// 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
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package com.google.protobuf;

import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.EnumDescriptor;
import com.google.protobuf.Descriptors.EnumValueDescriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.CharBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

Provide text parsing and formatting support for proto2 instances. The implementation largely
follows google/protobuf/text_format.cc.
Author:
wenboz@google.com Wenbo Zhu, kenton@google.com Kenton Varda/**
 * Provide text parsing and formatting support for proto2 instances. The implementation largely
 * follows google/protobuf/text_format.cc.
 *
 * @author wenboz@google.com Wenbo Zhu
 * @author kenton@google.com Kenton Varda
 */
public final class TextFormat {
  private TextFormat() {}

  private static final Logger logger = Logger.getLogger(TextFormat.class.getName());

  
Outputs a textual representation of the Protocol Message supplied into the parameter output.
(This representation is the new version of the classic "ProtocolPrinter" output from the
original Protocol Buffer system)
Deprecated:
Use printer().print(MessageOrBuilder, Appendable)/**
   * Outputs a textual representation of the Protocol Message supplied into the parameter output.
   * (This representation is the new version of the classic "ProtocolPrinter" output from the
   * original Protocol Buffer system)
   *
   * @deprecated Use {@code printer().print(MessageOrBuilder, Appendable)}
   */
  @Deprecated
  public static void print(final MessageOrBuilder message, final Appendable output)
      throws IOException {
    printer().print(message, output);
  }

  
Outputs a textual representation of fields to output. 
Deprecated:
Use printer().print(UnknownFieldSet, Appendable)/**
   * Outputs a textual representation of {@code fields} to {@code output}.
   *
   * @deprecated Use {@code printer().print(UnknownFieldSet, Appendable)}
   */
  @Deprecated
  public static void print(final UnknownFieldSet fields, final Appendable output)
      throws IOException {
    printer().print(fields, output);
  }

  
Same as print(), except that non-ASCII characters are not escaped. 
Deprecated:
Use printer().escapingNonAscii(false).print(MessageOrBuilder, Appendable)/**
   * Same as {@code print()}, except that non-ASCII characters are not escaped.
   *
   * @deprecated Use {@code printer().escapingNonAscii(false).print(MessageOrBuilder, Appendable)}
   */
  @Deprecated
  public static void printUnicode(final MessageOrBuilder message, final Appendable output)
      throws IOException {
    printer().escapingNonAscii(false).print(message, output);
  }

  
Same as print(), except that non-ASCII characters are not escaped. 
Deprecated:
Use printer().escapingNonAscii(false).print(UnknownFieldSet, Appendable)/**
   * Same as {@code print()}, except that non-ASCII characters are not escaped.
   *
   * @deprecated Use {@code printer().escapingNonAscii(false).print(UnknownFieldSet, Appendable)}
   */
  @Deprecated
  public static void printUnicode(final UnknownFieldSet fields, final Appendable output)
      throws IOException {
    printer().escapingNonAscii(false).print(fields, output);
  }

  
Generates a human readable form of this message, useful for debugging and other purposes, with no newline characters. This is just a trivial wrapper around Printer.shortDebugString(MessageOrBuilder). /**
   * Generates a human readable form of this message, useful for debugging and other purposes, with
   * no newline characters. This is just a trivial wrapper around
   * {@link TextFormat.Printer#shortDebugString(MessageOrBuilder)}.
   */
  public static String shortDebugString(final MessageOrBuilder message) {
    return printer().shortDebugString(message);
  }

  
Generates a human readable form of the field, useful for debugging and other purposes, with
no newline characters.
Deprecated:
Use printer().shortDebugString(FieldDescriptor, Object)/**
   * Generates a human readable form of the field, useful for debugging and other purposes, with
   * no newline characters.
   *
   * @deprecated Use {@code printer().shortDebugString(FieldDescriptor, Object)}
   */
  @Deprecated
  public static String shortDebugString(final FieldDescriptor field, final Object value) {
    return printer().shortDebugString(field, value);
  }
  //
  
Generates a human readable form of the unknown fields, useful for debugging and other
purposes, with no newline characters.
Deprecated:
Use printer().shortDebugString(UnknownFieldSet)/**
   * Generates a human readable form of the unknown fields, useful for debugging and other
   * purposes, with no newline characters.
   *
   * @deprecated Use {@code printer().shortDebugString(UnknownFieldSet)}
   */
  @Deprecated
  public static String shortDebugString(final UnknownFieldSet fields) {
    return printer().shortDebugString(fields);
  }

  
Like print(), but writes directly to a String and returns it. 
Deprecated:
Use Object.toString()/**
   * Like {@code print()}, but writes directly to a {@code String} and returns it.
   *
   * @deprecated Use {@link MessageOrBuilder#toString()}
   */
  @Deprecated
  public static String printToString(final MessageOrBuilder message) {
    return printer().printToString(message);
  }

  
Like print(), but writes directly to a String and returns it. 
Deprecated:
Use UnknownFieldSet.toString()/**
   * Like {@code print()}, but writes directly to a {@code String} and returns it.
   *
   * @deprecated Use {@link UnknownFieldSet#toString()}
   */
  @Deprecated
  public static String printToString(final UnknownFieldSet fields) {
    return printer().printToString(fields);
  }

  
Same as printToString(), except that non-ASCII characters in string type fields are not escaped in backslash+octals. 
Deprecated:
Use printer().escapingNonAscii(false).printToString(MessageOrBuilder)/**
   * Same as {@code printToString()}, except that non-ASCII characters in string type fields are not
   * escaped in backslash+octals.
   *
   * @deprecated Use {@code printer().escapingNonAscii(false).printToString(MessageOrBuilder)}
   */
  @Deprecated
  public static String printToUnicodeString(final MessageOrBuilder message) {
    return printer().escapingNonAscii(false).printToString(message);
  }

  
Same as printToString(), except that non-ASCII characters in string type fields are not escaped in backslash+octals. 
Deprecated:
Use printer().escapingNonAscii(false).printToString(UnknownFieldSet)/**
   * Same as {@code printToString()}, except that non-ASCII characters in string type fields are
   * not escaped in backslash+octals.
   *
   * @deprecated Use {@code printer().escapingNonAscii(false).printToString(UnknownFieldSet)}
   */
  @Deprecated
  public static String printToUnicodeString(final UnknownFieldSet fields) {
    return printer().escapingNonAscii(false).printToString(fields);
  }
  //
  
Deprecated:
Use printer().printField(FieldDescriptor, Object, Appendable)/** @deprecated Use {@code printer().printField(FieldDescriptor, Object, Appendable)} */
  @Deprecated
  public static void printField(
      final FieldDescriptor field, final Object value, final Appendable output)
      throws IOException {
    printer().printField(field, value, output);
  }
  //
  
Deprecated:
Use printer().printFieldToString(FieldDescriptor, Object)/** @deprecated Use {@code printer().printFieldToString(FieldDescriptor, Object)} */
  @Deprecated
  public static String printFieldToString(final FieldDescriptor field, final Object value) {
    return printer().printFieldToString(field, value);
  }
  //
  
Outputs a unicode textual representation of the value of given field value.
Same as printFieldValue(), except that non-ASCII characters in string type fields are not escaped in backslash+octals. 
Params:
field – the descriptor of the field
value – the value of the field
output – the output to which to append the formatted value
Throws:
ClassCastException – if the value is not appropriate for the given field descriptor
IOException – if there is an exception writing to the output
Deprecated:
Use printer().escapingNonAscii(false).printFieldValue(FieldDescriptor,
    Object, Appendable)/**
   * Outputs a unicode textual representation of the value of given field value.
   *
   * <p>Same as {@code printFieldValue()}, except that non-ASCII characters in string type fields
   * are not escaped in backslash+octals.
   *
   * @deprecated Use {@code printer().escapingNonAscii(false).printFieldValue(FieldDescriptor,
   *     Object, Appendable)}
   * @param field the descriptor of the field
   * @param value the value of the field
   * @param output the output to which to append the formatted value
   * @throws ClassCastException if the value is not appropriate for the given field descriptor
   * @throws IOException if there is an exception writing to the output
   */
  @Deprecated
  public static void printUnicodeFieldValue(
      final FieldDescriptor field, final Object value, final Appendable output)
      throws IOException {
    printer().escapingNonAscii(false).printFieldValue(field, value, output);
  }

  
Outputs a textual representation of the value of given field value.
Params:
field – the descriptor of the field
value – the value of the field
output – the output to which to append the formatted value
Throws:
ClassCastException – if the value is not appropriate for the given field descriptor
IOException – if there is an exception writing to the output
Deprecated:
Use printer().printFieldValue(FieldDescriptor, Object, Appendable)/**
   * Outputs a textual representation of the value of given field value.
   *
   * @deprecated Use {@code printer().printFieldValue(FieldDescriptor, Object, Appendable)}
   * @param field the descriptor of the field
   * @param value the value of the field
   * @param output the output to which to append the formatted value
   * @throws ClassCastException if the value is not appropriate for the given field descriptor
   * @throws IOException if there is an exception writing to the output
   */
  @Deprecated
  public static void printFieldValue(
      final FieldDescriptor field, final Object value, final Appendable output) throws IOException {
    printer().printFieldValue(field, value, output);
  }

  
Outputs a textual representation of the value of an unknown field.
Params:
tag – the field's tag number
value – the value of the field
output – the output to which to append the formatted value
Throws:
ClassCastException – if the value is not appropriate for the given field descriptor
IOException – if there is an exception writing to the output/**
   * Outputs a textual representation of the value of an unknown field.
   *
   * @param tag the field's tag number
   * @param value the value of the field
   * @param output the output to which to append the formatted value
   * @throws ClassCastException if the value is not appropriate for the given field descriptor
   * @throws IOException if there is an exception writing to the output
   */
  public static void printUnknownFieldValue(
      final int tag, final Object value, final Appendable output) throws IOException {
    printUnknownFieldValue(tag, value, multiLineOutput(output));
  }

  private static void printUnknownFieldValue(
      final int tag, final Object value, final TextGenerator generator) throws IOException {
    switch (WireFormat.getTagWireType(tag)) {
      case WireFormat.WIRETYPE_VARINT:
        generator.print(unsignedToString((Long) value));
        break;
      case WireFormat.WIRETYPE_FIXED32:
        generator.print(String.format((Locale) null, "0x%08x", (Integer) value));
        break;
      case WireFormat.WIRETYPE_FIXED64:
        generator.print(String.format((Locale) null, "0x%016x", (Long) value));
        break;
      case WireFormat.WIRETYPE_LENGTH_DELIMITED:
        try {
          // Try to parse and print the field as an embedded message
          UnknownFieldSet message = UnknownFieldSet.parseFrom((ByteString) value);
          generator.print("{");
          generator.eol();
          generator.indent();
          Printer.printUnknownFields(message, generator);
          generator.outdent();
          generator.print("}");
        } catch (InvalidProtocolBufferException e) {
          // If not parseable as a message, print as a String
          generator.print("\"");
          generator.print(escapeBytes((ByteString) value));
          generator.print("\"");
        }
        break;
      case WireFormat.WIRETYPE_START_GROUP:
        Printer.printUnknownFields((UnknownFieldSet) value, generator);
        break;
      default:
        throw new IllegalArgumentException("Bad tag: " + tag);
    }
  }

