281 lines
11 KiB
Markdown
281 lines
11 KiB
Markdown
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# to-regex-range [](https://www.npmjs.com/package/to-regex-range) [](https://npmjs.org/package/to-regex-range) [](https://npmjs.org/package/to-regex-range) [](https://travis-ci.org/micromatch/to-regex-range)
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> Pass two numbers, get a regex-compatible source string for matching ranges. Validated against more than 2.78 million test assertions.
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## Install
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Install with [npm](https://www.npmjs.com/):
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```sh
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$ npm install --save to-regex-range
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```
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Install with [yarn](https://yarnpkg.com):
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```sh
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$ yarn add to-regex-range
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```
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<details>
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<summary><strong>What does this do?</strong></summary>
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<br>
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This libary generates the `source` string to be passed to `new RegExp()` for matching a range of numbers.
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**Example**
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```js
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var toRegexRange = require('to-regex-range');
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var regex = new RegExp(toRegexRange('15', '95'));
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```
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A string is returned so that you can do whatever you need with it before passing it to `new RegExp()` (like adding `^` or `$` boundaries, defining flags, or combining it another string).
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<br>
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</details>
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<details>
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<summary><strong>Why use this library?</strong></summary>
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<br>
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### Convenience
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Creating regular expressions for matching numbers gets deceptively complicated pretty fast.
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For example, let's say you need a validation regex for matching part of a user-id, postal code, social security number, tax id, etc:
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* regex for matching `1` => `/1/` (easy enough)
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* regex for matching `1` through `5` => `/[1-5]/` (not bad...)
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* regex for matching `1` or `5` => `/(1|5)/` (still easy...)
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* regex for matching `1` through `50` => `/([1-9]|[1-4][0-9]|50)/` (uh-oh...)
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* regex for matching `1` through `55` => `/([1-9]|[1-4][0-9]|5[0-5])/` (no prob, I can do this...)
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* regex for matching `1` through `555` => `/([1-9]|[1-9][0-9]|[1-4][0-9]{2}|5[0-4][0-9]|55[0-5])/` (maybe not...)
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* regex for matching `0001` through `5555` => `/(0{3}[1-9]|0{2}[1-9][0-9]|0[1-9][0-9]{2}|[1-4][0-9]{3}|5[0-4][0-9]{2}|55[0-4][0-9]|555[0-5])/` (okay, I get the point!)
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The numbers are contrived, but they're also really basic. In the real world you might need to generate a regex on-the-fly for validation.
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**Learn more**
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If you're interested in learning more about [character classes](http://www.regular-expressions.info/charclass.html) and other regex features, I personally have always found [regular-expressions.info](http://www.regular-expressions.info/charclass.html) to be pretty useful.
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### Heavily tested
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As of April 27, 2017, this library runs [2,783,483 test assertions](./test/test.js) against generated regex-ranges to provide brute-force verification that results are indeed correct.
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Tests run in ~870ms on my MacBook Pro, 2.5 GHz Intel Core i7.
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### Highly optimized
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Generated regular expressions are highly optimized:
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* duplicate sequences and character classes are reduced using quantifiers
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* smart enough to use `?` conditionals when number(s) or range(s) can be positive or negative
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* uses fragment caching to avoid processing the same exact string more than once
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<br>
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</details>
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## Usage
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Add this library to your javascript application with the following line of code
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```js
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var toRegexRange = require('to-regex-range');
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```
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The main export is a function that takes two integers: the `min` value and `max` value (formatted as strings or numbers).
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```js
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var source = toRegexRange('15', '95');
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//=> 1[5-9]|[2-8][0-9]|9[0-5]
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var re = new RegExp('^' + source + '$');
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console.log(re.test('14')); //=> false
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console.log(re.test('50')); //=> true
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console.log(re.test('94')); //=> true
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console.log(re.test('96')); //=> false
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```
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## Options
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### options.capture
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**Type**: `boolean`
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**Deafault**: `undefined`
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Wrap the returned value in parentheses when there is more than one regex condition. Useful when you're dynamically generating ranges.
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```js
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console.log(toRegexRange('-10', '10'));
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//=> -[1-9]|-?10|[0-9]
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console.log(toRegexRange('-10', '10', {capture: true}));
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//=> (-[1-9]|-?10|[0-9])
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```
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### options.shorthand
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**Type**: `boolean`
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**Deafault**: `undefined`
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Use the regex shorthand for `[0-9]`:
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```js
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console.log(toRegexRange('0', '999999'));
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//=> [0-9]|[1-9][0-9]{1,5}
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console.log(toRegexRange('0', '999999', {shorthand: true}));
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//=> \d|[1-9]\d{1,5}
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```
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### options.relaxZeros
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**Type**: `boolean`
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**Default**: `true`
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This option only applies to **negative zero-padded ranges**. By default, when a negative zero-padded range is defined, the number of leading zeros is relaxed using `-0*`.
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```js
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console.log(toRegexRange('-001', '100'));
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//=> -0*1|0{2}[0-9]|0[1-9][0-9]|100
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console.log(toRegexRange('-001', '100', {relaxZeros: false}));
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//=> -0{2}1|0{2}[0-9]|0[1-9][0-9]|100
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```
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<details>
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<summary><strong>Why are zeros relaxed for negative zero-padded ranges by default?</strong></summary>
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Consider the following.
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```js
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var regex = toRegexRange('-001', '100');
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```
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_Note that `-001` and `100` are both three digits long_.
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In most zero-padding implementations, only a single leading zero is enough to indicate that zero-padding should be applied. Thus, the leading zeros would be "corrected" on the negative range in the example to `-01`, instead of `-001`, to make total length of each string no greater than the length of the largest number in the range (in other words, `-001` is 4 digits, but `100` is only three digits).
