159 lines
4.2 KiB
Java
159 lines
4.2 KiB
Java
/*
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* Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package com.sun.xml.internal.xsom.util;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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import java.util.NoSuchElementException;
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/**
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* {@link Collection} that returns the view of objects which are actually fetched
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* lazily from an {@link Iterator}.
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*
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* @author Kohsuke Kawaguchi
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*/
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public class DeferedCollection<T> implements Collection<T> {
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/**
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* The iterator that lazily evaluates SCD query.
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*/
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private final Iterator<T> result;
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/**
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* Stores values that are already fetched from {@link #result}.
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*/
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private final List<T> archive = new ArrayList<T>();
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public DeferedCollection(Iterator<T> result) {
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this.result = result;
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}
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public boolean isEmpty() {
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if(archive.isEmpty())
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fetch();
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return archive.isEmpty();
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}
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public int size() {
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fetchAll();
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return archive.size();
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}
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public boolean contains(Object o) {
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if(archive.contains(o))
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return true;
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while(result.hasNext()) {
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T value = result.next();
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archive.add(value);
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if(value.equals(o))
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return true;
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}
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return false;
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}
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public boolean containsAll(Collection<?> c) {
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for (Object o : c) {
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if(!contains(o))
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return false;
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}
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return true;
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}
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public Iterator<T> iterator() {
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return new Iterator<T>() {
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int idx=0;
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public boolean hasNext() {
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if(idx<archive.size())
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return true;
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return result.hasNext();
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}
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public T next() {
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if(idx==archive.size())
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fetch();
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if(idx==archive.size())
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throw new NoSuchElementException();
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return archive.get(idx++);
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}
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public void remove() {
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// TODO
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}
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};
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}
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public Object[] toArray() {
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fetchAll();
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return archive.toArray();
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}
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public <T>T[] toArray(T[] a) {
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fetchAll();
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return archive.toArray(a);
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}
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private void fetchAll() {
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while(result.hasNext())
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archive.add(result.next());
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}
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/**
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* Fetches another item from {@link
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*/
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private void fetch() {
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if(result.hasNext())
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archive.add(result.next());
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}
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// mutation methods are unsupported
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public boolean add(T o) {
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throw new UnsupportedOperationException();
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}
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public boolean remove(Object o) {
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throw new UnsupportedOperationException();
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}
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public boolean addAll(Collection<? extends T> c) {
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throw new UnsupportedOperationException();
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}
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public boolean removeAll(Collection<?> c) {
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throw new UnsupportedOperationException();
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}
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public boolean retainAll(Collection<?> c) {
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throw new UnsupportedOperationException();
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}
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public void clear() {
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throw new UnsupportedOperationException();
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}
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}
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