src/google/protobuf/compiler/java/java_string_field.cc

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// Author: kenton@google.com (Kenton Varda)
// Author: jonp@google.com (Jon Perlow)
//  Based on original Protocol Buffers design by
//  Sanjay Ghemawat, Jeff Dean, and others.

#include <map>
#include <string>

#include <google/protobuf/compiler/java/java_string_field.h>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/compiler/java/java_helpers.h>
#include <google/protobuf/io/printer.h>
#include <google/protobuf/wire_format.h>
#include <google/protobuf/stubs/strutil.h>

namespace google {
namespace protobuf {
namespace compiler {
namespace java {

using internal::WireFormat;
using internal::WireFormatLite;

namespace {

void SetPrimitiveVariables(const FieldDescriptor* descriptor,
                           int messageBitIndex,
                           int builderBitIndex,
                           map<string, string>* variables) {
  (*variables)["name"] =
    UnderscoresToCamelCase(descriptor);
  (*variables)["capitalized_name"] =
    UnderscoresToCapitalizedCamelCase(descriptor);
  (*variables)["constant_name"] = FieldConstantName(descriptor);
  (*variables)["number"] = SimpleItoa(descriptor->number());
  (*variables)["empty_list"] = "com.google.protobuf.LazyStringArrayList.EMPTY";

  (*variables)["default"] = DefaultValue(descriptor);
  (*variables)["default_init"] = ("= " + DefaultValue(descriptor));
  (*variables)["capitalized_type"] = "String";
  (*variables)["tag"] = SimpleItoa(WireFormat::MakeTag(descriptor));
  (*variables)["tag_size"] = SimpleItoa(
      WireFormat::TagSize(descriptor->number(), GetType(descriptor)));
  (*variables)["null_check"] =
      "  if (value == null) {\n"
      "    throw new NullPointerException();\n"
      "  }\n";

  // TODO(birdo): Add @deprecated javadoc when generating javadoc is supported
  // by the proto compiler
  (*variables)["deprecation"] = descriptor->options().deprecated()
      ? "@java.lang.Deprecated " : "";
  (*variables)["on_changed"] =
      HasDescriptorMethods(descriptor->containing_type()) ? "onChanged();" : "";

  // For singular messages and builders, one bit is used for the hasField bit.
  (*variables)["get_has_field_bit_message"] = GenerateGetBit(messageBitIndex);

  (*variables)["get_has_field_bit_builder"] = GenerateGetBit(builderBitIndex);
  (*variables)["set_has_field_bit_builder"] = GenerateSetBit(builderBitIndex);
  (*variables)["clear_has_field_bit_builder"] =
      GenerateClearBit(builderBitIndex);

  // For repated builders, one bit is used for whether the array is immutable.
  (*variables)["get_mutable_bit_builder"] = GenerateGetBit(builderBitIndex);
  (*variables)["set_mutable_bit_builder"] = GenerateSetBit(builderBitIndex);
  (*variables)["clear_mutable_bit_builder"] = GenerateClearBit(builderBitIndex);

  (*variables)["get_has_field_bit_from_local"] =
      GenerateGetBitFromLocal(builderBitIndex);
  (*variables)["set_has_field_bit_to_local"] =
      GenerateSetBitToLocal(messageBitIndex);
}

}  // namespace

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

StringFieldGenerator::
StringFieldGenerator(const FieldDescriptor* descriptor,
                     int messageBitIndex,
                     int builderBitIndex)
  : descriptor_(descriptor), messageBitIndex_(messageBitIndex),
    builderBitIndex_(builderBitIndex) {
  SetPrimitiveVariables(descriptor, messageBitIndex, builderBitIndex,
                        &variables_);
}