  
Printer instance which escapes non-ASCII characters. /** Printer instance which escapes non-ASCII characters. */
  public static Printer printer() {
    return Printer.DEFAULT;
  }

  
Helper class for converting protobufs to text. /** Helper class for converting protobufs to text. */
  public static final class Printer {

    // Printer instance which escapes non-ASCII characters.
    private static final Printer DEFAULT = new Printer(true, TypeRegistry.getEmptyTypeRegistry());

    
Whether to escape non ASCII characters with backslash and octal. /** Whether to escape non ASCII characters with backslash and octal. */
    private final boolean escapeNonAscii;

    private final TypeRegistry typeRegistry;

    private Printer(boolean escapeNonAscii, TypeRegistry typeRegistry) {
      this.escapeNonAscii = escapeNonAscii;
      this.typeRegistry = typeRegistry;
    }

    
Return a new Printer instance with the specified escape mode.
Params:
escapeNonAscii – If true, the new Printer will escape non-ASCII characters (this is the
    default behavior. If false, the new Printer will print non-ASCII characters as is. In
    either case, the new Printer still escapes newlines and quotes in strings.
Returns:
a new Printer that clones all other configurations from the current Printer, with the escape mode set to the given parameter./**
     * Return a new Printer instance with the specified escape mode.
     *
     * @param escapeNonAscii If true, the new Printer will escape non-ASCII characters (this is the
     *     default behavior. If false, the new Printer will print non-ASCII characters as is. In
     *     either case, the new Printer still escapes newlines and quotes in strings.
     * @return a new Printer that clones all other configurations from the current {@link Printer},
     *     with the escape mode set to the given parameter.
     */
    public Printer escapingNonAscii(boolean escapeNonAscii) {
      return new Printer(escapeNonAscii, typeRegistry);
    }

    
Creates a new Printer using the given typeRegistry. The new Printer clones all other configurations from the current Printer. 
Throws:
IllegalArgumentException – if a registry is already set./**
     * Creates a new {@link Printer} using the given typeRegistry. The new Printer clones all other
     * configurations from the current {@link Printer}.
     *
     * @throws IllegalArgumentException if a registry is already set.
     */
    public Printer usingTypeRegistry(TypeRegistry typeRegistry) {
      if (this.typeRegistry != TypeRegistry.getEmptyTypeRegistry()) {
        throw new IllegalArgumentException("Only one typeRegistry is allowed.");
      }
      return new Printer(escapeNonAscii, typeRegistry);
    }

    
Outputs a textual representation of the Protocol Message supplied into the parameter output.
(This representation is the new version of the classic "ProtocolPrinter" output from the
original Protocol Buffer system)
/**
     * Outputs a textual representation of the Protocol Message supplied into the parameter output.
     * (This representation is the new version of the classic "ProtocolPrinter" output from the
     * original Protocol Buffer system)
     */
    public void print(final MessageOrBuilder message, final Appendable output) throws IOException {
      print(message, multiLineOutput(output));
    }

    
Outputs a textual representation of fields to output. /** Outputs a textual representation of {@code fields} to {@code output}. */
    public void print(final UnknownFieldSet fields, final Appendable output) throws IOException {
      printUnknownFields(fields, multiLineOutput(output));
    }

    private void print(final MessageOrBuilder message, final TextGenerator generator)
        throws IOException {
      if (message.getDescriptorForType().getFullName().equals("google.protobuf.Any")
          && printAny(message, generator)) {
        return;
      }
      printMessage(message, generator);
    }

    
Attempt to print the 'google.protobuf.Any' message in a human-friendly format. Returns false
if the message isn't a valid 'google.protobuf.Any' message (in which case the message should
be rendered just like a regular message to help debugging).
/**
     * Attempt to print the 'google.protobuf.Any' message in a human-friendly format. Returns false
     * if the message isn't a valid 'google.protobuf.Any' message (in which case the message should
     * be rendered just like a regular message to help debugging).
     */
    private boolean printAny(final MessageOrBuilder message, final TextGenerator generator)
        throws IOException {
      Descriptor messageType = message.getDescriptorForType();
      FieldDescriptor typeUrlField = messageType.findFieldByNumber(1);
      FieldDescriptor valueField = messageType.findFieldByNumber(2);
      if (typeUrlField == null
          || typeUrlField.getType() != FieldDescriptor.Type.STRING
          || valueField == null
          || valueField.getType() != FieldDescriptor.Type.BYTES) {
        // The message may look like an Any but isn't actually an Any message (might happen if the
        // user tries to use DynamicMessage to construct an Any from incomplete Descriptor).
        return false;
      }
      String typeUrl = (String) message.getField(typeUrlField);
      // If type_url is not set, we will not be able to decode the content of the value, so just
      // print out the Any like a regular message.
      if (typeUrl.isEmpty()) {
        return false;
      }
      Object value = message.getField(valueField);

      Message.Builder contentBuilder = null;
      try {
        Descriptor contentType = typeRegistry.getDescriptorForTypeUrl(typeUrl);
        if (contentType == null) {
          return false;
        }
        contentBuilder = DynamicMessage.getDefaultInstance(contentType).newBuilderForType();
        contentBuilder.mergeFrom((ByteString) value);
      } catch (InvalidProtocolBufferException e) {
        // The value of Any is malformed. We cannot print it out nicely, so fallback to printing out
        // the type_url and value as bytes. Note that we fail open here to be consistent with
        // text_format.cc, and also to allow a way for users to inspect the content of the broken
        // message.
        return false;
      }
      generator.print("[");
      generator.print(typeUrl);
      generator.print("] {");
      generator.eol();
      generator.indent();
      print(contentBuilder, generator);
      generator.outdent();
      generator.print("}");
      generator.eol();
      return true;
    }

    public String printFieldToString(final FieldDescriptor field, final Object value) {
      try {
        final StringBuilder text = new StringBuilder();
        printField(field, value, text);
        return text.toString();
      } catch (IOException e) {
        throw new IllegalStateException(e);
      }
    }

    public void printField(final FieldDescriptor field, final Object value, final Appendable output)
        throws IOException {
      printField(field, value, multiLineOutput(output));
    }

    private void printField(
        final FieldDescriptor field, final Object value, final TextGenerator generator)
        throws IOException {
      if (field.isRepeated()) {
        // Repeated field.  Print each element.
        for (Object element : (List<?>) value) {
          printSingleField(field, element, generator);
        }
      } else {
        printSingleField(field, value, generator);
      }
    }

    
Outputs a textual representation of the value of given field value.
Params:
field – the descriptor of the field
value – the value of the field
output – the output to which to append the formatted value
Throws:
ClassCastException – if the value is not appropriate for the given field descriptor
IOException – if there is an exception writing to the output/**
     * Outputs a textual representation of the value of given field value.
     *
     * @param field the descriptor of the field
     * @param value the value of the field
     * @param output the output to which to append the formatted value
     * @throws ClassCastException if the value is not appropriate for the given field descriptor
     * @throws IOException if there is an exception writing to the output
     */
    public void printFieldValue(
        final FieldDescriptor field, final Object value, final Appendable output)
        throws IOException {
      printFieldValue(field, value, multiLineOutput(output));
    }

    private void printFieldValue(
        final FieldDescriptor field, final Object value, final TextGenerator generator)
        throws IOException {
      switch (field.getType()) {
        case INT32:
        case SINT32:
        case SFIXED32:
          generator.print(((Integer) value).toString());
          break;

        case INT64:
        case SINT64:
        case SFIXED64:
          generator.print(((Long) value).toString());
          break;

        case BOOL:
          generator.print(((Boolean) value).toString());
          break;

        case FLOAT:
          generator.print(((Float) value).toString());
          break;

        case DOUBLE:
          generator.print(((Double) value).toString());
          break;

        case UINT32:
        case FIXED32:
          generator.print(unsignedToString((Integer) value));
          break;

        case UINT64:
        case FIXED64:
          generator.print(unsignedToString((Long) value));
          break;

        case STRING:
          generator.print("\"");
          generator.print(
              escapeNonAscii
                  ? TextFormatEscaper.escapeText((String) value)
                  : escapeDoubleQuotesAndBackslashes((String) value).replace("\n", "\\n"));
          generator.print("\"");
          break;

        case BYTES:
          generator.print("\"");
          if (value instanceof ByteString) {
            generator.print(escapeBytes((ByteString) value));
          } else {
            generator.print(escapeBytes((byte[]) value));
          }
          generator.print("\"");
          break;

        case ENUM:
          generator.print(((EnumValueDescriptor) value).getName());
          break;

        case MESSAGE:
        case GROUP:
          print((Message) value, generator);
          break;
      }
    }

    
Like print(), but writes directly to a String and returns it. /** Like {@code print()}, but writes directly to a {@code String} and returns it. */
    public String printToString(final MessageOrBuilder message) {
      try {
        final StringBuilder text = new StringBuilder();
        print(message, text);
        return text.toString();
      } catch (IOException e) {
        throw new IllegalStateException(e);
      }
    }
    
Like print(), but writes directly to a String and returns it. /** Like {@code print()}, but writes directly to a {@code String} and returns it. */
    public String printToString(final UnknownFieldSet fields) {
      try {
        final StringBuilder text = new StringBuilder();
        print(fields, text);
        return text.toString();
      } catch (IOException e) {
        throw new IllegalStateException(e);
      }
    }

    
Generates a human readable form of this message, useful for debugging and other purposes,
with no newline characters.
/**
     * Generates a human readable form of this message, useful for debugging and other purposes,
     * with no newline characters.
     */
    public String shortDebugString(final MessageOrBuilder message) {
      try {
        final StringBuilder text = new StringBuilder();
        print(message, singleLineOutput(text));
        return text.toString();
      } catch (IOException e) {
        throw new IllegalStateException(e);
      }
    }

    
Generates a human readable form of the field, useful for debugging and other purposes, with
no newline characters.
/**
     * Generates a human readable form of the field, useful for debugging and other purposes, with
     * no newline characters.
     */
    public String shortDebugString(final FieldDescriptor field, final Object value) {
      try {
        final StringBuilder text = new StringBuilder();
        printField(field, value, singleLineOutput(text));
        return text.toString();
      } catch (IOException e) {
        throw new IllegalStateException(e);
      }
    }

