RegexGen.js is a JavaScript regular expression generator that helps to construct complex regular expressions, inspired by JSVerbalExpressions.
RegexGen.js is basically designed for people who know how the regular expression engine works, but not working with it regularly, i.e., they know how to make the regex works but may not remember every meta-characters that constructs the regex.
RegexGen.js helps people don't have to remember: meta-characters, shortcuts, what characters to escape and tricks about corner cases (http://stackoverflow.com/questions/5484084/what-literal-characters-should-be-escaped-in-a-regex/5484178#5484178).
RegexGen.js helps reusing regex patterns. (checkout the [Matching an IP Address] example bellow.)
RegexGen.js tries to ease two problems.
- While creating a regular expression, it's hard to remember the correct syntax and what characters to escape.
- After done creating a regular expression, it's hard to read and remember what the regex do.
RegexGen.js is designed to achieve the following goals.
- The written codes should be easy to read and easy to understand.
- The generated code should be as compact as possible, e.g., no redundant brackets and parentheses.
- No more character escaping reguired (except '\', or if you use regex overwrite.)
- If the generated code is not good enougth, bad parts can be easily replaced directly in the written codes.
The generator is exported as a regexGen() function.
To generate a regular expression, pass sub-expressions as parameters to the call of regexGen() function.
Sub-expressions which are separated by comma are concatenated together to form the whole regular expression.
Sub-expressions can either be a string, a number, a RegExp object, or any combinations of the call to methods (i.e., the sub-generators) of the regexGen() function object, as the following informal BNF syntax.
Strings passed to the the call of regexGen(), text(), maybe(), anyCharOf() and anyCharBut() functions, are always escaped as necessary, so you don't have to worry about which characters to escape.
The result of calling the regexGen() function is a RegExp object.
The basic usage can be expressed as the following informal BNF syntax.
RegExp object = regexGen( sub-expression [, sub-expression ...] [, modifier ...] )
sub-expression ::= string | number | RegExp object | term
term ::= sub-generator() [.term-quantifier()] [.term-lookahead()]
sub-generator() ::= regexGen.startOfLine() | regexGen.endOfLine()
| regexGen.wordBoundary() | regexGen.nonWordBoundary()
| regexGen.text() | regexGen.maybe() | regexGen.anyChar() | regexGen.anyCharOf() | regexGen.anyCharBut()
| regexGen.either() | regexGen.group() | regexGen.capture() | regexGen.sameAs()
| regex() | ... (checkout wiki for all sub-generators.)
term-quantifier() ::= .term-quantifier-generator() [.term-quantifier-modifier()]
term-quantifier-generator() ::= term.any() | term.many() | term.maybe() | term.repeat() | term.multiple()
term-quantifier-modifier() ::= term.greedy() | term.lazy() | term.reluctant()
term-lookahead() ::= term.contains() | term.notContains() | term.followedBy() | term.notFollowedBy()
modifier ::= regexGen.ignoreCase() | regexGen.searchAll() | regexGen.searchMultiLine()
Please check out regexgen.js and wiki for API documentations, and check out test.js for more examples.
If your are managing package dependencies with bower, your can install RegexGen.js using bower install command.
bower install regexgen.js
Or you can just download the regexgen.js or regexgen.min.js, and put it to where your scripts located in your project.
Since the generator is exported as the regexGen() function, everything must be referenced from it.
To simplify codes, assign it to a short variable is preferable.
var _ = regexGen;
var regex = regexGen(
_.startOfLine(),
_.capture( 'http', _.maybe( 's' ) ), '://',
_.capture( _.anyCharBut( ':/' ).repeat() ),
_.group( ':', _.capture( _.digital().multiple(2,4) ) ).maybe(), '/',
_.capture( _.anything() ),
_.endOfLine()
);
var matches = regex.exec( url );
If you still feel inconvenient, and don't mind the global object being polluted,
use the regexGen.mixin() function to export all member functions of the regexGen() function object to the global object.
regexGen.mixin( window );
var regex = regexGen(
startOfLine(),
capture( 'http', maybe( 's' ) ), '://',
capture( anyCharBut( ':/' ).repeat() ),
group( ':', capture( digital().multiple(2,4) ) ).maybe(), '/',
capture( anything() ),
endOfLine()
);
var matches = regex.exec( url );
Or, if you don't use the strict mode with use strict keyword,
you can use the with keyword (though not recommended) to refer to all member functions of the regexGen() function object.
with( regexGen ) {
var regex = regexGen(
startOfLine(),
capture( 'http', maybe( 's' ) ), '://',
capture( anyCharBut( ':/' ).repeat() ),
group( ':', capture( digital().multiple(2,4) ) ).maybe(), '/',
capture( anything() ),
endOfLine()
);
var matches = regex.exec( url );
}
The RegExp object returned from the call of regexGen() function, can be used directly as usual. In addition, there are four properties injected to the RegExp object: warnings array, captures array, extract() method and extractAll() method. Checkout wiki for details.
This example is taken from the article: Mastering Lookahead and Lookbehind.
regexGen.mixin( window );
var regex = regexGen(
// Anchor: the beginning of the string
startOfLine(),
// Match: six to ten word characters
word().multiple(6,10).
// Look ahead: anything, then a lower-case letter
contains( anything().reluctant(), anyCharOf(['a','z']) ).
// Look ahead: anything, then an upper-case letter
contains( anything().reluctant(), anyCharOf(['A','Z']) ).
