chromium/third_party/protobuf/src/google/protobuf/extension_set.h

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

// Author: [email protected] (Kenton Varda)
//  Based on original Protocol Buffers design by
//  Sanjay Ghemawat, Jeff Dean, and others.
//
// This header is logically internal, but is made public because it is used
// from protocol-compiler-generated code, which may reside in other components.

#ifndef GOOGLE_PROTOBUF_EXTENSION_SET_H__
#define GOOGLE_PROTOBUF_EXTENSION_SET_H__


#include <algorithm>
#include <cassert>
#include <map>
#include <string>
#include <utility>
#include <vector>

#include <google/protobuf/stubs/common.h>
#include <google/protobuf/stubs/logging.h>
#include <google/protobuf/io/coded_stream.h>
#include <google/protobuf/port.h>
#include <google/protobuf/parse_context.h>
#include <google/protobuf/repeated_field.h>
#include <google/protobuf/wire_format_lite.h>

// clang-format off
#include <google/protobuf/port_def.inc>  // Must be last
// clang-format on

#ifdef SWIG
#error "You cannot SWIG proto headers"
#endif

namespace google {
namespace protobuf {
class Arena;
class Descriptor;       // descriptor.h
class FieldDescriptor;  // descriptor.h
class DescriptorPool;   // descriptor.h
class MessageLite;      // message_lite.h
class Message;          // message.h
class MessageFactory;   // message.h
class Reflection;       // message.h
class UnknownFieldSet;  // unknown_field_set.h
namespace internal {
class FieldSkipper;  // wire_format_lite.h
enum class LazyVerifyOption;
}  // namespace internal
}  // namespace protobuf
}  // namespace google

namespace google {
namespace protobuf {
namespace internal {

class InternalMetadata;

// Used to store values of type WireFormatLite::FieldType without having to
// #include wire_format_lite.h.  Also, ensures that we use only one byte to
// store these values, which is important to keep the layout of
// ExtensionSet::Extension small.
FieldType;

// A function which, given an integer value, returns true if the number
// matches one of the defined values for the corresponding enum type.  This
// is used with RegisterEnumExtension, below.
EnumValidityFunc;

// Version of the above which takes an argument.  This is needed to deal with
// extensions that are not compiled in.
EnumValidityFuncWithArg;

// Information about a registered extension.
struct ExtensionInfo { … };

// An ExtensionFinder is an object which looks up extension definitions.  It
// must implement this method:
//
// bool Find(int number, ExtensionInfo* output);

// GeneratedExtensionFinder is an ExtensionFinder which finds extensions
// defined in .proto files which have been compiled into the binary.
class PROTOBUF_EXPORT GeneratedExtensionFinder { … };

// Note:  extension_set_heavy.cc defines DescriptorPoolExtensionFinder for
// finding extensions from a DescriptorPool.

// This is an internal helper class intended for use within the protocol buffer
// library and generated classes.  Clients should not use it directly.  Instead,
// use the generated accessors such as GetExtension() of the class being
// extended.
//
// This class manages extensions for a protocol message object.  The
// message's HasExtension(), GetExtension(), MutableExtension(), and
// ClearExtension() methods are just thin wrappers around the embedded
// ExtensionSet.  When parsing, if a tag number is encountered which is
// inside one of the message type's extension ranges, the tag is passed
// off to the ExtensionSet for parsing.  Etc.
class PROTOBUF_EXPORT ExtensionSet { … };

constexpr ExtensionSet::ExtensionSet()
    : … { … }

// These are just for convenience...
inline void ExtensionSet::SetString(int number, FieldType type,
                                    std::string value,
                                    const FieldDescriptor* descriptor) { … }
inline void ExtensionSet::SetRepeatedString(int number, int index,
                                            std::string value) { … }
inline void ExtensionSet::AddString(int number, FieldType type,
                                    std::string value,
                                    const FieldDescriptor* descriptor) { … }
// ===================================================================
// Glue for generated extension accessors

// -------------------------------------------------------------------
// Template magic

// First we have a set of classes representing "type traits" for different
// field types.  A type traits class knows how to implement basic accessors
// for extensions of a particular type given an ExtensionSet.  The signature
// for a type traits class looks like this:
//
//   class TypeTraits {
//    public:
//     typedef ? ConstType;
//     typedef ? MutableType;
//     // TypeTraits for singular fields and repeated fields will define the
//     // symbol "Singular" or "Repeated" respectively. These two symbols will
//     // be used in extension accessors to distinguish between singular
//     // extensions and repeated extensions. If the TypeTraits for the passed
//     // in extension doesn't have the expected symbol defined, it means the
//     // user is passing a repeated extension to a singular accessor, or the
//     // opposite. In that case the C++ compiler will generate an error
//     // message "no matching member function" to inform the user.
//     typedef ? Singular
//     typedef ? Repeated
//
//     static inline ConstType Get(int number, const ExtensionSet& set);
//     static inline void Set(int number, ConstType value, ExtensionSet* set);
//     static inline MutableType Mutable(int number, ExtensionSet* set);
//
//     // Variants for repeated fields.
//     static inline ConstType Get(int number, const ExtensionSet& set,
//                                 int index);
//     static inline void Set(int number, int index,
//                            ConstType value, ExtensionSet* set);
//     static inline MutableType Mutable(int number, int index,
//                                       ExtensionSet* set);
//     static inline void Add(int number, ConstType value, ExtensionSet* set);
//     static inline MutableType Add(int number, ExtensionSet* set);
//     This is used by the ExtensionIdentifier constructor to register
//     the extension at dynamic initialization.
//     template <typename ExtendeeT>
//     static void Register(int number, FieldType type, bool is_packed);
//   };
//
// Not all of these methods make sense for all field types.  For example, the
// "Mutable" methods only make sense for strings and messages, and the
// repeated methods only make sense for repeated types.  So, each type
// traits class implements only the set of methods from this signature that it
// actually supports.  This will cause a compiler error if the user tries to
// access an extension using a method that doesn't make sense for its type.
// For example, if "foo" is an extension of type "optional int32", then if you
// try to write code like:
//   my_message.MutableExtension(foo)
// you will get a compile error because PrimitiveTypeTraits<int32_t> does not
// have a "Mutable()" method.

