【源码】protobuf 中各个压缩（Serialize）、解压缩（Parse）函数辨析

PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromString(ConstStringParam data);

PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParsePartialFromString(

ConstStringParam data);

// Parse a protocol buffer contained in an array of bytes.

PROTOBUF_ATTRIBUTE_REINITIALIZES bool ParseFromArray(const void* data,

int size);

PROTOBUF_ATTRIBUTE_REINITIALIZES 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 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().

bool MergePartialFromCodedStream(io::CodedInputStream* input);

// Merge a protocol buffer contained in a string.

bool MergeFromString(ConstStringParam data);

---

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;

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;

bool SerializePartialToZeroCopyStream(io::ZeroCopyOutputStream* output) const;

// Serialize the message and store it in the given string. All required

// fields must be set.

bool SerializeToString(std::string* output) const;

bool SerializePartialToString(std::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;

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().

std::string SerializeAsString() const;

std::string SerializePartialAsString() const;

// Serialize the message and write it to the given file descriptor. All

// required fields must be set.

bool SerializeToFileDescriptor(int file_descriptor) const;

bool SerializePartialToFileDescriptor(int file_descriptor) const;

// Serialize the message and write it to the given C++ ostream. All

// required fields must be set.

bool SerializeToOstream(std::ostream* output) const;

bool SerializePartialToOstream(std::ostream* output) const;

// Like SerializeToString(), but appends to the data to the string’s

// existing contents. All required fields must be set.

bool AppendToString(std::string* output) const;

// Like AppendToString(), but allows missing required fields.

bool AppendPartialToString(std::string* output) const;

// Computes the serialized size of the message. This recursively calls

// ByteSizeLong() on all embedded messages.

//

// ByteSizeLong() is generally linear in the number of fields defined for the

// proto.

virtual size_t ByteSizeLong() const = 0;

// Legacy ByteSize() API.

PROTOBUF_DEPRECATED_MSG(“Please use ByteSizeLong() instead”)

int ByteSize() const { return internal::ToIntSize(ByteSizeLong()); }

// Serializes the message without recomputing the size. The message must not

// have changed since the last call to ByteSize(), and the value returned by

// ByteSize must be non-negative. Otherwise the results are undefined.

void SerializeWithCachedSizes(io::CodedOutputStream* output) const {

output->SetCur(_InternalSerialize(output->Cur(), output->EpsCopy()));

}

// Functions below here are not part of the public interface. It isn’t

// enforced, but they should be treated as private, and will be private

// at some future time. Unfortunately the implementation of the “friend”

// keyword in GCC is broken at the moment, but we expect it will be fixed.

// Like SerializeWithCachedSizes, but writes directly to *target, returning
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