CodeMirror: JavaScript mode

// Demo code (the actual new parser character stream implementation)

function StringStream(string) {

  this.pos = 0;

  this.string = string;

}

StringStream.prototype = {

  done: function() {return this.pos >= this.string.length;},

  peek: function() {return this.string.charAt(this.pos);},

  next: function() {

    if (this.pos < this.string.length)

      return this.string.charAt(this.pos++);

  },

  eat: function(match) {

    var ch = this.string.charAt(this.pos);

    if (typeof match == "string") var ok = ch == match;

    else var ok = ch && match.test ? match.test(ch) : match(ch);

    if (ok) {this.pos++; return ch;}

  },

  eatWhile: function(match) {

    var start = this.pos;

    while (this.eat(match));

    if (this.pos > start) return this.string.slice(start, this.pos);

  },

  backUp: function(n) {this.pos -= n;},

  column: function() {return this.pos;},

  eatSpace: function() {

    var start = this.pos;

    while (/\s/.test(this.string.charAt(this.pos))) this.pos++;

    return this.pos - start;

  },

  match: function(pattern, consume, caseInsensitive) {

    if (typeof pattern == "string") {

      function cased(str) {return caseInsensitive ? str.toLowerCase() : str;}

      if (cased(this.string).indexOf(cased(pattern), this.pos) == this.pos) {

        if (consume !== false) this.pos += str.length;

        return true;

      }

    }

    else {

      var match = this.string.slice(this.pos).match(pattern);

      if (match && consume !== false) this.pos += match[0].length;

      return match;

    }

  }

};