1 files changed, 154 insertions, 0 deletions
diff --git a/java/src/main/java/com/google/protobuf/LazyField.java b/java/src/main/java/com/google/protobuf/LazyField.java
new file mode 100644
index 0000000..3da8b90
--- /dev/null
+++ b/java/src/main/java/com/google/protobuf/LazyField.java
@@ -0,0 +1,154 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.util.Iterator;
+import java.util.Map.Entry;
+
+/**
+ * LazyField encapsulates the logic of lazily parsing message fields. It stores
+ * the message in a ByteString initially and then parse it on-demand.
+ *
+ * Most of key methods are implemented in {@link LazyFieldLite} but this class
+ * can contain default instance of the message to provide {@code hashCode()},
+ * {@code euqals()} and {@code toString()}.
+ *
+ * @author xiangl@google.com (Xiang Li)
+ */
+public class LazyField extends LazyFieldLite {
+
+  /**
+   * Carry a message's default instance which is used by {@code hashCode()}, {@code euqals()} and
+   * {@code toString()}.
+   */
+  private final MessageLite defaultInstance;
+
+  public LazyField(MessageLite defaultInstance,
+      ExtensionRegistryLite extensionRegistry, ByteString bytes) {
+    super(extensionRegistry, bytes);
+
+    this.defaultInstance = defaultInstance;
+  }
+
+  @Override
+  public boolean containsDefaultInstance() {
+    return super.containsDefaultInstance() || value == defaultInstance;
+  }
+
+  public MessageLite getValue() {
+    return getValue(defaultInstance);
+  }
+
+  @Override
+  public int hashCode() {
+    return getValue().hashCode();
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    return getValue().equals(obj);
+  }
+
+  @Override
+  public String toString() {
+    return getValue().toString();
+  }
+
+  // ====================================================
+
+  /**
+   * LazyEntry and LazyIterator are used to encapsulate the LazyField, when
+   * users iterate all fields from FieldSet.
+   */
+  static class LazyEntry<K> implements Entry<K, Object> {
+    private Entry<K, LazyField> entry;
+
+    private LazyEntry(Entry<K, LazyField> entry) {
+      this.entry = entry;
+    }
+
+    // @Override
+    public K getKey() {
+      return entry.getKey();
+    }
+
+    // @Override
+    public Object getValue() {
+      LazyField field = entry.getValue();
+      if (field == null) {
+        return null;
+      }
+      return field.getValue();
+    }
+
+    public LazyField getField() {
+      return entry.getValue();
+    }
+
+    // @Override
+    public Object setValue(Object value) {
+      if (!(value instanceof MessageLite)) {
+        throw new IllegalArgumentException(
+            "LazyField now only used for MessageSet, "
+            + "and the value of MessageSet must be an instance of MessageLite");
+      }
+      return entry.getValue().setValue((MessageLite) value);
+    }
+  }
+
+  static class LazyIterator<K> implements Iterator<Entry<K, Object>> {
+    private Iterator<Entry<K, Object>> iterator;
+
+    public LazyIterator(Iterator<Entry<K, Object>> iterator) {
+      this.iterator = iterator;
+    }
+
+    // @Override
+    public boolean hasNext() {
+      return iterator.hasNext();
+    }
+
+    @SuppressWarnings("unchecked")
+    // @Override
+    public Entry<K, Object> next() {
+      Entry<K, ?> entry = iterator.next();
+      if (entry.getValue() instanceof LazyField) {
+        return new LazyEntry<K>((Entry<K, LazyField>) entry);
+      }
+      return (Entry<K, Object>) entry;
+    }
+
+    // @Override
+    public void remove() {
+      iterator.remove();
+    }
+  }
+}