1 /* 2 * Copyright (C) 2011 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 5 * in compliance with the License. You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software distributed under the 10 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 11 * express or implied. See the License for the specific language governing permissions and 12 * limitations under the License. 13 */ 14 15 package com.google.common.collect; 16 17 import static com.google.common.base.Preconditions.checkNotNull; 18 import static com.google.common.base.Preconditions.checkState; 19 20 import com.google.common.annotations.GwtCompatible; 21 22 import javax.annotation.Nullable; 23 24 /** 25 * A path to a node in a binary search tree, originating at the root. 26 * 27 * @author Louis Wasserman 28 * @param <N> The type of nodes in this binary search tree. 29 * @param <P> This path type, and the path type of all suffix paths. 30 */ 31 @GwtCompatible 32 abstract class BstPath<N extends BstNode<?, N>, P extends BstPath<N, P>> { 33 private final N tip; 34 @Nullable 35 private final P prefix; 36 BstPath(N tip, @Nullable P prefix)37 BstPath(N tip, @Nullable P prefix) { 38 this.tip = checkNotNull(tip); 39 this.prefix = prefix; 40 } 41 42 /** 43 * Return the end of this {@code BstPath}, the deepest node in the path. 44 */ getTip()45 public final N getTip() { 46 return tip; 47 } 48 49 /** 50 * Returns {@code true} if this path has a prefix. 51 */ hasPrefix()52 public final boolean hasPrefix() { 53 return prefix != null; 54 } 55 56 /** 57 * Returns the prefix of this path, which reaches to the parent of the end of this path. Returns 58 * {@code null} if this path has no prefix. 59 */ 60 @Nullable prefixOrNull()61 public final P prefixOrNull() { 62 return prefix; 63 } 64 65 /** 66 * Returns the prefix of this path, which reaches to the parent of the end of this path. 67 * 68 * @throws IllegalStateException if this path has no prefix. 69 */ getPrefix()70 public final P getPrefix() { 71 checkState(hasPrefix()); 72 return prefix; 73 } 74 } 75