avro::Decoder Class Reference

Decoder is an interface implemented by every decoder capable of decoding Avro data. More...

#include <Decoder.hh>

Inheritance diagram for avro::Decoder:

Public Member Functions
virtual void	init (InputStream &is)=0
	All future decoding will come from is, which should be valid until replaced by another call to init() or this Decoder is destructed.
virtual void	decodeNull ()=0
	Decodes a null from the current stream.
virtual bool	decodeBool ()=0
	Decodes a bool from the current stream.
virtual int32_t	decodeInt ()=0
	Decodes a 32-bit int from the current stream.
virtual int64_t	decodeLong ()=0
	Decodes a 64-bit signed int from the current stream.
virtual float	decodeFloat ()=0
	Decodes a single-precision floating point number from current stream.
virtual double	decodeDouble ()=0
	Decodes a double-precision floating point number from current stream.
std::string	decodeString ()
	Decodes a UTF-8 string from the current stream.
virtual void	decodeString (std::string &value)=0
	Decodes a UTF-8 string from the stream and assigns it to value.
virtual void	skipString ()=0
	Skips a string on the current stream.
std::vector< uint8_t >	decodeBytes ()
	Decodes arbitrary binary data from the current stream.
virtual void	decodeBytes (std::vector< uint8_t > &value)=0
	Decodes arbitrary binary data from the current stream and puts it in value.
virtual void	skipBytes ()=0
	Skips bytes on the current stream.
std::vector< uint8_t >	decodeFixed (size_t n)
	Decodes fixed length binary from the current stream. More...
virtual void	decodeFixed (size_t n, std::vector< uint8_t > &value)=0
	Decodes a fixed from the current stream. More...
virtual void	skipFixed (size_t n)=0
	Skips fixed length binary on the current stream.
virtual size_t	decodeEnum ()=0
	Decodes enum from the current stream.
virtual size_t	arrayStart ()=0
	Start decoding an array. Returns the number of entries in first chunk.
virtual size_t	arrayNext ()=0
	Returns the number of entries in next chunk. 0 if last.
virtual size_t	skipArray ()=0
	Tries to skip an array. More...
virtual size_t	mapStart ()=0
	Start decoding a map. Returns the number of entries in first chunk.
virtual size_t	mapNext ()=0
	Returns the number of entries in next chunk. 0 if last.
virtual size_t	skipMap ()=0
	Tries to skip a map. More...
virtual size_t	decodeUnionIndex ()=0
	Decodes a branch of a union. The actual value is to follow.
virtual void	drain ()=0
	Drains any additional data at the end of the current entry in a stream. More...

Detailed Description

Decoder is an interface implemented by every decoder capable of decoding Avro data.

Member Function Documentation

decodeFixed() [1/2]

std::vector<uint8_t> avro::Decoder::decodeFixed ( size_t  n )

inline

Decodes fixed length binary from the current stream.

Parameters

[in]

n

The size (byte count) of the fixed being read.

Returns

The fixed data that has been read. The size of the returned vector is guaranteed to be equal to n.

Referenced by avro::codec_traits< std::array< uint8_t, N > >::decode().

decodeFixed() [2/2]

virtual void avro::Decoder::decodeFixed ( size_t  n, std::vector< uint8_t > &  value  )

pure virtual

Decodes a fixed from the current stream.

Parameters

[in]	n	The size (byte count) of the fixed being read.
[out]	value	The value that receives the fixed. The vector will be size-adjusted based on the fixed schema's size.

drain()

virtual void avro::Decoder::drain ( )

pure virtual

Drains any additional data at the end of the current entry in a stream.

It also returns any unused bytes back to any underlying input stream. One situation this happens is when the reader's schema and the writer's schema are records but are different and the writer's record has more fields at the end of the record. Leaving such data unread is usually not a problem. If multiple records are stored consecutively in a stream (e.g. Avro data file) any attempt to read the next record will automatically skip those extra fields of the current record. It would still leave the extra fields at the end of the last record in the stream. This would mean that the stream is not in a good state. For example, if some non-avro information is stored at the end of the stream, the consumers of such data would see the bytes left behind by the avro decoder. Similar set of problems occur if the Decoder consumes more than what it should.

skipArray()

virtual size_t avro::Decoder::skipArray ( )

pure virtual

Tries to skip an array.

If it can, it returns 0. Otherwise it returns the number of elements to be skipped. The client should skip the individual items. In such cases, skipArray is identical to arrayStart.

skipMap()

virtual size_t avro::Decoder::skipMap ( )

pure virtual

Tries to skip a map.

If it can, it returns 0. Otherwise it returns the number of elements to be skipped. The client should skip the individual items. In such cases, skipMap is identical to mapStart.

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The documentation for this class was generated from the following file:

• api/Decoder.hh