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/*
* Copyright (C) 2007 The Android Open Source Project
*
* 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.android.dx.util;
/**
* Very simple base class that implements a flag to control the mutability
* of instances. This class just provides the flag and a utility to check
* and throw the right exception, but it is up to subclasses to place calls
* to the checker in all the right places.
*/
public class MutabilityControl {
/** whether this instance is mutable */
private boolean mutable;
/**
* Constructs an instance. It is initially mutable.
*/
public MutabilityControl() {
mutable = true;
}
/**
* Constructs an instance, explicitly indicating the mutability.
*
* @param mutable {@code true} iff this instance is mutable
*/
public MutabilityControl(boolean mutable) {
this.mutable = mutable;
}
/**
* Makes this instance immutable.
*/
public void setImmutable() {
mutable = false;
}
/**
* Checks to see whether or not this instance is immutable. This is the
* same as calling {@code !isMutable()}.
*
* @return {@code true} iff this instance is immutable
*/
public final boolean isImmutable() {
return !mutable;
}
/**
* Checks to see whether or not this instance is mutable.
*
* @return {@code true} iff this instance is mutable
*/
public final boolean isMutable() {
return mutable;
}
/**
* Throws {@link MutabilityException} if this instance is
* immutable.
*/
public final void throwIfImmutable() {
if (!mutable) {
throw new MutabilityException("immutable instance");
}
}
/**
* Throws {@link MutabilityException} if this instance is mutable.
*/
public final void throwIfMutable() {
if (mutable) {
throw new MutabilityException("mutable instance");
}
}
}