Crazy Parser

A light-weight parser combinator.

Install

npm i crazy-parser

Example

Sign Parser

Import:

import {char} from "crazy-parser"

Build a sign parser:

const pSign = char("+").or(char("-")) 

Represent it with booleans:

const pSign = 
    char("+").cmap(true)
        .or(char("-").cmap(false))

Parse a sign:

console.log(pSign.eval("+")) // true
console.log(pSign.eval("-")) // false
console.log(pSign.eval("???") instanceof Error) // true

Add custom error messages:

class MissingSign extends Error {}

const pSign =
    char("+").cmap(true)
        .or(char("-").cmap(false))
        .error(new MissingSign())

Time Parser

import {digit} from "crazy-parser"

// Parse current hour
const d24 =
    // 2 digits
    digit.x(2)
        // Map them to a number
        .map(cs => parseInt(cs.join("")))
        // Add a constrain
        .where(x => 0 <= x && x <= 23)

// Parse current minute & second
const d60 = digit.x(2)
    .map(cs => parseInt(cs.join("")))
    .where(h => 0 <= h && h <= 59)

// Insert colons between them
const time = template`${d24}:${d60}:${d60}`
    // There shouldn't be anything else after the time
    ._$(eof)

console.log(time.eval("12:34:56"))
console.log(time.eval("12:34:56?") instanceof Error) // true
console.log(time.eval("99:99:99") instanceof Error) // true
console.log(time.eval("9:9:9") instanceof Error) // true

You can go to test folder for more examples. If you'd like to read the docs and the signatures, please go to the main module.

Development

Using make

Please make sure you have node, tsc and vitest installed.

Build

make

Build a tarball

make pack

Clean up

make clean

Test

The test takes about 6 seconds on my machine.

make test

Using npm

Please make sure you have tsc and vitest installed.

Build

npm run build

Build a tarball

npm run build
npm pack

Clean up

npm run clean

Test

npm run clean
npm run test