/*
* Copyright (C) 2011 The Guava Authors
*
* 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.common.collect;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.annotations.GwtCompatible;
import javax.annotation.Nullable;
/**
* A path to a node in a binary search tree, originating at the root.
*
* @author Louis Wasserman
* @param <N> The type of nodes in this binary search tree.
* @param <P> This path type, and the path type of all suffix paths.
*/
@GwtCompatible
abstract class BstPath<N extends BstNode<?, N>, P extends BstPath<N, P>> {
private final N tip;
@Nullable
private final P prefix;
BstPath(N tip, @Nullable P prefix) {
this.tip = checkNotNull(tip);
this.prefix = prefix;
}
/**
* Return the end of this {@code BstPath}, the deepest node in the path.
*/
public final N getTip() {
return tip;
}
/**
* Returns {@code true} if this path has a prefix.
*/
public final boolean hasPrefix() {
return prefix != null;
}
/**
* Returns the prefix of this path, which reaches to the parent of the end of this path. Returns
* {@code null} if this path has no prefix.
*/
@Nullable
public final P prefixOrNull() {
return prefix;
}
/**
* Returns the prefix of this path, which reaches to the parent of the end of this path.
*
* @throws IllegalStateException if this path has no prefix.
*/
public final P getPrefix() {
checkState(hasPrefix());
return prefix;
}
}
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