1 | # safe-regex
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2 |
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3 | detect potentially
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4 | [catastrophic](http://regular-expressions.mobi/catastrophic.html)
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5 | [exponential-time](http://perlgeek.de/blog-en/perl-tips/in-search-of-an-exponetial-regexp.html)
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6 | regular expressions by limiting the
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7 | [star height](https://en.wikipedia.org/wiki/Star_height) to 1
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8 |
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9 | WARNING: This module merely *seems* to work given all the catastrophic regular
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10 | expressions I could find scouring the internet, but I don't have enough of a
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11 | background in automata to be absolutely sure that this module will catch all
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12 | exponential-time cases.
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13 |
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14 | [![browser support](https://ci.testling.com/substack/safe-regex.png)](https://ci.testling.com/substack/safe-regex)
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15 |
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16 | [![build status](https://secure.travis-ci.org/substack/safe-regex.png)](http://travis-ci.org/substack/safe-regex)
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17 |
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18 | # example
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19 |
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20 | ``` js
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21 | var safe = require('safe-regex');
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22 | var regex = process.argv.slice(2).join(' ');
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23 | console.log(safe(regex));
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24 | ```
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25 |
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26 | ```
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27 | $ node safe.js '(x+x+)+y'
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28 | false
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29 | $ node safe.js '(beep|boop)*'
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30 | true
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31 | $ node safe.js '(a+){10}'
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32 | false
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33 | $ node safe.js '\blocation\s*:[^:\n]+\b(Oakland|San Francisco)\b'
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34 | true
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35 | ```
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36 |
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37 | # methods
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38 |
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39 | ``` js
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40 | var safe = require('safe-regex')
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41 | ```
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42 |
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43 | ## var ok = safe(re, opts={})
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44 |
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45 | Return a boolean `ok` whether or not the regex `re` is safe and not possibly
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46 | catastrophic.
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47 |
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48 | `re` can be a `RegExp` object or just a string.
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49 |
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50 | If the `re` is a string and is an invalid regex, returns `false`.
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51 |
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52 | * `opts.limit` - maximum number of allowed repetitions in the entire regex.
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53 | Default: `25`.
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54 |
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55 | # install
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56 |
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57 | With [npm](https://npmjs.org) do:
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58 |
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59 | ```
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60 | npm install safe-regex
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61 | ```
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62 |
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63 | # license
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64 |
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65 | MIT
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