    
Generates a human readable form of the unknown fields, useful for debugging and other
purposes, with no newline characters.
/**
     * Generates a human readable form of the unknown fields, useful for debugging and other
     * purposes, with no newline characters.
     */
    public String shortDebugString(final UnknownFieldSet fields) {
      try {
        final StringBuilder text = new StringBuilder();
        printUnknownFields(fields, singleLineOutput(text));
        return text.toString();
      } catch (IOException e) {
        throw new IllegalStateException(e);
      }
    }

    private static void printUnknownFieldValue(
        final int tag, final Object value, final TextGenerator generator) throws IOException {
      switch (WireFormat.getTagWireType(tag)) {
        case WireFormat.WIRETYPE_VARINT:
          generator.print(unsignedToString((Long) value));
          break;
        case WireFormat.WIRETYPE_FIXED32:
          generator.print(String.format((Locale) null, "0x%08x", (Integer) value));
          break;
        case WireFormat.WIRETYPE_FIXED64:
          generator.print(String.format((Locale) null, "0x%016x", (Long) value));
          break;
        case WireFormat.WIRETYPE_LENGTH_DELIMITED:
          try {
            // Try to parse and print the field as an embedded message
            UnknownFieldSet message = UnknownFieldSet.parseFrom((ByteString) value);
            generator.print("{");
            generator.eol();
            generator.indent();
            printUnknownFields(message, generator);
            generator.outdent();
            generator.print("}");
          } catch (InvalidProtocolBufferException e) {
            // If not parseable as a message, print as a String
            generator.print("\"");
            generator.print(escapeBytes((ByteString) value));
            generator.print("\"");
          }
          break;
        case WireFormat.WIRETYPE_START_GROUP:
          printUnknownFields((UnknownFieldSet) value, generator);
          break;
        default:
          throw new IllegalArgumentException("Bad tag: " + tag);
      }
    }

    private void printMessage(final MessageOrBuilder message, final TextGenerator generator)
        throws IOException {
      for (Map.Entry<FieldDescriptor, Object> field : message.getAllFields().entrySet()) {
        printField(field.getKey(), field.getValue(), generator);
      }
      printUnknownFields(message.getUnknownFields(), generator);
    }

    private void printSingleField(
        final FieldDescriptor field, final Object value, final TextGenerator generator)
        throws IOException {
      if (field.isExtension()) {
        generator.print("[");
        // We special-case MessageSet elements for compatibility with proto1.
        if (field.getContainingType().getOptions().getMessageSetWireFormat()
            && (field.getType() == FieldDescriptor.Type.MESSAGE)
            && (field.isOptional())
            // object equality
            && (field.getExtensionScope() == field.getMessageType())) {
          generator.print(field.getMessageType().getFullName());
        } else {
          generator.print(field.getFullName());
        }
        generator.print("]");
      } else {
        if (field.getType() == FieldDescriptor.Type.GROUP) {
          // Groups must be serialized with their original capitalization.
          generator.print(field.getMessageType().getName());
        } else {
          generator.print(field.getName());
        }
      }

      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
        generator.print(" {");
        generator.eol();
        generator.indent();
      } else {
        generator.print(": ");
      }

      printFieldValue(field, value, generator);

      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
        generator.outdent();
        generator.print("}");
      }
      generator.eol();
    }

    private static void printUnknownFields(
        final UnknownFieldSet unknownFields, final TextGenerator generator) throws IOException {
      for (Map.Entry<Integer, UnknownFieldSet.Field> entry : unknownFields.asMap().entrySet()) {
        final int number = entry.getKey();
        final UnknownFieldSet.Field field = entry.getValue();
        printUnknownField(number, WireFormat.WIRETYPE_VARINT, field.getVarintList(), generator);
        printUnknownField(number, WireFormat.WIRETYPE_FIXED32, field.getFixed32List(), generator);
        printUnknownField(number, WireFormat.WIRETYPE_FIXED64, field.getFixed64List(), generator);
        printUnknownField(
            number,
            WireFormat.WIRETYPE_LENGTH_DELIMITED,
            field.getLengthDelimitedList(),
            generator);
        for (final UnknownFieldSet value : field.getGroupList()) {
          generator.print(entry.getKey().toString());
          generator.print(" {");
          generator.eol();
          generator.indent();
          printUnknownFields(value, generator);
          generator.outdent();
          generator.print("}");
          generator.eol();
        }
      }
    }

    private static void printUnknownField(
        final int number, final int wireType, final List<?> values, final TextGenerator generator)
        throws IOException {
      for (final Object value : values) {
        generator.print(String.valueOf(number));
        generator.print(": ");
        printUnknownFieldValue(wireType, value, generator);
        generator.eol();
      }
    }
  }

  
Convert an unsigned 32-bit integer to a string. /** Convert an unsigned 32-bit integer to a string. */
  public static String unsignedToString(final int value) {
    if (value >= 0) {
      return Integer.toString(value);
    } else {
      return Long.toString(value & 0x00000000FFFFFFFFL);
    }
  }

  
Convert an unsigned 64-bit integer to a string. /** Convert an unsigned 64-bit integer to a string. */
  public static String unsignedToString(final long value) {
    if (value >= 0) {
      return Long.toString(value);
    } else {
      // Pull off the most-significant bit so that BigInteger doesn't think
      // the number is negative, then set it again using setBit().
      return BigInteger.valueOf(value & 0x7FFFFFFFFFFFFFFFL).setBit(63).toString();
    }
  }

  private static TextGenerator multiLineOutput(Appendable output) {
    return new TextGenerator(output, false);
  }

  private static TextGenerator singleLineOutput(Appendable output) {
    return new TextGenerator(output, true);
  }

  
An inner class for writing text to the output stream. /** An inner class for writing text to the output stream. */
  private static final class TextGenerator {
    private final Appendable output;
    private final StringBuilder indent = new StringBuilder();
    private final boolean singleLineMode;
    // While technically we are "at the start of a line" at the very beginning of the output, all
    // we would do in response to this is emit the (zero length) indentation, so it has no effect.
    // Setting it false here does however suppress an unwanted leading space in single-line mode.
    private boolean atStartOfLine = false;

    private TextGenerator(final Appendable output, boolean singleLineMode) {
      this.output = output;
      this.singleLineMode = singleLineMode;
    }

    
Indent text by two spaces. After calling Indent(), two spaces will be inserted at the
beginning of each line of text. Indent() may be called multiple times to produce deeper
indents.
/**
     * Indent text by two spaces. After calling Indent(), two spaces will be inserted at the
     * beginning of each line of text. Indent() may be called multiple times to produce deeper
     * indents.
     */
    public void indent() {
      indent.append("  ");
    }

    
Reduces the current indent level by two spaces, or crashes if the indent level is zero. /** Reduces the current indent level by two spaces, or crashes if the indent level is zero. */
    public void outdent() {
      final int length = indent.length();
      if (length == 0) {
        throw new IllegalArgumentException(" Outdent() without matching Indent().");
      }
      indent.setLength(length - 2);
    }

    
Print text to the output stream. Bare newlines are never expected to be passed to this
method; to indicate the end of a line, call "eol()".
/**
     * Print text to the output stream. Bare newlines are never expected to be passed to this
     * method; to indicate the end of a line, call "eol()".
     */
    public void print(final CharSequence text) throws IOException {
      if (atStartOfLine) {
        atStartOfLine = false;
        output.append(singleLineMode ? " " : indent);
      }
      output.append(text);
    }

    
Signifies reaching the "end of the current line" in the output. In single-line mode, this
does not result in a newline being emitted, but ensures that a separating space is written
before the next output.
/**
     * Signifies reaching the "end of the current line" in the output. In single-line mode, this
     * does not result in a newline being emitted, but ensures that a separating space is written
     * before the next output.
     */
    public void eol() throws IOException {
      if (!singleLineMode) {
        output.append("\n");
      }
      atStartOfLine = true;
    }
  }

  // =================================================================
  // Parsing

  
Represents a stream of tokens parsed from a String. 
The Java standard library provides many classes that you might think would be useful for
implementing this, but aren't. For example:

  
java.io.StreamTokenizer: This almost does what we want -- or, at least, something that would get us close to what we want -- except for one fatal flaw: It automatically un-escapes strings using Java escape sequences, which do not include all the escape sequences we need to support (e.g. '\x'). 
java.util.Scanner: This seems like a great way at least to parse regular expressions out of a stream (so we wouldn't have to load the entire input into a single string before parsing). Sadly, Scanner requires that tokens be delimited with some delimiter. Thus, although the text "foo:" should parse to two tokens ("foo" and ":"), Scanner would recognize it only as a single token. Furthermore, 
      Scanner provides no way to inspect the contents of delimiters, making it impossible to keep track of line and column numbers. 
Luckily, Java's regular expression support does manage to be useful to us. (Barely: We need Matcher.usePattern(), which is new in Java 1.5.) So, we can use that, at least. Unfortunately, this implies that we need to have the entire input in one contiguous string. /**
   * Represents a stream of tokens parsed from a {@code String}.
   *
   * <p>The Java standard library provides many classes that you might think would be useful for
   * implementing this, but aren't. For example:
   *
   * <ul>
   *   <li>{@code java.io.StreamTokenizer}: This almost does what we want -- or, at least, something
   *       that would get us close to what we want -- except for one fatal flaw: It automatically
   *       un-escapes strings using Java escape sequences, which do not include all the escape
   *       sequences we need to support (e.g. '\x').
   *   <li>{@code java.util.Scanner}: This seems like a great way at least to parse regular
   *       expressions out of a stream (so we wouldn't have to load the entire input into a single
   *       string before parsing). Sadly, {@code Scanner} requires that tokens be delimited with
   *       some delimiter. Thus, although the text "foo:" should parse to two tokens ("foo" and
   *       ":"), {@code Scanner} would recognize it only as a single token. Furthermore, {@code
   *       Scanner} provides no way to inspect the contents of delimiters, making it impossible to
   *       keep track of line and column numbers.
   * </ul>
   *
   * <p>Luckily, Java's regular expression support does manage to be useful to us. (Barely: We need
   * {@code Matcher.usePattern()}, which is new in Java 1.5.) So, we can use that, at least.
   * Unfortunately, this implies that we need to have the entire input in one contiguous string.
   */
  private static final class Tokenizer {
    private final CharSequence text;
    private final Matcher matcher;
    private String currentToken;

    // The character index within this.text at which the current token begins.
    private int pos = 0;

    // The line and column numbers of the current token.
    private int line = 0;
    private int column = 0;

    // The line and column numbers of the previous token (allows throwing
    // errors *after* consuming).
    private int previousLine = 0;
    private int previousColumn = 0;

    // We use possessive quantifiers (*+ and ++) because otherwise the Java
    // regex matcher has stack overflows on large inputs.
    private static final Pattern WHITESPACE = Pattern.compile("(\\s|(#.*$))++", Pattern.MULTILINE);
    private static final Pattern TOKEN =
        Pattern.compile(
            "[a-zA-Z_][0-9a-zA-Z_+-]*+|" // an identifier
                + "[.]?[0-9+-][0-9a-zA-Z_.+-]*+|" // a number
                + "\"([^\"\n\\\\]|\\\\.)*+(\"|\\\\?$)|" // a double-quoted string
                + "\'([^\'\n\\\\]|\\\\.)*+(\'|\\\\?$)", // a single-quoted string
            Pattern.MULTILINE);

    private static final Pattern DOUBLE_INFINITY =
        Pattern.compile("-?inf(inity)?", Pattern.CASE_INSENSITIVE);
    private static final Pattern FLOAT_INFINITY =
        Pattern.compile("-?inf(inity)?f?", Pattern.CASE_INSENSITIVE);
    private static final Pattern FLOAT_NAN = Pattern.compile("nanf?", Pattern.CASE_INSENSITIVE);

    
Construct a tokenizer that parses tokens from the given text. /** Construct a tokenizer that parses tokens from the given text. */
    private Tokenizer(final CharSequence text) {
      this.text = text;
      this.matcher = WHITESPACE.matcher(text);
      skipWhitespace();
      nextToken();
    }

    int getPreviousLine() {
      return previousLine;
    }

    int getPreviousColumn() {
      return previousColumn;
    }

    int getLine() {
      return line;
    }

    int getColumn() {
      return column;
    }

    
Are we at the end of the input? /** Are we at the end of the input? */
    public boolean atEnd() {
      return currentToken.length() == 0;
    }