StringFieldGenerator::~StringFieldGenerator() {}

int StringFieldGenerator::GetNumBitsForMessage() const {
  return 1;
}

int StringFieldGenerator::GetNumBitsForBuilder() const {
  return 1;
}

// A note about how strings are handled. This code used to just store a String
// in the Message. This had two issues:
//
//  1. It wouldn't roundtrip byte arrays that were not vaid UTF-8 encoded
//     strings, but rather fields that were raw bytes incorrectly marked
//     as strings in the proto file. This is common because in the proto1
//     syntax, string was the way to indicate bytes and C++ engineers can
//     easily make this mistake without affecting the C++ API. By converting to
//     strings immediately, some java code might corrupt these byte arrays as
//     it passes through a java server even if the field was never accessed by
//     application code.
//
//  2. There's a performance hit to converting between bytes and strings and
//     it many cases, the field is never even read by the application code. This
//     avoids unnecessary conversions in the common use cases.
//
// So now, the field for String is maintained as an Object reference which can
// either store a String or a ByteString. The code uses an instanceof check
// to see which one it has and converts to the other one if needed. It remembers
// the last value requested (in a thread safe manner) as this is most likely
// the one needed next. The thread safety is such that if two threads both
// convert the field because the changes made by each thread were not visible to
// the other, they may cause a conversion to happen more times than would
// otherwise be necessary. This was deemed better than adding synchronization
// overhead. It will not cause any corruption issues or affect the behavior of
// the API. The instanceof check is also highly optimized in the JVM and we
// decided it was better to reduce the memory overhead by not having two
// separate fields but rather use dynamic type checking.
//
// For single fields, the logic for this is done inside the generated code. For
// repeated fields, the logic is done in LazyStringArrayList and
// UnmodifiableLazyStringList.
void StringFieldGenerator::
GenerateInterfaceMembers(io::Printer* printer) const {
  printer->Print(variables_,
    "$deprecation$boolean has$capitalized_name$();\n"
    "$deprecation$String get$capitalized_name$();\n");
}

void StringFieldGenerator::
GenerateMembers(io::Printer* printer) const {
  printer->Print(variables_,
    "private Object $name$_;\n"
    "$deprecation$public boolean has$capitalized_name$() {\n"
    "  return $get_has_field_bit_message$;\n"
    "}\n");

  printer->Print(variables_,
    "$deprecation$public String get$capitalized_name$() {\n"
    "  Object ref = $name$_;\n"
    "  if (ref instanceof String) {\n"
    "    return (String) ref;\n"
    "  } else {\n"
    "    com.google.protobuf.ByteString bs = \n"
    "        (com.google.protobuf.ByteString) ref;\n"
    "    String s = bs.toStringUtf8();\n"
    "    if (com.google.protobuf.Internal.isValidUtf8(bs)) {\n"
    "      $name$_ = s;\n"
    "    }\n"
    "    return s;\n"
    "  }\n"
    "}\n"
    "private com.google.protobuf.ByteString get$capitalized_name$Bytes() {\n"
    "  Object ref = $name$_;\n"
    "  if (ref instanceof String) {\n"
    "    com.google.protobuf.ByteString b = \n"
    "        com.google.protobuf.ByteString.copyFromUtf8((String) ref);\n"
    "    $name$_ = b;\n"
    "    return b;\n"
    "  } else {\n"
    "    return (com.google.protobuf.ByteString) ref;\n"
    "  }\n"
    "}\n");
}

void StringFieldGenerator::
GenerateBuilderMembers(io::Printer* printer) const {
  printer->Print(variables_,
    "private Object $name$_ $default_init$;\n"
    "$deprecation$public boolean has$capitalized_name$() {\n"
    "  return $get_has_field_bit_builder$;\n"
    "}\n");

  printer->Print(variables_,
    "$deprecation$public String get$capitalized_name$() {\n"
    "  Object ref = $name$_;\n"
    "  if (!(ref instanceof String)) {\n"
    "    String s = ((com.google.protobuf.ByteString) ref).toStringUtf8();\n"
    "    $name$_ = s;\n"
    "    return s;\n"
    "  } else {\n"
    "    return (String) ref;\n"
    "  }\n"
    "}\n");

  printer->Print(variables_,
    "$deprecation$public Builder set$capitalized_name$(String value) {\n"
    "$null_check$"
    "  $set_has_field_bit_builder$;\n"
    "  $name$_ = value;\n"
    "  $on_changed$\n"
    "  return this;\n"
    "}\n"
    "$deprecation$public Builder clear$capitalized_name$() {\n"
    "  $clear_has_field_bit_builder$;\n");
  // The default value is not a simple literal so we want to avoid executing
  // it multiple times.  Instead, get the default out of the default instance.
  printer->Print(variables_,
    "  $name$_ = getDefaultInstance().get$capitalized_name$();\n");
  printer->Print(variables_,
    "  $on_changed$\n"
    "  return this;\n"
    "}\n");

  printer->Print(variables_,
    "void set$capitalized_name$(com.google.protobuf.ByteString value) {\n"
    "  $set_has_field_bit_builder$;\n"
    "  $name$_ = value;\n"
    "  $on_changed$\n"
    "}\n");
}

