root/third_party/protobuf/java/src/main/java/com/google/protobuf/FieldSet.java

DEFINITIONS

1. getNumber
2. getLiteType
3. getLiteJavaType
4. isRepeated
5. isPacked
6. getEnumType
7. internalMergeFrom
8. newFieldSet
9. SuppressWarnings
10. emptySet
11. SuppressWarnings
12. SuppressWarnings
13. makeImmutable
14. isImmutable
15. clone
16. clear
17. getAllFields
18. cloneFieldEntry
19. iterator
20. hasField
21. getField
22. SuppressWarnings
23. setField
24. clearField
25. getRepeatedFieldCount
26. getRepeatedField
27. SuppressWarnings
28. setRepeatedField
29. SuppressWarnings
30. addRepeatedField
31. verifyType
32. isInitialized
33. SuppressWarnings
34. isInitialized
35. getWireFormatForFieldType
36. mergeFrom
37. SuppressWarnings
38. mergeFromField
39. readPrimitiveField
40. writeTo
41. writeMessageSetTo
42. writeMessageSetTo
43. writeElement
44. writeElementNoTag
45. writeField
46. getSerializedSize
47. getMessageSetSerializedSize
48. getMessageSetSerializedSize
49. computeElementSize
50. computeElementSizeNoTag
51. computeFieldSize

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// http://code.google.com/p/protobuf/
//
// 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 com.google.protobuf.LazyField.LazyIterator;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

/**
 * A class which represents an arbitrary set of fields of some message type.
 * This is used to implement {@link DynamicMessage}, and also to represent
 * extensions in {@link GeneratedMessage}.  This class is package-private,
 * since outside users should probably be using {@link DynamicMessage}.
 *
 * @author kenton@google.com Kenton Varda
 */
final class FieldSet<FieldDescriptorType extends
      FieldSet.FieldDescriptorLite<FieldDescriptorType>> {
  /**
   * Interface for a FieldDescriptor or lite extension descriptor.  This
   * prevents FieldSet from depending on {@link Descriptors.FieldDescriptor}.
   */
  public interface FieldDescriptorLite<T extends FieldDescriptorLite<T>>
      extends Comparable<T> {
    int getNumber();
    WireFormat.FieldType getLiteType();
    WireFormat.JavaType getLiteJavaType();
    boolean isRepeated();
    boolean isPacked();
    Internal.EnumLiteMap<?> getEnumType();

    // If getLiteJavaType() == MESSAGE, this merges a message object of the
    // type into a builder of the type.  Returns {@code to}.
    MessageLite.Builder internalMergeFrom(
        MessageLite.Builder to, MessageLite from);
  }

  private final SmallSortedMap<FieldDescriptorType, Object> fields;
  private boolean isImmutable;
  private boolean hasLazyField = false;

  /** Construct a new FieldSet. */
  private FieldSet() {
    this.fields = SmallSortedMap.newFieldMap(16);
  }

  /**
   * Construct an empty FieldSet.  This is only used to initialize
   * DEFAULT_INSTANCE.
   */
  private FieldSet(final boolean dummy) {
    this.fields = SmallSortedMap.newFieldMap(0);
    makeImmutable();
  }

  /** Construct a new FieldSet. */
  public static <T extends FieldSet.FieldDescriptorLite<T>>
      FieldSet<T> newFieldSet() {
    return new FieldSet<T>();
  }

  /** Get an immutable empty FieldSet. */
  @SuppressWarnings("unchecked")
  public static <T extends FieldSet.FieldDescriptorLite<T>>
      FieldSet<T> emptySet() {
    return DEFAULT_INSTANCE;
  }
  @SuppressWarnings("rawtypes")
  private static final FieldSet DEFAULT_INSTANCE = new FieldSet(true);

  /** Make this FieldSet immutable from this point forward. */
  @SuppressWarnings("unchecked")
  public void makeImmutable() {
    if (isImmutable) {
      return;
    }
    fields.makeImmutable();
    isImmutable = true;
  }

  /**
   * Returns whether the FieldSet is immutable. This is true if it is the
   * {@link #emptySet} or if {@link #makeImmutable} were called.
   *
   * @return whether the FieldSet is immutable.
   */
  public boolean isImmutable() {
    return isImmutable;
  }

