1. // Demo code (the actual new parser character stream implementation)
2.  
3. function StringStream(string) {
4.   this.pos = 0;
5.   this.string = string;
6. }
7.  
8. StringStream.prototype = {
9.   done: function() {return this.pos >= this.string.length;},
10.   peek: function() {return this.string.charAt(this.pos);},
11.   next: function() {
12.     if (this.pos < this.string.length)
13.       return this.string.charAt(this.pos++);
14.   },
15.   eat: function(match) {
16.     var ch = this.string.charAt(this.pos);
17.     if (typeof match == "string") var ok = ch == match;
18.     else var ok = ch && match.test ? match.test(ch) : match(ch);
19.     if (ok) {this.pos++; return ch;}
20.   },
21.   eatWhile: function(match) {
22.     var start = this.pos;
23.     while (this.eat(match));
24.     if (this.pos > start) return this.string.slice(start, this.pos);
25.   },
26.   backUp: function(n) {this.pos -= n;},
27.   column: function() {return this.pos;},
28.   eatSpace: function() {
29.     var start = this.pos;
30.     while (/\s/.test(this.string.charAt(this.pos))) this.pos++;
31.     return this.pos - start;
32.   },
33.   match: function(pattern, consume, caseInsensitive) {
34.     if (typeof pattern == "string") {
35.       function cased(str) {return caseInsensitive ? str.toLowerCase() : str;}
36.       if (cased(this.string).indexOf(cased(pattern), this.pos) == this.pos) {
37.         if (consume !== false) this.pos += str.length;
38.         return true;
39.       }
40.     }
41.     else {
42.       var match = this.string.slice(this.pos).match(pattern);
43.       if (match && consume !== false) this.pos += match[0].length;
44.       return match;
45.     }
46.   }
47. };
48.