    
Advance to the next token. /** Advance to the next token. */
    public void nextToken() {
      previousLine = line;
      previousColumn = column;

      // Advance the line counter to the current position.
      while (pos < matcher.regionStart()) {
        if (text.charAt(pos) == '\n') {
          ++line;
          column = 0;
        } else {
          ++column;
        }
        ++pos;
      }

      // Match the next token.
      if (matcher.regionStart() == matcher.regionEnd()) {
        // EOF
        currentToken = "";
      } else {
        matcher.usePattern(TOKEN);
        if (matcher.lookingAt()) {
          currentToken = matcher.group();
          matcher.region(matcher.end(), matcher.regionEnd());
        } else {
          // Take one character.
          currentToken = String.valueOf(text.charAt(pos));
          matcher.region(pos + 1, matcher.regionEnd());
        }

        skipWhitespace();
      }
    }

    
Skip over any whitespace so that the matcher region starts at the next token. /** Skip over any whitespace so that the matcher region starts at the next token. */
    private void skipWhitespace() {
      matcher.usePattern(WHITESPACE);
      if (matcher.lookingAt()) {
        matcher.region(matcher.end(), matcher.regionEnd());
      }
    }

    
If the next token exactly matches token, consume it and return true. Otherwise, return false without doing anything. /**
     * If the next token exactly matches {@code token}, consume it and return {@code true}.
     * Otherwise, return {@code false} without doing anything.
     */
    public boolean tryConsume(final String token) {
      if (currentToken.equals(token)) {
        nextToken();
        return true;
      } else {
        return false;
      }
    }

    
If the next token exactly matches token, consume it. Otherwise, throw a ParseException. /**
     * If the next token exactly matches {@code token}, consume it. Otherwise, throw a {@link
     * ParseException}.
     */
    public void consume(final String token) throws ParseException {
      if (!tryConsume(token)) {
        throw parseException("Expected \"" + token + "\".");
      }
    }

    
Returns true if the next token is an integer, but does not consume it. /** Returns {@code true} if the next token is an integer, but does not consume it. */
    public boolean lookingAtInteger() {
      if (currentToken.length() == 0) {
        return false;
      }

      final char c = currentToken.charAt(0);
      return ('0' <= c && c <= '9') || c == '-' || c == '+';
    }

    
Returns true if the current token's text is equal to that specified. /** Returns {@code true} if the current token's text is equal to that specified. */
    public boolean lookingAt(String text) {
      return currentToken.equals(text);
    }

    
If the next token is an identifier, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is an identifier, consume it and return its value. Otherwise, throw a
     * {@link ParseException}.
     */
    public String consumeIdentifier() throws ParseException {
      for (int i = 0; i < currentToken.length(); i++) {
        final char c = currentToken.charAt(i);
        if (('a' <= c && c <= 'z')
            || ('A' <= c && c <= 'Z')
            || ('0' <= c && c <= '9')
            || (c == '_')
            || (c == '.')) {
          // OK
        } else {
          throw parseException("Expected identifier. Found '" + currentToken + "'");
        }
      }

      final String result = currentToken;
      nextToken();
      return result;
    }

    
If the next token is an identifier, consume it and return true. Otherwise, return false without doing anything. /**
     * If the next token is an identifier, consume it and return {@code true}. Otherwise, return
     * {@code false} without doing anything.
     */
    public boolean tryConsumeIdentifier() {
      try {
        consumeIdentifier();
        return true;
      } catch (ParseException e) {
        return false;
      }
    }

    
If the next token is a 32-bit signed integer, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a 32-bit signed integer, consume it and return its value. Otherwise,
     * throw a {@link ParseException}.
     */
    public int consumeInt32() throws ParseException {
      try {
        final int result = parseInt32(currentToken);
        nextToken();
        return result;
      } catch (NumberFormatException e) {
        throw integerParseException(e);
      }
    }

    
If the next token is a 32-bit unsigned integer, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a 32-bit unsigned integer, consume it and return its value. Otherwise,
     * throw a {@link ParseException}.
     */
    public int consumeUInt32() throws ParseException {
      try {
        final int result = parseUInt32(currentToken);
        nextToken();
        return result;
      } catch (NumberFormatException e) {
        throw integerParseException(e);
      }
    }

    
If the next token is a 64-bit signed integer, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a 64-bit signed integer, consume it and return its value. Otherwise,
     * throw a {@link ParseException}.
     */
    public long consumeInt64() throws ParseException {
      try {
        final long result = parseInt64(currentToken);
        nextToken();
        return result;
      } catch (NumberFormatException e) {
        throw integerParseException(e);
      }
    }

    
If the next token is a 64-bit signed integer, consume it and return true. Otherwise, return false without doing anything. /**
     * If the next token is a 64-bit signed integer, consume it and return {@code true}. Otherwise,
     * return {@code false} without doing anything.
     */
    public boolean tryConsumeInt64() {
      try {
        consumeInt64();
        return true;
      } catch (ParseException e) {
        return false;
      }
    }

    
If the next token is a 64-bit unsigned integer, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a 64-bit unsigned integer, consume it and return its value. Otherwise,
     * throw a {@link ParseException}.
     */
    public long consumeUInt64() throws ParseException {
      try {
        final long result = parseUInt64(currentToken);
        nextToken();
        return result;
      } catch (NumberFormatException e) {
        throw integerParseException(e);
      }
    }

    
If the next token is a 64-bit unsigned integer, consume it and return true. Otherwise, return false without doing anything. /**
     * If the next token is a 64-bit unsigned integer, consume it and return {@code true}.
     * Otherwise, return {@code false} without doing anything.
     */
    public boolean tryConsumeUInt64() {
      try {
        consumeUInt64();
        return true;
      } catch (ParseException e) {
        return false;
      }
    }

    
If the next token is a double, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a double, consume it and return its value. Otherwise, throw a {@link
     * ParseException}.
     */
    public double consumeDouble() throws ParseException {
      // We need to parse infinity and nan separately because
      // Double.parseDouble() does not accept "inf", "infinity", or "nan".
      if (DOUBLE_INFINITY.matcher(currentToken).matches()) {
        final boolean negative = currentToken.startsWith("-");
        nextToken();
        return negative ? Double.NEGATIVE_INFINITY : Double.POSITIVE_INFINITY;
      }
      if (currentToken.equalsIgnoreCase("nan")) {
        nextToken();
        return Double.NaN;
      }
      try {
        final double result = Double.parseDouble(currentToken);
        nextToken();
        return result;
      } catch (NumberFormatException e) {
        throw floatParseException(e);
      }
    }

    
If the next token is a double, consume it and return true. Otherwise, return 
false without doing anything. /**
     * If the next token is a double, consume it and return {@code true}. Otherwise, return {@code
     * false} without doing anything.
     */
    public boolean tryConsumeDouble() {
      try {
        consumeDouble();
        return true;
      } catch (ParseException e) {
        return false;
      }
    }

    
If the next token is a float, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a float, consume it and return its value. Otherwise, throw a {@link
     * ParseException}.
     */
    public float consumeFloat() throws ParseException {
      // We need to parse infinity and nan separately because
      // Float.parseFloat() does not accept "inf", "infinity", or "nan".
      if (FLOAT_INFINITY.matcher(currentToken).matches()) {
        final boolean negative = currentToken.startsWith("-");
        nextToken();
        return negative ? Float.NEGATIVE_INFINITY : Float.POSITIVE_INFINITY;
      }
      if (FLOAT_NAN.matcher(currentToken).matches()) {
        nextToken();
        return Float.NaN;
      }
      try {
        final float result = Float.parseFloat(currentToken);
        nextToken();
        return result;
      } catch (NumberFormatException e) {
        throw floatParseException(e);
      }
    }

    
If the next token is a float, consume it and return true. Otherwise, return 
false without doing anything. /**
     * If the next token is a float, consume it and return {@code true}. Otherwise, return {@code
     * false} without doing anything.
     */
    public boolean tryConsumeFloat() {
      try {
        consumeFloat();
        return true;
      } catch (ParseException e) {
        return false;
      }
    }

    
If the next token is a boolean, consume it and return its value. Otherwise, throw a ParseException. /**
     * If the next token is a boolean, consume it and return its value. Otherwise, throw a {@link
     * ParseException}.
     */
    public boolean consumeBoolean() throws ParseException {
      if (currentToken.equals("true")
          || currentToken.equals("True")
          || currentToken.equals("t")
          || currentToken.equals("1")) {
        nextToken();
        return true;
      } else if (currentToken.equals("false")
          || currentToken.equals("False")
          || currentToken.equals("f")
          || currentToken.equals("0")) {
        nextToken();
        return false;
      } else {
        throw parseException("Expected \"true\" or \"false\". Found \"" + currentToken + "\".");
      }
    }

    
If the next token is a string, consume it and return its (unescaped) value. Otherwise, throw a ParseException. /**
     * If the next token is a string, consume it and return its (unescaped) value. Otherwise, throw
     * a {@link ParseException}.
     */
    public String consumeString() throws ParseException {
      return consumeByteString().toStringUtf8();
    }

    
If the next token is a string, consume it and return true. Otherwise, return false. /** If the next token is a string, consume it and return true. Otherwise, return false. */
    public boolean tryConsumeString() {
      try {
        consumeString();
        return true;
      } catch (ParseException e) {
        return false;
      }
    }

    
If the next token is a string, consume it, unescape it as a ByteString, and return it. Otherwise, throw a ParseException. /**
     * If the next token is a string, consume it, unescape it as a {@link ByteString}, and return
     * it. Otherwise, throw a {@link ParseException}.
     */
    public ByteString consumeByteString() throws ParseException {
      List<ByteString> list = new ArrayList<ByteString>();
      consumeByteString(list);
      while (currentToken.startsWith("'") || currentToken.startsWith("\"")) {
        consumeByteString(list);
      }
      return ByteString.copyFrom(list);
    }

    
Like consumeByteString() but adds each token of the string to the given list. String literals (whether bytes or text) may come in multiple adjacent tokens which are automatically concatenated, like in C or Python. /**
     * Like {@link #consumeByteString()} but adds each token of the string to the given list. String
     * literals (whether bytes or text) may come in multiple adjacent tokens which are automatically
     * concatenated, like in C or Python.
     */
    private void consumeByteString(List<ByteString> list) throws ParseException {
      final char quote = currentToken.length() > 0 ? currentToken.charAt(0) : '\0';
      if (quote != '\"' && quote != '\'') {
        throw parseException("Expected string.");
      }

      if (currentToken.length() < 2 || currentToken.charAt(currentToken.length() - 1) != quote) {
        throw parseException("String missing ending quote.");
      }

      try {
        final String escaped = currentToken.substring(1, currentToken.length() - 1);
        final ByteString result = unescapeBytes(escaped);
        nextToken();
        list.add(result);
      } catch (InvalidEscapeSequenceException e) {
        throw parseException(e.getMessage());
      }
    }

    
Returns a ParseException with the current line and column numbers in the description, suitable for throwing. /**
     * Returns a {@link ParseException} with the current line and column numbers in the description,
     * suitable for throwing.
     */
    public ParseException parseException(final String description) {
      // Note:  People generally prefer one-based line and column numbers.
      return new ParseException(line + 1, column + 1, description);
    }

