Initial checkin.
git-svn-id: https://google-guice.googlecode.com/svn/trunk@2 d779f126-a31b-0410-b53b-1d3aecad763e
diff --git a/src/com/google/inject/Scope.java b/src/com/google/inject/Scope.java
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+++ b/src/com/google/inject/Scope.java
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+/**
+ * Copyright (C) 2006 Google Inc.
+ *
+ * Licensed 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.
+ */
+
+package com.google.inject;
+
+import java.util.concurrent.Callable;
+
+/**
+ * Scope of an injected objects.
+ *
+ * @author crazybob
+ */
+public enum Scope {
+
+ /**
+ * One instance per injection.
+ */
+ DEFAULT {
+ <T> InternalFactory<? extends T> scopeFactory(Class<T> type, String name,
+ InternalFactory<? extends T> factory) {
+ return factory;
+ }
+ },
+
+ /**
+ * One instance per container.
+ */
+ SINGLETON {
+ <T> InternalFactory<? extends T> scopeFactory(Class<T> type, String name,
+ final InternalFactory<? extends T> factory) {
+ return new InternalFactory<T>() {
+ T instance;
+ public T create(InternalContext context) {
+ synchronized (context.getContainer()) {
+ if (instance == null) {
+ instance = factory.create(context);
+ }
+ return instance;
+ }
+ }
+
+ public String toString() {
+ return factory.toString();
+ }
+ };
+ }
+ },
+
+ /**
+ * One instance per thread.
+ *
+ * <p><b>Note:</b> if a thread local object strongly references its {@link
+ * Container}, neither the {@code Container} nor the object will be
+ * eligible for garbage collection, i.e. memory leak.
+ */
+ THREAD {
+ <T> InternalFactory<? extends T> scopeFactory(Class<T> type, String name,
+ final InternalFactory<? extends T> factory) {
+ return new InternalFactory<T>() {
+ final ThreadLocal<T> threadLocal = new ThreadLocal<T>();
+ public T create(final InternalContext context) {
+ T t = threadLocal.get();
+ if (t == null) {
+ t = factory.create(context);
+ threadLocal.set(t);
+ }
+ return t;
+ }
+
+ public String toString() {
+ return factory.toString();
+ }
+ };
+ }
+ },
+
+ /**
+ * One instance per request.
+ */
+ REQUEST {
+ <T> InternalFactory<? extends T> scopeFactory(final Class<T> type,
+ final String name, final InternalFactory<? extends T> factory) {
+ return new InternalFactory<T>() {
+ public T create(InternalContext context) {
+ Strategy strategy = context.getScopeStrategy();
+ try {
+ return strategy.findInRequest(
+ type, name, toCallable(context, factory));
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ public String toString() {
+ return factory.toString();
+ }
+ };
+ }
+ },
+
+ /**
+ * One instance per session.
+ */
+ SESSION {
+ <T> InternalFactory<? extends T> scopeFactory(final Class<T> type,
+ final String name, final InternalFactory<? extends T> factory) {
+ return new InternalFactory<T>() {
+ public T create(InternalContext context) {
+ Strategy strategy = context.getScopeStrategy();
+ try {
+ return strategy.findInSession(
+ type, name, toCallable(context, factory));
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ public String toString() {
+ return factory.toString();
+ }
+ };
+ }
+ },
+
+ /**
+ * One instance per wizard.
+ */
+ WIZARD {
+ <T> InternalFactory<? extends T> scopeFactory(final Class<T> type,
+ final String name, final InternalFactory<? extends T> factory) {
+ return new InternalFactory<T>() {
+ public T create(InternalContext context) {
+ Strategy strategy = context.getScopeStrategy();
+ try {
+ return strategy.findInWizard(
+ type, name, toCallable(context, factory));
+ } catch (Exception e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ public String toString() {
+ return factory.toString();
+ }
+ };
+ }
+ };
+
+ <T> Callable<? extends T> toCallable(final InternalContext context,
+ final InternalFactory<? extends T> factory) {
+ return new Callable<T>() {
+ public T call() throws Exception {
+ return factory.create(context);
+ }
+ };
+ }
+
+ /**
+ * Wraps factory with scoping logic.
+ */
+ abstract <T> InternalFactory<? extends T> scopeFactory(
+ Class<T> type, String name, InternalFactory<? extends T> factory);
+
+ /**
+ * Pluggable scoping strategy. Enables users to provide custom
+ * implementations of request, session, and wizard scopes. Implement and
+ * pass to {@link
+ * Container#setScopeStrategy(com.google.inject.Scope.Strategy)}.
+ */
+ public interface Strategy {
+
+ /**
+ * Finds an object for the given type and name in the request scope.
+ * Creates a new object if necessary using the given factory.
+ */
+ <T> T findInRequest(Class<T> type, String name,
+ Callable<? extends T> factory) throws Exception;
+
+ /**
+ * Finds an object for the given type and name in the session scope.
+ * Creates a new object if necessary using the given factory.
+ */
+ <T> T findInSession(Class<T> type, String name,
+ Callable<? extends T> factory) throws Exception;
+
+ /**
+ * Finds an object for the given type and name in the wizard scope.
+ * Creates a new object if necessary using the given factory.
+ */
+ <T> T findInWizard(Class<T> type, String name,
+ Callable<? extends T> factory) throws Exception;
+ }
+}