linuxcommandgitbook/node_modules/lodash/internal/bindCallback.js

var identity = require('../utility/identity');

/**
 * A specialized version of `baseCallback` which only supports `this` binding
 * and specifying the number of arguments to provide to `func`.
 *
 * @private
 * @param {Function} func The function to bind.
 * @param {*} thisArg The `this` binding of `func`.
 * @param {number} [argCount] The number of arguments to provide to `func`.
 * @returns {Function} Returns the callback.
 */
function bindCallback(func, thisArg, argCount) {
  if (typeof func != 'function') {
    return identity;
  }
  if (thisArg === undefined) {
    return func;
  }
  switch (argCount) {
    case 1: return function(value) {
      return func.call(thisArg, value);
    };
    case 3: return function(value, index, collection) {
      return func.call(thisArg, value, index, collection);
    };
    case 4: return function(accumulator, value, index, collection) {
      return func.call(thisArg, accumulator, value, index, collection);
    };
    case 5: return function(value, other, key, object, source) {
      return func.call(thisArg, value, other, key, object, source);
    };
  }
  return function() {
    return func.apply(thisArg, arguments);
  };
}

module.exports = bindCallback;