rocksdb/thrift/lib/cpp/protocol/TJSONProtocol.h

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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
#ifndef THRIFT_PROTOCOL_TJSONPROTOCOL_H_
#define THRIFT_PROTOCOL_TJSONPROTOCOL_H_ 1
#include "TVirtualProtocol.h"
#include <stack>
namespace apache { namespace thrift { namespace protocol {
// Forward declaration
class TJSONContext;
/**
* JSON protocol for Thrift.
*
* Implements a protocol which uses JSON as the wire-format.
*
* Thrift types are represented as described below:
*
* 1. Every Thrift integer type is represented as a JSON number.
*
* 2. Thrift doubles are represented as JSON numbers. Some special values are
* represented as strings:
* a. "NaN" for not-a-number values
* b. "Infinity" for positive infinity
* c. "-Infinity" for negative infinity
*
* 3. Thrift string values are emitted as JSON strings, with appropriate
* escaping.
*
* 4. Thrift binary values are encoded into Base64 and emitted as JSON strings.
* The readBinary() method is written such that it will properly skip if
* called on a Thrift string (although it will decode garbage data).
*
* 5. Thrift structs are represented as JSON objects, with the field ID as the
* key, and the field value represented as a JSON object with a single
* key-value pair. The key is a short string identifier for that type,
* followed by the value. The valid type identifiers are: "tf" for bool,
* "i8" for byte, "i16" for 16-bit integer, "i32" for 32-bit integer, "i64"
* for 64-bit integer, "dbl" for double-precision floating point, "str" for
* string (including binary), "rec" for struct ("records"), "map" for map,
* "lst" for list, "set" for set.
*
* 6. Thrift lists and sets are represented as JSON arrays, with the first
* element of the JSON array being the string identifier for the Thrift
* element type and the second element of the JSON array being the count of
* the Thrift elements. The Thrift elements then follow.
*
* 7. Thrift maps are represented as JSON arrays, with the first two elements
* of the JSON array being the string identifiers for the Thrift key type
* and value type, followed by the count of the Thrift pairs, followed by a
* JSON object containing the key-value pairs. Note that JSON keys can only
* be strings, which means that the key type of the Thrift map should be
* restricted to numeric or string types -- in the case of numerics, they
* are serialized as strings.
*
* 8. Thrift messages are represented as JSON arrays, with the protocol
* version #, the message name, the message type, and the sequence ID as
* the first 4 elements.
*
* More discussion of the double handling is probably warranted. The aim of
* the current implementation is to match as closely as possible the behavior
* of Java's Double.toString(), which has no precision loss. Implementors in
* other languages should strive to achieve that where possible. I have not
* yet verified whether boost:lexical_cast, which is doing that work for me in
* C++, loses any precision, but I am leaving this as a future improvement. I
* may try to provide a C component for this, so that other languages could
* bind to the same underlying implementation for maximum consistency.
*
* Note further that JavaScript itself is not capable of representing
* floating point infinities -- presumably when we have a JavaScript Thrift
* client, this would mean that infinities get converted to not-a-number in
* transmission. I don't know of any work-around for this issue.
*
*/
class TJSONProtocol : public TVirtualProtocol<TJSONProtocol> {
public:
TJSONProtocol(boost::shared_ptr<TTransport> ptrans);
~TJSONProtocol();
private:
void pushContext(boost::shared_ptr<TJSONContext> c);
void popContext();
protected:
uint32_t writeJSONEscapeChar(uint8_t ch);
uint32_t writeJSONChar(uint8_t ch);
uint32_t writeJSONString(const std::string &str);
uint32_t writeJSONBase64(const std::string &str);
template <typename NumberType>
uint32_t writeJSONInteger(NumberType num);
uint32_t writeJSONBool(bool value);
uint32_t writeJSONDouble(double num);
uint32_t writeJSONObjectStart() ;
uint32_t writeJSONObjectEnd();
uint32_t writeJSONArrayStart();
uint32_t writeJSONArrayEnd();
uint32_t readJSONSyntaxChar(uint8_t ch);
uint32_t readJSONEscapeChar(uint8_t *out);
uint32_t readJSONString(std::string &str, bool skipContext = false);
uint32_t readJSONBase64(std::string &str);
uint32_t readJSONNumericChars(std::string &str);
template <typename NumberType>
uint32_t readJSONInteger(NumberType &num);
uint32_t readJSONDouble(double &num);
uint32_t readJSONObjectStart();
uint32_t readJSONObjectEnd();
uint32_t readJSONArrayStart();
uint32_t readJSONArrayEnd();
public:
/**
* Writing functions.