    
Returns a ParseException with the line and column numbers of the previous token in the description, suitable for throwing. /**
     * Returns a {@link ParseException} with the line and column numbers of the previous token in
     * the description, suitable for throwing.
     */
    public ParseException parseExceptionPreviousToken(final String description) {
      // Note:  People generally prefer one-based line and column numbers.
      return new ParseException(previousLine + 1, previousColumn + 1, description);
    }

    
Constructs an appropriate ParseException for the given NumberFormatException when trying to parse an integer. /**
     * Constructs an appropriate {@link ParseException} for the given {@code NumberFormatException}
     * when trying to parse an integer.
     */
    private ParseException integerParseException(final NumberFormatException e) {
      return parseException("Couldn't parse integer: " + e.getMessage());
    }

    
Constructs an appropriate ParseException for the given NumberFormatException when trying to parse a float or double. /**
     * Constructs an appropriate {@link ParseException} for the given {@code NumberFormatException}
     * when trying to parse a float or double.
     */
    private ParseException floatParseException(final NumberFormatException e) {
      return parseException("Couldn't parse number: " + e.getMessage());
    }

    
Returns a UnknownFieldParseException with the line and column numbers of the previous token in the description, and the unknown field name, suitable for throwing. /**
     * Returns a {@link UnknownFieldParseException} with the line and column numbers of the previous
     * token in the description, and the unknown field name, suitable for throwing.
     */
    public UnknownFieldParseException unknownFieldParseExceptionPreviousToken(
        final String unknownField, final String description) {
      // Note:  People generally prefer one-based line and column numbers.
      return new UnknownFieldParseException(
          previousLine + 1, previousColumn + 1, unknownField, description);
    }
  }

  
Thrown when parsing an invalid text format message. /** Thrown when parsing an invalid text format message. */
  public static class ParseException extends IOException {
    private static final long serialVersionUID = 3196188060225107702L;

    private final int line;
    private final int column;

    
Create a new instance, with -1 as the line and column numbers. /** Create a new instance, with -1 as the line and column numbers. */
    public ParseException(final String message) {
      this(-1, -1, message);
    }

    
Create a new instance
Params:
line – the line number where the parse error occurred, using 1-offset.
column – the column number where the parser error occurred, using 1-offset./**
     * Create a new instance
     *
     * @param line the line number where the parse error occurred, using 1-offset.
     * @param column the column number where the parser error occurred, using 1-offset.
     */
    public ParseException(final int line, final int column, final String message) {
      super(Integer.toString(line) + ":" + column + ": " + message);
      this.line = line;
      this.column = column;
    }

    
Return the line where the parse exception occurred, or -1 when none is provided. The value is
specified as 1-offset, so the first line is line 1.
/**
     * Return the line where the parse exception occurred, or -1 when none is provided. The value is
     * specified as 1-offset, so the first line is line 1.
     */
    public int getLine() {
      return line;
    }

    
Return the column where the parse exception occurred, or -1 when none is provided. The value
is specified as 1-offset, so the first line is line 1.
/**
     * Return the column where the parse exception occurred, or -1 when none is provided. The value
     * is specified as 1-offset, so the first line is line 1.
     */
    public int getColumn() {
      return column;
    }
  }

  
Thrown when encountering an unknown field while parsing a text format message. /** Thrown when encountering an unknown field while parsing a text format message. */
  public static class UnknownFieldParseException extends ParseException {
    private final String unknownField;

    
Create a new instance, with -1 as the line and column numbers, and an empty unknown field
name.
/**
     * Create a new instance, with -1 as the line and column numbers, and an empty unknown field
     * name.
     */
    public UnknownFieldParseException(final String message) {
      this(-1, -1, "", message);
    }

    
Create a new instance
Params:
line – the line number where the parse error occurred, using 1-offset.
column – the column number where the parser error occurred, using 1-offset.
unknownField – the name of the unknown field found while parsing./**
     * Create a new instance
     *
     * @param line the line number where the parse error occurred, using 1-offset.
     * @param column the column number where the parser error occurred, using 1-offset.
     * @param unknownField the name of the unknown field found while parsing.
     */
    public UnknownFieldParseException(
        final int line, final int column, final String unknownField, final String message) {
      super(line, column, message);
      this.unknownField = unknownField;
    }

    
Return the name of the unknown field encountered while parsing the protocol buffer string.
/**
     * Return the name of the unknown field encountered while parsing the protocol buffer string.
     */
    public String getUnknownField() {
      return unknownField;
    }
  }

  private static final Parser PARSER = Parser.newBuilder().build();

  
Return a Parser instance which can parse text-format messages. The returned instance is thread-safe. /**
   * Return a {@link Parser} instance which can parse text-format messages. The returned instance is
   * thread-safe.
   */
  public static Parser getParser() {
    return PARSER;
  }

  
Parse a text-format message from input and merge the contents into builder. /** Parse a text-format message from {@code input} and merge the contents into {@code builder}. */
  public static void merge(final Readable input, final Message.Builder builder) throws IOException {
    PARSER.merge(input, builder);
  }

  
Parse a text-format message from input and merge the contents into builder. /** Parse a text-format message from {@code input} and merge the contents into {@code builder}. */
  public static void merge(final CharSequence input, final Message.Builder builder)
      throws ParseException {
    PARSER.merge(input, builder);
  }

  
Parse a text-format message from input. 
Returns:
the parsed message, guaranteed initialized/**
   * Parse a text-format message from {@code input}.
   *
   * @return the parsed message, guaranteed initialized
   */
  public static <T extends Message> T parse(final CharSequence input, final Class<T> protoClass)
      throws ParseException {
    Message.Builder builder = Internal.getDefaultInstance(protoClass).newBuilderForType();
    merge(input, builder);
    @SuppressWarnings("unchecked")
    T output = (T) builder.build();
    return output;
  }

  
Parse a text-format message from input and merge the contents into builder. Extensions will be recognized if they are registered in extensionRegistry. /**
   * Parse a text-format message from {@code input} and merge the contents into {@code builder}.
   * Extensions will be recognized if they are registered in {@code extensionRegistry}.
   */
  public static void merge(
      final Readable input,
      final ExtensionRegistry extensionRegistry,
      final Message.Builder builder)
      throws IOException {
    PARSER.merge(input, extensionRegistry, builder);
  }


  
Parse a text-format message from input and merge the contents into builder. Extensions will be recognized if they are registered in extensionRegistry. /**
   * Parse a text-format message from {@code input} and merge the contents into {@code builder}.
   * Extensions will be recognized if they are registered in {@code extensionRegistry}.
   */
  public static void merge(
      final CharSequence input,
      final ExtensionRegistry extensionRegistry,
      final Message.Builder builder)
      throws ParseException {
    PARSER.merge(input, extensionRegistry, builder);
  }

  
Parse a text-format message from input. Extensions will be recognized if they are registered in extensionRegistry. 
Returns:
the parsed message, guaranteed initialized/**
   * Parse a text-format message from {@code input}. Extensions will be recognized if they are
   * registered in {@code extensionRegistry}.
   *
   * @return the parsed message, guaranteed initialized
   */
  public static <T extends Message> T parse(
      final CharSequence input,
      final ExtensionRegistry extensionRegistry,
      final Class<T> protoClass)
      throws ParseException {
    Message.Builder builder = Internal.getDefaultInstance(protoClass).newBuilderForType();
    merge(input, extensionRegistry, builder);
    @SuppressWarnings("unchecked")
    T output = (T) builder.build();
    return output;
  }


  
Parser for text-format proto2 instances. This class is thread-safe. The implementation largely
follows google/protobuf/text_format.cc.
Use TextFormat.getParser() to obtain the default parser, or Builder to control the parser behavior. /**
   * Parser for text-format proto2 instances. This class is thread-safe. The implementation largely
   * follows google/protobuf/text_format.cc.
   *
   * <p>Use {@link TextFormat#getParser()} to obtain the default parser, or {@link Builder} to
   * control the parser behavior.
   */
  public static class Parser {
    
Determines if repeated values for non-repeated fields and oneofs are permitted. For example,
given required/optional field "foo" and a oneof containing "baz" and "qux":

  
"foo: 1 foo: 2"
  
"baz: 1 qux: 2"
  
merging "foo: 2" into a proto in which foo is already set, or
  
merging "qux: 2" into a proto in which baz is already set.

/**
     * Determines if repeated values for non-repeated fields and oneofs are permitted. For example,
     * given required/optional field "foo" and a oneof containing "baz" and "qux":
     *
     * <ul>
     *   <li>"foo: 1 foo: 2"
     *   <li>"baz: 1 qux: 2"
     *   <li>merging "foo: 2" into a proto in which foo is already set, or
     *   <li>merging "qux: 2" into a proto in which baz is already set.
     * </ul>
     */
    public enum SingularOverwritePolicy {
      
Later values are merged with earlier values. For primitive fields or conflicting oneofs,
the last value is retained.
/**
       * Later values are merged with earlier values. For primitive fields or conflicting oneofs,
       * the last value is retained.
       */
      ALLOW_SINGULAR_OVERWRITES,
      
An error is issued. /** An error is issued. */
      FORBID_SINGULAR_OVERWRITES
    }

    private final TypeRegistry typeRegistry;
    private final boolean allowUnknownFields;
    private final boolean allowUnknownEnumValues;
    private final boolean allowUnknownExtensions;
    private final SingularOverwritePolicy singularOverwritePolicy;
    private TextFormatParseInfoTree.Builder parseInfoTreeBuilder;

    private Parser(
        TypeRegistry typeRegistry,
        boolean allowUnknownFields,
        boolean allowUnknownEnumValues,
        boolean allowUnknownExtensions,
        SingularOverwritePolicy singularOverwritePolicy,
        TextFormatParseInfoTree.Builder parseInfoTreeBuilder) {
      this.typeRegistry = typeRegistry;
      this.allowUnknownFields = allowUnknownFields;
      this.allowUnknownEnumValues = allowUnknownEnumValues;
      this.allowUnknownExtensions = allowUnknownExtensions;
      this.singularOverwritePolicy = singularOverwritePolicy;
      this.parseInfoTreeBuilder = parseInfoTreeBuilder;
    }

    
Returns a new instance of Builder. /** Returns a new instance of {@link Builder}. */
    public static Builder newBuilder() {
      return new Builder();
    }

    
Builder that can be used to obtain new instances of Parser. /** Builder that can be used to obtain new instances of {@link Parser}. */
    public static class Builder {
      private boolean allowUnknownFields = false;
      private boolean allowUnknownEnumValues = false;
      private boolean allowUnknownExtensions = false;
      private SingularOverwritePolicy singularOverwritePolicy =
          SingularOverwritePolicy.ALLOW_SINGULAR_OVERWRITES;
      private TextFormatParseInfoTree.Builder parseInfoTreeBuilder = null;
      private TypeRegistry typeRegistry = TypeRegistry.getEmptyTypeRegistry();

      
Sets the TypeRegistry for resolving Any. If this is not set, TextFormat will not be able to
parse Any unless Any is write as bytes.
Throws:
IllegalArgumentException – if a registry is already set./**
       * Sets the TypeRegistry for resolving Any. If this is not set, TextFormat will not be able to
       * parse Any unless Any is write as bytes.
       *
       * @throws IllegalArgumentException if a registry is already set.
       */
      public Builder setTypeRegistry(TypeRegistry typeRegistry) {
        this.typeRegistry = typeRegistry;
        return this;
      }

