|
|
- var apply = require('./_apply'),
- arrayMap = require('./_arrayMap'),
- baseIteratee = require('./_baseIteratee'),
- baseRest = require('./_baseRest');
-
- /** Error message constants. */
- var FUNC_ERROR_TEXT = 'Expected a function';
-
- /**
- * Creates a function that iterates over `pairs` and invokes the corresponding
- * function of the first predicate to return truthy. The predicate-function
- * pairs are invoked with the `this` binding and arguments of the created
- * function.
- *
- * @static
- * @memberOf _
- * @since 4.0.0
- * @category Util
- * @param {Array} pairs The predicate-function pairs.
- * @returns {Function} Returns the new composite function.
- * @example
- *
- * var func = _.cond([
- * [_.matches({ 'a': 1 }), _.constant('matches A')],
- * [_.conforms({ 'b': _.isNumber }), _.constant('matches B')],
- * [_.stubTrue, _.constant('no match')]
- * ]);
- *
- * func({ 'a': 1, 'b': 2 });
- * // => 'matches A'
- *
- * func({ 'a': 0, 'b': 1 });
- * // => 'matches B'
- *
- * func({ 'a': '1', 'b': '2' });
- * // => 'no match'
- */
- function cond(pairs) {
- var length = pairs == null ? 0 : pairs.length,
- toIteratee = baseIteratee;
-
- pairs = !length ? [] : arrayMap(pairs, function(pair) {
- if (typeof pair[1] != 'function') {
- throw new TypeError(FUNC_ERROR_TEXT);
- }
- return [toIteratee(pair[0]), pair[1]];
- });
-
- return baseRest(function(args) {
- var index = -1;
- while (++index < length) {
- var pair = pairs[index];
- if (apply(pair[0], this, args)) {
- return apply(pair[1], this, args);
- }
- }
- });
- }
-
- module.exports = cond;
|