Add clone() method support for nano.

Upstreamed from Another Place (cr/57247854).

Change-Id: I2aaf59544c0f5ae21a51891d8a5eeda1dc722c90

6 files changed, 94 insertions, 2 deletions

diff --git a/javanano/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java b/javanano/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
index b979390d..aeacbbf3 100644
--- a/javanano/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
+++ b/javanano/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
@@ -184,4 +184,11 @@ public abstract class ExtendableMessageNano<M extends ExtendableMessageNano<M>>
         return (unknownFieldData == null || unknownFieldData.isEmpty()
                 ? 0 : unknownFieldData.hashCode());
     }
+
+    @Override
+    public M clone() throws CloneNotSupportedException {
+        M cloned = (M) super.clone();
+        InternalNano.cloneUnknownFieldData(this, cloned);
+        return cloned;
+    }
 }
diff --git a/javanano/src/main/java/com/google/protobuf/nano/FieldArray.java b/javanano/src/main/java/com/google/protobuf/nano/FieldArray.java
index cdb66da2..c2044f6a 100644
--- a/javanano/src/main/java/com/google/protobuf/nano/FieldArray.java
+++ b/javanano/src/main/java/com/google/protobuf/nano/FieldArray.java
@@ -37,7 +37,7 @@ package com.google.protobuf.nano;
  *
  * Based on {@link android.support.v4.util.SpareArrayCompat}.
  */
-class FieldArray {
+class FieldArray implements Cloneable {
     private static final FieldData DELETED = new FieldData();
     private boolean mGarbage = false;
 
@@ -270,4 +270,19 @@ class FieldArray {
         }
         return true;
     }
+
+    @Override
+    public final FieldArray clone() {
+        // Trigger GC so we compact and don't copy DELETED elements.
+        int size = size();
+        FieldArray clone = new FieldArray(size);
+        System.arraycopy(mFieldNumbers, 0, clone.mFieldNumbers, 0, size);
+        for (int i = 0; i < size; i++) {
+            if (mData[i] != null) {
+                clone.mData[i] = mData[i].clone();
+            }
+        }
+        clone.mSize = size;
+        return clone;
+    }
 }
diff --git a/javanano/src/main/java/com/google/protobuf/nano/FieldData.java b/javanano/src/main/java/com/google/protobuf/nano/FieldData.java
index 21ead88b..ebebabc8 100644
--- a/javanano/src/main/java/com/google/protobuf/nano/FieldData.java
+++ b/javanano/src/main/java/com/google/protobuf/nano/FieldData.java
@@ -39,7 +39,7 @@ import java.util.List;
  * Stores unknown fields. These might be extensions or fields that the generated API doesn't
  * know about yet.
  */
-class FieldData {
+class FieldData implements Cloneable {
     private Extension<?, ?> cachedExtension;
     private Object value;
     /** The serialised values for this object. Will be cleared if getValue is called */
@@ -187,4 +187,54 @@ class FieldData {
         return result;
     }
 
+    @Override
+    public final FieldData clone() {
+        FieldData clone = new FieldData();
+        try {
+            clone.cachedExtension = cachedExtension;
+            if (unknownFieldData == null) {
+                clone.unknownFieldData = null;
+            } else {
+                clone.unknownFieldData.addAll(unknownFieldData);
+            }
+
+            // Whether we need to deep clone value depends on its type. Primitive reference types
+            // (e.g. Integer, Long etc.) are ok, since they're immutable. We need to clone arrays
+            // and messages.
+            if (value == null) {
+                // No cloning required.
+            } else if (value instanceof MessageNano) {
+                clone.value = ((MessageNano) value).clone();
+            } else if (value instanceof byte[]) {
+                clone.value = ((byte[]) value).clone();
+            } else if (value instanceof byte[][]) {
+                byte[][] valueArray = (byte[][]) value;
+                byte[][] cloneArray = new byte[valueArray.length][];
+                clone.value = cloneArray;
+                for (int i = 0; i < valueArray.length; i++) {
+                    cloneArray[i] = valueArray[i].clone();
+                }
+            } else if (value instanceof boolean[]) {
+                clone.value = ((boolean[]) value).clone();
+            } else if (value instanceof int[]) {
+                clone.value = ((int[]) value).clone();
+            } else if (value instanceof long[]) {
+                clone.value = ((long[]) value).clone();
+            } else if (value instanceof float[]) {
+                clone.value = ((float[]) value).clone();
+            } else if (value instanceof double[]) {
+                clone.value = ((double[]) value).clone();
+            } else if (value instanceof MessageNano[]) {
+                MessageNano[] valueArray = (MessageNano[]) value;
+                MessageNano[] cloneArray = new MessageNano[valueArray.length];
+                clone.value = cloneArray;
+                for (int i = 0; i < valueArray.length; i++) {
+                    cloneArray[i] = valueArray[i].clone();
+                }
+            }
+            return clone;
+        } catch (CloneNotSupportedException e) {
+            throw new AssertionError(e);
+        }
+    }
 }
diff --git a/javanano/src/main/java/com/google/protobuf/nano/InternalNano.java b/javanano/src/main/java/com/google/protobuf/nano/InternalNano.java
index e7ba8d12..f1263df5 100644
--- a/javanano/src/main/java/com/google/protobuf/nano/InternalNano.java
+++ b/javanano/src/main/java/com/google/protobuf/nano/InternalNano.java
@@ -536,4 +536,12 @@ public final class InternalNano {
     }
     return o.hashCode();
   }
+
+  // This avoids having to make FieldArray public.
+  public static void cloneUnknownFieldData(ExtendableMessageNano original,
+      ExtendableMessageNano cloned) {
+    if (original.unknownFieldData != null) {
+      cloned.unknownFieldData = (FieldArray) original.unknownFieldData.clone();
+    }
+  }
 }
diff --git a/javanano/src/main/java/com/google/protobuf/nano/MessageNano.java b/javanano/src/main/java/com/google/protobuf/nano/MessageNano.java
index 81e58571..23475027 100644
--- a/javanano/src/main/java/com/google/protobuf/nano/MessageNano.java
+++ b/javanano/src/main/java/com/google/protobuf/nano/MessageNano.java
@@ -187,4 +187,12 @@ public abstract class MessageNano {
     public String toString() {
         return MessageNanoPrinter.print(this);
     }
+
+    /**
+     * Provides support for cloning. This only works if you specify the generate_clone method.
+     */
+    @Override
+    public MessageNano clone() throws CloneNotSupportedException {
+        return (MessageNano) super.clone();
+    }
 }
diff --git a/javanano/src/main/java/com/google/protobuf/nano/UnknownFieldData.java b/javanano/src/main/java/com/google/protobuf/nano/UnknownFieldData.java
index a17fccf3..b1678d1b 100644
--- a/javanano/src/main/java/com/google/protobuf/nano/UnknownFieldData.java
+++ b/javanano/src/main/java/com/google/protobuf/nano/UnknownFieldData.java
@@ -42,6 +42,10 @@ import java.util.Arrays;
 final class UnknownFieldData {
 
     final int tag;
+    /**
+     * Important: this should be treated as immutable, even though it's possible
+     * to change the array values.
+     */
     final byte[] bytes;
 
     UnknownFieldData(int tag, byte[] bytes) {