1 files changed, 60 insertions, 27 deletions
diff --git a/java/src/main/java/com/google/protobuf/LazyStringArrayList.java b/java/src/main/java/com/google/protobuf/LazyStringArrayList.java
index 2d40a51f..a2997e1c 100644
--- a/java/src/main/java/com/google/protobuf/LazyStringArrayList.java
+++ b/java/src/main/java/com/google/protobuf/LazyStringArrayList.java
@@ -62,11 +62,20 @@ import java.util.RandomAccess;
  *
  * @author jonp@google.com (Jon Perlow)
  */
-public class LazyStringArrayList extends AbstractList<String>
+public class LazyStringArrayList extends AbstractProtobufList<String>
     implements LazyStringList, RandomAccess {
+  
+  private static final LazyStringArrayList EMPTY_LIST = new LazyStringArrayList();
+  static {
+    EMPTY_LIST.makeImmutable();
+  }
+  
+  static LazyStringArrayList emptyList() {
+    return EMPTY_LIST;
+  }
 
-  public static final LazyStringList EMPTY =
-      new LazyStringArrayList().getUnmodifiableView();
+  // For compatibility with older runtimes.
+  public static final LazyStringList EMPTY = EMPTY_LIST;
 
   private final List<Object> list;
 
@@ -116,12 +125,26 @@ public class LazyStringArrayList extends AbstractList<String>
 
   @Override
   public String set(int index, String s) {
+    ensureIsMutable();
     Object o = list.set(index, s);
     return asString(o);
   }
 
   @Override
   public void add(int index, String element) {
+    ensureIsMutable();
+    list.add(index, element);
+    modCount++;
+  }
+  
+  private void add(int index, ByteString element) {
+    ensureIsMutable();
+    list.add(index, element);
+    modCount++;
+  }
+  
+  private void add(int index, byte[] element) {
+    ensureIsMutable();
     list.add(index, element);
     modCount++;
   }
@@ -137,6 +160,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
   @Override
   public boolean addAll(int index, Collection<? extends String> c) {
+    ensureIsMutable();
     // When copying from another LazyStringList, directly copy the underlying
     // elements rather than forcing each element to be decoded to a String.
     Collection<?> collection = c instanceof LazyStringList
@@ -148,6 +172,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
   // @Override
   public boolean addAllByteString(Collection<? extends ByteString> values) {
+    ensureIsMutable();
     boolean ret = list.addAll(values);
     modCount++;
     return ret;
@@ -155,6 +180,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
   // @Override
   public boolean addAllByteArray(Collection<byte[]> c) {
+    ensureIsMutable();
     boolean ret = list.addAll(c);
     modCount++;
     return ret;
@@ -162,6 +188,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
   @Override
   public String remove(int index) {
+    ensureIsMutable();
     Object o = list.remove(index);
     modCount++;
     return asString(o);
@@ -169,18 +196,21 @@ public class LazyStringArrayList extends AbstractList<String>
 
   @Override
   public void clear() {
+    ensureIsMutable();
     list.clear();
     modCount++;
   }
 
   // @Override
   public void add(ByteString element) {
+    ensureIsMutable();
     list.add(element);
     modCount++;
   }
   
   // @Override
   public void add(byte[] element) {
+    ensureIsMutable();
     list.add(element);
     modCount++;
   }
@@ -207,14 +237,23 @@ public class LazyStringArrayList extends AbstractList<String>
 
   // @Override
   public void set(int index, ByteString s) {
-    list.set(index, s);
+    setAndReturn(index, s);
+  }
+  
+  private Object setAndReturn(int index, ByteString s) {
+    ensureIsMutable();
+    return list.set(index, s);
   }
 
   // @Override
   public void set(int index, byte[] s) {
-    list.set(index, s);
+    setAndReturn(index, s);
+  }
+  
+  private Object setAndReturn(int index, byte[] s) {
+    ensureIsMutable();
+    return list.set(index, s);
   }
-
 
   private static String asString(Object o) {
     if (o instanceof String) {
@@ -253,6 +292,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
   // @Override
   public void mergeFrom(LazyStringList other) {
+    ensureIsMutable();
     for (Object o : other.getUnderlyingElements()) {
       if (o instanceof byte[]) {
         byte[] b = (byte[]) o;
@@ -267,20 +307,15 @@ public class LazyStringArrayList extends AbstractList<String>
 
   private static class ByteArrayListView extends AbstractList<byte[]>
       implements RandomAccess {
-    private final List<Object> list;
+    private final LazyStringArrayList list;
     
-    ByteArrayListView(List<Object> list) {
+    ByteArrayListView(LazyStringArrayList list) {
       this.list = list;
     }
     
     @Override
     public byte[] get(int index) {
-      Object o = list.get(index);
-      byte[] b = asByteArray(o);
-      if (b != o) {
-        list.set(index, b);
-      }
-      return b;
+      return list.getByteArray(index);
     }
 
     @Override
@@ -290,7 +325,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
     @Override
     public byte[] set(int index, byte[] s) {
-      Object o = list.set(index, s);
+      Object o = list.setAndReturn(index, s);
       modCount++;
       return asByteArray(o);
     }
@@ -311,25 +346,20 @@ public class LazyStringArrayList extends AbstractList<String>
   
   // @Override
   public List<byte[]> asByteArrayList() {
-    return new ByteArrayListView(list);
+    return new ByteArrayListView(this);
   }
 
   private static class ByteStringListView extends AbstractList<ByteString>
       implements RandomAccess {
-    private final List<Object> list;
+    private final LazyStringArrayList list;
 
-    ByteStringListView(List<Object> list) {
+    ByteStringListView(LazyStringArrayList list) {
       this.list = list;
     }
 
     @Override
     public ByteString get(int index) {
-      Object o = list.get(index);
-      ByteString b = asByteString(o);
-      if (b != o) {
-        list.set(index, b);
-      }
-      return b;
+      return list.getByteString(index);
     }
 
     @Override
@@ -339,7 +369,7 @@ public class LazyStringArrayList extends AbstractList<String>
 
     @Override
     public ByteString set(int index, ByteString s) {
-      Object o = list.set(index, s);
+      Object o = list.setAndReturn(index, s);
       modCount++;
       return asByteString(o);
     }
@@ -360,12 +390,15 @@ public class LazyStringArrayList extends AbstractList<String>
 
   // @Override
   public List<ByteString> asByteStringList() {
-    return new ByteStringListView(list);
+    return new ByteStringListView(this);
   }
 
   // @Override
   public LazyStringList getUnmodifiableView() {
-    return new UnmodifiableLazyStringList(this);
+    if (isModifiable()) {
+      return new UnmodifiableLazyStringList(this);
+    }
+    return this;
   }
 
 }