import { char, either, sequence, many, map } from 'combo-parser';

// Parse either a quoted string or unquoted word
const stringParser = either(
  sequence(char('"'), many(char.match(/[^"]/)), char('"')),
  many(char.match(/\w/))
).map(([_, content]) => content.join(''));

// Parse "hello" or hello
console.log(stringParser('"hello"', 0)); // { success: true, value: 'hello' }
console.log(stringParser('world', 0));    // { success: true, value: 'world' }

import { char, digit, letters } from 'combo-parser';

char('a')    // Match exact character
digit()      // Match 0-9  
letters()    // Match a-zA-Z

import { either, sequence, many, optional } from 'combo-parser';

either(a, b)     // Try parser A, then B
sequence(a, b)   // Match A then B
many(a)          // Match 0+ occurrences
optional(a)      // Make parser optional

const parser = either(digit(), letters());
const result = parser('!', 0);

if (!result.success) {
  console.log(`Error at position ${result.index}:`);
  result.errors.forEach(err => 
    console.log(`- Expected ${err.expected}`)
  );
}