1 files changed, 370 insertions, 6 deletions
diff --git a/java/src/main/java/com/google/protobuf/MapFieldLite.java b/java/src/main/java/com/google/protobuf/MapFieldLite.java
index 7f94c690..c17fa7b1 100644
--- a/java/src/main/java/com/google/protobuf/MapFieldLite.java
+++ b/java/src/main/java/com/google/protobuf/MapFieldLite.java
@@ -31,9 +31,12 @@
 package com.google.protobuf;
 
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
-import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Internal representation of map fields in generated lite-runtime messages.
@@ -41,16 +44,21 @@ import java.util.Map;
  * This class is a protobuf implementation detail. Users shouldn't use this
  * class directly.
  */
-public class MapFieldLite<K, V> {
-  private Map<K, V> mapData;
+public class MapFieldLite<K, V> implements MutabilityOracle {
+  private MutatabilityAwareMap<K, V> mapData;
+  private boolean isMutable;
   
   private MapFieldLite(Map<K, V> mapData) {
-    this.mapData = mapData;
+    this.mapData = new MutatabilityAwareMap<K, V>(this, mapData);
+    this.isMutable = true;
   }
   
   @SuppressWarnings({"rawtypes", "unchecked"})
   private static final MapFieldLite EMPTY_MAP_FIELD =
       new MapFieldLite(Collections.emptyMap());
+  static {
+    EMPTY_MAP_FIELD.makeImmutable();
+  }
   
   /** Returns an singleton immutable empty MapFieldLite instance. */
   @SuppressWarnings({"unchecked", "cast"})
@@ -60,7 +68,7 @@ public class MapFieldLite<K, V> {
   
   /** Creates a new MapFieldLite instance. */
   public static <K, V> MapFieldLite<K, V> newMapField() {
-    return new MapFieldLite<K, V>(new HashMap<K, V>());
+    return new MapFieldLite<K, V>(new LinkedHashMap<K, V>());
   }
   
