org.webharvest.ioc.AttributeHolderScope Maven / Gradle / Ivy
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/*
Copyright (c) 2006-2012 the original author or authors.
Redistribution and use of this software in source and binary forms,
with or without modification, are permitted provided that the following
conditions are met:
* Redistributions of source code must retain the above
copyright notice, this list of conditions and the
following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the
following disclaimer in the documentation and/or other
materials provided with the distribution.
* The name of Web-Harvest may not be used to endorse or promote
products derived from this software without specific prior
written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
package org.webharvest.ioc;
import java.util.Stack;
import com.google.inject.Key;
import com.google.inject.OutOfScopeException;
import com.google.inject.Provider;
import com.google.inject.Scope;
/**
* A {@code Scope} that uses an {@link AttributeHolder} as the backing store for
* its scoped objects. {@link AttributeHolderScope} supports nested scopes, that
* is, client code can enter scope as many times as required. Nested scopes are
* separated from each other.
*
* Based on work of Matthias Treydte .
*
* @author Robert Bala
* @author Piotr Dyraga
* @since 2.1.0-SNAPSHOT
* @version %I%, %G%
*/
public class AttributeHolderScope
implements Scope, Provider {
private final ThreadLocal> holder =
new ThreadLocal>() {
protected java.util.Stack initialValue() {
return new Stack();
};
};
/**
* Lets the current {@code Thread} enter this {@code Scope}.
*
* @param holder
* the {@link AttributeHolder} instance for the {@code Scope}
*/
public void enter(final AHT holder) {
if (holder == null) {
throw new IllegalArgumentException();
}
this.holder.get().add(holder);
}
/**
* Lets the current {@code Thread} leave this {@code Scope}.
*
* @throws OutOfScopeException if the current thread is not in
* this {@code Scope}
*/
public void exit() throws OutOfScopeException {
assertInScope();
this.holder.get().pop();
}
/**
* {@inheritDoc}
*
* @return {@docRoot}
* @throws OutOfScopeException if the current thread is not in
* this {@code Scope}
*/
@Override
public AHT get() throws OutOfScopeException {
assertInScope();
return this.holder.get().peek();
}
/**
* {@inheritDoc}
*/
@Override
public final Provider scope(
final Key key, final Provider outer) {
return new Provider() {
@Override
public T get() {
assertInScope();
final AttributeHolder ah = holder.get().peek();
synchronized (ah.getAttributeLock()) {
T current = (T) ah.getAttribute(key);
if ((current == null) && !ah.hasAttribute(key)) {
current = outer.get();
ah.putAttribute(key, current);
}
return current;
}
}
@Override
public String toString() {
return "Provider [scope=" + //NOI18N
AttributeHolderScope.this.getClass().getSimpleName() +
", outer=" + outer.toString() + "]"; //NOI18N
}
};
}
private void assertInScope() throws OutOfScopeException {
if (holder.get().isEmpty()) {
throw new OutOfScopeException("not in "
+ getClass().getSimpleName()); //NOI18N
}
}
}