aaac7fed
 liuqimichale
add
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var parse = require('ret');
var types = parse.types;
module.exports = function (re, opts) {
if (!opts) opts = {};
var replimit = opts.limit === undefined ? 25 : opts.limit;
if (isRegExp(re)) re = re.source;
else if (typeof re !== 'string') re = String(re);
try { re = parse(re) }
catch (err) { return false }
var reps = 0;
return (function walk (node, starHeight) {
if (node.type === types.REPETITION) {
starHeight ++;
reps ++;
if (starHeight > 1) return false;
if (reps > replimit) return false;
}
if (node.options) {
for (var i = 0, len = node.options.length; i < len; i++) {
var ok = walk({ stack: node.options[i] }, starHeight);
if (!ok) return false;
}
}
var stack = node.stack || (node.value && node.value.stack);
if (!stack) return true;
for (var i = 0; i < stack.length; i++) {
var ok = walk(stack[i], starHeight);
if (!ok) return false;
}
return true;
})(re, 0);
};
function isRegExp (x) {
return {}.toString.call(x) === '[object RegExp]';
}
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