77 lines
1.8 KiB
JavaScript
77 lines
1.8 KiB
JavaScript
'use strict'
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const parse = require('ret')
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const { types } = require('ret')
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/**
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* @param {*} node
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* @param {object} opts
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* @param {number} opts.reps - The number of repetitions encountered
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* @param {number} opts.limit - The maximum number of repetitions allowed
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* @param {number} starHeight - The current height of the star in the regex tree
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* @returns {boolean}
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*/
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function walk (node, opts, starHeight) {
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let i
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let ok
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let len
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if (node.type === types.REPETITION) {
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starHeight++
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opts.reps++
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if (starHeight > 1) return false
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if (opts.reps > opts.limit) return false
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}
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const options = node.options || node.value?.options
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if (options) {
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for (i = 0, len = options.length; i < len; i++) {
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ok = walk({ stack: options[i] }, opts, starHeight)
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if (!ok) return false
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}
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}
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const stack = node.stack || node.value?.stack
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if (!stack) return true
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for (i = 0, len = stack.length; i < len; i++) {
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ok = walk(stack[i], opts, starHeight)
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if (!ok) return false
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}
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return true
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}
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/**
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* @param {string|RegExp} re - The regular expression to check, can be a string or RegExp object
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* @param {object} [options]
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* @param {number} [options.limit=25] - The maximum number of repetitions allowed
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* @returns {boolean} - Returns true if the regex is safe, false if it is unsafe or invalid
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*/
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function safeRegex (re, options) {
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const opts = {
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reps: 0,
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limit: options?.limit ?? 25
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}
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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 {
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return walk(parse(re), opts, 0)
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} catch {
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return false
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}
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}
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/**
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* @param {*} x
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* @returns {x is RegExp}
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*/
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function isRegExp (x) {
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return Object.prototype.toString.call(x) === '[object RegExp]'
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}
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module.exports = safeRegex
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module.exports.default = safeRegex
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module.exports.safeRegex = safeRegex
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