  /**
   * Clones the FieldSet. The returned FieldSet will be mutable even if the
   * original FieldSet was immutable.
   *
   * @return the newly cloned FieldSet
   */
  @Override
  public FieldSet<FieldDescriptorType> clone() {
    // We can't just call fields.clone because List objects in the map
    // should not be shared.
    FieldSet<FieldDescriptorType> clone = FieldSet.newFieldSet();
    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
      Map.Entry<FieldDescriptorType, Object> entry = fields.getArrayEntryAt(i);
      FieldDescriptorType descriptor = entry.getKey();
      clone.setField(descriptor, entry.getValue());
    }
    for (Map.Entry<FieldDescriptorType, Object> entry :
             fields.getOverflowEntries()) {
      FieldDescriptorType descriptor = entry.getKey();
      clone.setField(descriptor, entry.getValue());
    }
    clone.hasLazyField = hasLazyField;
    return clone;
  }

  // =================================================================

  /** See {@link Message.Builder#clear()}. */
  public void clear() {
    fields.clear();
    hasLazyField = false;
  }

  /**
   * Get a simple map containing all the fields.
   */
  public Map<FieldDescriptorType, Object> getAllFields() {
    if (hasLazyField) {
      SmallSortedMap<FieldDescriptorType, Object> result =
          SmallSortedMap.newFieldMap(16);
      for (int i = 0; i < fields.getNumArrayEntries(); i++) {
        cloneFieldEntry(result, fields.getArrayEntryAt(i));
      }
      for (Map.Entry<FieldDescriptorType, Object> entry :
          fields.getOverflowEntries()) {
        cloneFieldEntry(result, entry);
      }
      if (fields.isImmutable()) {
        result.makeImmutable();
      }
      return result;
    }
    return fields.isImmutable() ? fields : Collections.unmodifiableMap(fields);
  }

  private void cloneFieldEntry(Map<FieldDescriptorType, Object> map,
      Map.Entry<FieldDescriptorType, Object> entry) {
    FieldDescriptorType key = entry.getKey();
    Object value = entry.getValue();
    if (value instanceof LazyField) {
      map.put(key, ((LazyField) value).getValue());
    } else {
      map.put(key, value);
    }
  }

  /**
   * Get an iterator to the field map. This iterator should not be leaked out
   * of the protobuf library as it is not protected from mutation when fields
   * is not immutable.
   */
  public Iterator<Map.Entry<FieldDescriptorType, Object>> iterator() {
    if (hasLazyField) {
      return new LazyIterator<FieldDescriptorType>(
          fields.entrySet().iterator());
    }
    return fields.entrySet().iterator();
  }

  /**
   * Useful for implementing
   * {@link Message#hasField(Descriptors.FieldDescriptor)}.
   */
  public boolean hasField(final FieldDescriptorType descriptor) {
    if (descriptor.isRepeated()) {
      throw new IllegalArgumentException(
        "hasField() can only be called on non-repeated fields.");
    }

    return fields.get(descriptor) != null;
  }

  /**
   * Useful for implementing
   * {@link Message#getField(Descriptors.FieldDescriptor)}.  This method
   * returns {@code null} if the field is not set; in this case it is up
   * to the caller to fetch the field's default value.
   */
  public Object getField(final FieldDescriptorType descriptor) {
    Object o = fields.get(descriptor);
    if (o instanceof LazyField) {
      return ((LazyField) o).getValue();
    }
    return o;
  }

  /**
   * Useful for implementing
   * {@link Message.Builder#setField(Descriptors.FieldDescriptor,Object)}.
   */
  @SuppressWarnings({"unchecked", "rawtypes"})
  public void setField(final FieldDescriptorType descriptor,
                       Object value) {
    if (descriptor.isRepeated()) {
      if (!(value instanceof List)) {
        throw new IllegalArgumentException(
          "Wrong object type used with protocol message reflection.");
      }

      // Wrap the contents in a new list so that the caller cannot change
      // the list's contents after setting it.
      final List newList = new ArrayList();
      newList.addAll((List) value);
      for (final Object element : newList) {
        verifyType(descriptor.getLiteType(), element);
      }
      value = newList;
    } else {
      verifyType(descriptor.getLiteType(), value);
    }

    if (value instanceof LazyField) {
      hasLazyField = true;
    }
    fields.put(descriptor, value);
  }

