px4-firmware/apps/systemlib/bson/tinybson.h

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 /**
 * @file tinybson.h
 *
 * A simple subset SAX-style BSON parser and generator. See http://bsonspec.org
 *
 * Some types and defines taken from the standalone BSON parser/generator 
 * in the Mongo C connector.
 */

#ifndef _TINYBSON_H
#define _TINYBSON_H

#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>

/** subset of the BSON node types we might care about */
typedef enum {
	BSON_EOO = 0,
	BSON_DOUBLE = 1,
	BSON_STRING = 2,
	BSON_OBJECT = 3,
	BSON_ARRAY = 4,
	BSON_BINDATA = 5,
	BSON_UNDEFINED = 6,
	BSON_BOOL = 8,
	BSON_DATE = 9,
	BSON_NULL = 10,
	BSON_INT = 16,
	BSON_TIMESTAMP = 17,
	BSON_LONG = 18
} bson_type_t;

typedef enum bson_binary_subtype {
	BSON_BIN_BINARY = 0,
	BSON_BIN_USER = 128
} bson_binary_subtype_t;

/**
 * Maximum node name length.
 */
#define BSON_MAXNAME		32

/**
 * Node structure passed to the callback.
 */
typedef struct bson_node_s
{
	char			name[BSON_MAXNAME];
	bson_type_t		type;
	bson_binary_subtype_t	subtype;
	union {
		int32_t		i;
		double		d;
		bool		b;
	};
} *bson_node_t;

typedef struct bson_decoder_s *bson_decoder_t;

/**
 * Node callback.
 */
typedef int	(* bson_decoder_callback)(bson_decoder_t decoder, void *private, bson_node_t node);

struct bson_decoder_s
{
	int			fd;
	bson_decoder_callback	callback;
	void			*private;
	unsigned		nesting;
	struct bson_node_s	node;
	int32_t			pending;
};

/**
 * Initialise the decoder.
 *
 * @param decoder		Decoder state structure to be initialised.
 * @param fd			File to read BSON data from.
 * @param callback		Callback to be invoked by bson_decoder_next
 * @param private		Callback private data, stored in node.
 * @return			Zero on success.
 */
__EXPORT int bson_decoder_init(bson_decoder_t decoder, int fd, bson_decoder_callback callback, void *private);

/**
 * Process the next node from the stream and invoke the callback.
 *
 * @param decoder		Decoder state, must have been initialised with bson_decoder_init.
 * @return			-1 if parsing encountered an error, 0 if the BSON stream has ended,
 *				otherwise the return value from the callback.
 */
__EXPORT int bson_decoder_next(bson_decoder_t decoder);

/**
 * Copy node data.
 *
 * @param decoder		Decoder state, must have been initialised with bson_decoder_init.
 */
__EXPORT int bson_decoder_copy_data(bson_decoder_t decoder, void *buf);

/**
 * Report copyable data size.
 *
 * @param decoder		Decoder state, must have been initialised with bson_decoder_init.
 */
__EXPORT size_t bson_decoder_data_pending(bson_decoder_t decoder);

/**
 * Encoder state structure.
 */
typedef struct bson_encoder_s
{
	int		fd;

} *bson_encoder_t;

/**
 * Initialze the encoder.
 */
__EXPORT int bson_encoder_init(bson_encoder_t encoder, int fd);

/**
 * Finalise the encoded stream.
 */
__EXPORT int bson_encoder_fini(bson_encoder_t encoder);

/**
 * Append an integer to the encoded stream.
 */
__EXPORT int bson_encoder_append_int(bson_encoder_t encoder, const char *name, int32_t value);

/**
 * Append a double to the encoded stream
 */
__EXPORT int bson_encoder_append_double(bson_encoder_t encoder, const char *name, double value);

/** 
 * Append a string to the encoded stream.
 */
__EXPORT int bson_encoder_append_string(bson_encoder_t encoder, const char *name, const char *string);

/**
 * Append a binary blob to the encoded stream.
 */
__EXPORT int bson_encoder_append_binary(bson_encoder_t encoder, const char *name, bson_binary_subtype_t subtype, size_t size, const void *data);


#endif