mathjs/lib/type/boolean.js

'use strict';

var deepMap = require('./../utils/collection/deepMap');

function factory (type, config, load, typed) {
  /**
   * Create a boolean or convert a string or number to a boolean.
   * In case of a number, `true` is returned for non-zero numbers, and `false` in
   * case of zero.
   * Strings can be `'true'` or `'false'`, or can contain a number.
   * When value is a matrix, all elements will be converted to boolean.
   *
   * Syntax:
   *
   *    math.boolean(x)
   *
   * Examples:
   *
   *    math.boolean(0);     // returns false
   *    math.boolean(1);     // returns true
   *    math.boolean(-3);     // returns true
   *    math.boolean('true');     // returns true
   *    math.boolean('false');     // returns false
   *    math.boolean([1, 0, 1, 1]);     // returns [true, false, true, true]
   *
   * See also:
   *
   *    bignumber, complex, index, matrix, string, unit
   *
   * @param {string | number | boolean | Array | Matrix | null} value  A value of any type
   * @return {boolean | Array | Matrix} The boolean value
   */
  var bool = typed('bool', {
    '': function () {
      return false;
    },

    'boolean': function (x) {
      return x;
    },

    'number': function (x) {
      return !!x;
    },

    'BigNumber': function (x) {
      return !x.isZero();
    },

    'string': function (x) {
      // try case insensitive
      var lcase = x.toLowerCase();
      if (lcase === 'true') {
        return true;
      }
      else if (lcase === 'false') {
        return false;
      }

      // test whether value is a valid number
      var num = Number(x);
      if (x != '' && !isNaN(num)) {
        return !!num;
      }

      throw new Error('Cannot convert "' + x + '" to a boolean');
    },

    'Array | Matrix': function (x) {
      return deepMap(x, bool);
    }
  });

  return bool;
}

exports.name = 'boolean';
exports.factory = factory;