package org.apache.maven;
/*
* 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.
*/
import java.util.LinkedList;
import java.util.Map;
import com.google.common.collect.Maps;
import com.google.inject.Key;
import com.google.inject.OutOfScopeException;
import com.google.inject.Provider;
import com.google.inject.Scope;
import com.google.inject.util.Providers;
public class SessionScope
implements Scope
{
private static final Provider<Object> SEEDED_KEY_PROVIDER = new Provider<Object>()
{
public Object get()
{
throw new IllegalStateException();
}
};
private static final class ScopeState
{
public final Map<Key<?>, Provider<?>> seeded = Maps.newHashMap();
public final Map<Key<?>, Object> provided = Maps.newHashMap();
}
private final ThreadLocal<LinkedList<ScopeState>> values = new ThreadLocal<LinkedList<ScopeState>>();
public void enter()
{
LinkedList<ScopeState> stack = values.get();
if ( stack == null )
{
stack = new LinkedList<ScopeState>();
values.set( stack );
}
stack.addFirst( new ScopeState() );
}
private ScopeState getScopeState()
{
LinkedList<ScopeState> stack = values.get();
if ( stack == null || stack.isEmpty() )
{
throw new IllegalStateException();
}
return stack.getFirst();
}
public void exit()
{
final LinkedList<ScopeState> stack = values.get();
if ( stack == null || stack.isEmpty() )
{
throw new IllegalStateException();
}
stack.removeFirst();
if ( stack.isEmpty() )
{
values.remove();
}
}
public <T> void seed( Class<T> clazz, Provider<T> value )
{
getScopeState().seeded.put( Key.get( clazz ), value );
}
public <T> void seed( Class<T> clazz, final T value )
{
getScopeState().seeded.put( Key.get( clazz ), Providers.of( value ) );
}
public <T> Provider<T> scope( final Key<T> key, final Provider<T> unscoped )
{
return new Provider<T>()
{
@SuppressWarnings( "unchecked" )
public T get()
{
LinkedList<ScopeState> stack = values.get();
if ( stack == null || stack.isEmpty() )
{
throw new OutOfScopeException( "Cannot access " + key + " outside of a scoping block" );
}
ScopeState state = stack.getFirst();
Provider<?> seeded = state.seeded.get( key );
if ( seeded != null )
{
return (T) seeded.get();
}
T provided = (T) state.provided.get( key );
if ( provided == null && unscoped != null )
{
provided = unscoped.get();
state.provided.put( key, provided );
}
return provided;
}
};
}
@SuppressWarnings( { "unchecked" } )
public static <T> Provider<T> seededKeyProvider()
{
return (Provider<T>) SEEDED_KEY_PROVIDER;
}
}