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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_Generic_hh__
#define avro_Generic_hh__
#include <boost/utility.hpp>
#include "Config.hh"
#include "Types.hh"
#include "Encoder.hh"
#include "Decoder.hh"
#include "GenericDatum.hh"
namespace avro {
/**
* A utility class to read generic datum from decoders.
*/
class AVRO_DECL GenericReader : boost::noncopyable {
const ValidSchema schema_;
const bool isResolving_;
const DecoderPtr decoder_;
static void read(GenericDatum& datum, Decoder& d, bool isResolving);
public:
/**
* Constructs a reader for the given schema using the given decoder.
*/
GenericReader(const ValidSchema& s, const DecoderPtr& decoder);
/**
* Constructs a reader for the given reader's schema \c readerSchema
* using the given
* decoder which holds data matching writer's schema \c writerSchema.
*/
GenericReader(const ValidSchema& writerSchema,
const ValidSchema& readerSchema, const DecoderPtr& decoder);
/**
* Reads a value off the decoder.
*/
void read(GenericDatum& datum) const;
/**
* Drains any residual bytes in the input stream (e.g. because
* reader's schema has no use of them) and return unused bytes
* back to the underlying input stream.
*/
void drain() {
decoder_->drain();
}
/**
* Reads a generic datum from the stream, using the given schema.
*/
static void read(Decoder& d, GenericDatum& g);
/**
* Reads a generic datum from the stream, using the given schema.
*/
static void read(Decoder& d, GenericDatum& g, const ValidSchema& s);
};
/**
* A utility class to write generic datum to encoders.
*/
class AVRO_DECL GenericWriter : boost::noncopyable {
const ValidSchema schema_;
const EncoderPtr encoder_;
static void write(const GenericDatum& datum, Encoder& e);
public:
/**
* Constructs a writer for the given schema using the given encoder.
*/
GenericWriter(const ValidSchema& s, const EncoderPtr& encoder);
/**
* Writes a value onto the encoder.
*/
void write(const GenericDatum& datum) const;
/**
* Writes a generic datum on to the stream.
*/
static void write(Encoder& e, const GenericDatum& g);
/**
* Writes a generic datum on to the stream, using the given schema.
* Retained for backward compatibility.
*/
static void write(Encoder& e, const GenericDatum& g, const ValidSchema&) {
write(e, g);
}
};
template <typename T> struct codec_traits;
/**
* Specialization of codec_traits for Generic datum along with its schema.
* This is maintained for compatibility with old code. Please use the
* cleaner codec_traits<GenericDatum> instead.
*/
template <> struct codec_traits<std::pair<ValidSchema, GenericDatum> > {
/** Encodes */
static void encode(Encoder& e,
const std::pair<ValidSchema, GenericDatum>& p) {
GenericWriter::write(e, p.second, p.first);
}
/** Decodes */
static void decode(Decoder& d, std::pair<ValidSchema, GenericDatum>& p) {
GenericReader::read(d, p.second, p.first);
}
};
/**
* Specialization of codec_traits for GenericDatum.
*/
template <> struct codec_traits<GenericDatum> {
/** Encodes */
static void encode(Encoder& e, const GenericDatum& g) {
GenericWriter::write(e, g);
}
/** Decodes */
static void decode(Decoder& d, GenericDatum& g) {
GenericReader::read(d, g);
}
};
} // namespace avro
#endif
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