Gparse NPM | npm.io

gparse

gparse is a Parser Combinator library in Typescript that enables the creation of efficient and reliable parsers for any possible Context Free Grammar (CFG).

Feature list

0 external dependencies.
Tested using BDD concepts.
Rich documentation using TSDoc and TypeDoc here.
Minimal parser combinator set.
Best (known) time complexities on all parser combinator implementations.
Can create parsers for any CFG grammar.
Full support for semantic data and parse tree generation.
Includes error recovery capabilites.

Installation

gparse is available on npm and can be installed via:

    npm install gparse

Usage

A simple calculator in gparse can be implemented as follows:

import * as gparse from 'gparse';

// Error definitions
const eof = new gparse.StaticSemantics("EOF", null);
const match = new gparse.StaticSemantics("match", null);
const divideByZeroError = new gparse.StaticSemantics('', "DivideByZeroError");

// Token definitions

const number: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.map(gparse.regex(/^[0-9]+/, (_) => eof, () => match), (state) => new gparse.StaticSemantics('', +state.result[state.result.length - 1]), (state) => state.error));
const lparen: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.str("(", (_) => eof, (_) => match));
const rparen: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.str(")", (_) => eof, (_) => match));
const addOp: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.str("+", (_) => eof, (_) => match));
const minusOp: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.str("-", (_) => eof, (_) => match));
const multiplyOp: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.str("*", (_) => eof, (_) => match));
const divideOp: gparse.SymbolParser<any, any> = gparse.SymbolParser.toSymbol(gparse.str("/", (_) => eof, (_) => match));

// Symbols

const primary: gparse.SymbolParser<any, any> = gparse.SymbolParser.lazy(() => gparse.alternatives([
    number,
    gparse.chain([lparen, expression, rparen], (data) => {
        return new gparse.StaticSemantics('', data[2].value);
    }),
]));
const term: gparse.SymbolParser<any, any> = gparse.SymbolParser.lazy(() => gparse.alternatives([
    gparse.chain([term, multiplyOp, primary], (data) => {
        return new gparse.StaticSemantics('', data[0].value * data[2].value);
    }),
    gparse.chain([term, divideOp, gparse.assert(primary, (state) => {
                if (!state.isError && state.data.value === 0) {
                    return divideByZeroError;
                } else {
                    return null;
                }
            })], (data) => {
        return new gparse.StaticSemantics('', data[0].value / data[2].value);
    }),
    primary,
]));
const expression: gparse.SymbolParser<any, any> = gparse.SymbolParser.lazy(() => gparse.alternatives([
    gparse.chain([expression, addOp, term], (data) => {
        return new gparse.StaticSemantics('', data[0].value + data[2].value);
    }),
    gparse.chain([expression, minusOp, term], (data) => {
        return new gparse.StaticSemantics('', data[0].value - data[2].value);
    }),
    term,
]));

console.log("1+2-3+4*5-10/5");  // 18

Full documentation on the library can be found here.

Also, a Cookbook with many more examples is under developement.