Irregex

Irregular expressions. Simplify implementation of classes that fulfil a regex-compatible contract.

Irregex class

Abstract class for regex-compatible classes to inherit from.

At minimum, derived classes must implement the getMatch method, which is stateful and relies on the lastIndex property.

For convenience, you can also use the fromIter helper, which caches iterable results for a given input string and handles reading of lastIndex.

Examples

Matching words in a string:

import { Irregex } from 'irregex'

class WordMatcher extends Irregex {
    segmenter: Intl.Segmenter

    constructor(locale: string) {
        super()
        this.segmenter = new Intl.Segmenter(locale, { granularity: 'word' })
    }

    getMatch(str: string) {
        return this.fromIter(str, function* () {
            for (const segmentData of this.segmenter.segment(str)) {
                if (segmentData.isWordLike && /\p{L}/u.test(segmentData.segment)) {
                    const arr: [string] = [segmentData.segment]

                    yield Object.assign(arr, {
                        ...segmentData,
                        groups: {
                            abbr: segmentData.segment.match(/^.{0,3}/u)![0],
                        },
                    })
                }
            }
        })
    }
}

new WordMatcher('en-US')[Symbol.replace](
    'Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday',
    '($<abbr>)',
)
// "(Mon), (Tue), (Wed), (Thu), (Fri), (Sat), (Sun)"

new WordMatcher('zh-CN')[Symbol.match]('此地无银三百两')
// ["此地", "无", "银", "三百", "两"]

Matching IPv4 addresses:

class Ipv4Matcher extends Irregex {
    re = /(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/g

    constructor() {
        super()
        this.trackLastIndex = [this.re]
    }

    getMatch(str: string) {
        while (true) {
            const m = this.re.exec(str)
            if (m == null) return null

            if (m.slice(1).every((x) => Number(x) < 256)) {
                return m
            }
        }
    }
}

new Ipv4Matcher()[Symbol.match]('192.168.1.1\n999.999.999.999\n255.255.255.255')
// ["192.168.1.1", "255.255.255.255"]

CombinedMatcher class

Combine multiple matchers (RegExps, Irregexes) to iterate through them in sync.

Examples

Combining different types of matchers:

import { CombinedMatcher } from 'irregex'

const matcher = new CombinedMatcher([
    new WordMatcher('en-US'),
    new Ipv4Matcher(),
])

matcher[Symbol.match]('One two three 1 2 3 192.168.1.1 999.999.999.999 255.255.255.255 five!')
// ["One", "two", "three", "192.168.1.1", "255.255.255.255", "five"]

Combining case-sensitive and case-insensitive regexes:

import { CombinedMatcher } from 'irregex'

const matcher = new CombinedMatcher([
    /a/g,
    /b/gi,
])

matcher[Symbol.match]('a A b B')
// ["a", "b", "B"]