      
Set whether this parser will allow unknown fields. By default, an exception is thrown if an
unknown field is encountered. If this is set, the parser will only log a warning. Allow
unknown fields will also allow unknown extensions.
Use of this parameter is discouraged which may hide some errors (e.g.
spelling error on field name).
/**
       * Set whether this parser will allow unknown fields. By default, an exception is thrown if an
       * unknown field is encountered. If this is set, the parser will only log a warning. Allow
       * unknown fields will also allow unknown extensions.
       *
       * <p>Use of this parameter is discouraged which may hide some errors (e.g.
       * spelling error on field name).
       */
      public Builder setAllowUnknownFields(boolean allowUnknownFields) {
        this.allowUnknownFields = allowUnknownFields;
        return this;
      }

      
Set whether this parser will allow unknown extensions. By default, an
exception is thrown if unknown extension is encountered. If this is set true,
the parser will only log a warning. Allow unknown extensions does not mean
allow normal unknown fields.
/**
       * Set whether this parser will allow unknown extensions. By default, an
       * exception is thrown if unknown extension is encountered. If this is set true,
       * the parser will only log a warning. Allow unknown extensions does not mean
       * allow normal unknown fields.
       */
      public Builder setAllowUnknownExtensions(boolean allowUnknownExtensions) {
        this.allowUnknownExtensions = allowUnknownExtensions;
        return this;
      }

      
Sets parser behavior when a non-repeated field appears more than once. /** Sets parser behavior when a non-repeated field appears more than once. */
      public Builder setSingularOverwritePolicy(SingularOverwritePolicy p) {
        this.singularOverwritePolicy = p;
        return this;
      }

      public Builder setParseInfoTreeBuilder(TextFormatParseInfoTree.Builder parseInfoTreeBuilder) {
        this.parseInfoTreeBuilder = parseInfoTreeBuilder;
        return this;
      }

      public Parser build() {
        return new Parser(
            typeRegistry,
            allowUnknownFields,
            allowUnknownEnumValues,
            allowUnknownExtensions,
            singularOverwritePolicy,
            parseInfoTreeBuilder);
      }
    }

    
Parse a text-format message from input and merge the contents into builder. /**
     * Parse a text-format message from {@code input} and merge the contents into {@code builder}.
     */
    public void merge(final Readable input, final Message.Builder builder) throws IOException {
      merge(input, ExtensionRegistry.getEmptyRegistry(), builder);
    }

    
Parse a text-format message from input and merge the contents into builder. /**
     * Parse a text-format message from {@code input} and merge the contents into {@code builder}.
     */
    public void merge(final CharSequence input, final Message.Builder builder)
        throws ParseException {
      merge(input, ExtensionRegistry.getEmptyRegistry(), builder);
    }

    
Parse a text-format message from input and merge the contents into builder. Extensions will be recognized if they are registered in extensionRegistry. /**
     * Parse a text-format message from {@code input} and merge the contents into {@code builder}.
     * Extensions will be recognized if they are registered in {@code extensionRegistry}.
     */
    public void merge(
        final Readable input,
        final ExtensionRegistry extensionRegistry,
        final Message.Builder builder)
        throws IOException {
      // Read the entire input to a String then parse that.

      // If StreamTokenizer were not quite so crippled, or if there were a kind
      // of Reader that could read in chunks that match some particular regex,
      // or if we wanted to write a custom Reader to tokenize our stream, then
      // we would not have to read to one big String.  Alas, none of these is
      // the case.  Oh well.

      merge(toStringBuilder(input), extensionRegistry, builder);
    }


    private static final int BUFFER_SIZE = 4096;

    // TODO(chrisn): See if working around java.io.Reader#read(CharBuffer)
    // overhead is worthwhile
    private static StringBuilder toStringBuilder(final Readable input) throws IOException {
      final StringBuilder text = new StringBuilder();
      final CharBuffer buffer = CharBuffer.allocate(BUFFER_SIZE);
      while (true) {
        final int n = input.read(buffer);
        if (n == -1) {
          break;
        }
        buffer.flip();
        text.append(buffer, 0, n);
      }
      return text;
    }

    static final class UnknownField {
      static enum Type {
        FIELD, EXTENSION;
      }

      final String message;
      final Type type;

      UnknownField(String message, Type type) {
        this.message = message;
        this.type = type;
      }
    }

    // Check both unknown fields and unknown extensions and log warning messages
    // or throw exceptions according to the flag.
    private void checkUnknownFields(final List<UnknownField> unknownFields) throws ParseException {
      if (unknownFields.isEmpty()) {
        return;
      }

      StringBuilder msg = new StringBuilder("Input contains unknown fields and/or extensions:");
      for (UnknownField field : unknownFields) {
        msg.append('\n').append(field.message);
      }

      if (allowUnknownFields) {
        logger.warning(msg.toString());
        return;
      }

      int firstErrorIndex = 0;
      if (allowUnknownExtensions) {
        boolean allUnknownExtensions = true;
        for (UnknownField field : unknownFields) {
          if (field.type == UnknownField.Type.FIELD) {
            allUnknownExtensions = false;
            break;
          }
          ++firstErrorIndex;
        }
        if (allUnknownExtensions) {
          logger.warning(msg.toString());
          return;
        }
      }

      String[] lineColumn = unknownFields.get(firstErrorIndex).message.split(":");
      throw new ParseException(
          Integer.parseInt(lineColumn[0]), Integer.parseInt(lineColumn[1]), msg.toString());
    }

    
Parse a text-format message from input and merge the contents into builder. Extensions will be recognized if they are registered in extensionRegistry. /**
     * Parse a text-format message from {@code input} and merge the contents into {@code builder}.
     * Extensions will be recognized if they are registered in {@code extensionRegistry}.
     */
    public void merge(
        final CharSequence input,
        final ExtensionRegistry extensionRegistry,
        final Message.Builder builder)
        throws ParseException {
      final Tokenizer tokenizer = new Tokenizer(input);
      MessageReflection.BuilderAdapter target = new MessageReflection.BuilderAdapter(builder);

      List<UnknownField> unknownFields = new ArrayList<UnknownField>();

      while (!tokenizer.atEnd()) {
        mergeField(tokenizer, extensionRegistry, target, unknownFields);
      }

      checkUnknownFields(unknownFields);
    }


    
Parse a single field from tokenizer and merge it into builder. /** Parse a single field from {@code tokenizer} and merge it into {@code builder}. */
    private void mergeField(
        final Tokenizer tokenizer,
        final ExtensionRegistry extensionRegistry,
        final MessageReflection.MergeTarget target,
        List<UnknownField> unknownFields)
        throws ParseException {
      mergeField(
          tokenizer,
          extensionRegistry,
          target,
          parseInfoTreeBuilder,
          unknownFields);
    }

    
Parse a single field from tokenizer and merge it into target. /** Parse a single field from {@code tokenizer} and merge it into {@code target}. */
    private void mergeField(
        final Tokenizer tokenizer,
        final ExtensionRegistry extensionRegistry,
        final MessageReflection.MergeTarget target,
        TextFormatParseInfoTree.Builder parseTreeBuilder,
        List<UnknownField> unknownFields)
        throws ParseException {
      FieldDescriptor field = null;
      int startLine = tokenizer.getLine();
      int startColumn = tokenizer.getColumn();
      final Descriptor type = target.getDescriptorForType();
      ExtensionRegistry.ExtensionInfo extension = null;

      if (tokenizer.tryConsume("[")) {
        // An extension.
        final StringBuilder name = new StringBuilder(tokenizer.consumeIdentifier());
        while (tokenizer.tryConsume(".")) {
          name.append('.');
          name.append(tokenizer.consumeIdentifier());
        }

        extension = target.findExtensionByName(extensionRegistry, name.toString());

        if (extension == null) {
          String message =
              (tokenizer.getPreviousLine() + 1)
                  + ":"
                  + (tokenizer.getPreviousColumn() + 1)
                  + ":\t"
                  + type.getFullName()
                  + ".["
                  + name
                  + "]";
          unknownFields.add(new UnknownField(message, UnknownField.Type.EXTENSION));
        } else {
          if (extension.descriptor.getContainingType() != type) {
            throw tokenizer.parseExceptionPreviousToken(
                "Extension \""
                    + name
                    + "\" does not extend message type \""
                    + type.getFullName()
                    + "\".");
          }
          field = extension.descriptor;
        }

        tokenizer.consume("]");
      } else {
        final String name = tokenizer.consumeIdentifier();
        field = type.findFieldByName(name);

        // Group names are expected to be capitalized as they appear in the
        // .proto file, which actually matches their type names, not their field
        // names.
        if (field == null) {
          // Explicitly specify US locale so that this code does not break when
          // executing in Turkey.
          final String lowerName = name.toLowerCase(Locale.US);
          field = type.findFieldByName(lowerName);
          // If the case-insensitive match worked but the field is NOT a group,
          if (field != null && field.getType() != FieldDescriptor.Type.GROUP) {
            field = null;
          }
        }
        // Again, special-case group names as described above.
        if (field != null
            && field.getType() == FieldDescriptor.Type.GROUP
            && !field.getMessageType().getName().equals(name)) {
          field = null;
        }

        if (field == null) {
          String message = (tokenizer.getPreviousLine() + 1)
                           + ":"
                           + (tokenizer.getPreviousColumn() + 1)
                           + ":\t"
                           + type.getFullName()
                           + "."
                           + name;
          unknownFields.add(new UnknownField(message, UnknownField.Type.FIELD));
        }
      }

      // Skips unknown fields.
      if (field == null) {
        // Try to guess the type of this field.
        // If this field is not a message, there should be a ":" between the
        // field name and the field value and also the field value should not
        // start with "{" or "<" which indicates the beginning of a message body.
        // If there is no ":" or there is a "{" or "<" after ":", this field has
        // to be a message or the input is ill-formed.
        if (tokenizer.tryConsume(":") && !tokenizer.lookingAt("{") && !tokenizer.lookingAt("<")) {
          skipFieldValue(tokenizer);
        } else {
          skipFieldMessage(tokenizer);
        }
        return;
      }

      // Handle potential ':'.
      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
        tokenizer.tryConsume(":"); // optional
        if (parseTreeBuilder != null) {
          TextFormatParseInfoTree.Builder childParseTreeBuilder =
              parseTreeBuilder.getBuilderForSubMessageField(field);
          consumeFieldValues(
              tokenizer,
              extensionRegistry,
              target,
              field,
              extension,
              childParseTreeBuilder,
              unknownFields);
        } else {
          consumeFieldValues(
              tokenizer,
              extensionRegistry,
              target,
              field,
              extension,
              parseTreeBuilder,
              unknownFields);
        }
      } else {
        tokenizer.consume(":"); // required
        consumeFieldValues(
            tokenizer,
            extensionRegistry,
            target,
            field,
            extension,
            parseTreeBuilder,
            unknownFields);
      }

      if (parseTreeBuilder != null) {
        parseTreeBuilder.setLocation(field, TextFormatParseLocation.create(startLine, startColumn));
      }

      // For historical reasons, fields may optionally be separated by commas or
      // semicolons.
      if (!tokenizer.tryConsume(";")) {
        tokenizer.tryConsume(",");
      }
    }