  /**
   * Useful for implementing
   * {@link Message.Builder#clearField(Descriptors.FieldDescriptor)}.
   */
  public void clearField(final FieldDescriptorType descriptor) {
    fields.remove(descriptor);
    if (fields.isEmpty()) {
      hasLazyField = false;
    }
  }

  /**
   * Useful for implementing
   * {@link Message#getRepeatedFieldCount(Descriptors.FieldDescriptor)}.
   */
  public int getRepeatedFieldCount(final FieldDescriptorType descriptor) {
    if (!descriptor.isRepeated()) {
      throw new IllegalArgumentException(
        "getRepeatedField() can only be called on repeated fields.");
    }

    final Object value = getField(descriptor);
    if (value == null) {
      return 0;
    } else {
      return ((List<?>) value).size();
    }
  }

  /**
   * Useful for implementing
   * {@link Message#getRepeatedField(Descriptors.FieldDescriptor,int)}.
   */
  public Object getRepeatedField(final FieldDescriptorType descriptor,
                                 final int index) {
    if (!descriptor.isRepeated()) {
      throw new IllegalArgumentException(
        "getRepeatedField() can only be called on repeated fields.");
    }

    final Object value = getField(descriptor);

    if (value == null) {
      throw new IndexOutOfBoundsException();
    } else {
      return ((List<?>) value).get(index);
    }
  }

  /**
   * Useful for implementing
   * {@link Message.Builder#setRepeatedField(Descriptors.FieldDescriptor,int,Object)}.
   */
  @SuppressWarnings("unchecked")
  public void setRepeatedField(final FieldDescriptorType descriptor,
                               final int index,
                               final Object value) {
    if (!descriptor.isRepeated()) {
      throw new IllegalArgumentException(
        "getRepeatedField() can only be called on repeated fields.");
    }

    final Object list = getField(descriptor);
    if (list == null) {
      throw new IndexOutOfBoundsException();
    }

    verifyType(descriptor.getLiteType(), value);
    ((List<Object>) list).set(index, value);
  }

  /**
   * Useful for implementing
   * {@link Message.Builder#addRepeatedField(Descriptors.FieldDescriptor,Object)}.
   */
  @SuppressWarnings("unchecked")
  public void addRepeatedField(final FieldDescriptorType descriptor,
                               final Object value) {
    if (!descriptor.isRepeated()) {
      throw new IllegalArgumentException(
        "addRepeatedField() can only be called on repeated fields.");
    }

    verifyType(descriptor.getLiteType(), value);

    final Object existingValue = getField(descriptor);
    List<Object> list;
    if (existingValue == null) {
      list = new ArrayList<Object>();
      fields.put(descriptor, list);
    } else {
      list = (List<Object>) existingValue;
    }

    list.add(value);
  }

  /**
   * Verifies that the given object is of the correct type to be a valid
   * value for the given field.  (For repeated fields, this checks if the
   * object is the right type to be one element of the field.)
   *
   * @throws IllegalArgumentException The value is not of the right type.
   */
  private static void verifyType(final WireFormat.FieldType type,
                                 final Object value) {
    if (value == null) {
      throw new NullPointerException();
    }

    boolean isValid = false;
    switch (type.getJavaType()) {
      case INT:          isValid = value instanceof Integer   ; break;
      case LONG:         isValid = value instanceof Long      ; break;
      case FLOAT:        isValid = value instanceof Float     ; break;
      case DOUBLE:       isValid = value instanceof Double    ; break;
      case BOOLEAN:      isValid = value instanceof Boolean   ; break;
      case STRING:       isValid = value instanceof String    ; break;
      case BYTE_STRING:  isValid = value instanceof ByteString; break;
      case ENUM:
        // TODO(kenton):  Caller must do type checking here, I guess.
        isValid = value instanceof Internal.EnumLite;
        break;
      case MESSAGE:
        // TODO(kenton):  Caller must do type checking here, I guess.
        isValid =
            (value instanceof MessageLite) || (value instanceof LazyField);
        break;
    }

    if (!isValid) {
      // TODO(kenton):  When chaining calls to setField(), it can be hard to
      //   tell from the stack trace which exact call failed, since the whole
      //   chain is considered one line of code.  It would be nice to print
      //   more information here, e.g. naming the field.  We used to do that.
      //   But we can't now that FieldSet doesn't use descriptors.  Maybe this
      //   isn't a big deal, though, since it would only really apply when using
      //   reflection and generally people don't chain reflection setters.
      throw new IllegalArgumentException(
        "Wrong object type used with protocol message reflection.");
    }
  }