*/
uint32_t writeMessageBegin(const std::string& name,
const TMessageType messageType,
const int32_t seqid);
uint32_t writeMessageEnd();
uint32_t writeStructBegin(const char* name);
uint32_t writeStructEnd();
uint32_t writeFieldBegin(const char* name,
const TType fieldType,
const int16_t fieldId);
uint32_t writeFieldEnd();
uint32_t writeFieldStop();
uint32_t writeMapBegin(const TType keyType,
const TType valType,
const uint32_t size);
uint32_t writeMapEnd();
uint32_t writeListBegin(const TType elemType,
const uint32_t size);
uint32_t writeListEnd();
uint32_t writeSetBegin(const TType elemType,
const uint32_t size);
uint32_t writeSetEnd();
uint32_t writeBool(const bool value);
uint32_t writeByte(const int8_t byte);
uint32_t writeI16(const int16_t i16);
uint32_t writeI32(const int32_t i32);
uint32_t writeI64(const int64_t i64);
uint32_t writeDouble(const double dub);
uint32_t writeString(const std::string& str);
uint32_t writeBinary(const std::string& str);
/**
* Reading functions
*/
uint32_t readMessageBegin(std::string& name,
TMessageType& messageType,
int32_t& seqid);
uint32_t readMessageEnd();
uint32_t readStructBegin(std::string& name);
uint32_t readStructEnd();
uint32_t readFieldBegin(std::string& name,
TType& fieldType,
int16_t& fieldId);
uint32_t readFieldEnd();
uint32_t readMapBegin(TType& keyType,
TType& valType,
uint32_t& size);
uint32_t readMapEnd();
uint32_t readListBegin(TType& elemType,
uint32_t& size);
uint32_t readListEnd();
uint32_t readSetBegin(TType& elemType,
uint32_t& size);
uint32_t readSetEnd();
uint32_t readBool(bool& value);
// Provide the default readBool() implementation for std::vector<bool>
using TVirtualProtocol<TJSONProtocol>::readBool;
uint32_t readByte(int8_t& byte);
uint32_t readI16(int16_t& i16);
uint32_t readI32(int32_t& i32);
uint32_t readI64(int64_t& i64);
uint32_t readDouble(double& dub);
uint32_t readString(std::string& str);
uint32_t readBinary(std::string& str);
class LookaheadReader {
public:
LookaheadReader(TTransport &trans) :
trans_(&trans),
hasData_(false) {
}
uint8_t read() {
if (hasData_) {
hasData_ = false;
}
else {
trans_->readAll(&data_, 1);
}
return data_;
}
uint8_t peek() {
if (!hasData_) {
trans_->readAll(&data_, 1);
}
hasData_ = true;
return data_;
}
private:
TTransport *trans_;
bool hasData_;
uint8_t data_;
};
private:
TTransport* trans_;
std::stack<boost::shared_ptr<TJSONContext> > contexts_;
boost::shared_ptr<TJSONContext> context_;
LookaheadReader reader_;
};
/**
* Constructs input and output protocol objects given transports.
*/
class TJSONProtocolFactory : public TProtocolFactory {
public:
TJSONProtocolFactory() {}
virtual ~TJSONProtocolFactory() {}
boost::shared_ptr<TProtocol> getProtocol(boost::shared_ptr<TTransport> trans) {
return boost::shared_ptr<TProtocol>(new TJSONProtocol(trans));
}
};
}}} // apache::thrift::protocol
// TODO(dreiss): Move part of ThriftJSONString into a .cpp file and remove this.
#include "thrift/lib/cpp/transport/TBufferTransports.h"
/*namespace apache { namespace thrift {
template<typename ThriftStruct>
std::string ThriftJSONString(const ThriftStruct& ts) {
using namespace apache::thrift::transport;
using namespace apache::thrift::protocol;
TMemoryBuffer* buffer = new TMemoryBuffer;
boost::shared_ptr<TTransport> trans(buffer);
TJSONProtocol protocol(trans);
ts.write(&protocol);
uint8_t* buf;
uint32_t size;
buffer->getBuffer(&buf, &size);
return std::string((char*)buf, (unsigned int)size);
}
}} // apache::thrift
*/
#endif // #define THRIFT_PROTOCOL_TJSONPROTOCOL_H_ 1