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      1 /*
      2  * Copyright 2012, Google Inc.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are
      7  * met:
      8  *
      9  *     * Redistributions of source code must retain the above copyright
     10  * notice, this list of conditions and the following disclaimer.
     11  *     * Redistributions in binary form must reproduce the above
     12  * copyright notice, this list of conditions and the following disclaimer
     13  * in the documentation and/or other materials provided with the
     14  * distribution.
     15  *     * Neither the name of Google Inc. nor the names of its
     16  * contributors may be used to endorse or promote products derived from
     17  * this software without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 package org.jf.dexlib2.dexbacked.util;
     33 
     34 import com.google.common.collect.AbstractIterator;
     35 import org.jf.dexlib2.dexbacked.DexBackedDexFile;
     36 import org.jf.dexlib2.dexbacked.DexReader;
     37 
     38 import javax.annotation.Nonnull;
     39 import javax.annotation.Nullable;
     40 import java.util.Iterator;
     41 
     42 public abstract class VariableSizeLookaheadIterator<T> extends AbstractIterator<T> implements Iterator<T> {
     43     @Nonnull private final DexReader reader;
     44 
     45     protected VariableSizeLookaheadIterator(@Nonnull DexBackedDexFile dexFile, int offset) {
     46         this.reader = dexFile.readerAt(offset);
     47     }
     48 
     49     /**
     50      * Reads the next item from reader. If the end of the list has been reached, it should call endOfData.
     51      *
     52      * endOfData has a return value of T, so you can simply {@code return endOfData()}
     53      *
     54      * @return The item that was read. If endOfData was called, the return value is ignored.
     55      */
     56     @Nullable protected abstract T readNextItem(@Nonnull DexReader reader);
     57 
     58     @Override
     59     protected T computeNext() {
     60         return readNextItem(reader);
     61     }
     62 
     63     public final int getReaderOffset() {
     64         return reader.getOffset();
     65     }
     66 }
     67