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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
*
* https://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 avro_Encoder_hh__
#define avro_Encoder_hh__
#include "Config.hh"
#include <cstdint>
#include <memory>
#include <string>
#include <vector>
#include "Stream.hh"
#include "ValidSchema.hh"
/// \file
///
/// Low level support for encoding avro values.
/// This class has two types of functions. One type of functions support
/// the writing of leaf values (for example, encodeLong and
/// encodeString). These functions have analogs in Decoder.
///
/// The other type of functions support the writing of maps and arrays.
/// These functions are arrayStart, startItem, and arrayEnd
/// (and similar functions for maps).
/// Some implementations of Encoder handle the
/// buffering required to break large maps and arrays into blocks,
/// which is necessary for applications that want to do streaming.
namespace avro {
/**
* The abstract base class for all Avro encoders. The implementations
* differ in the method of encoding (binary versus JSON) or in capabilities
* such as ability to verify the order of invocation of different functions.
*/
class AVRO_DECL Encoder {
public:
virtual ~Encoder() = default;
/// All future encodings will go to os, which should be valid until
/// it is reset with another call to init() or the encoder is
/// destructed.
virtual void init(OutputStream &os) = 0;
/// Flushes any data in internal buffers.
virtual void flush() = 0;
/// Returns the number of bytes produced so far.
/// For a meaningful value, do a flush() before invoking this function.
virtual int64_t byteCount() const = 0;
/// Encodes a null to the current stream.
virtual void encodeNull() = 0;
/// Encodes a bool to the current stream
virtual void encodeBool(bool b) = 0;
/// Encodes a 32-bit int to the current stream.
virtual void encodeInt(int32_t i) = 0;
/// Encodes a 64-bit signed int to the current stream.
virtual void encodeLong(int64_t l) = 0;
/// Encodes a single-precision floating point number to the current stream.
virtual void encodeFloat(float f) = 0;
/// Encodes a double-precision floating point number to the current stream.
virtual void encodeDouble(double d) = 0;
/// Encodes a UTF-8 string to the current stream.
virtual void encodeString(const std::string &s) = 0;
/**
* Encodes arbitrary binary data into the current stream as Avro "bytes"
* data type.
* \param bytes Where the data is
* \param len Number of bytes at \p bytes.
*/
virtual void encodeBytes(const uint8_t *bytes, size_t len) = 0;
/**
* Encodes arbitrary binary data into the current stream as Avro "bytes"
* data type.
* \param bytes The data.
*/
void encodeBytes(const std::vector<uint8_t> &bytes) {
uint8_t b = 0;
encodeBytes(bytes.empty() ? &b : bytes.data(), bytes.size());
}
/// Encodes fixed length binary to the current stream.
virtual void encodeFixed(const uint8_t *bytes, size_t len) = 0;
/**
* Encodes an Avro data type Fixed.
* \param bytes The fixed, the length of which is taken as the size
* of fixed.
*/
void encodeFixed(const std::vector<uint8_t> &bytes) {
encodeFixed(bytes.data(), bytes.size());
}
/// Encodes enum to the current stream.
virtual void encodeEnum(size_t e) = 0;
/// Indicates that an array of items is being encoded.
virtual void arrayStart() = 0;
/// Indicates that the current array of items have ended.
virtual void arrayEnd() = 0;
/// Indicates that a map of items is being encoded.
virtual void mapStart() = 0;
/// Indicates that the current map of items have ended.
virtual void mapEnd() = 0;
/// Indicates that count number of items are to follow in the current array
/// or map.
virtual void setItemCount(size_t count) = 0;
/// Marks a beginning of an item in the current array or map.
virtual void startItem() = 0;
/// Encodes a branch of a union. The actual value is to follow.
virtual void encodeUnionIndex(size_t e) = 0;
};
/**
* Shared pointer to Encoder.
*/
using EncoderPtr = std::shared_ptr<Encoder>;
/**
* Returns an encoder that can encode binary Avro standard.
*/
AVRO_DECL EncoderPtr binaryEncoder();
/**
* Returns an encoder that validates sequence of calls to an underlying
* Encoder against the given schema.
*/
AVRO_DECL EncoderPtr validatingEncoder(const ValidSchema &schema,
const EncoderPtr &base);
/**
* Returns an encoder that encodes Avro standard for JSON.
*/
AVRO_DECL EncoderPtr jsonEncoder(const ValidSchema &schema);
/**
* Returns an encoder that encodes Avro standard for pretty printed JSON.
*/
AVRO_DECL EncoderPtr jsonPrettyEncoder(const ValidSchema &schema);
} // namespace avro
#endif
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