void StringFieldGenerator::
GenerateFieldBuilderInitializationCode(io::Printer* printer)  const {
  // noop for primitives
}

void StringFieldGenerator::
GenerateInitializationCode(io::Printer* printer) const {
  printer->Print(variables_, "$name$_ = $default$;\n");
}

void StringFieldGenerator::
GenerateBuilderClearCode(io::Printer* printer) const {
  printer->Print(variables_,
    "$name$_ = $default$;\n"
    "$clear_has_field_bit_builder$;\n");
}

void StringFieldGenerator::
GenerateMergingCode(io::Printer* printer) const {
  printer->Print(variables_,
    "if (other.has$capitalized_name$()) {\n"
    "  set$capitalized_name$(other.get$capitalized_name$());\n"
    "}\n");
}

void StringFieldGenerator::
GenerateBuildingCode(io::Printer* printer) const {
  printer->Print(variables_,
    "if ($get_has_field_bit_from_local$) {\n"
    "  $set_has_field_bit_to_local$;\n"
    "}\n"
    "result.$name$_ = $name$_;\n");
}

void StringFieldGenerator::
GenerateParsingCode(io::Printer* printer) const {
  printer->Print(variables_,
    "$set_has_field_bit_builder$;\n"
    "$name$_ = input.readBytes();\n");
}

void StringFieldGenerator::
GenerateSerializationCode(io::Printer* printer) const {
  printer->Print(variables_,
    "if ($get_has_field_bit_message$) {\n"
    "  output.writeBytes($number$, get$capitalized_name$Bytes());\n"
    "}\n");
}

void StringFieldGenerator::
GenerateSerializedSizeCode(io::Printer* printer) const {
  printer->Print(variables_,
    "if ($get_has_field_bit_message$) {\n"
    "  size += com.google.protobuf.CodedOutputStream\n"
    "    .computeBytesSize($number$, get$capitalized_name$Bytes());\n"
    "}\n");
}

void StringFieldGenerator::
GenerateEqualsCode(io::Printer* printer) const {
  printer->Print(variables_,
    "result = result && get$capitalized_name$()\n"
    "    .equals(other.get$capitalized_name$());\n");
}

void StringFieldGenerator::
GenerateHashCode(io::Printer* printer) const {
  printer->Print(variables_,
    "hash = (37 * hash) + $constant_name$;\n");
  printer->Print(variables_,
    "hash = (53 * hash) + get$capitalized_name$().hashCode();\n");
}

string StringFieldGenerator::GetBoxedType() const {
  return "String";
}


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

RepeatedStringFieldGenerator::
RepeatedStringFieldGenerator(const FieldDescriptor* descriptor,
                             int messageBitIndex,
                             int builderBitIndex)
  : descriptor_(descriptor), messageBitIndex_(messageBitIndex),
    builderBitIndex_(builderBitIndex) {
  SetPrimitiveVariables(descriptor, messageBitIndex, builderBitIndex,
                        &variables_);
}

RepeatedStringFieldGenerator::~RepeatedStringFieldGenerator() {}

int RepeatedStringFieldGenerator::GetNumBitsForMessage() const {
  return 0;
}

int RepeatedStringFieldGenerator::GetNumBitsForBuilder() const {
  return 1;
}

void RepeatedStringFieldGenerator::
GenerateInterfaceMembers(io::Printer* printer) const {
  printer->Print(variables_,
    "$deprecation$java.util.List<String> get$capitalized_name$List();\n"
    "$deprecation$int get$capitalized_name$Count();\n"
    "$deprecation$String get$capitalized_name$(int index);\n");
}


void RepeatedStringFieldGenerator::
GenerateMembers(io::Printer* printer) const {
  printer->Print(variables_,
    "private com.google.protobuf.LazyStringList $name$_;\n"
    "$deprecation$public java.util.List<String>\n"
    "    get$capitalized_name$List() {\n"
    "  return $name$_;\n"   // note:  unmodifiable list
    "}\n"
    "$deprecation$public int get$capitalized_name$Count() {\n"
    "  return $name$_.size();\n"
    "}\n"
    "$deprecation$public String get$capitalized_name$(int index) {\n"
    "  return $name$_.get(index);\n"
    "}\n");

