Noosfero/noosfero

var patch = (function () {
    /*jshint evil: true */

    "use strict";

    var global = new Function("return this;")(), // Get a reference to the global object
        fnProps = Object.getOwnPropertyNames(Function); // Get the own ("static") properties of the Function constructor

    return function (original, originalRef, patches) {

        var ref = global[originalRef] = original, // Maintain a reference to the original constructor as a new property on the global object
            args = [],
            newRef, // This will be the new patched constructor
            i;

        patches.called = patches.called || originalRef; // If we are not patching static calls just pass them through to the original function

        for (i = 0; i < original.length; i++) { // Match the arity of the original constructor
            args[i] = "a" + i; // Give the arguments a name (native constructors don't care, but user-defined ones will break otherwise)
        }

        if (patches.constructed) { // This string is evaluated to create the patched constructor body in the case that we are patching newed calls
            args.push("'use strict'; return (!!this ? " + patches.constructed + " : " + patches.called + ").apply(null, arguments);"); 
        } else { // This string is evaluated to create the patched constructor body in the case that we are only patching static calls
            args.push("'use strict'; return (!!this ? new (Function.prototype.bind.apply(" + originalRef + ", [{}].concat([].slice.call(arguments))))() : " + patches.called + ".apply(null, arguments));");
        }

        newRef = new (Function.prototype.bind.apply(Function, [{}].concat(args)))(); // Create a new function to wrap the patched constructor
        newRef.prototype = original.prototype; // Keep a reference to the original prototype to ensure instances of the patch appear as instances of the original
        newRef.prototype.constructor = newRef; // Ensure the constructor of patched instances is the patched constructor

        Object.getOwnPropertyNames(ref).forEach(function (property) { // Add any "static" properties of the original constructor to the patched one
            if (fnProps.indexOf(property) < 0) { // Don't include static properties of Function since the patched constructor will already have them
                newRef[property] = ref[property];
            }
        });

        return newRef; // Return the patched constructor
    };

}());