// -------------------------------------------------------------------
// PrimitiveTypeTraits

// Since the ExtensionSet has different methods for each primitive type,
// we must explicitly define the methods of the type traits class for each
// known type.
template <typename Type>
class PrimitiveTypeTraits { … };

template <typename Type>
class RepeatedPrimitiveTypeTraits { … };

class PROTOBUF_EXPORT RepeatedPrimitiveDefaults { … };

#define PROTOBUF_DEFINE_PRIMITIVE_TYPE …

PROTOBUF_DEFINE_PRIMITIVE_TYPE
PROTOBUF_DEFINE_PRIMITIVE_TYPE
PROTOBUF_DEFINE_PRIMITIVE_TYPE
PROTOBUF_DEFINE_PRIMITIVE_TYPE
PROTOBUF_DEFINE_PRIMITIVE_TYPE
PROTOBUF_DEFINE_PRIMITIVE_TYPE
PROTOBUF_DEFINE_PRIMITIVE_TYPE

#undef PROTOBUF_DEFINE_PRIMITIVE_TYPE

// -------------------------------------------------------------------
// StringTypeTraits

// Strings support both Set() and Mutable().
class PROTOBUF_EXPORT StringTypeTraits { … };

class PROTOBUF_EXPORT RepeatedStringTypeTraits { … };

// -------------------------------------------------------------------
// EnumTypeTraits

// ExtensionSet represents enums using integers internally, so we have to
// static_cast around.
template <typename Type, bool IsValid(int)>
class EnumTypeTraits { … };

template <typename Type, bool IsValid(int)>
class RepeatedEnumTypeTraits { … };

// -------------------------------------------------------------------
// MessageTypeTraits

// ExtensionSet guarantees that when manipulating extensions with message
// types, the implementation used will be the compiled-in class representing
// that type.  So, we can static_cast down to the exact type we expect.
template <typename Type>
class MessageTypeTraits { … };

// Used by WireFormatVerify to extract the verify function from the registry.
LazyEagerVerifyFnType FindExtensionLazyEagerVerifyFn(
    const MessageLite* extendee, int number);

// forward declaration.
class RepeatedMessageGenericTypeTraits;

template <typename Type>
class RepeatedMessageTypeTraits { … };

template <typename Type>
inline const typename RepeatedMessageTypeTraits<Type>::RepeatedFieldType*
RepeatedMessageTypeTraits<Type>::GetDefaultRepeatedField() { … }

// -------------------------------------------------------------------
// ExtensionIdentifier

// This is the type of actual extension objects.  E.g. if you have:
//   extend Foo {
//     optional int32 bar = 1234;
//   }
// then "bar" will be defined in C++ as:
//   ExtensionIdentifier<Foo, PrimitiveTypeTraits<int32_t>, 5, false> bar(1234);
//
// Note that we could, in theory, supply the field number as a template
// parameter, and thus make an instance of ExtensionIdentifier have no
// actual contents.  However, if we did that, then using an extension
// identifier would not necessarily cause the compiler to output any sort
// of reference to any symbol defined in the extension's .pb.o file.  Some
// linkers will actually drop object files that are not explicitly referenced,
// but that would be bad because it would cause this extension to not be
// registered at static initialization, and therefore using it would crash.

template <typename ExtendeeType, typename TypeTraitsType, FieldType field_type,
          bool is_packed>
class ExtensionIdentifier { … };

// -------------------------------------------------------------------
// Generated accessors


// Used to retrieve a lazy extension, may return nullptr in some environments.
extern PROTOBUF_ATTRIBUTE_WEAK ExtensionSet::LazyMessageExtension*
MaybeCreateLazyExtension(Arena* arena);

}  // namespace internal

// Call this function to ensure that this extensions's reflection is linked into
// the binary:
//
//   google::protobuf::LinkExtensionReflection(Foo::my_extension);
//
// This will ensure that the following lookup will succeed:
//
//   DescriptorPool::generated_pool()->FindExtensionByName("Foo.my_extension");
//
// This is often relevant for parsing extensions in text mode.
//
// As a side-effect, it will also guarantee that anything else from the same
// .proto file will also be available for lookup in the generated pool.
//
// This function does not actually register the extension, so it does not need
// to be called before the lookup.  However it does need to occur in a function
// that cannot be stripped from the binary (ie. it must be reachable from main).
//
// Best practice is to call this function as close as possible to where the
// reflection is actually needed.  This function is very cheap to call, so you
// should not need to worry about its runtime overhead except in tight loops (on
// x86-64 it compiles into two "mov" instructions).
template <typename ExtendeeType, typename TypeTraitsType,
          internal::FieldType field_type, bool is_packed>
void LinkExtensionReflection(
    const google::protobuf::internal::ExtensionIdentifier<
        ExtendeeType, TypeTraitsType, field_type, is_packed>& extension) { … }

}  // namespace protobuf
}  // namespace google

#include <google/protobuf/port_undef.inc>

#endif  // GOOGLE_PROTOBUF_EXTENSION_SET_H__