lodash/lodash._basecallback/index.js

/**
 * lodash 3.0.0 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.7.0 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseClone = require('lodash._baseclone'),
    baseIsEqual = require('lodash._baseisequal'),
    baseProperty = require('lodash._baseproperty'),
    bindCallback = require('lodash._bindcallback'),
    keys = require('lodash.keys');

/**
 * Converts `value` to a string if it is not one. An empty string is returned
 * for `null` or `undefined` values.
 *
 * @private
 * @param {*} value The value to process.
 * @returns {string} Returns the string.
 */
function baseToString(value) {
  if (typeof value == 'string') {
    return value;
  }
  return value == null ? '' : (value + '');
}

/** Used for native method references. */
var objectProto = Object.prototype;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/**
 * The base implementation of `_.callback` which supports specifying the
 * number of arguments to provide to `func`.
 *
 * @private
 * @param {*} [func=_.identity] The value to convert to a callback.
 * @param {*} [thisArg] The `this` binding of `func`.
 * @param {number} [argCount] The number of arguments to provide to `func`.
 * @returns {Function} Returns the callback.
 */
function baseCallback(func, thisArg, argCount) {
  var type = typeof func;
  if (type == 'function') {
    return (typeof thisArg != 'undefined')
      ? bindCallback(func, thisArg, argCount)
      : func;
  }
  if (func == null) {
    return identity;
  }
  // Handle "_.property" and "_.matches" style callback shorthands.
  return type == 'object'
    ? baseMatches(func, !argCount)
    : baseProperty(argCount ? baseToString(func) : func);
}

/**
 * The base implementation of `_.isMatch` without support for callback
 * shorthands or `this` binding.
 *
 * @private
 * @param {Object} source The object to inspect.
 * @param {Array} props The source property names to match.
 * @param {Array} values The source values to match.
 * @param {Array} strictCompareFlags Strict comparison flags for source values.
 * @param {Function} [customizer] The function to customize comparing objects.
 * @returns {boolean} Returns `true` if `object` is a match, else `false`.
 */
function baseIsMatch(object, props, values, strictCompareFlags, customizer) {
  var length = props.length;
  if (object == null) {
    return !length;
  }
  var index = -1,
      noCustomizer = !customizer;

  while (++index < length) {
    if ((noCustomizer && strictCompareFlags[index])
          ? values[index] !== object[props[index]]
          : !hasOwnProperty.call(object, props[index])
        ) {
      return false;
    }
  }
  index = -1;
  while (++index < length) {
    var key = props[index];
    if (noCustomizer && strictCompareFlags[index]) {
      var result = hasOwnProperty.call(object, key);
    } else {
      var objValue = object[key],
          srcValue = values[index];

      result = customizer ? customizer(objValue, srcValue, key) : undefined;
      if (typeof result == 'undefined') {
        result = baseIsEqual(srcValue, objValue, customizer, true);
      }
    }
    if (!result) {
      return false;
    }
  }
  return true;
}

/**
 * The base implementation of `_.matches` which supports specifying whether
 * `source` should be cloned.
 *
 * @private
 * @param {Object} source The object of property values to match.
 * @param {boolean} [isCloned] Specify cloning the source object.
 * @returns {Function} Returns the new function.
 */
function baseMatches(source, isCloned) {
  var props = keys(source),
      length = props.length;

  if (length == 1) {
    var key = props[0],
        value = source[key];

    if (isStrictComparable(value)) {
      return function(object) {
        return object != null && value === object[key] && hasOwnProperty.call(object, key);
      };
    }
  }
  if (isCloned) {
    source = baseClone(source, true);
  }
  var values = Array(length),
      strictCompareFlags = Array(length);

  while (length--) {
    value = source[props[length]];
    values[length] = value;
    strictCompareFlags[length] = isStrictComparable(value);
  }
  return function(object) {
    return baseIsMatch(object, props, values, strictCompareFlags);
  };
}

/**
 * Checks if `value` is suitable for strict equality comparisons, i.e. `===`.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` if suitable for strict
 *  equality comparisons, else `false`.
 */
function isStrictComparable(value) {
  return value === value && (value === 0 ? ((1 / value) > 0) : !isObject(value));
}

/**
 * Checks if `value` is the language type of `Object`.
 * (e.g. arrays, functions, objects, regexes, `new Number(0)`, and `new String('')`)
 *
 * **Note:** See the [ES5 spec](https://es5.github.io/#x8) for more details.
 *
 * @static
 * @memberOf _
 * @category Lang
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is an object, else `false`.
 * @example
 *
 * _.isObject({});
 * // => true
 *
 * _.isObject([1, 2, 3]);
 * // => true
 *
 * _.isObject(1);
 * // => false
 */
function isObject(value) {
  // Avoid a V8 JIT bug in Chrome 19-20.
  // See https://code.google.com/p/v8/issues/detail?id=2291 for more details.
  var type = typeof value;
  return type == 'function' || (value && type == 'object') || false;
}

/**
 * This method returns the first argument provided to it.
 *
 * @static
 * @memberOf _
 * @category Utility
 * @param {*} value Any value.
 * @returns {*} Returns `value`.
 * @example
 *
 * var object = { 'user': 'fred' };
 * _.identity(object) === object;
 * // => true
 */
function identity(value) {
  return value;
}

module.exports = baseCallback;