mout/function/makeIterator_.js

var identity = require('./identity');
var prop = require('./prop');
var deepMatches = require('../object/deepMatches');

    /**
     * Converts argument into a valid iterator.
     * Used internally on most array/object/collection methods that receives a
     * callback/iterator providing a shortcut syntax.
     */
    function makeIterator(src, thisObj){
        if (src == null) {
            return identity;
        }
        switch(typeof src) {
            case 'function':
                // function is the first to improve perf (most common case)
                // also avoid using `Function#call` if not needed, which boosts
                // perf a lot in some cases
                return (typeof thisObj !== 'undefined')? function(val, i, arr){
                    return src.call(thisObj, val, i, arr);
                } : src;
            case 'object':
                return function(val){
                    return deepMatches(val, src);
                };
            case 'string':
            case 'number':
                return prop(src);
        }
    }

    module.exports = makeIterator;