regexp-coder

Building readable JavaScript/TypeScript regular expressions gracefully.

API Documentation

RegExp Coder API Documentation

Introduction

The regexp-coder is using fluent APIs (with nested parameters) to help you to build regular expressions in a readable way.

• Sample: Check IPv4

Let's see how to use the util to define a IPv4 address in decimal number. IPv4 address is presented in format of: <0-255>.<0-255>.<0-255>.<0-255>. There are two elements, one is decimal number which is from 0 to 255, and another element is .. We can define the decimal part as subIP: /\d|\d\d|[1]\d\d|2[0-4]\d|25[0-5]/ and the do element as dot: /\./

For example:

import { RegExpCoder } from 'regexp-coder';

const subIP = /(\d|\d\d|1\d\d|2[0-4]\d|25[0-5])/;
const dot = /\./;
const ipv4Exp = RegExpCoder.new()
    .join(
        subIP,
        dot,
        subIP,
        dot,
        subIP,
        dot,
        subIP,
    )
    .enableMatchWhole()
    .toRegExp();

console.log(ipv4Exp.test('192.168.0.1')); // true
console.log(ipv4Exp.test('192-168-0-1')); // false

• If you like fluent API, you can use the define-build pattern.

You can define elements sub-ip and dot as variables and use them later. For example:

import { RegExpCoder } from 'regexp-coder';

const ipv4Exp = RegExpCoder.new()
    .define('sub-ip', /(\d|\d\d|1\d\d|2[0-4]\d|25[0-5])/)
    .define('dot', /\./)
    .join(
        'sub-ip',
        'dot',
        'sub-ip',
        'dot',
        'sub-ip',
        'dot',
        'sub-ip',
    )
    .enableMatchWhole()
    .toRegExp();

console.log(ipv4Exp.test('192.168.0.1')); // true
console.log(ipv4Exp.test('192-168-0-1')); // false

• For complex variables, you use build-stash-build pattern. The stash() method will save the current result as a variable, then get the object cleared.

For example:

import { RegExpCoder } from 'regexp-coder';

const ipv4Exp = RegExpCoder.new()
    .group(
        RegExpCoder.new().or(
            /\d/,
            /\d\d/,
            /1\d\d/,
            /2[0-4]\d/,
            /25[0-5]/,
        ),
    )
    .stash('sub-ip')
    .define('dot', /\./)
    .join(
        'sub-ip',
        'dot',
        'sub-ip',
        'dot',
        'sub-ip',
        'dot',
        'sub-ip',
    )
    .enableMatchWhole()
    .toRegExp();

console.log(ipv4Exp.test('192.168.0.1')); // true
console.log(ipv4Exp.test('192-168-0-1')); // false

Main classes

RegExpCoder

Method	Description
static methods:
encodeRegExp	Encode a raw string to a regular expression string.
	For example, it will convert . -> \.
new()	Create an instance of RegExpCoder
instance methods:
join()	Append an expression, .e.g xyz
group()	Append a group expression, e.g. (xyz)
or()	Append an or expression, e.g. `x
set()	Append a set expression, e.g. [xyz]
negatedSet()	Append a negated set expression, e.g. [^xyz]
lookahead()	Append a lookahead expression, e.g. x(?=y)
negatedLookahead()	Append a negated lookahead expression, e.g. x(?!y)
lookbehind()	Append a lookbehind expression, e.g. (?<=y)x
negatedLookbehind()	Append a negated lookbehind expression, e.g. (?<!y)x
define()	Define an expression, .e.g xyz
defineGroup()	Define a group expression, e.g. (xyz)
defineOr()	Define an or expression, e.g. `x
defineSet()	Define a set expression, e.g. [xyz]
defineNegatedSet()	Define a negated set expression, e.g. [^xyz]
defineLookahead()	Define a lookahead expression, e.g. x(?=y)
defineNegatedLookahead()	Define a negated lookahead expression, e.g. x(?!y)
defineLookbehind()	Define a lookbehind expression, e.g. (?<=y)x
defineNegatedLookbehind()	Define a negated lookbehind expression, e.g. (?<!y)x
stash()	Define an expression from the current state.
source	Get the source of the current state.
toRegExp()	Get the RegExp instance of the current state.
enableMatchWhole	Enable the expression to match the whole string. e.g. ^x$
beginGroup	Begin a group expression. e.g. (
endGroup	End the group expression, e.g. ')'

RegExpOptions

For example:

import { RegExpCoder } from 'regexp-coder';

const group = true;
const ipv4Exp = RegExpCoder.new()
    .or(
        /\d/,
        /\d\d/,
        /1\d\d/,
        /2[0-4]\d/,
        /25[0-5]/,
        { group }, // <-- Use options here
    )
    .stash('sub-ip')
    .define('dot', /\./)
    .join(
        'sub-ip',
        'dot',
        'sub-ip',
        'dot',
        'sub-ip',
        'dot',
        'sub-ip',
    )
    .enableMatchWhole()
    .toRegExp();

console.log(ipv4Exp.test('192.168.0.1')); // true
console.log(ipv4Exp.test('192-168-0-1')); // false

Members	Description
qualifier	(xyz)*, Define qualifier for the current expression
groupQualifiedItem	(xyz)*, If need to add a group before the qualifier for the current expression
notRememberQualifiedItem	(?:xyz)*, If need not to remember the qualifier group for the current expression
groupItem	(x)(y)(z), If need to add a group for each items of the current expression
group	(xyz), If need to add a group for the current expression
name	(?name:xyz)*, name for the group
notRemember	(?:xyz), If need not to remember the group for the current expression
or	`x
set	[xyz], If use the set operation for the items in the expression
negated	[^xyz], If use the negated set operation for the items in the expression

RegExpSpec

This is one to one members of Regular Expressions.