pullDebugger || Prototype.emptyFunction)(
  34         'slice: <code>' + slice + '</code>');
  35
  36     slice.extractJSON().each((function(statement) {
  37       (this.options.pullDebugger || Prototype.emptyFunction)(
  38           'extracted statement: <code>' + statement + '</code>');
  39       this.handler(eval( '(' + statement + ')' ));
  40       this.pullPointer += statement.length + 1;
  41     }).bind(this));
  42
  43   },
  44
  45 });
  46
  47
  48 Object.extend(String.prototype, {
  49   extractJSON: function() {
  50     var insideString = false;
  51     var sBrackets = cBrackets = parens = 0;
  52     var statements = new Array();
  53     var start = i = 0;
  54     for(i = 0; i < this.length; i++) {
  55       if( cBrackets < 0 || sBrackets < 0 || parens < 0 ) {
  56         // raise syntax error?
  57       }
  58       if(insideString) {
  59         switch(this[i]) {
  60           case '\\': i++; break;
  61           case '"': insideString = false; break;
  62         }
  63       } else {
  64         switch(this[i]) {
  65           case '"': insideString = true; break;
  66           case '{': cBrackets++; break;
  67           case '}': cBrackets--; break;
  68           case '[': sBrackets++; break;
  69           case ']': sBrackets--; break;
  70           case '(': parens++; break;
  71           case ')': parens++; break;
  72           case ';':
  73             if(cBrackets == 0 && sBrackets == 0 && parens == 0) {
  74               statements.push(this.slice(start, i));
  75               start = i+1;
  76             }
  77         }
  78       }
  79       // if the last statement doesn't have a semicolon, it's okay
  80       // if(i != start && cBrackets == 0 && sBrackets == 0 && parens == 0)
  81       //         statements.push(this.slice(start));
  82     }
  83     return statements;
  84   }
  85 });