krl-parser

krl-parser

Parse KRL source code into an AST

Usage

var parser = require('krl-parser');

var src = ...//somehow get your krl string

var ast = parser(src);

AST Specification

The specification is found in spec.md

API

ast = parser(src[, options])

• src - your krl source code string
• options.filename - If provided, it will be used on parsing errors so the user know what file failed to parse.

This function will throw errors when it can't parse. When applicable, the Error object may have a where property. i.e.

var src = 'function(a, b] { a + b }';
try{
  ast = parser(src, {filename: 'bad-function.krl'});
}catch(err){
  console.log(err.where);
}

{ filename: 'bad-function.krl',
  line: 1,
  col: 14,
  excerpt: 'function(a, b] { a + b }\n             ^' }

Developing

The parser is built using nearley. It uses the Earley parser algorithm.

The KRL grammar is defined here: src/grammar.ne

When developing run this:

$ npm start

It will watch for file changes, rebuild the grammar and run tests.

To rebuild and run tests once, run this:

$ npm test

Sometimes you may unwittingly introduce an ambiguity into the grammar. Run this script to help you find it:

$ node tests/ambiguityFinder.js

It will generate and try to parse random KRL programs (using tests/unparse.js). When it finds an ambiguity it will stop and diff the outputs to help you spot the ambiguity.

License

MIT

Changelog

0.49.0 - November 29, 2018

• user defined . operators i.e. a.b(c) is syntax sugar for b(a, c) - see 171
• performance optimization for ent:v := ent:v.append(..) - see 425
• compiler performance hint for ent:v := ent:v.put(..) - see 425
• /api/db-dump is gone! The UI scales better now - see 424
• enhance subscriptions tab - see 7a4ccc31
• Add redirect directive - see ebeb516d