  // =================================================================
  // Parsing and serialization

  /**
   * See {@link Message#isInitialized()}.  Note:  Since {@code FieldSet}
   * itself does not have any way of knowing about required fields that
   * aren't actually present in the set, it is up to the caller to check
   * that all required fields are present.
   */
  public boolean isInitialized() {
    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
      if (!isInitialized(fields.getArrayEntryAt(i))) {
        return false;
      }
    }
    for (final Map.Entry<FieldDescriptorType, Object> entry :
             fields.getOverflowEntries()) {
      if (!isInitialized(entry)) {
        return false;
      }
    }
    return true;
  }

  @SuppressWarnings("unchecked")
  private boolean isInitialized(
      final Map.Entry<FieldDescriptorType, Object> entry) {
    final FieldDescriptorType descriptor = entry.getKey();
    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE) {
      if (descriptor.isRepeated()) {
        for (final MessageLite element:
                 (List<MessageLite>) entry.getValue()) {
          if (!element.isInitialized()) {
            return false;
          }
        }
      } else {
        Object value = entry.getValue();
        if (value instanceof MessageLite) {
          if (!((MessageLite) value).isInitialized()) {
            return false;
          }
        } else if (value instanceof LazyField) {
          return true;
        } else {
          throw new IllegalArgumentException(
              "Wrong object type used with protocol message reflection.");
        }
      }
    }
    return true;
  }

  /**
   * Given a field type, return the wire type.
   *
   * @returns One of the {@code WIRETYPE_} constants defined in
   *          {@link WireFormat}.
   */
  static int getWireFormatForFieldType(final WireFormat.FieldType type,
                                       boolean isPacked) {
    if (isPacked) {
      return WireFormat.WIRETYPE_LENGTH_DELIMITED;
    } else {
      return type.getWireType();
    }
  }

  /**
   * Like {@link Message.Builder#mergeFrom(Message)}, but merges from another 
   * {@link FieldSet}.
   */
  public void mergeFrom(final FieldSet<FieldDescriptorType> other) {
    for (int i = 0; i < other.fields.getNumArrayEntries(); i++) {
      mergeFromField(other.fields.getArrayEntryAt(i));
    }
    for (final Map.Entry<FieldDescriptorType, Object> entry :
             other.fields.getOverflowEntries()) {
      mergeFromField(entry);
    }
  }

  @SuppressWarnings({"unchecked", "rawtypes"})
  private void mergeFromField(
      final Map.Entry<FieldDescriptorType, Object> entry) {
    final FieldDescriptorType descriptor = entry.getKey();
    Object otherValue = entry.getValue();
    if (otherValue instanceof LazyField) {
      otherValue = ((LazyField) otherValue).getValue();
    }

    if (descriptor.isRepeated()) {
      Object value = getField(descriptor);
      if (value == null) {
        // Our list is empty, but we still need to make a defensive copy of
        // the other list since we don't know if the other FieldSet is still
        // mutable.
        fields.put(descriptor, new ArrayList((List) otherValue));
      } else {
        // Concatenate the lists.
        ((List) value).addAll((List) otherValue);
      }
    } else if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE) {
      Object value = getField(descriptor);
      if (value == null) {
        fields.put(descriptor, otherValue);
      } else {
        // Merge the messages.
        fields.put(
            descriptor,
            descriptor.internalMergeFrom(
                ((MessageLite) value).toBuilder(), (MessageLite) otherValue)
            .build());
      }
    } else {
      fields.put(descriptor, otherValue);
    }
  }

  // TODO(kenton):  Move static parsing and serialization methods into some
  //   other class.  Probably WireFormat.