    
Parse a one or more field values from tokenizer and merge it into builder. /**
     * Parse a one or more field values from {@code tokenizer} and merge it into {@code builder}.
     */
    private void consumeFieldValues(
        final Tokenizer tokenizer,
        final ExtensionRegistry extensionRegistry,
        final MessageReflection.MergeTarget target,
        final FieldDescriptor field,
        final ExtensionRegistry.ExtensionInfo extension,
        final TextFormatParseInfoTree.Builder parseTreeBuilder,
        List<UnknownField> unknownFields)
        throws ParseException {
      // Support specifying repeated field values as a comma-separated list.
      // Ex."foo: [1, 2, 3]"
      if (field.isRepeated() && tokenizer.tryConsume("[")) {
        if (!tokenizer.tryConsume("]")) { // Allow "foo: []" to be treated as empty.
          while (true) {
            consumeFieldValue(
                tokenizer,
                extensionRegistry,
                target,
                field,
                extension,
                parseTreeBuilder,
                unknownFields);
            if (tokenizer.tryConsume("]")) {
              // End of list.
              break;
            }
            tokenizer.consume(",");
          }
        }
      } else {
        consumeFieldValue(
            tokenizer,
            extensionRegistry,
            target,
            field,
            extension,
            parseTreeBuilder,
            unknownFields);
      }
    }

    
Parse a single field value from tokenizer and merge it into builder. /** Parse a single field value from {@code tokenizer} and merge it into {@code builder}. */
    private void consumeFieldValue(
        final Tokenizer tokenizer,
        final ExtensionRegistry extensionRegistry,
        final MessageReflection.MergeTarget target,
        final FieldDescriptor field,
        final ExtensionRegistry.ExtensionInfo extension,
        final TextFormatParseInfoTree.Builder parseTreeBuilder,
        List<UnknownField> unknownFields)
        throws ParseException {
      if (singularOverwritePolicy == SingularOverwritePolicy.FORBID_SINGULAR_OVERWRITES
          && !field.isRepeated()) {
        if (target.hasField(field)) {
          throw tokenizer.parseExceptionPreviousToken(
              "Non-repeated field \"" + field.getFullName() + "\" cannot be overwritten.");
        } else if (field.getContainingOneof() != null
            && target.hasOneof(field.getContainingOneof())) {
          Descriptors.OneofDescriptor oneof = field.getContainingOneof();
          throw tokenizer.parseExceptionPreviousToken(
              "Field \""
                  + field.getFullName()
                  + "\" is specified along with field \""
                  + target.getOneofFieldDescriptor(oneof).getFullName()
                  + "\", another member of oneof \""
                  + oneof.getName()
                  + "\".");
        }
      }

      Object value = null;

      if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
        final String endToken;
        if (tokenizer.tryConsume("<")) {
          endToken = ">";
        } else {
          tokenizer.consume("{");
          endToken = "}";
        }

        // Try to parse human readable format of Any in the form: [type_url]: { ... }
        if (field.getMessageType().getFullName().equals("google.protobuf.Any")
            && tokenizer.tryConsume("[")) {
          value =
              consumeAnyFieldValue(
                  tokenizer, extensionRegistry, field, parseTreeBuilder, unknownFields);
          tokenizer.consume(endToken);
        } else {
          Message defaultInstance = (extension == null) ? null : extension.defaultInstance;
          MessageReflection.MergeTarget subField =
              target.newMergeTargetForField(field, defaultInstance);

          while (!tokenizer.tryConsume(endToken)) {
            if (tokenizer.atEnd()) {
              throw tokenizer.parseException("Expected \"" + endToken + "\".");
            }
            mergeField(tokenizer, extensionRegistry, subField, parseTreeBuilder, unknownFields);
          }

          value = subField.finish();
        }

      } else {
        switch (field.getType()) {
          case INT32:
          case SINT32:
          case SFIXED32:
            value = tokenizer.consumeInt32();
            break;

          case INT64:
          case SINT64:
          case SFIXED64:
            value = tokenizer.consumeInt64();
            break;

          case UINT32:
          case FIXED32:
            value = tokenizer.consumeUInt32();
            break;

          case UINT64:
          case FIXED64:
            value = tokenizer.consumeUInt64();
            break;

          case FLOAT:
            value = tokenizer.consumeFloat();
            break;

          case DOUBLE:
            value = tokenizer.consumeDouble();
            break;

          case BOOL:
            value = tokenizer.consumeBoolean();
            break;

          case STRING:
            value = tokenizer.consumeString();
            break;

          case BYTES:
            value = tokenizer.consumeByteString();
            break;

          case ENUM:
            final EnumDescriptor enumType = field.getEnumType();

            if (tokenizer.lookingAtInteger()) {
              final int number = tokenizer.consumeInt32();
              value = enumType.findValueByNumber(number);
              if (value == null) {
                String unknownValueMsg =
                    "Enum type \""
                        + enumType.getFullName()
                        + "\" has no value with number "
                        + number
                        + '.';
                if (allowUnknownEnumValues) {
                  logger.warning(unknownValueMsg);
                  return;
                } else {
                  throw tokenizer.parseExceptionPreviousToken(
                      "Enum type \""
                          + enumType.getFullName()
                          + "\" has no value with number "
                          + number
                          + '.');
                }
              }
            } else {
              final String id = tokenizer.consumeIdentifier();
              value = enumType.findValueByName(id);
              if (value == null) {
                String unknownValueMsg =
                    "Enum type \""
                        + enumType.getFullName()
                        + "\" has no value named \""
                        + id
                        + "\".";
                if (allowUnknownEnumValues) {
                  logger.warning(unknownValueMsg);
                  return;
                } else {
                  throw tokenizer.parseExceptionPreviousToken(unknownValueMsg);
                }
              }
            }

            break;

          case MESSAGE:
          case GROUP:
            throw new RuntimeException("Can't get here.");
        }
      }

      if (field.isRepeated()) {
        // TODO(b/29122459): If field.isMapField() and FORBID_SINGULAR_OVERWRITES mode,
        //     check for duplicate map keys here.
        target.addRepeatedField(field, value);
      } else {
        target.setField(field, value);
      }
    }

    private Object consumeAnyFieldValue(
        final Tokenizer tokenizer,
        final ExtensionRegistry extensionRegistry,
        final FieldDescriptor field,
        final TextFormatParseInfoTree.Builder parseTreeBuilder,
        List<UnknownField> unknownFields)
        throws ParseException {
      // Try to parse human readable format of Any in the form: [type_url]: { ... }
      StringBuilder typeUrlBuilder = new StringBuilder();
      // Parse the type_url inside [].
      while (true) {
        typeUrlBuilder.append(tokenizer.consumeIdentifier());
        if (tokenizer.tryConsume("]")) {
          break;
        }
        if (tokenizer.tryConsume("/")) {
          typeUrlBuilder.append("/");
        } else if (tokenizer.tryConsume(".")) {
          typeUrlBuilder.append(".");
        } else {
          throw tokenizer.parseExceptionPreviousToken("Expected a valid type URL.");
        }
      }
      tokenizer.tryConsume(":");
      final String anyEndToken;
      if (tokenizer.tryConsume("<")) {
        anyEndToken = ">";
      } else {
        tokenizer.consume("{");
        anyEndToken = "}";
      }
      String typeUrl = typeUrlBuilder.toString();
      Descriptor contentType = null;
      try {
        contentType = typeRegistry.getDescriptorForTypeUrl(typeUrl);
      } catch (InvalidProtocolBufferException e) {
        throw tokenizer.parseException("Invalid valid type URL. Found: " + typeUrl);
      }
      if (contentType == null) {
        throw tokenizer.parseException(
            "Unable to parse Any of type: "
                + typeUrl
                + ". Please make sure that the TypeRegistry contains the descriptors for the given"
                + " types.");
      }
      Message.Builder contentBuilder =
          DynamicMessage.getDefaultInstance(contentType).newBuilderForType();
      MessageReflection.BuilderAdapter contentTarget =
          new MessageReflection.BuilderAdapter(contentBuilder);
      while (!tokenizer.tryConsume(anyEndToken)) {
        mergeField(tokenizer, extensionRegistry, contentTarget, parseTreeBuilder, unknownFields);
      }

      // Serialize the content and put it back into an Any. Note that we can't depend on Any here
      // because of a cyclic dependency (java_proto_library for any_java_proto depends on the
      // protobuf_impl), so we need to construct the Any using proto reflection.
      Descriptor anyDescriptor = field.getMessageType();
      Message.Builder anyBuilder =
          DynamicMessage.getDefaultInstance(anyDescriptor).newBuilderForType();
      anyBuilder.setField(anyDescriptor.findFieldByName("type_url"), typeUrlBuilder.toString());
      anyBuilder.setField(
          anyDescriptor.findFieldByName("value"), contentBuilder.build().toByteString());

      return anyBuilder.build();
    }

    
Skips the next field including the field's name and value. /** Skips the next field including the field's name and value. */
    private void skipField(Tokenizer tokenizer) throws ParseException {
      if (tokenizer.tryConsume("[")) {
        // Extension name.
        do {
          tokenizer.consumeIdentifier();
        } while (tokenizer.tryConsume("."));
        tokenizer.consume("]");
      } else {
        tokenizer.consumeIdentifier();
      }

      // Try to guess the type of this field.
      // If this field is not a message, there should be a ":" between the
      // field name and the field value and also the field value should not
      // start with "{" or "<" which indicates the beginning of a message body.
      // If there is no ":" or there is a "{" or "<" after ":", this field has
      // to be a message or the input is ill-formed.
      if (tokenizer.tryConsume(":") && !tokenizer.lookingAt("<") && !tokenizer.lookingAt("{")) {
        skipFieldValue(tokenizer);
      } else {
        skipFieldMessage(tokenizer);
      }
      // For historical reasons, fields may optionally be separated by commas or
      // semicolons.
      if (!tokenizer.tryConsume(";")) {
        tokenizer.tryConsume(",");
      }
    }

    
Skips the whole body of a message including the beginning delimiter and the ending delimiter.
/**
     * Skips the whole body of a message including the beginning delimiter and the ending delimiter.
     */
    private void skipFieldMessage(Tokenizer tokenizer) throws ParseException {
      final String delimiter;
      if (tokenizer.tryConsume("<")) {
        delimiter = ">";
      } else {
        tokenizer.consume("{");
        delimiter = "}";
      }
      while (!tokenizer.lookingAt(">") && !tokenizer.lookingAt("}")) {
        skipField(tokenizer);
      }
      tokenizer.consume(delimiter);
    }

    
Skips a field value. /** Skips a field value. */
    private void skipFieldValue(Tokenizer tokenizer) throws ParseException {
      if (tokenizer.tryConsumeString()) {
        while (tokenizer.tryConsumeString()) {}
        return;
      }
      if (!tokenizer.tryConsumeIdentifier() // includes enum & boolean
          && !tokenizer.tryConsumeInt64() // includes int32
          && !tokenizer.tryConsumeUInt64() // includes uint32
          && !tokenizer.tryConsumeDouble()
          && !tokenizer.tryConsumeFloat()) {
        throw tokenizer.parseException("Invalid field value: " + tokenizer.currentToken);
      }
    }
  }

  // =================================================================
  // Utility functions
  //
  // Some of these methods are package-private because Descriptors.java uses
  // them.

