/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*/
/**
* @fileoverview This provides a mechanism to export symbols, across all
* cases below. This implementation works best when used with ClosureJsCompiler.
*
* "global" object, ie: feature=globals.
* feature directive: <exports type="js">gadgets</exports>
* code: var gadgets = {};
*
* "singleton" object, ie: feature=rpc.
* feature directive: <exports type="js">gadgets.foo.bar</exports>
* gadgets.foo = function() {
* return { bar : function() { ... } };
* }();
*
* "closured" object, ie: feature=shindig.uri.
* This wraps to a function that exports any resulting properties it returns
* in an Object. feature directive: <exports type="js">gadgets.foo.bar</exports>
* gadgets.foo = (function() {
* return { bar : function() { ... } };
* })();
*
* "prototype" object, ie: feature=container.
* feature directive: <exports type="js">gadgets.foo.prototype.bar</exports>
* gadgets.foo = function() {};
* gadgets.foo.prototype.bar = function() { ... };
*
* "static" object.
* feature directive: <exports type="js">gadgets.foo.bar</exports>
* gadgets.foo = {};
* gadgets.foo.bar = function() { ... };
*
* Support for deferred symbol binding (via deferJs()) is also provided.
* A 'real' method is executed with the enqueued arguments when in deferMap.
*/
function exportJs(namespace, components, opt_props) {
var JSL = '___jsl';
var DEFER_KEY = 'df';
var base = window;
var prevBase = null;
var nsParts = namespace.split('.');
// Set up defer function queue.
var deferMap = ((window[JSL] = window[JSL] || {})[DEFER_KEY] = window[JSL][DEFER_KEY] || {});
for (var i = 0, part; part = nsParts.shift(); i++) {
base[part] = base[part] || components[i] || {};
prevBase = base;
base = base[part];
}
/**
* Exports properties/functions on the provided base object.
* If a property to export is a function, does not exist in its full
* form, and deferred mode is enabled, a stub is created.
* The stub enqueues requests that are executed by the real method
* when it is loaded and exported.
*
* @param {Object} root Base object to which to attach properties.
*/
function exportProps(root) {
var props = opt_props || {};
for (var prop in props) {
if (props.hasOwnProperty(prop)) {
var curalias = props[prop];
var fulltok = namespace + '.' + curalias;
if (root.hasOwnProperty(prop)) {
if (!root[curalias]) {
root[curalias] = root[prop];
} else if (deferMap[fulltok]) {
// Executes enqueued requests for the method,
// then replaces the export.
deferMap[fulltok](root, root[prop]);
delete deferMap[fulltok];
root[curalias] = root[prop];
}
}
}
}
};
if (typeof base === 'object') {
exportProps(base);
} else if (typeof base === 'function') {
var exportedFn = function() {
var result = base.apply(null, arguments);
if (typeof result === 'object') {
exportProps(result);
}
return result;
};
prevBase[part] = exportedFn;
}
}
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