  if (descriptor_->options().packed() &&
      HasGeneratedMethods(descriptor_->containing_type())) {
    printer->Print(variables_,
      "private int $name$MemoizedSerializedSize = -1;\n");
  }
}

void RepeatedStringFieldGenerator::
GenerateBuilderMembers(io::Printer* printer) const {
  // One field is the list and the bit field keeps track of whether the
  // list is immutable. If it's immutable, the invariant is that it must
  // either an instance of Collections.emptyList() or it's an ArrayList
  // wrapped in a Collections.unmodifiableList() wrapper and nobody else has
  // a refererence to the underlying ArrayList. This invariant allows us to
  // share instances of lists between protocol buffers avoiding expensive
  // memory allocations. Note, immutable is a strong guarantee here -- not
  // just that the list cannot be modified via the reference but that the
  // list can never be modified.
  printer->Print(variables_,
    "private com.google.protobuf.LazyStringList $name$_ = $empty_list$;\n");

  printer->Print(variables_,
    "private void ensure$capitalized_name$IsMutable() {\n"
    "  if (!$get_mutable_bit_builder$) {\n"
    "    $name$_ = new com.google.protobuf.LazyStringArrayList($name$_);\n"
    "    $set_mutable_bit_builder$;\n"
    "   }\n"
    "}\n");

    // Note:  We return an unmodifiable list because otherwise the caller
    //   could hold on to the returned list and modify it after the message
    //   has been built, thus mutating the message which is supposed to be
    //   immutable.
  printer->Print(variables_,
    "$deprecation$public java.util.List<String>\n"
    "    get$capitalized_name$List() {\n"
    "  return java.util.Collections.unmodifiableList($name$_);\n"
    "}\n"
    "$deprecation$public int get$capitalized_name$Count() {\n"
    "  return $name$_.size();\n"
    "}\n"
    "$deprecation$public String get$capitalized_name$(int index) {\n"
    "  return $name$_.get(index);\n"
    "}\n"
    "$deprecation$public Builder set$capitalized_name$(\n"
    "    int index, String value) {\n"
    "$null_check$"
    "  ensure$capitalized_name$IsMutable();\n"
    "  $name$_.set(index, value);\n"
    "  $on_changed$\n"
    "  return this;\n"
    "}\n"
    "$deprecation$public Builder add$capitalized_name$(String value) {\n"
    "$null_check$"
    "  ensure$capitalized_name$IsMutable();\n"
    "  $name$_.add(value);\n"
    "  $on_changed$\n"
    "  return this;\n"
    "}\n"
    "$deprecation$public Builder addAll$capitalized_name$(\n"
    "    java.lang.Iterable<String> values) {\n"
    "  ensure$capitalized_name$IsMutable();\n"
    "  super.addAll(values, $name$_);\n"
    "  $on_changed$\n"
    "  return this;\n"
    "}\n"
    "$deprecation$public Builder clear$capitalized_name$() {\n"
    "  $name$_ = $empty_list$;\n"
    "  $clear_mutable_bit_builder$;\n"
    "  $on_changed$\n"
    "  return this;\n"
    "}\n");

  printer->Print(variables_,
    "void add$capitalized_name$(com.google.protobuf.ByteString value) {\n"
    "  ensure$capitalized_name$IsMutable();\n"
    "  $name$_.add(value);\n"
    "  $on_changed$\n"
    "}\n");
}

void RepeatedStringFieldGenerator::
GenerateFieldBuilderInitializationCode(io::Printer* printer)  const {
  // noop for primitives
}

void RepeatedStringFieldGenerator::
GenerateInitializationCode(io::Printer* printer) const {
  printer->Print(variables_, "$name$_ = $empty_list$;\n");
}

void RepeatedStringFieldGenerator::
GenerateBuilderClearCode(io::Printer* printer) const {
  printer->Print(variables_,
    "$name$_ = $empty_list$;\n"
    "$clear_mutable_bit_builder$;\n");
}

void RepeatedStringFieldGenerator::
GenerateMergingCode(io::Printer* printer) const {
  // The code below does two optimizations:
  //   1. If the other list is empty, there's nothing to do. This ensures we
  //      don't allocate a new array if we already have an immutable one.
  //   2. If the other list is non-empty and our current list is empty, we can
  //      reuse the other list which is guaranteed to be immutable.
  printer->Print(variables_,
    "if (!other.$name$_.isEmpty()) {\n"
    "  if ($name$_.isEmpty()) {\n"
    "    $name$_ = other.$name$_;\n"
    "    $clear_mutable_bit_builder$;\n"
    "  } else {\n"
    "    ensure$capitalized_name$IsMutable();\n"
    "    $name$_.addAll(other.$name$_);\n"
    "  }\n"
    "  $on_changed$\n"
    "}\n");
}

void RepeatedStringFieldGenerator::
GenerateBuildingCode(io::Printer* printer) const {
  // The code below ensures that the result has an immutable list. If our
  // list is immutable, we can just reuse it. If not, we make it immutable.

