anybase/js/anybase.js

convert from and to numeric bases from base 2 to base 62

// Generated by CoffeeScript 1.6.3
(function() {
  var base_to_dec, char, chars, dec_to_base, i, map, _i, _j, _k, _len;

  chars = (function() {
    var _i, _results;
    _results = [];
    for (i = _i = 0; _i < 10; i = ++_i) {
      _results.push(String(i));
    }
    return _results;
  })();

  for (i = _i = 65; _i <= 90; i = ++_i) {
    chars.push(String.fromCharCode(i));
  }

  for (i = _j = 97; _j <= 122; i = ++_j) {
    chars.push(String.fromCharCode(i));
  }

  map = {};

  for (i = _k = 0, _len = chars.length; _k < _len; i = ++_k) {
    char = chars[i];
    map[char] = i;
  }

  base_to_dec = function(n, base) {
    var n10, _l, _len1;
    n10 = 0;
    for (_l = 0, _len1 = n.length; _l < _len1; _l++) {
      char = n[_l];
      n10 = n10 * base + map[char];
    }
    return n10;
  };

  dec_to_base = function(n, base) {
    var mod, nx;
    nx = '';
    while (n > 0) {
      mod = n % base;
      n = (n - mod) / base;
      nx = chars[mod] + nx;
    }
    return nx;
  };

  module.exports = function(base, n, orig_base, digits_min, digits_max) {
    var int_check, v, _l, _len1, _ref;
    if (orig_base == null) {
      orig_base = 10;
    }
    if (digits_min == null) {
      digits_min = 0;
    }
    if (digits_max == null) {
      digits_max = 0;
    }
    int_check = function(n, min, max) {
      if (min == null) {
        min = false;
      }
      if (max == null) {
        max = false;
      }
      return !(isNaN(n) || Math.round(n) !== n || (min !== false && n < min) || (max !== false && n > max));
    };
    base = Number(base);
    orig_base = Number(orig_base);
    digits_min = Number(digits_min);
    digits_max = Number(digits_max);
    if (!int_check(base, 2, 62)) {
      throw new Error('Invalid target numeric base specified: `' + base + '` (expected: 2 .. 62)');
    }
    if (!int_check(orig_base, 2, 62)) {
      throw new Error('Invalid original numeric base specified: `' + orig_base + '` (expected: 2 .. 62)');
    }
    if (!int_check(digits_min, 0, 64)) {
      throw new Error('Invalid minimum digits requested: `' + digits_min + '` (expected: 1 .. 64)');
    }
    if (!int_check(digits_max, 0, 64)) {
      throw new Error('Invalid minimum digits requested: `' + digits_max + '` (expected: 1 .. 64)');
    }
    _ref = String(n);
    for (_l = 0, _len1 = _ref.length; _l < _len1; _l++) {
      char = _ref[_l];
      if ((v = map[char]) > orig_base || (v == null)) {
        throw new Error('Invalid digit(s) in number `' + n + '` for numeric ' + 'base `' + orig_base + '` (expected positive integer ' + 'composed of alphanumeric characters only)');
      }
    }
    if (orig_base !== 10) {
      n = base_to_dec(n, orig_base);
    } else {
      n = Number(n);
    }
    if (base !== 10) {
      n = dec_to_base(n, base);
    }
    while (digits_min && String(n).length < digits_min) {
      n = '0' + n;
    }
    if (digits_max && String(n).length > digits_max) {
      n = String(n).substr(0, digits_max);
    }
    if (n === '') {
      return '0';
    }
    return n;
  };

}).call(this);