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   1  /**
   2   * Simple JSON serializer.
   3   *
   4   * @requires javelin-install
   5   * @provides javelin-json
   6   * @javelin
   7   */
   8  
   9  /**
  10   * JSON serializer and parser. This class uses the native JSON parser if it is
  11   * available; if not, it provides an eval-based parser and a simple serializer.
  12   *
  13   * NOTE: This class uses eval() on some systems, without sanitizing input. It is
  14   * not safe to use with untrusted data. Javelin does not provide a library
  15   * suitable for parsing untrusted JSON.
  16   *
  17   * Usage is straightforward:
  18   *
  19   *    JX.JSON.stringify({"bees":"knees"}); // Returns string: '{"bees":"knees"}'
  20   *    JX.JSON.parse('{"bees":"knees"}');   // Returns object: {"bees":"knees"}
  21   *
  22   * @task json      JSON Manipulation
  23   * @task internal  Internal
  24   */
  25  JX.install('JSON', {
  26    statics : {
  27  
  28  
  29  /* -(  JSON Manipulation  )-------------------------------------------------- */
  30  
  31  
  32      /**
  33       * Parse a **trusted** JSON string into an object. Accepts a valid JSON
  34       * string and returns the object it encodes.
  35       *
  36       * NOTE: This method does not sanitize input and uses an eval-based parser
  37       * on some systems. It is **NOT SAFE** to use with untrusted inputs.
  38       *
  39       * @param   string A valid, trusted JSON string.
  40       * @return  object The object encoded by the JSON string.
  41       * @task json
  42       */
  43      parse : function(data) {
  44        if (typeof data != 'string') {
  45          return null;
  46        }
  47  
  48        if (window.JSON && JSON.parse) {
  49          var obj;
  50          try {
  51            obj = JSON.parse(data);
  52          } catch (e) {}
  53          return obj || null;
  54        }
  55  
  56        return eval('(' + data + ')');
  57      },
  58  
  59      /**
  60       * Serialize an object into a JSON string. Accepts an object comprised of
  61       * maps, lists and scalars and transforms it into a JSON representation.
  62       * This method has undefined behavior if you pass in other complicated
  63       * things, e.g. object graphs containing cycles, document.body, or Date
  64       * objects.
  65       *
  66       * @param   object  An object comprised of maps, lists and scalars.
  67       * @return  string  JSON representation of the object.
  68       * @task json
  69       */
  70      stringify : function(val) {
  71        if (window.JSON && JSON.stringify) {
  72          return JSON.stringify(val);
  73        }
  74  
  75        var out = [];
  76        if (
  77          val === null || val === true || val === false || typeof val == 'number'
  78        ) {
  79          return '' + val;
  80        }
  81  
  82        if (val.push && val.pop) {
  83          var v;
  84          for (var ii = 0; ii < val.length; ii++) {
  85  
  86            // For consistency with JSON.stringify(), encode undefined array
  87            // indices as null.
  88            v = (typeof val[ii] == 'undefined') ? null : val[ii];
  89  
  90            out.push(JX.JSON.stringify(v));
  91          }
  92          return '[' + out.join(',') + ']';
  93        }
  94  
  95        if (typeof val == 'string') {
  96          return JX.JSON._esc(val);
  97        }
  98  
  99        for (var k in val) {
 100          out.push(JX.JSON._esc(k) + ':' + JX.JSON.stringify(val[k]));
 101        }
 102        return '{' + out.join(',') + '}';
 103      },
 104  
 105  
 106  /* -(  Internal  )----------------------------------------------------------- */
 107  
 108  
 109      // Lifted more or less directly from Crockford's JSON2.
 110      _escexp : /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
 111  
 112      // List of control character escape codes.
 113      _meta : {
 114        '\b' : '\\b',
 115        '\t' : '\\t',
 116        '\n' : '\\n',
 117        '\f' : '\\f',
 118        '\r' : '\\r',
 119        '"'  : '\\"',
 120        '\\' : '\\\\'
 121      },
 122  
 123      /**
 124       * Quote and escape a string for inclusion in serialized JSON. Finds
 125       * characters in the string which need to be escaped and uses
 126       * @{method:_replace} to escape them.
 127       *
 128       * @param string Unescaped string.
 129       * @return string Escaped string.
 130       * @task internal
 131       */
 132      _esc : function(str) {
 133        JX.JSON._escexp.lastIndex = 0;
 134        return JX.JSON._escexp.test(str) ?
 135          '"' + str.replace(JX.JSON._escexp, JX.JSON._replace) + '"' :
 136          '"' + str + '"';
 137      },
 138  
 139      /**
 140       * Helper callback for @{method:_esc}, escapes characters which can't be
 141       * represented normally in serialized JSON.
 142       *
 143       * @param string Unescaped character.
 144       * @return string Escaped character.
 145       * @task internal
 146       */
 147      _replace : function(m) {
 148        if (m in JX.JSON._meta) {
 149          return JX.JSON._meta[m];
 150        }
 151        return '\\u' + (('0000' + m.charCodeAt(0).toString(16)).slice(-4));
 152      }
 153    }
 154  });