  printer->Print(variables_,
    "if ($get_mutable_bit_builder$) {\n"
    "  $name$_ = new com.google.protobuf.UnmodifiableLazyStringList(\n"
    "      $name$_);\n"
    "  $clear_mutable_bit_builder$;\n"
    "}\n"
    "result.$name$_ = $name$_;\n");
}

void RepeatedStringFieldGenerator::
GenerateParsingCode(io::Printer* printer) const {
  printer->Print(variables_,
    "ensure$capitalized_name$IsMutable();\n"
    "$name$_.add(input.readBytes());\n");
}

void RepeatedStringFieldGenerator::
GenerateParsingCodeFromPacked(io::Printer* printer) const {
  printer->Print(variables_,
    "int length = input.readRawVarint32();\n"
    "int limit = input.pushLimit(length);\n"
    "while (input.getBytesUntilLimit() > 0) {\n"
    "  add$capitalized_name$(input.read$capitalized_type$());\n"
    "}\n"
    "input.popLimit(limit);\n");
}

void RepeatedStringFieldGenerator::
GenerateSerializationCode(io::Printer* printer) const {
  if (descriptor_->options().packed()) {
    printer->Print(variables_,
      "if (get$capitalized_name$List().size() > 0) {\n"
      "  output.writeRawVarint32($tag$);\n"
      "  output.writeRawVarint32($name$MemoizedSerializedSize);\n"
      "}\n"
      "for (int i = 0; i < $name$_.size(); i++) {\n"
      "  output.write$capitalized_type$NoTag($name$_.get(i));\n"
      "}\n");
  } else {
    printer->Print(variables_,
      "for (int i = 0; i < $name$_.size(); i++) {\n"
      "  output.writeBytes($number$, $name$_.getByteString(i));\n"
      "}\n");
  }
}

void RepeatedStringFieldGenerator::
GenerateSerializedSizeCode(io::Printer* printer) const {
  printer->Print(variables_,
    "{\n"
    "  int dataSize = 0;\n");
  printer->Indent();

  printer->Print(variables_,
    "for (int i = 0; i < $name$_.size(); i++) {\n"
    "  dataSize += com.google.protobuf.CodedOutputStream\n"
    "    .computeBytesSizeNoTag($name$_.getByteString(i));\n"
    "}\n");

  printer->Print(
      "size += dataSize;\n");

  if (descriptor_->options().packed()) {
    printer->Print(variables_,
      "if (!get$capitalized_name$List().isEmpty()) {\n"
      "  size += $tag_size$;\n"
      "  size += com.google.protobuf.CodedOutputStream\n"
      "      .computeInt32SizeNoTag(dataSize);\n"
      "}\n");
  } else {
    printer->Print(variables_,
      "size += $tag_size$ * get$capitalized_name$List().size();\n");
  }

  // cache the data size for packed fields.
  if (descriptor_->options().packed()) {
    printer->Print(variables_,
      "$name$MemoizedSerializedSize = dataSize;\n");
  }

  printer->Outdent();
  printer->Print("}\n");
}

void RepeatedStringFieldGenerator::
GenerateEqualsCode(io::Printer* printer) const {
  printer->Print(variables_,
    "result = result && get$capitalized_name$List()\n"
    "    .equals(other.get$capitalized_name$List());\n");
}

void RepeatedStringFieldGenerator::
GenerateHashCode(io::Printer* printer) const {
  printer->Print(variables_,
    "if (get$capitalized_name$Count() > 0) {\n"
    "  hash = (37 * hash) + $constant_name$;\n"
    "  hash = (53 * hash) + get$capitalized_name$List().hashCode();\n"
    "}\n");
}

string RepeatedStringFieldGenerator::GetBoxedType() const {
  return "String";
}

}  // namespace java
}  // namespace compiler
}  // namespace protobuf
}  // namespace google