// 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.
// Authors: wink@google.com (Wink Saville),
// kenton@google.com (Kenton Varda)
// Based on original Protocol Buffers design by
// Sanjay Ghemawat, Jeff Dean, and others.
//
// Defines MessageLite, the abstract interface implemented by all (lite
// and non-lite) protocol message objects.
#ifndef GOOGLE_PROTOBUF_MESSAGE_LITE_H__
#define GOOGLE_PROTOBUF_MESSAGE_LITE_H__
#include <google/protobuf/stubs/common.h>
namespace google {
namespace protobuf {
class Arena;
namespace io {
class CodedInputStream;
class CodedOutputStream;
class ZeroCopyInputStream;
class ZeroCopyOutputStream;
}
// Interface to light weight protocol messages.
//
// This interface is implemented by all protocol message objects. Non-lite
// messages additionally implement the Message interface, which is a
// subclass of MessageLite. Use MessageLite instead when you only need
// the subset of features which it supports -- namely, nothing that uses
// descriptors or reflection. You can instruct the protocol compiler
// to generate classes which implement only MessageLite, not the full
// Message interface, by adding the following line to the .proto file:
//
// option optimize_for = LITE_RUNTIME;
//
// This is particularly useful on resource-constrained systems where
// the full protocol buffers runtime library is too big.
//
// Note that on non-constrained systems (e.g. servers) when you need
// to link in lots of protocol definitions, a better way to reduce
// total code footprint is to use optimize_for = CODE_SIZE. This
// will make the generated code smaller while still supporting all the
// same features (at the expense of speed). optimize_for = LITE_RUNTIME
// is best when you only have a small number of message types linked
// into your binary, in which case the size of the protocol buffers
// runtime itself is the biggest problem.
class LIBPROTOBUF_EXPORT MessageLite {
public:
inline MessageLite() {}
virtual ~MessageLite();
// Basic Operations ------------------------------------------------
// Get the name of this message type, e.g. "foo.bar.BazProto".
virtual string GetTypeName() const = 0;
// Construct a new instance of the same type. Ownership is passed to the
// caller.
virtual MessageLite* New() const = 0;
// Construct a new instance on the arena. Ownership is passed to the caller
// if arena is a NULL. Default implementation for backwards compatibility.
virtual MessageLite* New(::google::protobuf::Arena* arena) const;
// Get the arena, if any, associated with this message. Virtual method
// required for generic operations but most arena-related operations should
// use the GetArenaNoVirtual() generated-code method. Default implementation
// to reduce code size by avoiding the need for per-type implementations when
// types do not implement arena support.
virtual ::google::protobuf::Arena* GetArena() const { return NULL; }
// Get a pointer that may be equal to this message's arena, or may not be. If
// the value returned by this method is equal to some arena pointer, then this
// message is on that arena; however, if this message is on some arena, this
// method may or may not return that arena's pointer. As a tradeoff, this
// method may be more efficient than GetArena(). The intent is to allow
// underlying representations that use e.g. tagged pointers to sometimes store
// the arena pointer directly, and sometimes in a more indirect way, and allow
// a fastpath comparison against the arena pointer when it's easy to obtain.
virtual void* GetMaybeArenaPointer() const { return GetArena(); }
// Clear all fields of the message and set them to their default values.
// Clear() avoids freeing memory, assuming that any memory allocated
// to hold parts of the message will be needed again to hold the next
// message. If you actually want to free the memory used by a Message,
// you must delete it.
virtual void Clear() = 0;
// Quickly check if all required fields have values set.
virtual bool IsInitialized() const = 0;
// This is not implemented for Lite messages -- it just returns "(cannot
// determine missing fields for lite message)". However, it is implemented
// for full messages. See message.h.
virtual string InitializationErrorString() const;
// If |other| is the exact same class as this, calls MergeFrom(). Otherwise,
// results are undefined (probably crash).
virtual void CheckTypeAndMergeFrom(const MessageLite& other) = 0;
// Parsing ---------------------------------------------------------
// Methods for parsing in protocol buffer format. Most of these are
// just simple wrappers around MergeFromCodedStream(). Clear() will be called
// before merging the input.
// Fill the message with a protocol buffer parsed from the given input stream.
// Returns false on a read error or if the input is in the wrong format. A
// successful return does not indicate the entire input is consumed, ensure
// you call ConsumedEntireMessage() to check that if applicable.
bool ParseFromCodedStream(io::CodedInputStream* input);
// Like ParseFromCodedStream(), but accepts messages that are missing
// required fields.
bool ParsePartialFromCodedStream(io::CodedInputStream* input);
// Read a protocol buffer from the given zero-copy input stream. If
// successful, the entire input will be consumed.
bool ParseFromZeroCopyStream(io::ZeroCopyInputStream* input);
// Like ParseFromZeroCopyStream(), but accepts messages that are missing
// required fields.
bool ParsePartialFromZeroCopyStream(io::ZeroCopyInputStream* input);
// Read a protocol buffer from the given zero-copy input stream, expecting
// the message to be exactly "size" bytes long. If successful, exactly
// this many bytes will have been consumed from the input.
bool ParseFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, int size);
// Like ParseFromBoundedZeroCopyStream(), but accepts messages that are
// missing required fields.
bool ParsePartialFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input,
int size);
// Parses a protocol buffer contained in a string. Returns true on success.
