var npos = require('npos');
var parser = npos.parser();
var buffer = fs.readFileSync('sample.bin');

parser.parse(buffer).then(function (ast) {
  console.log(ast);
});

var npos = require('npos');
var rules = {};

rules[npos.ESC] = {     // 'ESC' commands
  '!': 1,               // 'ESC !' command. Swallow one parameter byte
  '$': 2,           
  '%': 1,
  '&': [0, ycc],        // 'ESC &' command. Using 'ycc' function to decode from offset 0
  '*': [0, 'bitimage'], // 'ESC *' command. Using builtin decoder to decode from offset 0.
  '-': 1,
  '2': 0,
  '3': 1,
  '=': 1,
  '?': 1,
  '@': 0,
  'D': [0, 'escd'],
  'E': 1,
  'G': 1,
  'J': 1,
  'L': 0,
  'M': 1,
  'R': 1,
  'S': 0,
  'T': 1,
  'V': 1,
  'W': 8,
  '\\': 2,
  'a': 1,
  'c': 2,
  'd': 1,
  'p': 3,
  'r': 0, // Select print color
  't': 1,
  '{': 1,
  'B': 2, // Unknown Command
  'Z': [3, 'd16']
};

// Custom decoder with parameter buffer and offset specified with rule.
function ycc(buf, offset) {
  if (buf.length - offset < 3) {
    return buf.length;
  }
  var k = buf[offset + 2] - buf[offset + 1] + 1;
  var num = 3;
  for (var i = 0; i < k; i++) {
    num += buf[offset + num] * buf[offset] + 1;
  }
  return num;
};

var npos = require('npos');

rules[npos.ESC]['&'] = [0, ycc];