--- /dev/null
+// A framework for simple tokenizers. Takes care of newlines and
+// white-space, and of getting the text from the source stream into
+// the token object. A state is a function of two arguments -- a
+// string stream and a setState function. The second can be used to
+// change the tokenizer's state, and can be ignored for stateless
+// tokenizers. This function should advance the stream over a token
+// and return a string or object containing information about the next
+// token, or null to pass and have the (new) state be called to finish
+// the token. When a string is given, it is wrapped in a {style, type}
+// object. In the resulting object, the characters consumed are stored
+// under the content property. Any whitespace following them is also
+// automatically consumed, and added to the value property. (Thus,
+// content is the actual meaningful part of the token, while value
+// contains all the text it spans.)
+
+function tokenizer(source, state) {
+ // Newlines are always a separate token.
+ function isWhiteSpace(ch) {
+ // The messy regexp is because IE's regexp matcher is of the
+ // opinion that non-breaking spaces are no whitespace.
+ return ch != "\n" && /^[\s\u00a0]*$/.test(ch);
+ }
+
+ var tokenizer = {
+ state: state,
+
+ take: function(type) {
+ if (typeof(type) == "string")
+ type = {style: type, type: type};
+
+ type.content = (type.content || "") + source.get();
+ if (!/\n$/.test(type.content))
+ source.nextWhile(isWhiteSpace);
+ type.value = type.content + source.get();
+ return type;
+ },
+
+ next: function () {
+ if (!source.more()) throw StopIteration;
+
+ var type;
+ if (source.equals("\n")) {
+ source.next();
+ return this.take("whitespace");
+ }
+
+ if (source.applies(isWhiteSpace))
+ type = "whitespace";
+ else
+ while (!type)
+ type = this.state(source, function(s) {tokenizer.state = s;});
+
+ return this.take(type);
+ }
+ };
+ return tokenizer;
+}