  /**
   * Read a field of any primitive type from a CodedInputStream.  Enums,
   * groups, and embedded messages are not handled by this method.
   *
   * @param input The stream from which to read.
   * @param type Declared type of the field.
   * @return An object representing the field's value, of the exact
   *         type which would be returned by
   *         {@link Message#getField(Descriptors.FieldDescriptor)} for
   *         this field.
   */
  public static Object readPrimitiveField(
      CodedInputStream input,
      final WireFormat.FieldType type) throws IOException {
    switch (type) {
      case DOUBLE  : return input.readDouble  ();
      case FLOAT   : return input.readFloat   ();
      case INT64   : return input.readInt64   ();
      case UINT64  : return input.readUInt64  ();
      case INT32   : return input.readInt32   ();
      case FIXED64 : return input.readFixed64 ();
      case FIXED32 : return input.readFixed32 ();
      case BOOL    : return input.readBool    ();
      case STRING  : return input.readString  ();
      case BYTES   : return input.readBytes   ();
      case UINT32  : return input.readUInt32  ();
      case SFIXED32: return input.readSFixed32();
      case SFIXED64: return input.readSFixed64();
      case SINT32  : return input.readSInt32  ();
      case SINT64  : return input.readSInt64  ();

      case GROUP:
        throw new IllegalArgumentException(
          "readPrimitiveField() cannot handle nested groups.");
      case MESSAGE:
        throw new IllegalArgumentException(
          "readPrimitiveField() cannot handle embedded messages.");
      case ENUM:
        // We don't handle enums because we don't know what to do if the
        // value is not recognized.
        throw new IllegalArgumentException(
          "readPrimitiveField() cannot handle enums.");
    }

    throw new RuntimeException(
      "There is no way to get here, but the compiler thinks otherwise.");
  }

  /** See {@link Message#writeTo(CodedOutputStream)}. */
  public void writeTo(final CodedOutputStream output)
                      throws IOException {
    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
      final Map.Entry<FieldDescriptorType, Object> entry =
          fields.getArrayEntryAt(i);
      writeField(entry.getKey(), entry.getValue(), output);
    }
    for (final Map.Entry<FieldDescriptorType, Object> entry :
         fields.getOverflowEntries()) {
      writeField(entry.getKey(), entry.getValue(), output);
    }
  }

  /**
   * Like {@link #writeTo} but uses MessageSet wire format.
   */
  public void writeMessageSetTo(final CodedOutputStream output)
                                throws IOException {
    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
      writeMessageSetTo(fields.getArrayEntryAt(i), output);
    }
    for (final Map.Entry<FieldDescriptorType, Object> entry :
             fields.getOverflowEntries()) {
      writeMessageSetTo(entry, output);
    }
  }

  private void writeMessageSetTo(
      final Map.Entry<FieldDescriptorType, Object> entry,
      final CodedOutputStream output) throws IOException {
    final FieldDescriptorType descriptor = entry.getKey();
    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE &&
        !descriptor.isRepeated() && !descriptor.isPacked()) {
      output.writeMessageSetExtension(entry.getKey().getNumber(),
                                      (MessageLite) entry.getValue());
    } else {
      writeField(descriptor, entry.getValue(), output);
    }
  }

  /**
   * Write a single tag-value pair to the stream.
   *
   * @param output The output stream.
   * @param type   The field's type.
   * @param number The field's number.
   * @param value  Object representing the field's value.  Must be of the exact
   *               type which would be returned by
   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
   *               this field.
   */
  private static void writeElement(final CodedOutputStream output,
                                   final WireFormat.FieldType type,
                                   final int number,
                                   final Object value) throws IOException {
    // Special case for groups, which need a start and end tag; other fields
    // can just use writeTag() and writeFieldNoTag().
    if (type == WireFormat.FieldType.GROUP) {
      output.writeGroup(number, (MessageLite) value);
    } else {
      output.writeTag(number, getWireFormatForFieldType(type, false));
      writeElementNoTag(output, type, value);
    }
  }

