Collaboration diagram for Codec interface:

Data Structures
struct	VOLK_Codec
	Prototype for initializing a dataset decoding loop. More...

Macros
#define	CHUNK_SIZE 4096

Typedefs
typedef VOLK_rc(*	decode_ds_fn_t) (FILE fh, const char sh, VOLK_Store store, void udata, size_t ct, char *err_p)
	Prototype for decoding a dataset.
typedef VOLK_rc(*	decode_gr_fn_t) (FILE fh, const char sh, VOLK_Graph gr, size_t ct, char **err)
	Prototype for decoding a complete RDF document file into a graph.
typedef VOLK_rc(*	decode_term_fn_t) (const char rep, VOLK_Term *term)
	Prototype for decoding a string into a VOLK_Term.
typedef void(*	encode_ds_done_fn_t) (void *it)
	Finalize a dataset encoding operation.
typedef void (	encode_ds_init_fn_t) (const VOLK_Graph **dset)
	Initialize a dataset encoding loop.
typedef VOLK_rc(*	encode_ds_iter_fn_t) (void it, const VOLK_Graph gr, char **res)
	Perform one dataset encoding iteration.
typedef void(*	encode_gr_done_fn_t) (void *it)
	Finalize a graph encoding operation.
typedef void (	encode_gr_init_fn_t) (const VOLK_Graph gr, void udata)
	Initialize a graph encoding loop.
typedef VOLK_rc(*	encode_gr_iter_fn_t) (void it, char *res)
	Perform one graph encoding iteration.
typedef void(*	encode_store_done_fn_t) (void *it)
	Finalize a store encoding operation.
typedef void (	encode_store_init_fn_t) (VOLK_Store *store)
	Initialize a store encoding loop.
typedef VOLK_rc(*	encode_store_iter_fn_t) (void it, char *res)
	Perform one store encoding iteration.
typedef VOLK_rc(*	encode_term_fn_t) (const VOLK_Term term, char *rep)
	Term encoder prototype.

Enumerations
enum	VOLK_CodecFeatures { VOLK_CODEC_FEAT_ENCODE_TERM = 1<<0 , VOLK_CODEC_FEAT_DECODE_TERM = 1<<1 , VOLK_CODEC_FEAT_ENCODE_GR = 1<<2 , VOLK_CODEC_FEAT_DECODE_GR = 1<<3 , VOLK_CODEC_FEAT_ENCODE_DS = 1<<4 , VOLK_CODEC_FEAT_DECODE_DS = 1<<5 , VOLK_CODEC_FEAT_ENCODE_STORE = 1<<6 , VOLK_CODEC_FEAT_DECODE_STORE = 1<<7 }
	Feature flags applicable to a codec. More...
enum	VOLK_CodecFlags { VOLK_CODEC_NO_PROLOG = 1<<0 , CODEC_EXT_TXN = 1<<1 , VOLK_CODEC_INDENT = 1<<2 }
	Parse error information. More...

Functions
VOLK_rc	escape_lit (const char in, char *out)
	Add escape character (backslash) to illegal literal characters.
char *	fmt_header (char *pfx)
	Format an informational header.
uint8_t *	uint8_dup (const uint8_t *str)
	strdup() for unsigned char.
uint8_t *	uint8_ndup (const uint8_t *str, size_t size)
	strndup() for unsigned char.
char	unescape_char (const char c)
	Unescape a single character.
uint8_t *	unescape_unicode (const uint8_t *esc_str, size_t size)
	Replace \uxxxx and \Uxxxxxxxx with Unicode bytes.

Detailed Description

Macro Definition Documentation

◆ CHUNK_SIZE

#define CHUNK_SIZE 4096

Max data size passed to the scanner and parser at each iteration.

Definition at line 78 of file codec_interface.h.

Typedef Documentation

◆ decode_ds_fn_t

typedef VOLK_rc(* decode_ds_fn_t) (FILE *fh, const char *sh, VOLK_Store *store, void *udata, size_t *ct, char **err_p)

Prototype for decoding a dataset.

