ascoders/syntax-parser

import { createLexer } from 'syntax-parser';

const myLexer = createLexer([
  {
    type: 'whitespace',
    regexes: [/^(\s+)/],
    ignore: true
  },
  {
    type: 'word',
    regexes: [/^([a-zA-Z0-9]+)/]
  },
  {
    type: 'operator',
    regexes: [/^(\+)/]
  }
]);

myLexer('a + b');
// [
//   { "type": "word", "value": "a", "position": [0, 1] },
//   { "type": "operator", "value": "+", "position": [2, 3] },
//   { "type": "word", "value": "b", "position": [4, 5] }
// ]

import { createParser, chain, matchTokenType, many } from 'syntax-parser';

const root = () => chain(addExpr)(ast => ast[0]);

const addExpr = () =>
  chain(matchTokenType('word'), many(addPlus))(ast => ({
    left: ast[0].value,
    operator: ast[1] && ast[1][0].operator,
    right: ast[1] && ast[1][0].term
  }));

const addPlus = () =>
  chain('+', root)(ast => ({
    operator: ast[0].value,
    term: ast[1]
  }));

const myParser = createParser(
  root, // Root grammar.
  myLexer // Created in lexer example.
);

myParser('a + b');
// ast:
// [{
//   "left": "a",
//   "operator": "+",
//   "right": {
//     "left": "b",
//     "operator": null,
//     "right": null
//   }
// }]

chain('select', 'table'); // Match 'select table'

chain('select', ['table', 'chart']); // Match both 'select table' and 'select chart'

chain('select', matchTokenType('word')); // Match 'select [any word!]'

const a = () => chain('select', b);
const b = () => chain('table');

const a = () => chain('select', optional('table')); // Match both 'select' and 'select table'
const b = () => chain('select', many(',', matchTokenType('word'))); // Match both 'select' and 'select a' and 'select a, b' .. and so on.

chain('select', 'table')(
  ast => ast[0] // return 'select'
);

npm test

npm run docs