// Look ahead: anything, then one digit
contains( anything().reluctant(), digital() ),
// Anchor: the end of the string
endOfLine()
);
Generates:
/^(?=.*?[a-z])(?=.*?[A-Z])(?=.*?\d)\w{6,10}$/
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var d1 = group( anyCharOf( '0', '1' ).maybe(), digital(), digital().maybe() );
var d2 = group( '2', anyCharOf( ['0', '4'] ), digital() );
var d3 = group( '25', anyCharOf( ['0', '5'] ) );
var d255 = capture( either( d1, d2, d3 ) );
var regex = regexGen(
startOfLine(),
d255, '.', d255, '.', d255, '.', d255,
endOfLine()
);
Generates:
/^([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])$/
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var regex = regexGen(
'(',
anyCharBut( '()' ).any(),
group(
'(',
anyCharBut( '()' ).any(),
')',
anyCharBut( '()' ).any()
).any(),
')'
);
Generates:
/\([^()]*(?:\([^()]*\)[^()]*)*\)/
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
function nestingParentheses( level ) {
if ( level < 0 ) {
return '';
}
if ( level === 0 ) {
return anyCharBut( '()' ).any();
}
return either(
anyCharBut( '()' ),
group(
'(',
nestingParentheses( level - 1 ),
')'
)
).any();
}
Given 1 level of nesting:
var regex = regexGen(
'(', nestingParentheses( 1 ), ')'
);
Generates:
/\((?:[^()]|\([^()]*\))*\)/
Given 3 levels of nesting:
var regex = regexGen(
'(', nestingParentheses( 3 ), ')'
);
Generates:
/\((?:[^()]|\((?:[^()]|\((?:[^()]|\([^()]*\))*\))*\))*\)/
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var regex = regexGen(
'<',
either(
group( '"', anyCharBut('"').any(), '"' ),
group( "'", anyCharBut("'").any(), "'" ),
group( anyCharBut( '"', "'", '>' ) )
).any(),
'>'
);
Generates:
/<(?:"[^"]*"|'[^']*'|[^"'>])*>/
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var regexLink = regexGen(
'<a',
wordBoundary(),
capture(
anyCharBut( '>' ).many()
),
'>',
capture(
label( 'Link' ),
anything().lazy()
),
'</a>',
ignoreCase(),
searchAll()
);
var regexUrl = regexGen(
wordBoundary(),
'href',
space().any(), '=', space().any(),
either(
group( '"', capture( anyCharBut( '"' ).any() ), '"' ),
group( "'", capture( anyCharBut( "'" ).any() ), "'" ),
capture( anyCharBut( "'", '"', '>', space() ).many() )
),
ignoreCase()
);
Generates:
/<a\b([^>]+)>(.*?)<\/a>/gi
/\bhref\s*=\s*(?:"([^"]*)"|'([^']*)'|([^'">\s]+))/i
Here's how to iterate all links:
var capture, guts, link, url, html = document.documentElement.outerHTML;
while ( (capture = regexLink.exec( html )) ) {
guts = capture[ 1 ];
link = capture[ 2 ];
if ( (capture = regexUrl.exec( guts )) ) {
url = capture[ 1 ] || capture[ 2 ] || capture[ 3 ];
}
console.log( url + ' with link text: ' + link );
}
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var regex = regexGen(
startOfLine(),
'http', maybe( 's' ), '://',
capture( anyCharBut( '/:' ).many() ),
group( ':', capture( digital().many() ) ).maybe(),
capture( '/', anything() ).maybe(),
endOfLine()
);
Generates:
/^https?:\/\/([^/:]+)(?::(\d+))?(\/.*)?$/
Here's a snippet to report about a URL:
var capture = location.href.match( regex );
var host = capture[1];
var port = capture[2] || 80;
var path = capture[3] || '/';
console.log( 'host:' + host + ', port:' + port + ', path:' + path );
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var regex = regexGen(
startOfLine(),
// One or more dot-separated parts . . .
either(
group(
anyCharOf( ['a', 'z'], ['0', '9'] ),
'.'
),
group(
anyCharOf( ['a', 'z'], ['0', '9'] ),
anyCharOf( '-', ['a', 'z'], ['0', '9'] ).multiple( 0, 61 ),
anyCharOf( ['a', 'z'], ['0', '9'] ),
'.'
)
).any(),
// Followed by the final suffix part . . .
either(
'com', 'edu', 'gov', 'int', 'mil', 'net', 'org', 'biz', 'info', 'name', 'museum', 'coop', 'aero',
group( anyCharOf( ['a', 'z'] ), anyCharOf( ['a', 'z'] ) )
),
endOfLine()
);
Generates:
/^(?:[a-z0-9]\.|[a-z0-9][-a-z0-9]{0,61}[a-z0-9]\.)*(?:com|edu|gov|int|mil|net|org|biz|info|name|museum|coop|aero|[a-z][a-z])$/
This example is taken from the book: Mastering Regular Expressions
regexGen.mixin( window );
var regex = regexGen(
either( startOfLine(), ',' ),
either(
// Either a double-quoted field (with "" for each ")
group(
// double-quoted field's opening quote
'"',
capture(
anyCharBut( '"' ).any(),
group(
'""',
anyCharBut( '"' ).any()
).any()
),
// double-quoted field's closing quote
'"'
),
// Or some non-quote/non-comma text....
capture(
anyCharBut( '",' ).any()
)
)
);
Generates:
/(?:^|,)(?:"([^"]*(?:""[^"]*)*)"|([^",]*))/