Parameters

[in]	fh	Open file handle pointing to the RDF data. Implementations MUST NOT close the file handle. This is mutually exclusive with sh.
[in]	sh	string handle for the RDF data. This is mutually exclusive with fh. If both are specified, fh has precedence.
[in]	Store	handle to be populated. The store MUST be initialized and MAY be not empty.
[in]	udata	User data that may be used by implementations.
[out]	ct	Handle to be populated with the count of parsed triples. It MAY be NULL.
[out]	err	Handle to be populated with the error message in case of error.

Returns: Pointer to opaque data to be passed to #decode_ds_iter_fn_t and #decode_ds_done_fn_t.

Definition at line 462 of file codec_interface.h.

◆ decode_gr_fn_t

typedef VOLK_rc(* decode_gr_fn_t) (FILE *fh, const char *sh, VOLK_Graph *gr, size_t *ct, char **err)

Prototype for decoding a complete RDF document file into a graph.

Implementations SHOULD consume data from the file handle in chunks and MAY read a string handle .

Parameters

[in]	fh	Open file handle pointing to the RDF data. Implementations MUST NOT close the file handle. This is exclusive with sh.
[in]	sh	string handle for the RDF data. This is exclusive with fh. If both are specified, fh has precedence.
[out]	gr	Graph handle to be populated with decoded data. The graph MUST be initialized and MAY be non-empty.
[out]	ct	If not NULL, it MAY be populated with the number of triples parsed (which may be different from the resulting graph size). Implementations MAY choose not not use this.
[out]	err	Pointer to error info string. If no error occurs, it yields NULL.

Returns: Implementations MUST return VOLK_OK on success and a negative value on parsing error.

Definition at line 436 of file codec_interface.h.

◆ decode_term_fn_t

typedef VOLK_rc(* decode_term_fn_t) (const char *rep, VOLK_Term **term)

Prototype for decoding a string into a VOLK_Term.

Implementations MAY ignore any other tokens after finding the first one.

Parameters

[in]	rep	NT representation of the term.
[out]	RDF term and triple module	Pointer to the term handle to be created. Implementaions SHOULD return NULL on a parse error.

Returns: Implementations MUST return VOLK_OK on success and a negative value on parsing error.

Definition at line 409 of file codec_interface.h.

◆ encode_ds_done_fn_t

typedef void(* encode_ds_done_fn_t) (void *it)

Finalize a dataset encoding operation.

TODO not implemented in any of the current codecs.

Implementations SHOULD use this function to perform all necessary steps to clean up memory and free the iterator handle after a graph has been completely encoded.

Parameters

[in] it Iterator handle.

Definition at line 346 of file codec_interface.h.

◆ encode_ds_init_fn_t

typedef void *(* encode_ds_init_fn_t) (const VOLK_Graph **dset)

Initialize a dataset encoding loop.

TODO not implemented in any of the current codecs.

This prototype is to be implemented by dataset encoding loops. A dataset source is defined as a number of named graphs that get passed one at a time to encode_ds_iter_fn_t after this function is called. Each graph is encoded into the same document that gets output in chunks as a single stream.

Returns: A void pointer to be passed to a encode_gr_iter_fn_t function and, eventually, to a encode_gr_done_fn_t function. The data structure of the pointer is defined by each codec according to its own needs to keep state across iterations.

Definition at line 310 of file codec_interface.h.

◆ encode_ds_iter_fn_t

typedef VOLK_rc(* encode_ds_iter_fn_t) (void *it, const VOLK_Graph *gr, char **res)

Perform one dataset encoding iteration.

Implementations of this prototype MUST perform all the steps to encode one complete graph into an RDF fragment representing that graph.

TODO not implemented in any of the current codecs.

Parameters

[in]	it	Iterator handle.
[out]	res	Handle to be populated with a string obtained from encoding. The output data SHOULD be UTF-8 encoded. This pointer must be initialized (even to NULL) and should be eventually freed by the caller at the end of the loop. Implementations MAY reallocate this memory at each iteration, and users SHOULD expect that memory from a previous iteration may be overwritten with new data.

Returns: VOLK_OK if a new graph was processed; VOLK_END if the end of the loop was reached.

Definition at line 332 of file codec_interface.h.

◆ encode_gr_done_fn_t

typedef void(* encode_gr_done_fn_t) (void *it)

Finalize a graph encoding operation.

