[danik.js]

Добавил поддержку символьных классов (кроме исключающих) и групп.

<meta charset="utf-8">
<form id="form">
	<p><label>Регулярка:</label><input name="input"> <button name="run" type="button">Герерировать</button></p>
	<p><label>Результат:</label><input name="output"></p>
</form>
<script src="http://libs.useso.com/js/require.js/2.1.11/require.min.js"></script>
<script>
	require.config({
		baseUrl: "http://jex.im/regulex",
	});
	require(['dest/parse'], function(parse) {
		var form = document.forms.form;
		form.run.onclick = function() {
			var root = parse(form.input.value);
			form.output.value = generateMatchingString(root.tree);
		}
	});

	var charClasses = {
		'd': {ranges: ['09']},
		's': {chars: ' \f\n\r\t\v'},
		'w': {ranges: ['09', 'az', 'AZ'], chars: '_'}
	};

	function rangeToChars(range) {
		var chars = '';
		for (var i = range.charCodeAt(0); i < range.charCodeAt(1); i++) {
			chars += String.fromCharCode(i);
		}
		return chars;
	}

	function classToChars(charClass) {
		var chars = '';
		var derivedChars = charClasses[charClass];
		if (derivedChars.chars)
			chars += derivedChars.chars;
		if (derivedChars.ranges)
			chars += derivedChars.ranges.map(rangeToChars).join('');
		return chars;
	}

	function charSet(chars, classes, ranges) {
		chars += classes.map(classToChars).join('');
		chars += ranges.map(rangeToChars).join('');
		return chars;
	}

	var generateNode = {
		exact: function(node) {
			return node.chars;
		},
		dot: function(node) {
			return String.fromCharCode(65 + Math.round(Math.random() * 25));
		},
		choice: function(node) {
			return generateMatchingString(node.branches[Math.round(Math.random()*node.branches.length)]);
		},
		repeat: function(node) {
			var result = [];
			for (var i = 0; i < node.repeat.min; i++) {
				result.push(generateNode[node.type](node));
			}
			return result.join('');
		},
		charset: function(node) {
			var chars = charSet(node.chars, node.classes, node.ranges);
			return chars[Math.round(Math.random()*chars.length)];
		},
		group: function(node) {
			return generateMatchingString(node.sub);
		}
	};

	function generateMatchingString(tree) {
		var chunks = tree.map(function(node){
			if (node.repeat)
				return generateNode.repeat(node);
			else
				return generateNode[node.type](node);
		});
		return chunks.join('');
	}
 
</script>