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44 lines
1.2 KiB
44 lines
1.2 KiB
6 years ago
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var parse = require('ret');
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var types = parse.types;
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module.exports = function (re, opts) {
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if (!opts) opts = {};
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var replimit = opts.limit === undefined ? 25 : opts.limit;
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if (isRegExp(re)) re = re.source;
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else if (typeof re !== 'string') re = String(re);
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try { re = parse(re) }
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catch (err) { return false }
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var reps = 0;
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return (function walk (node, starHeight) {
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if (node.type === types.REPETITION) {
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starHeight ++;
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reps ++;
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if (starHeight > 1) return false;
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if (reps > replimit) return false;
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}
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if (node.options) {
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for (var i = 0, len = node.options.length; i < len; i++) {
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var ok = walk({ stack: node.options[i] }, starHeight);
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if (!ok) return false;
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}
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}
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var stack = node.stack || (node.value && node.value.stack);
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if (!stack) return true;
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for (var i = 0; i < stack.length; i++) {
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var ok = walk(stack[i], starHeight);
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if (!ok) return false;
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}
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return true;
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})(re, 0);
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};
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function isRegExp (x) {
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return {}.toString.call(x) === '[object RegExp]';
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}
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