Rename VariableSizeIterator to VariableSizeLookaheadIterator

This improves the implementation, and is now used for debug info

dexlib2/src/main/java/org/jf/dexlib2/dexbacked/DexBackedMethodImplementation.java

@@ -35,7 +35,7 @@ import com.google.common.collect.ImmutableList;
 import org.jf.dexlib2.dexbacked.instruction.DexBackedInstruction;
 import org.jf.dexlib2.dexbacked.util.DebugInfo;
 import org.jf.dexlib2.dexbacked.util.FixedSizeList;
-import org.jf.dexlib2.dexbacked.util.VariableSizeIterator;
+import org.jf.dexlib2.dexbacked.util.VariableSizeLookaheadIterator;
 import org.jf.dexlib2.iface.MethodImplementation;
 import org.jf.dexlib2.iface.MethodParameter;
 import org.jf.dexlib2.iface.TryBlock;
@@ -79,9 +79,9 @@ public class DexBackedMethodImplementation implements MethodImplementation {
         return new Iterable<Instruction>() {
             @Override
             public Iterator<Instruction> iterator() {
-                return new VariableSizeIterator<Instruction>(dexBuf, instructionsStartOffset) {
+                return new VariableSizeLookaheadIterator<Instruction>(dexBuf, instructionsStartOffset) {
                     @Override
-                    protected Instruction readItem(@Nonnull DexReader reader, int index) {
+                    protected Instruction readNextItem(@Nonnull DexReader reader) {
                         if (reader.getOffset() >= endOffset) {
                             return null;
                         }

dexlib2/src/main/java/org/jf/dexlib2/dexbacked/util/DebugInfo.java

@@ -50,7 +50,6 @@ import javax.annotation.Nullable;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
-import java.util.NoSuchElementException;
 
 public abstract class DebugInfo implements Iterable<DebugItem> {
     @Nonnull public abstract List<? extends MethodParameter> getParametersWithNames();
@@ -140,24 +139,16 @@ public abstract class DebugInfo implements Iterable<DebugItem> {
                 }
             }
 
-            return new Iterator<DebugItem>() {
+            return new VariableSizeLookaheadIterator<DebugItem>(dexBuf, parameterIterator.getReaderOffset()) {
-                @Nonnull private DexReader reader = dexBuf.readerAt(parameterIterator.getReaderOffset());
-                private boolean finished = false;
                 private int codeAddress = 0;
                 private int lineNumber = lineNumberStart;
 
-                @Nullable private DebugItem nextItem;
-
                 @Nullable
-                protected DebugItem readItem() {
+                protected DebugItem readNextItem(@Nonnull DexReader reader) {
-                    if (finished) {
-                        return null;
-                    }
                     while (true) {
                         int next = reader.readUbyte();
                         switch (next) {
                             case DebugItemType.END_SEQUENCE: {
-                                finished = true;
                                 return null;
                             }
                             case DebugItemType.ADVANCE_PC: {
@@ -236,38 +227,6 @@ public abstract class DebugInfo implements Iterable<DebugItem> {
                         }
                     }
                 }
-
-                @Override
-                public boolean hasNext() {
-                    if (finished || nextItem != null) {
-                        return false;
-                    }
-                    nextItem = readItem();
-                    return nextItem != null;
-                }
-
-                @Nonnull
-                @Override
-                public DebugItem next() {
-                    if (finished) {
-                        throw new NoSuchElementException();
-                    }
-                    if (nextItem == null) {
-                        DebugItem ret = readItem();
-                        if (ret == null) {
-                            throw new NoSuchElementException();
-                        }
-                        return ret;
-                    }
-                    DebugItem ret = nextItem;
-                    nextItem = null;
-                    return ret;
-                }
-
-                @Override
-                public void remove() {
-                    throw new UnsupportedOperationException();
-                }
             };
         }
 

dexlib2/src/main/java/org/jf/dexlib2/dexbacked/util/VariableSizeLookaheadIterator.java

@@ -37,26 +37,24 @@ import org.jf.dexlib2.dexbacked.DexReader;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Iterator;
+import java.util.NoSuchElementException;
 
-public abstract class VariableSizeIterator<T> implements Iterator<T> {
+public abstract class VariableSizeLookaheadIterator<T> implements Iterator<T> {
-    private final DexReader reader;
+    @Nonnull private final DexReader reader;
 
-    private int index = 0;
     private T cachedItem = null;
 
-    protected VariableSizeIterator(DexBuffer dexBuf, int offset) {
+    protected VariableSizeLookaheadIterator(@Nonnull DexBuffer dexBuf, int offset) {
         this.reader = dexBuf.readerAt(offset);
-        cachedItem = readItem(reader, index++);
+        cachedItem = readNextItem(reader);
     }
 
     /**
      * Reads the next item from reader. If the end of the list has been reached, it should return null.
      *
-     * @param reader The {@code DexReader} to read from
-     * @param index The index of the item that is being read
      * @return The item that was read, or null if the end of the list has been reached.
      */
-    @Nullable protected abstract T readItem(@Nonnull DexReader reader, int index);
+    @Nullable protected abstract T readNextItem(@Nonnull DexReader reader);
 
     @Override
     public boolean hasNext() {
@@ -64,9 +62,13 @@ public abstract class VariableSizeIterator<T> implements Iterator<T> {
     }
 
     @Override
+    @Nonnull
     public T next() {
+        if (cachedItem == null) {
+            throw new NoSuchElementException();
+        }
         T ret = cachedItem;
-        cachedItem = readItem(reader, index++);
+        cachedItem = readNextItem(reader);
         return ret;
     }