75 lines
2.3 KiB
Java
75 lines
2.3 KiB
Java
/*
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* Copyright (C) 2008 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.collect;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import com.google.common.annotations.GwtCompatible;
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/**
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* An iterator that supports a one-element lookahead while iterating.
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*
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* <p>
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* See the Guava User Guide article on <a href=
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* "http://code.google.com/p/guava-libraries/wiki/CollectionHelpersExplained#PeekingIterator">
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* {@code PeekingIterator}</a>.
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*
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* @author Mick Killianey
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* @since 2.0 (imported from Google Collections Library)
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*/
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@GwtCompatible
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public interface PeekingIterator<E> extends Iterator<E> {
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/**
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* Returns the next element in the iteration, without advancing the iteration.
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*
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* <p>
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* Calls to {@code peek()} should not change the state of the iteration, except
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* that it <i>may</i> prevent removal of the most recent element via
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* {@link #remove()}.
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*
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* @throws NoSuchElementException if the iteration has no more elements
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* according to {@link #hasNext()}
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*/
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E peek();
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/**
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* {@inheritDoc}
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*
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* <p>
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* The objects returned by consecutive calls to {@link #peek()} then
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* {@link #next()} are guaranteed to be equal to each other.
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*/
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@Override
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E next();
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/**
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* {@inheritDoc}
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*
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* <p>
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* Implementations may or may not support removal when a call to {@link #peek()}
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* has occurred since the most recent call to {@link #next()}.
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*
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* @throws IllegalStateException if there has been a call to {@link #peek()}
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* since the most recent call to {@link #next()}
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* and this implementation does not support this
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* sequence of calls (optional)
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*/
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@Override
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void remove();
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}
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