   /** Gets the content of this MapField as a read-only Map. */
@@ -168,7 +176,7 @@ public class MapFieldLite<K, V> {
    */
   @SuppressWarnings("unchecked")
   static <K, V> Map<K, V> copy(Map<K, V> map) {
-    Map<K, V> result = new HashMap<K, V>();
+    Map<K, V> result = new LinkedHashMap<K, V>();
     for (Map.Entry<K, V> entry : map.entrySet()) {
       result.put(entry.getKey(), (V) copy(entry.getValue()));
     }
@@ -179,4 +187,360 @@ public class MapFieldLite<K, V> {
   public MapFieldLite<K, V> copy() {
     return new MapFieldLite<K, V>(copy(mapData));
   }
+  
+  /**
+   * Makes this field immutable. All subsequent modifications will throw an
+   * {@link UnsupportedOperationException}.
+   */
+  public void makeImmutable() {
+    isMutable = false;
+  }
+  
+  /**
+   * Returns whether this field can be modified.
+   */
+  public boolean isMutable() {
+    return isMutable;
+  }
+  
+  @Override
+  public void ensureMutable() {
+    if (!isMutable()) {
+      throw new UnsupportedOperationException();
+    }
+  }
+
+  /**
+   * An internal map that checks for mutability before delegating.
+   */
+  static class MutatabilityAwareMap<K, V> implements Map<K, V> {    
+    private final MutabilityOracle mutabilityOracle;
+    private final Map<K, V> delegate;
+    
+    MutatabilityAwareMap(MutabilityOracle mutabilityOracle, Map<K, V> delegate) {
+      this.mutabilityOracle = mutabilityOracle;
+      this.delegate = delegate;
+    }
+
+    @Override
+    public int size() {
+      return delegate.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+      return delegate.isEmpty();
+    }
+
+    @Override
+    public boolean containsKey(Object key) {
+      return delegate.containsKey(key);
+    }
+
+    @Override
+    public boolean containsValue(Object value) {
+      return delegate.containsValue(value);
+    }
+
+    @Override
+    public V get(Object key) {
+      return delegate.get(key);
+    }
+
+    @Override
+    public V put(K key, V value) {
+      mutabilityOracle.ensureMutable();
+      return delegate.put(key, value);
+    }
+
+    @Override
+    public V remove(Object key) {
+      mutabilityOracle.ensureMutable();
+      return delegate.remove(key);
+    }
+
+    @Override
+    public void putAll(Map<? extends K, ? extends V> m) {
+      mutabilityOracle.ensureMutable();
+      delegate.putAll(m);
+    }
+
+    @Override
+    public void clear() {
+      mutabilityOracle.ensureMutable();
+      delegate.clear();
+    }
+
+    @Override
+    public Set<K> keySet() {
+      return new MutatabilityAwareSet<K>(mutabilityOracle, delegate.keySet());
+    }
+
+    @Override
+    public Collection<V> values() {
+      return new MutatabilityAwareCollection<V>(mutabilityOracle, delegate.values());
+    }
+
+    @Override
+    public Set<java.util.Map.Entry<K, V>> entrySet() {
+      return new MutatabilityAwareSet<Entry<K, V>>(mutabilityOracle, delegate.entrySet());
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      return delegate.equals(o);
+    }
+
+    @Override
+    public int hashCode() {
+      return delegate.hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return delegate.toString();
+    }
+  }
+
+  /**
+   * An internal collection that checks for mutability before delegating.
+   */
+  private static class MutatabilityAwareCollection<E> implements Collection<E> {
+    private final MutabilityOracle mutabilityOracle;
+    private final Collection<E> delegate;
+    
+    MutatabilityAwareCollection(MutabilityOracle mutabilityOracle, Collection<E> delegate) {
+      this.mutabilityOracle = mutabilityOracle;
+      this.delegate = delegate;
+    }
+
+    @Override
+    public int size() {
+      return delegate.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+      return delegate.isEmpty();
+    }
+
+    @Override
+    public boolean contains(Object o) {
+      return delegate.contains(o);
+    }
+
+    @Override
+    public Iterator<E> iterator() {
+      return new MutatabilityAwareIterator<E>(mutabilityOracle, delegate.iterator());
+    }
+
+    @Override
+    public Object[] toArray() {
+      return delegate.toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] a) {
+      return delegate.toArray(a);
+    }
+
+    @Override
+    public boolean add(E e) {
+      // Unsupported operation in the delegate.
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+      mutabilityOracle.ensureMutable();
+      return delegate.remove(o);
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> c) {
+      return delegate.containsAll(c);
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends E> c) {
+      // Unsupported operation in the delegate.
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> c) {
+      mutabilityOracle.ensureMutable();
+      return delegate.removeAll(c);
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> c) {
+      mutabilityOracle.ensureMutable();
+      return delegate.retainAll(c);
+    }
+
+    @Override
+    public void clear() {
+      mutabilityOracle.ensureMutable();
+      delegate.clear();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      return delegate.equals(o);
+    }
+
+    @Override
+    public int hashCode() {
+      return delegate.hashCode();
+    }
+    
+    @Override
+    public String toString() {
+      return delegate.toString();
+    }
+  }
+
+  /**
+   * An internal set that checks for mutability before delegating.
+   */
+  private static class MutatabilityAwareSet<E> implements Set<E> {
+    private final MutabilityOracle mutabilityOracle;
+    private final Set<E> delegate;
+    
+    MutatabilityAwareSet(MutabilityOracle mutabilityOracle, Set<E> delegate) {
+      this.mutabilityOracle = mutabilityOracle;
+      this.delegate = delegate;
+    }
+
+    @Override
+    public int size() {
+      return delegate.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+      return delegate.isEmpty();
+    }
+
+    @Override
+    public boolean contains(Object o) {
+      return delegate.contains(o);
+    }
+
+    @Override
+    public Iterator<E> iterator() {
+      return new MutatabilityAwareIterator<E>(mutabilityOracle, delegate.iterator());
+    }
+
+    @Override
+    public Object[] toArray() {
+      return delegate.toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] a) {
+      return delegate.toArray(a);
+    }
+
+    @Override
+    public boolean add(E e) {
+      mutabilityOracle.ensureMutable();
+      return delegate.add(e);
+    }
+
+    @Override
+    public boolean remove(Object o) {
+      mutabilityOracle.ensureMutable();
+      return delegate.remove(o);
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> c) {
+      return delegate.containsAll(c);
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends E> c) {
+      mutabilityOracle.ensureMutable();
+      return delegate.addAll(c);
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> c) {
+      mutabilityOracle.ensureMutable();
+      return delegate.retainAll(c);
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> c) {
+      mutabilityOracle.ensureMutable();
+      return delegate.removeAll(c);
+    }
+
+    @Override
+    public void clear() {
+      mutabilityOracle.ensureMutable();
+      delegate.clear();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      return delegate.equals(o);
+    }
+
+    @Override
+    public int hashCode() {
+      return delegate.hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return delegate.toString();
+    }
+  }
+  
+  /**
+   * An internal iterator that checks for mutability before delegating.
+   */
+  private static class MutatabilityAwareIterator<E> implements Iterator<E> {
+    private final MutabilityOracle mutabilityOracle;
+    private final Iterator<E> delegate;
+    
+    MutatabilityAwareIterator(MutabilityOracle mutabilityOracle, Iterator<E> delegate) {
+      this.mutabilityOracle = mutabilityOracle;
+      this.delegate = delegate;
+    }
+
+    @Override
+    public boolean hasNext() {
+      return delegate.hasNext();
+    }
+
+    @Override
+    public E next() {
+      return delegate.next();
+    }
+
+    @Override
+    public void remove() {
+      mutabilityOracle.ensureMutable();
+      delegate.remove();
+    }
+    
+    @Override
+    public boolean equals(Object obj) {
+      return delegate.equals(obj);
+    }
+    
+    @Override
+    public int hashCode() {
+      return delegate.hashCode();
+    }
+
+    @Override
+    public String toString() {
+      return delegate.toString();
+    }
+  }
 }