  /**
   * Write a field of arbitrary type, without its tag, to the stream.
   *
   * @param output The output stream.
   * @param type The field's type.
   * @param value  Object representing the field's value.  Must be of the exact
   *               type which would be returned by
   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
   *               this field.
   */
  private static void writeElementNoTag(
      final CodedOutputStream output,
      final WireFormat.FieldType type,
      final Object value) throws IOException {
    switch (type) {
      case DOUBLE  : output.writeDoubleNoTag  ((Double     ) value); break;
      case FLOAT   : output.writeFloatNoTag   ((Float      ) value); break;
      case INT64   : output.writeInt64NoTag   ((Long       ) value); break;
      case UINT64  : output.writeUInt64NoTag  ((Long       ) value); break;
      case INT32   : output.writeInt32NoTag   ((Integer    ) value); break;
      case FIXED64 : output.writeFixed64NoTag ((Long       ) value); break;
      case FIXED32 : output.writeFixed32NoTag ((Integer    ) value); break;
      case BOOL    : output.writeBoolNoTag    ((Boolean    ) value); break;
      case STRING  : output.writeStringNoTag  ((String     ) value); break;
      case GROUP   : output.writeGroupNoTag   ((MessageLite) value); break;
      case MESSAGE : output.writeMessageNoTag ((MessageLite) value); break;
      case BYTES   : output.writeBytesNoTag   ((ByteString ) value); break;
      case UINT32  : output.writeUInt32NoTag  ((Integer    ) value); break;
      case SFIXED32: output.writeSFixed32NoTag((Integer    ) value); break;
      case SFIXED64: output.writeSFixed64NoTag((Long       ) value); break;
      case SINT32  : output.writeSInt32NoTag  ((Integer    ) value); break;
      case SINT64  : output.writeSInt64NoTag  ((Long       ) value); break;

      case ENUM:
        output.writeEnumNoTag(((Internal.EnumLite) value).getNumber());
        break;
    }
  }

  /** Write a single field. */
  public static void writeField(final FieldDescriptorLite<?> descriptor,
                                final Object value,
                                final CodedOutputStream output)
                                throws IOException {
    WireFormat.FieldType type = descriptor.getLiteType();
    int number = descriptor.getNumber();
    if (descriptor.isRepeated()) {
      final List<?> valueList = (List<?>)value;
      if (descriptor.isPacked()) {
        output.writeTag(number, WireFormat.WIRETYPE_LENGTH_DELIMITED);
        // Compute the total data size so the length can be written.
        int dataSize = 0;
        for (final Object element : valueList) {
          dataSize += computeElementSizeNoTag(type, element);
        }
        output.writeRawVarint32(dataSize);
        // Write the data itself, without any tags.
        for (final Object element : valueList) {
          writeElementNoTag(output, type, element);
        }
      } else {
        for (final Object element : valueList) {
          writeElement(output, type, number, element);
        }
      }
    } else {
      if (value instanceof LazyField) {
        writeElement(output, type, number, ((LazyField) value).getValue());
      } else {
        writeElement(output, type, number, value);
      }
    }
  }

  /**
   * See {@link Message#getSerializedSize()}.  It's up to the caller to cache
   * the resulting size if desired.
   */
  public int getSerializedSize() {
    int size = 0;
    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
      final Map.Entry<FieldDescriptorType, Object> entry =
          fields.getArrayEntryAt(i);
      size += computeFieldSize(entry.getKey(), entry.getValue());
    }
    for (final Map.Entry<FieldDescriptorType, Object> entry :
         fields.getOverflowEntries()) {
      size += computeFieldSize(entry.getKey(), entry.getValue());
    }
    return size;
  }

  /**
   * Like {@link #getSerializedSize} but uses MessageSet wire format.
   */
  public int getMessageSetSerializedSize() {
    int size = 0;
    for (int i = 0; i < fields.getNumArrayEntries(); i++) {
      size += getMessageSetSerializedSize(fields.getArrayEntryAt(i));
    }
    for (final Map.Entry<FieldDescriptorType, Object> entry :
             fields.getOverflowEntries()) {
      size += getMessageSetSerializedSize(entry);
    }
    return size;
  }

  private int getMessageSetSerializedSize(
      final Map.Entry<FieldDescriptorType, Object> entry) {
    final FieldDescriptorType descriptor = entry.getKey();
    Object value = entry.getValue();
    if (descriptor.getLiteJavaType() == WireFormat.JavaType.MESSAGE
        && !descriptor.isRepeated() && !descriptor.isPacked()) {
      if (value instanceof LazyField) {
        return CodedOutputStream.computeLazyFieldMessageSetExtensionSize(
            entry.getKey().getNumber(), (LazyField) value);
      } else {
        return CodedOutputStream.computeMessageSetExtensionSize(
            entry.getKey().getNumber(), (MessageLite) value);
      }
    } else {
      return computeFieldSize(descriptor, value);
    }
  }

