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Diffstat (limited to 'guava/src/com/google/common/collect/LexicographicalOrdering.java')
-rw-r--r-- | guava/src/com/google/common/collect/LexicographicalOrdering.java | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/guava/src/com/google/common/collect/LexicographicalOrdering.java b/guava/src/com/google/common/collect/LexicographicalOrdering.java new file mode 100644 index 0000000..0d993e4 --- /dev/null +++ b/guava/src/com/google/common/collect/LexicographicalOrdering.java @@ -0,0 +1,78 @@ +/* + * Copyright (C) 2007 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 com.google.common.annotations.GwtCompatible; + +import java.io.Serializable; +import java.util.Iterator; + +import javax.annotation.Nullable; + +/** + * An ordering which sorts iterables by comparing corresponding elements + * pairwise. + */ +@GwtCompatible(serializable = true) +final class LexicographicalOrdering<T> + extends Ordering<Iterable<T>> implements Serializable { + final Ordering<? super T> elementOrder; + + LexicographicalOrdering(Ordering<? super T> elementOrder) { + this.elementOrder = elementOrder; + } + + @Override public int compare( + Iterable<T> leftIterable, Iterable<T> rightIterable) { + Iterator<T> left = leftIterable.iterator(); + Iterator<T> right = rightIterable.iterator(); + while (left.hasNext()) { + if (!right.hasNext()) { + return LEFT_IS_GREATER; // because it's longer + } + int result = elementOrder.compare(left.next(), right.next()); + if (result != 0) { + return result; + } + } + if (right.hasNext()) { + return RIGHT_IS_GREATER; // because it's longer + } + return 0; + } + + @Override public boolean equals(@Nullable Object object) { + if (object == this) { + return true; + } + if (object instanceof LexicographicalOrdering) { + LexicographicalOrdering<?> that = (LexicographicalOrdering<?>) object; + return this.elementOrder.equals(that.elementOrder); + } + return false; + } + + @Override public int hashCode() { + return elementOrder.hashCode() ^ 2075626741; // meaningless + } + + @Override public String toString() { + return elementOrder + ".lexicographical()"; + } + + private static final long serialVersionUID = 0; +} |