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/*
* Copyright (C) 2014 The Project Lombok Authors.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package lombok.core;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Map;
import java.util.WeakHashMap;
/**
* Augments a instance of a type with a boolean field.
* <p>
* If the type already declares a boolean field, that field is used. Otherwise the field will be augmented.
*
* @param <T> the type to augment.
*/
public abstract class BooleanFieldAugment<T> {
/**
* Augments a instance of a type with a boolean field.
* <p>
* If the type already declares a boolean instance field, that field might be used. Otherwise the field will be augmented.
* <p>
* This code assumes that for any combination of {@code type} and {@code name} this method is only called once.
* Otherwise, whether state is shared is undefined.
*
* @param type to augment
* @param name of the field
* @throws NullPointerException if {@code type} or {@code name} is {@code null}
*/
public static <T> BooleanFieldAugment<T> augment(Class<T> type, String name) {
checkNotNull(type, "type");
checkNotNull(name, "name");
Field booleanField = getBooleanField(type, name);
if (booleanField == null) {
return new MapFieldAugment<T>();
}
return new ExistingFieldAugment<T>(booleanField);
}
private BooleanFieldAugment() {
// prevent external instantiation
}
private static Field getBooleanField(Class<?> type, String name) {
try {
Field result = type.getDeclaredField(name);
if (Modifier.isStatic(result.getModifiers()) || result.getType() != boolean.class) {
return null;
}
result.setAccessible(true);
return result;
} catch (Throwable t) {
return null;
}
}
/**
* Sets the field to {@code true}.
* @returns the previous value
* @throws NullPointerException if {@code object} is {@code null}
*/
public abstract boolean set(T object);
/**
* Sets the field to {@code false}.
* @returns the previous value
* @throws NullPointerException if {@code object} is {@code null}
*/
public abstract boolean clear(T object);
/**
* @eturn {code true} if the field is set, otherwise {@code false}.
* @throws NullPointerException if {@code object} is {@code null}
*/
public abstract boolean get(T object);
private static class MapFieldAugment<T> extends BooleanFieldAugment<T> {
private static final Object MARKER = new Object();
private final Map<T, Object> values = new WeakHashMap<T,Object>();
public boolean set(T object) {
checkNotNull(object, "object");
synchronized (values) {
return values.put(object, MARKER) != null;
}
}
public boolean clear(T object) {
checkNotNull(object, "object");
synchronized (values) {
return values.remove(object) != null;
}
}
public boolean get(T object) {
checkNotNull(object, "object");
synchronized (values) {
return values.get(object) != null;
}
}
}
private static class ExistingFieldAugment<T> extends BooleanFieldAugment<T> {
private final Object lock = new Object();
private final Field booleanField;
private ExistingFieldAugment(Field booleanField) {
this.booleanField = booleanField;
}
@Override public boolean set(T object) {
checkNotNull(object, "object");
try {
synchronized (lock) {
boolean result = booleanField.getBoolean(object);
booleanField.setBoolean(object, true);
return result;
}
} catch (IllegalAccessException e) {
throw sneakyThrow(e);
}
}
@Override public boolean clear(T object) {
checkNotNull(object, "object");
try {
synchronized (lock) {
boolean result = booleanField.getBoolean(object);
booleanField.setBoolean(object, false);
return result;
}
} catch (IllegalAccessException e) {
throw sneakyThrow(e);
}
}
@Override public boolean get(T object) {
checkNotNull(object, "object");
try {
synchronized (lock) {
return booleanField.getBoolean(object);
}
} catch (IllegalAccessException e) {
throw sneakyThrow(e);
}
}
}
private static <T> T checkNotNull(T object, String name) {
if (object == null) throw new NullPointerException(name);
return object;
}
private static RuntimeException sneakyThrow(Throwable t) {
if (t == null) throw new NullPointerException("t");
BooleanFieldAugment.<RuntimeException>sneakyThrow0(t);
return null;
}
@SuppressWarnings("unchecked")
private static <T extends Throwable> void sneakyThrow0(Throwable t) throws T {
throw (T)t;
}
}
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