  
Escapes bytes in the format used in protocol buffer text format, which is the same as the
format used for C string literals. All bytes that are not printable 7-bit ASCII characters are
escaped, as well as backslash, single-quote, and double-quote characters. Characters for which
no defined short-hand escape sequence is defined will be escaped using 3-digit octal sequences.
/**
   * Escapes bytes in the format used in protocol buffer text format, which is the same as the
   * format used for C string literals. All bytes that are not printable 7-bit ASCII characters are
   * escaped, as well as backslash, single-quote, and double-quote characters. Characters for which
   * no defined short-hand escape sequence is defined will be escaped using 3-digit octal sequences.
   */
  public static String escapeBytes(ByteString input) {
    return TextFormatEscaper.escapeBytes(input);
  }

  
Like escapeBytes(ByteString), but used for byte array. /** Like {@link #escapeBytes(ByteString)}, but used for byte array. */
  public static String escapeBytes(byte[] input) {
    return TextFormatEscaper.escapeBytes(input);
  }

  
Un-escape a byte sequence as escaped using escapeBytes(ByteString). Two-digit hex escapes (starting with "\x") are also recognized. /**
   * Un-escape a byte sequence as escaped using {@link #escapeBytes(ByteString)}. Two-digit hex
   * escapes (starting with "\x") are also recognized.
   */
  public static ByteString unescapeBytes(final CharSequence charString)
      throws InvalidEscapeSequenceException {
    // First convert the Java character sequence to UTF-8 bytes.
    ByteString input = ByteString.copyFromUtf8(charString.toString());
    // Then unescape certain byte sequences introduced by ASCII '\\'.  The valid
    // escapes can all be expressed with ASCII characters, so it is safe to
    // operate on bytes here.
    //
    // Unescaping the input byte array will result in a byte sequence that's no
    // longer than the input.  That's because each escape sequence is between
    // two and four bytes long and stands for a single byte.
    final byte[] result = new byte[input.size()];
    int pos = 0;
    for (int i = 0; i < input.size(); i++) {
      byte c = input.byteAt(i);
      if (c == '\\') {
        if (i + 1 < input.size()) {
          ++i;
          c = input.byteAt(i);
          if (isOctal(c)) {
            // Octal escape.
            int code = digitValue(c);
            if (i + 1 < input.size() && isOctal(input.byteAt(i + 1))) {
              ++i;
              code = code * 8 + digitValue(input.byteAt(i));
            }
            if (i + 1 < input.size() && isOctal(input.byteAt(i + 1))) {
              ++i;
              code = code * 8 + digitValue(input.byteAt(i));
            }
            // TODO: Check that 0 <= code && code <= 0xFF.
            result[pos++] = (byte) code;
          } else {
            switch (c) {
              case 'a':
                result[pos++] = 0x07;
                break;
              case 'b':
                result[pos++] = '\b';
                break;
              case 'f':
                result[pos++] = '\f';
                break;
              case 'n':
                result[pos++] = '\n';
                break;
              case 'r':
                result[pos++] = '\r';
                break;
              case 't':
                result[pos++] = '\t';
                break;
              case 'v':
                result[pos++] = 0x0b;
                break;
              case '\\':
                result[pos++] = '\\';
                break;
              case '\'':
                result[pos++] = '\'';
                break;
              case '"':
                result[pos++] = '\"';
                break;

              case 'x':
                // hex escape
                int code = 0;
                if (i + 1 < input.size() && isHex(input.byteAt(i + 1))) {
                  ++i;
                  code = digitValue(input.byteAt(i));
                } else {
                  throw new InvalidEscapeSequenceException(
                      "Invalid escape sequence: '\\x' with no digits");
                }
                if (i + 1 < input.size() && isHex(input.byteAt(i + 1))) {
                  ++i;
                  code = code * 16 + digitValue(input.byteAt(i));
                }
                result[pos++] = (byte) code;
                break;

              default:
                throw new InvalidEscapeSequenceException(
                    "Invalid escape sequence: '\\" + (char) c + '\'');
            }
          }
        } else {
          throw new InvalidEscapeSequenceException(
              "Invalid escape sequence: '\\' at end of string.");
        }
      } else {
        result[pos++] = c;
      }
    }

    return result.length == pos
        ? ByteString.wrap(result) // This reference has not been out of our control.
        : ByteString.copyFrom(result, 0, pos);
  }

  
Thrown by TextFormat.unescapeBytes and TextFormat.unescapeText when an invalid escape sequence is seen. /**
   * Thrown by {@link TextFormat#unescapeBytes} and {@link TextFormat#unescapeText} when an invalid
   * escape sequence is seen.
   */
  public static class InvalidEscapeSequenceException extends IOException {
    private static final long serialVersionUID = -8164033650142593304L;

    InvalidEscapeSequenceException(final String description) {
      super(description);
    }
  }

  
Like escapeBytes(ByteString), but escapes a text string. Non-ASCII characters are first encoded as UTF-8, then each byte is escaped individually as a 3-digit octal escape. Yes, it's weird. /**
   * Like {@link #escapeBytes(ByteString)}, but escapes a text string. Non-ASCII characters are
   * first encoded as UTF-8, then each byte is escaped individually as a 3-digit octal escape. Yes,
   * it's weird.
   */
  static String escapeText(final String input) {
    return escapeBytes(ByteString.copyFromUtf8(input));
  }

  
Escape double quotes and backslashes in a String for emittingUnicode output of a message. /** Escape double quotes and backslashes in a String for emittingUnicode output of a message. */
  public static String escapeDoubleQuotesAndBackslashes(final String input) {
    return TextFormatEscaper.escapeDoubleQuotesAndBackslashes(input);
  }

  
Un-escape a text string as escaped using escapeText(String). Two-digit hex escapes (starting with "\x") are also recognized. /**
   * Un-escape a text string as escaped using {@link #escapeText(String)}. Two-digit hex escapes
   * (starting with "\x") are also recognized.
   */
  static String unescapeText(final String input) throws InvalidEscapeSequenceException {
    return unescapeBytes(input).toStringUtf8();
  }

  
Is this an octal digit? /** Is this an octal digit? */
  private static boolean isOctal(final byte c) {
    return '0' <= c && c <= '7';
  }

  
Is this a hex digit? /** Is this a hex digit? */
  private static boolean isHex(final byte c) {
    return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F');
  }

  
Interpret a character as a digit (in any base up to 36) and return the numeric value. This is like Character.digit() but we don't accept non-ASCII digits. /**
   * Interpret a character as a digit (in any base up to 36) and return the numeric value. This is
   * like {@code Character.digit()} but we don't accept non-ASCII digits.
   */
  private static int digitValue(final byte c) {
    if ('0' <= c && c <= '9') {
      return c - '0';
    } else if ('a' <= c && c <= 'z') {
      return c - 'a' + 10;
    } else {
      return c - 'A' + 10;
    }
  }

  
Parse a 32-bit signed integer from the text. Unlike the Java standard 
Integer.parseInt(), this function recognizes the prefixes "0x" and "0" to signify hexadecimal and octal numbers, respectively. /**
   * Parse a 32-bit signed integer from the text. Unlike the Java standard {@code
   * Integer.parseInt()}, this function recognizes the prefixes "0x" and "0" to signify hexadecimal
   * and octal numbers, respectively.
   */
  static int parseInt32(final String text) throws NumberFormatException {
    return (int) parseInteger(text, true, false);
  }

  
Parse a 32-bit unsigned integer from the text. Unlike the Java standard 
Integer.parseInt(), this function recognizes the prefixes "0x" and "0" to signify hexadecimal and octal numbers, respectively. The result is coerced to a (signed) int when returned since Java has no unsigned integer type. /**
   * Parse a 32-bit unsigned integer from the text. Unlike the Java standard {@code
   * Integer.parseInt()}, this function recognizes the prefixes "0x" and "0" to signify hexadecimal
   * and octal numbers, respectively. The result is coerced to a (signed) {@code int} when returned
   * since Java has no unsigned integer type.
   */
  static int parseUInt32(final String text) throws NumberFormatException {
    return (int) parseInteger(text, false, false);
  }

  
Parse a 64-bit signed integer from the text. Unlike the Java standard 
Integer.parseInt(), this function recognizes the prefixes "0x" and "0" to signify hexadecimal and octal numbers, respectively. /**
   * Parse a 64-bit signed integer from the text. Unlike the Java standard {@code
   * Integer.parseInt()}, this function recognizes the prefixes "0x" and "0" to signify hexadecimal
   * and octal numbers, respectively.
   */
  static long parseInt64(final String text) throws NumberFormatException {
    return parseInteger(text, true, true);
  }

  
Parse a 64-bit unsigned integer from the text. Unlike the Java standard 
Integer.parseInt(), this function recognizes the prefixes "0x" and "0" to signify hexadecimal and octal numbers, respectively. The result is coerced to a (signed) long when returned since Java has no unsigned long type. /**
   * Parse a 64-bit unsigned integer from the text. Unlike the Java standard {@code
   * Integer.parseInt()}, this function recognizes the prefixes "0x" and "0" to signify hexadecimal
   * and octal numbers, respectively. The result is coerced to a (signed) {@code long} when returned
   * since Java has no unsigned long type.
   */
  static long parseUInt64(final String text) throws NumberFormatException {
    return parseInteger(text, false, true);
  }

  private static long parseInteger(final String text, final boolean isSigned, final boolean isLong)
      throws NumberFormatException {
    int pos = 0;

    boolean negative = false;
    if (text.startsWith("-", pos)) {
      if (!isSigned) {
        throw new NumberFormatException("Number must be positive: " + text);
      }
      ++pos;
      negative = true;
    }

    int radix = 10;
    if (text.startsWith("0x", pos)) {
      pos += 2;
      radix = 16;
    } else if (text.startsWith("0", pos)) {
      radix = 8;
    }

    final String numberText = text.substring(pos);

    long result = 0;
    if (numberText.length() < 16) {
      // Can safely assume no overflow.
      result = Long.parseLong(numberText, radix);
      if (negative) {
        result = -result;
      }

      // Check bounds.
      // No need to check for 64-bit numbers since they'd have to be 16 chars
      // or longer to overflow.
      if (!isLong) {
        if (isSigned) {
          if (result > Integer.MAX_VALUE || result < Integer.MIN_VALUE) {
            throw new NumberFormatException(
                "Number out of range for 32-bit signed integer: " + text);
          }
        } else {
          if (result >= (1L << 32) || result < 0) {
            throw new NumberFormatException(
                "Number out of range for 32-bit unsigned integer: " + text);
          }
        }
      }
    } else {
      BigInteger bigValue = new BigInteger(numberText, radix);
      if (negative) {
        bigValue = bigValue.negate();
      }

      // Check bounds.
      if (!isLong) {
        if (isSigned) {
          if (bigValue.bitLength() > 31) {
            throw new NumberFormatException(
                "Number out of range for 32-bit signed integer: " + text);
          }
        } else {
          if (bigValue.bitLength() > 32) {
            throw new NumberFormatException(
                "Number out of range for 32-bit unsigned integer: " + text);
          }
        }
      } else {
        if (isSigned) {
          if (bigValue.bitLength() > 63) {
            throw new NumberFormatException(
                "Number out of range for 64-bit signed integer: " + text);
          }
        } else {
          if (bigValue.bitLength() > 64) {
            throw new NumberFormatException(
                "Number out of range for 64-bit unsigned integer: " + text);
          }
        }
      }

      result = bigValue.longValue();
    }

    return result;
  }
}