From d9f17dca83bf2c9e75a302b322a4b3bc2ea0d627 Mon Sep 17 00:00:00 2001
From: Victor Woeltjen <victor.woeltjen@nasa.gov>
Date: Wed, 5 Nov 2014 14:51:08 -0800
Subject: [PATCH] [Framework] Initial service compositor implementation

Initial implementation of the service compositor, which
is responsible for registering components which follow
the provider-aggregator-decorator pattern as named
services within Angular. WTD-518.
---
 .../src/register/ServiceCompositor.js         | 162 ++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 platform/framework/src/register/ServiceCompositor.js

diff --git a/platform/framework/src/register/ServiceCompositor.js b/platform/framework/src/register/ServiceCompositor.js
new file mode 100644
index 0000000000..bf65c529a9
--- /dev/null
+++ b/platform/framework/src/register/ServiceCompositor.js
@@ -0,0 +1,162 @@
+/*global define,Promise*/
+
+/**
+ * Module defining ServiceCompositor. Created by vwoeltje on 11/5/14.
+ */
+define(
+    [],
+    function () {
+        "use strict";
+
+        /**
+         *
+         * @constructor
+         */
+        function ServiceCompositor(app, $log) {
+            var latest = {},
+                providerLists = {}; // Track latest services registered
+
+            function warn(extension, category, message) {
+                var msg = message || "No service provided by";
+                $log.warn([
+                    msg,
+                    " ",
+                    category,
+                    " ",
+                    extension.key,
+                    " from bundle ",
+                    extension.bundle.path,
+                    "; skipping."
+                ].join(""));
+            }
+
+            // Echo arguments; used to represent groups of non-built-in
+            // extensions as a single dependency.
+            function echoMany() {
+                return Array.prototype.slice.call(arguments);
+            }
+
+            // Echo arguments; used to represent groups of non-built-in
+            // extensions as a single dependency.
+            function echoSingle() {
+                return arguments[0];
+            }
+
+            function makeName(category, service, index) {
+                return [
+                    service,
+                    "[",
+                    category,
+                    "#",
+                    index,
+                    "]"
+                ].join("");
+            }
+
+            function registerProvider(provider, index) {
+                var service = provider.provides,
+                    dependencies = provider.depends || [],
+                    name = makeName("provider", service, index);
+
+                if (!service) {
+                    return warn(provider, "provider");
+                }
+
+                providerLists[service] = providerLists[service] || [];
+                providerLists[service].push(name);
+
+                // This provider is the latest candidate for resolving
+                // the composite service.
+                latest[service] = name;
+
+                app.service(name, dependencies.concat([provider]));
+            }
+
+            function registerProviderSets() {
+                Object.keys(providerLists).forEach(function (service) {
+                    var name = makeName("provider", service, "*"),
+                        list = providerLists[service];
+
+                    app.service(name, list.concat([echoMany]));
+                });
+            }
+
+            function registerAggregator(aggregator, index) {
+                var service = aggregator.provides,
+                    dependencies = aggregator.depends || [],
+                    providerSetName = makeName("provider", service, "*"),
+                    name = makeName("aggregator", service, index);
+
+                if (!service) {
+                    return warn(aggregator, "aggregator");
+                }
+
+                // Aggregators need other services to aggregate, otherwise they
+                // do nothing.
+                if (!latest[service]) {
+                    return warn(
+                        aggregator,
+                        "aggregator",
+                        "No services to aggregate for"
+                    );
+                }
+
+                dependencies = dependencies.concat([providerSetName]);
+                latest[service] = name;
+
+                app.service(name, dependencies.concat([aggregator]));
+            }
+
+            function registerDecorator(decorator, index) {
+                var service = decorator.provides,
+                    dependencies = decorator.depends || [],
+                    name = makeName("decorator", service, index);
+
+                if (!service) {
+                    return warn(decorator, "decorator");
+                }
+
+                // Decorators need other services to decorate, otherwise they
+                // do nothing.
+                if (!latest[service]) {
+                    return warn(
+                        decorator,
+                        "decorator",
+                        "No services to decorate for"
+                    );
+                }
+
+                dependencies = dependencies.concat([latest[service]]);
+                latest[service] = name;
+
+                app.service(name, dependencies.concat([decorator]));
+            }
+
+            // Alias the latest services of various types back to the
+            // more general service declaration.
+            function registerLatest() {
+                Object.keys(latest).forEach(function (service) {
+                    app.service(service, [latest[service], echoSingle]);
+                });
+            }
+
+            function registerComposites(providers, aggregators, decorators) {
+                providers.forEach(registerProvider);
+                registerProviderSets();
+                aggregators.forEach(registerAggregator);
+                decorators.forEach(registerDecorator);
+                registerLatest();
+            }
+
+            return {
+                /**
+                 *
+                 * @param {Array} components extensions of type component
+                 */
+                registerCompositeServices: registerComposites
+            };
+        }
+
+        return ServiceCompositor;
+    }
+);
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