  /**
   * Compute the number of bytes that would be needed to encode a
   * single tag/value pair of arbitrary type.
   *
   * @param type   The field's type.
   * @param number The field's number.
   * @param value  Object representing the field's value.  Must be of the exact
   *               type which would be returned by
   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
   *               this field.
   */
  private static int computeElementSize(
      final WireFormat.FieldType type,
      final int number, final Object value) {
    int tagSize = CodedOutputStream.computeTagSize(number);
    if (type == WireFormat.FieldType.GROUP) {
      tagSize *= 2;
    }
    return tagSize + computeElementSizeNoTag(type, value);
  }

  /**
   * Compute the number of bytes that would be needed to encode a
   * particular value of arbitrary type, excluding tag.
   *
   * @param type   The field's type.
   * @param value  Object representing the field's value.  Must be of the exact
   *               type which would be returned by
   *               {@link Message#getField(Descriptors.FieldDescriptor)} for
   *               this field.
   */
  private static int computeElementSizeNoTag(
      final WireFormat.FieldType type, final Object value) {
    switch (type) {
      // Note:  Minor violation of 80-char limit rule here because this would
      //   actually be harder to read if we wrapped the lines.
      case DOUBLE  : return CodedOutputStream.computeDoubleSizeNoTag  ((Double     )value);
      case FLOAT   : return CodedOutputStream.computeFloatSizeNoTag   ((Float      )value);
      case INT64   : return CodedOutputStream.computeInt64SizeNoTag   ((Long       )value);
      case UINT64  : return CodedOutputStream.computeUInt64SizeNoTag  ((Long       )value);
      case INT32   : return CodedOutputStream.computeInt32SizeNoTag   ((Integer    )value);
      case FIXED64 : return CodedOutputStream.computeFixed64SizeNoTag ((Long       )value);
      case FIXED32 : return CodedOutputStream.computeFixed32SizeNoTag ((Integer    )value);
      case BOOL    : return CodedOutputStream.computeBoolSizeNoTag    ((Boolean    )value);
      case STRING  : return CodedOutputStream.computeStringSizeNoTag  ((String     )value);
      case GROUP   : return CodedOutputStream.computeGroupSizeNoTag   ((MessageLite)value);
      case BYTES   : return CodedOutputStream.computeBytesSizeNoTag   ((ByteString )value);
      case UINT32  : return CodedOutputStream.computeUInt32SizeNoTag  ((Integer    )value);
      case SFIXED32: return CodedOutputStream.computeSFixed32SizeNoTag((Integer    )value);
      case SFIXED64: return CodedOutputStream.computeSFixed64SizeNoTag((Long       )value);
      case SINT32  : return CodedOutputStream.computeSInt32SizeNoTag  ((Integer    )value);
      case SINT64  : return CodedOutputStream.computeSInt64SizeNoTag  ((Long       )value);

      case MESSAGE:
        if (value instanceof LazyField) {
          return CodedOutputStream.computeLazyFieldSizeNoTag((LazyField) value);
        } else {
          return CodedOutputStream.computeMessageSizeNoTag((MessageLite) value);
        }

      case ENUM:
        return CodedOutputStream.computeEnumSizeNoTag(
            ((Internal.EnumLite) value).getNumber());
    }

    throw new RuntimeException(
      "There is no way to get here, but the compiler thinks otherwise.");
  }

  /**
   * Compute the number of bytes needed to encode a particular field.
   */
  public static int computeFieldSize(final FieldDescriptorLite<?> descriptor,
                                     final Object value) {
    WireFormat.FieldType type = descriptor.getLiteType();
    int number = descriptor.getNumber();
    if (descriptor.isRepeated()) {
      if (descriptor.isPacked()) {
        int dataSize = 0;
        for (final Object element : (List<?>)value) {
          dataSize += computeElementSizeNoTag(type, element);
        }
        return dataSize +
            CodedOutputStream.computeTagSize(number) +
            CodedOutputStream.computeRawVarint32Size(dataSize);
      } else {
        int size = 0;
        for (final Object element : (List<?>)value) {
          size += computeElementSize(type, number, element);
        }
        return size;
      }
    } else {
      return computeElementSize(type, number, value);
    }
  }
}