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Get all matches of a regexp with corresponding start and end positions

License: GNU General Public License v3.0

JavaScript 100.00%

regex regexp regex-preprocessing javascript

multiregexp2's Introduction

MultiRegExp2

This class gets all matches, with start and end position, within the string, for a given regexp.

From high level the source code is:

Ensuring that each character is captured by a group: eg. /ab(cd)ef/ => /(ab)(cd)(ef)/
Calling exec on the converted regexp with a given string
Summing lengths of previous groups for start position of current group, add length of current group for end position

API

MultiRegexp2(baseRegExp: Regexp)

will setup parsed regexp, returns instance

execForAllGroups(string: string, includeFullMatch: boolean)

will find all matching groups, returns array<{match: string, start: Number, end: Number}>

execForGroup(string: string, group: Number)

will find match for group number, returns {match: string, start: Number, end: Number}

Usage

let regex = /a(?: )bc(def(ghi)xyz)/g;
let regex2 = new MultiRegExp2(regex);

let matches = regex2.execForAllGroups('ababa bcdefghixyzXXXX');
console.log(matches);
// reset to beginning: regex2.regexp.lastIndex = 0;

Will output:

[ { match: 'defghixyz', start: 8, end: 17 },
  { match: 'ghi', start: 11, end: 14 } ]

If you want to include the full match (group 0) then add true as the second parameter.

Also available:

let matches = regex2.execForGroup('ababa bcdefghixyzXXXX', 2);
= { match: 'ghi', start: 11, end: 14 }

Contribution

to compile the module to ES5 run npm install && npm run build && npm run test

multiregexp2's People

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multiregexp2's Issues

Wrong start position

Hi
There is a problem when i use following regex: ((http)(s))(:\/\/)

The problem is in group4. When we run above regex on something like https://regex101.com, the start index of group 4 should be 5, but 10 given!

Sorry for bad English

Invalid group recognition with a negative lookbehind (?<!)

Currently, when supplying a regular expression with a negative lookbehind (?<!), the library turns (?<! to ()(?<(!). By looking at the code, it seems the library doesn't support this group construct.

Another wrong case

Here's a case that doesn't currently parse correctly:
/\[(?:a=(.*?))?(?:b=(.*?))?]/

The regex it generates internally is
/(\[)(?:(a=)(.*?)()?)(?:(b=)(.*?))?]/

Notice that the first optional capture group from the original has been converted into a non-optional capture group!
ie

                    | There should be a ? here before the )
(\[)(?:(a=)(.*?)()?)(?:(b=)(.*?))?]

                |-| This optional capture group shouldn't exist?
(\[)(?:(a=)(.*?)()?)(?:(b=)(.*?))?]

Update: I tried to simplify the regex when i opened the issue but I realised that the simplification wasn't valid because I was using non-greedy capture groups without an end character in the regex

another parsing problem

code:

let r = new MultiRegExp2(/a(?:(b))?/);
console.log(r.regExp.source);

result:

(a(?:)(b))?

expected:

(a)(?:(b))?

Error when parsing /\(/i

new MultiRegExp2(/\(/);

ouput:

Invalid regular expression: /(\)(/: Unterminated group

wrong capture index

Please look into this code:

let str = "aaaaaaaaa";
let reg = /((a{2})a(\2))/ig;
let mreg = new MultiRegExp2(reg);
let matches = mreg.execForAllGroups(str, true);
for (let m of matches) {
    console.log(m.match, m.start, m.end);
}

output:

aaaaa 0 5
aa 0 2
aa 3 5

expected:

aaaaa 0 4
aa 0 1
aa 3 4

CDN link , web distribution

It will be very helpful if there is a CDN link so that lib can be tested .

https://github.com/valoricDe/MultiRegExp2/blob/master/dist/multiRegExp2.js
file is also wrong for web distribution as ther is no UMD wrapper

Just paste code in any jsfiddle and run to see compatibility

some case wrong

like next line RegExp, which with repeat symbol ( + or * ), it will be wrong
/(ba)+.(a*)/

regexp.execForAllGroups('bababaaaaa', true);

matches:  [ { match: 'ba', start: 0, end: 2 },
  { match: 'aaa', start: 3, end: 6 } ]

I think the regexp should change to /((ba)+).(a*)/ when calculate the next match position

nested groups do not work

regex101:
https://regex101.com/r/Whivxv/1

JSFIDDLE: (with MultiRegExp2 usage for same test case)
https://jsfiddle.net/bababalcksheep/o104bcq6/18/

should return 2 matches , each macth has 1 full match and 2 gruops

| (or) in combination with capturing parentheses doesn't work

I have a problem with the | operator and capturing groups in my regexp:

const MultiRegExp2 = require('multi-regexp2').default;

const matches = new MultiRegExp2(new RegExp('(a)|(b)')).execForAllGroups('b', true);

console.log(matches);
// -> null

Normally the matches should looks like this:
https://regex101.com/r/jn9DU9/1

Full match	0-1	b
Group 2.	0-1	b