+/* String streams are the things fed to parsers (which can feed them
+ * to a tokenizer if they want). They provide peek and next methods
+ * for looking at the current character (next 'consumes' this
+ * character, peek does not), and a get method for retrieving all the
+ * text that was consumed since the last time get was called.
+ *
+ * An easy mistake to make is to let a StopIteration exception finish
+ * the token stream while there are still characters pending in the
+ * string stream (hitting the end of the buffer while parsing a
+ * token). To make it easier to detect such errors, the strings throw
+ * an exception when this happens.
+ */
+
+// Make a string stream out of an iterator that returns strings. This
+// is applied to the result of traverseDOM (see codemirror.js), and
+// the resulting stream is fed to the parser.
+window.stringStream = function(source){
+ // String that's currently being iterated over.
+ var current = "";
+ // Position in that string.
+ var pos = 0;
+ // Accumulator for strings that have been iterated over but not
+ // get()-ed yet.
+ var accum = "";
+ // Make sure there are more characters ready, or throw
+ // StopIteration.
+ function ensureChars() {
+ while (pos == current.length) {
+ accum += current;
+ current = ""; // In case source.next() throws
+ pos = 0;
+ try {current = source.next();}
+ catch (e) {
+ if (e != StopIteration) throw e;
+ else return false;
+ }
+ }
+ return true;
+ }
+
+ return {
+ // Return the next character in the stream.
+ peek: function() {
+ if (!ensureChars()) return null;
+ return current.charAt(pos);
+ },
+ // Get the next character, throw StopIteration if at end, check
+ // for unused content.
+ next: function() {
+ if (!ensureChars()) {
+ if (accum.length > 0)
+ throw "End of stringstream reached without emptying buffer ('" + accum + "').";
+ else
+ throw StopIteration;
+ }
+ return current.charAt(pos++);
+ },
+ // Return the characters iterated over since the last call to
+ // .get().
+ get: function() {
+ var temp = accum;
+ accum = "";
+ if (pos > 0){
+ temp += current.slice(0, pos);
+ current = current.slice(pos);
+ pos = 0;
+ }
+ return temp;
+ },
+ // Push a string back into the stream.
+ push: function(str) {
+ current = current.slice(0, pos) + str + current.slice(pos);
+ },
+ lookAhead: function(str, consume, skipSpaces, caseInsensitive) {
+ function cased(str) {return caseInsensitive ? str.toLowerCase() : str;}
+ str = cased(str);
+ var found = false;
+
+ var _accum = accum, _pos = pos;
+ if (skipSpaces) this.nextWhileMatches(/[\s\u00a0]/);
+
+ while (true) {
+ var end = pos + str.length, left = current.length - pos;
+ if (end <= current.length) {
+ found = str == cased(current.slice(pos, end));
+ pos = end;
+ break;
+ }
+ else if (str.slice(0, left) == cased(current.slice(pos))) {
+ accum += current; current = "";
+ try {current = source.next();}
+ catch (e) {break;}
+ pos = 0;
+ str = str.slice(left);
+ }
+ else {
+ break;
+ }
+ }
+
+ if (!(found && consume)) {
+ current = accum.slice(_accum.length) + current;
+ pos = _pos;
+ accum = _accum;
+ }
+
+ return found;
+ },
+
+ // Utils built on top of the above
+ more: function() {
+ return this.peek() !== null;
+ },
+ applies: function(test) {
+ var next = this.peek();
+ return (next !== null && test(next));
+ },
+ nextWhile: function(test) {
+ var next;
+ while ((next = this.peek()) !== null && test(next))
+ this.next();
+ },
+ matches: function(re) {
+ var next = this.peek();
+ return (next !== null && re.test(next));
+ },
+ nextWhileMatches: function(re) {
+ var next;
+ while ((next = this.peek()) !== null && re.test(next))
+ this.next();
+ },
+ equals: function(ch) {
+ return ch === this.peek();
+ },
+ endOfLine: function() {
+ var next = this.peek();
+ return next == null || next == "\n";
+ }
+ };
+};