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If zeros were not relaxed by default, you might expect the resulting regex of the above pattern to match `-001` - given that it's defined that way in the arguments - _but it wouldn't_. It would, however, match `-01`. This gets even more ambiguous with large ranges, like `-01` to `1000000`.
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Thus, we relax zeros by default to provide a more predictable experience for users.
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</details>
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## Examples
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| **Range** | **Result** | **Compile time** |
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| --- | --- | --- |
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| `toRegexRange('5, 5')` | `5` | _33μs_ |
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| `toRegexRange('5, 6')` | `5\|6` | _53μs_ |
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| `toRegexRange('29, 51')` | `29\|[34][0-9]\|5[01]` | _699μs_ |
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| `toRegexRange('31, 877')` | `3[1-9]\|[4-9][0-9]\|[1-7][0-9]{2}\|8[0-6][0-9]\|87[0-7]` | _711μs_ |
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| `toRegexRange('111, 555')` | `11[1-9]\|1[2-9][0-9]\|[2-4][0-9]{2}\|5[0-4][0-9]\|55[0-5]` | _62μs_ |
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| `toRegexRange('-10, 10')` | `-[1-9]\|-?10\|[0-9]` | _74μs_ |
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| `toRegexRange('-100, -10')` | `-1[0-9]\|-[2-9][0-9]\|-100` | _49μs_ |
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| `toRegexRange('-100, 100')` | `-[1-9]\|-?[1-9][0-9]\|-?100\|[0-9]` | _45μs_ |
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| `toRegexRange('001, 100')` | `0{2}[1-9]\|0[1-9][0-9]\|100` | _158μs_ |
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| `toRegexRange('0010, 1000')` | `0{2}1[0-9]\|0{2}[2-9][0-9]\|0[1-9][0-9]{2}\|1000` | _61μs_ |
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| `toRegexRange('1, 2')` | `1\|2` | _10μs_ |
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| `toRegexRange('1, 5')` | `[1-5]` | _24μs_ |
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| `toRegexRange('1, 10')` | `[1-9]\|10` | _23μs_ |
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| `toRegexRange('1, 100')` | `[1-9]\|[1-9][0-9]\|100` | _30μs_ |
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| `toRegexRange('1, 1000')` | `[1-9]\|[1-9][0-9]{1,2}\|1000` | _52μs_ |
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| `toRegexRange('1, 10000')` | `[1-9]\|[1-9][0-9]{1,3}\|10000` | _47μs_ |
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| `toRegexRange('1, 100000')` | `[1-9]\|[1-9][0-9]{1,4}\|100000` | _44μs_ |
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| `toRegexRange('1, 1000000')` | `[1-9]\|[1-9][0-9]{1,5}\|1000000` | _49μs_ |
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| `toRegexRange('1, 10000000')` | `[1-9]\|[1-9][0-9]{1,6}\|10000000` | _63μs_ |
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## Heads up!
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**Order of arguments**
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When the `min` is larger than the `max`, values will be flipped to create a valid range:
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```js
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toRegexRange('51', '29');
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```
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Is effectively flipped to:
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```js
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toRegexRange('29', '51');
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//=> 29|[3-4][0-9]|5[0-1]
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```
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**Steps / increments**
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This library does not support steps (increments). A pr to add support would be welcome.
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## History
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### v2.0.0 - 2017-04-21
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**New features**
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Adds support for zero-padding!
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### v1.0.0
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**Optimizations**
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Repeating ranges are now grouped using quantifiers. rocessing time is roughly the same, but the generated regex is much smaller, which should result in faster matching.
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## Attribution
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Inspired by the python library [range-regex](https://github.com/dimka665/range-regex).
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## About
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### Related projects
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* [expand-range](https://www.npmjs.com/package/expand-range): Fast, bash-like range expansion. Expand a range of numbers or letters, uppercase or lowercase. See… [more](https://github.com/jonschlinkert/expand-range) | [homepage](https://github.com/jonschlinkert/expand-range "Fast, bash-like range expansion. Expand a range of numbers or letters, uppercase or lowercase. See the benchmarks. Used by micromatch.")
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* [fill-range](https://www.npmjs.com/package/fill-range): Fill in a range of numbers or letters, optionally passing an increment or `step` to… [more](https://github.com/jonschlinkert/fill-range) | [homepage](https://github.com/jonschlinkert/fill-range "Fill in a range of numbers or letters, optionally passing an increment or `step` to use, or create a regex-compatible range with `options.toRegex`")
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* [micromatch](https://www.npmjs.com/package/micromatch): Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch. | [homepage](https://github.com/jonschlinkert/micromatch "Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch.")
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* [repeat-element](https://www.npmjs.com/package/repeat-element): Create an array by repeating the given value n times. | [homepage](https://github.com/jonschlinkert/repeat-element "Create an array by repeating the given value n times.")
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* [repeat-string](https://www.npmjs.com/package/repeat-string): Repeat the given string n times. Fastest implementation for repeating a string. | [homepage](https://github.com/jonschlinkert/repeat-string "Repeat the given string n times. Fastest implementation for repeating a string.")
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### Contributing
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Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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### Building docs
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_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
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To generate the readme, run the following command:
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```sh
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$ npm install -g verbose/verb#dev verb-generate-readme && verb
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```
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### Running tests
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Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
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```sh
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$ npm install && npm test
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```
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### Author
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**Jon Schlinkert**
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* [github/jonschlinkert](https://github.com/jonschlinkert)
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* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
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### License
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Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
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Released under the [MIT License](LICENSE).
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***
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_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on April 27, 2017._
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