// This function takes a string in the (non-human-readable) binary wire
// format, matching the encoding output by MessageLite::SerializeToString().
// If you'd like to convert a human-readable string into a protocol buffer
// object, see google::protobuf::TextFormat::ParseFromString().
bool ParseFromString(const string& data);
// Like ParseFromString(), but accepts messages that are missing
// required fields.
bool ParsePartialFromString(const string& data);
// Parse a protocol buffer contained in an array of bytes.
bool ParseFromArray(const void* data, int size);
// Like ParseFromArray(), but accepts messages that are missing
// required fields.
bool ParsePartialFromArray(const void* data, int size);
// Reads a protocol buffer from the stream and merges it into this
// Message. Singular fields read from the input overwrite what is
// already in the Message and repeated fields are appended to those
// already present.
//
// It is the responsibility of the caller to call input->LastTagWas()
// (for groups) or input->ConsumedEntireMessage() (for non-groups) after
// this returns to verify that the message's end was delimited correctly.
//
// ParsefromCodedStream() is implemented as Clear() followed by
// MergeFromCodedStream().
bool MergeFromCodedStream(io::CodedInputStream* input);
// Like MergeFromCodedStream(), but succeeds even if required fields are
// missing in the input.
//
// MergeFromCodedStream() is just implemented as MergePartialFromCodedStream()
// followed by IsInitialized().
virtual bool MergePartialFromCodedStream(io::CodedInputStream* input) = 0;
// Serialization ---------------------------------------------------
// Methods for serializing in protocol buffer format. Most of these
// are just simple wrappers around ByteSize() and SerializeWithCachedSizes().
// Write a protocol buffer of this message to the given output. Returns
// false on a write error. If the message is missing required fields,
// this may GOOGLE_CHECK-fail.
bool SerializeToCodedStream(io::CodedOutputStream* output) const;
// Like SerializeToCodedStream(), but allows missing required fields.
bool SerializePartialToCodedStream(io::CodedOutputStream* output) const;
// Write the message to the given zero-copy output stream. All required
// fields must be set.
bool SerializeToZeroCopyStream(io::ZeroCopyOutputStream* output) const;
// Like SerializeToZeroCopyStream(), but allows missing required fields.
bool SerializePartialToZeroCopyStream(io::ZeroCopyOutputStream* output) const;
// Serialize the message and store it in the given string. All required
// fields must be set.
bool SerializeToString(string* output) const;
// Like SerializeToString(), but allows missing required fields.
bool SerializePartialToString(string* output) const;
// Serialize the message and store it in the given byte array. All required
// fields must be set.
bool SerializeToArray(void* data, int size) const;
// Like SerializeToArray(), but allows missing required fields.
bool SerializePartialToArray(void* data, int size) const;
// Make a string encoding the message. Is equivalent to calling
// SerializeToString() on a string and using that. Returns the empty
// string if SerializeToString() would have returned an error.
// Note: If you intend to generate many such strings, you may
// reduce heap fragmentation by instead re-using the same string
// object with calls to SerializeToString().
string SerializeAsString() const;
// Like SerializeAsString(), but allows missing required fields.
string SerializePartialAsString() const;
// Like SerializeToString(), but appends to the data to the string's existing
// contents. All required fields must be set.
bool AppendToString(string* output) const;
// Like AppendToString(), but allows missing required fields.
bool AppendPartialToString(string* output) const;
// Computes the serialized size of the message. This recursively calls
// ByteSize() on all embedded messages. If a subclass does not override
// this, it MUST override SetCachedSize().
//
// ByteSize() is generally linear in the number of fields defined for the
// proto.
virtual int ByteSize() const = 0;
// Serializes the message without recomputing the size. The message must
// not have changed since the last call to ByteSize(); if it has, the results
// are undefined.
virtual void SerializeWithCachedSizes(
io::CodedOutputStream* output) const = 0;
// Like SerializeWithCachedSizes, but writes directly to *target, returning
// a pointer to the byte immediately after the last byte written. "target"
// must point at a byte array of at least ByteSize() bytes.
virtual uint8* SerializeWithCachedSizesToArray(uint8* target) const;
// Returns the result of the last call to ByteSize(). An embedded message's
// size is needed both to serialize it (because embedded messages are
// length-delimited) and to compute the outer message's size. Caching
// the size avoids computing it multiple times.
//
// ByteSize() does not automatically use the cached size when available
// because this would require invalidating it every time the message was
// modified, which would be too hard and expensive. (E.g. if a deeply-nested
// sub-message is changed, all of its parents' cached sizes would need to be
// invalidated, which is too much work for an otherwise inlined setter
// method.)
virtual int GetCachedSize() const = 0;
private:
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageLite);
};
} // namespace protobuf
} // namespace google
#endif // GOOGLE_PROTOBUF_MESSAGE_LITE_H__