Implementations SHOULD use this function to perform all necessary steps to clean up memory and free the iterator handle after a graph has been completely encoded.

Parameters

[in] it Iterator handle.

Definition at line 293 of file codec_interface.h.

◆ encode_gr_init_fn_t

typedef void *(* encode_gr_init_fn_t) (const VOLK_Graph *gr, void *udata)

Initialize a graph encoding loop.

This prototype is to be implemented by graph encoding loops. It should create an iterator and perform all initial setup for finding triples.

Parameters

[in]	gr	The graph to be encoded. The graph's namespace map is used by the codec for namespace prefixing. The graph may only be freed after the loop is finalized.
[in]	udata	Additional data passed to the iterator. Implementations MAY decide whether and how to use this.

Returns: A void pointer to be passed to a encode_gr_iter_fn_t function and, eventually, to a encode_gr_done_fn_t function. The data structure behind the pointer is defined by each codec according to its own needs to keep state across iterations.

Definition at line 260 of file codec_interface.h.

◆ encode_gr_iter_fn_t

typedef VOLK_rc(* encode_gr_iter_fn_t) (void *it, char **res)

Perform one graph encoding iteration.

Implementations of this prototype MUST perform all the steps to encode one or more complete triples into an RDF fragment representing those triples. The input and output units are up to the implementation and a caller SHOULD assume that multiple lines may be yielded at each iteration.

Parameters

[in]	it	Iterator handle.
[out]	res	Handle to be populated with a string obtained from encoding. The output data should be UTF-8 encoded. This pointer must be initialized (even to NULL) and should be eventually freed manually at the end of the loop. Implementations MAY reallocate this memory at each iteration, and users SHOULD expect that memory from a previous iteration may be overwritten with new data.

Returns: VOLK_OK if a new token was processed; VOLK_END if the end of the loop was reached.

Definition at line 282 of file codec_interface.h.

◆ encode_store_done_fn_t

typedef void(* encode_store_done_fn_t) (void *it)

Finalize a store encoding operation.

Parameters

[in] it Iterator handle.

Definition at line 389 of file codec_interface.h.

◆ encode_store_init_fn_t

typedef void *(* encode_store_init_fn_t) (VOLK_Store *store)

Initialize a store encoding loop.

This prototype is to be implemented by codecs featuring language to encode named graphs, such as TriG. Its scope is to encode a whole store.

Parameters

[in] Backend store module Store to encode. The store MUST implement the VOLK_STORE_CTX feature.

Returns: A void pointer to be passed to an encode_store_iter_fn_t function and, eventually, to an encode_store_done_fn_t function. The data structure of the pointer is defined by each codec according to its own needs to keep state across iterations.

Definition at line 362 of file codec_interface.h.

◆ encode_store_iter_fn_t

typedef VOLK_rc(* encode_store_iter_fn_t) (void *it, char **res)

Perform one store encoding iteration.

This function generates a chunk of RDF as a string. The scope of the RDF contained in the string is left to the implementation.

Parameters

[in]	it	Iterator handle created with encode_store_init_fn_t().
[out]	res	Handle to be populated with a string obtained from encoding. The output data MUST be UTF-8 encoded. This pointer MUST be initialized (even to NULL) and should be eventually freed by the caller at the end of the loop. Implementations MAY reallocate this memory at each iteration, and users SHOULD expect that memory from a previous iteration may be overwritten with new data.

Returns: VOLK_OK if a new graph was processed; VOLK_END if the end of the loop was reached.

Definition at line 382 of file codec_interface.h.

◆ encode_term_fn_t

typedef VOLK_rc(* encode_term_fn_t) (const VOLK_Term *term, char **rep)

Term encoder prototype.

Parameters

[in]	RDF term and triple module	Single term handle.
[out]	rep	Pointer to a string to be filled with the encoded term. The string is reallocated and, if reused for multiple calls to this function, it only needs to be freed after the last call. It MUST be initialized to NULL at the beginning.

Returns: VOLK_OK on successful encoding; <0 for other errors.

Definition at line 240 of file codec_interface.h.

Enumeration Type Documentation

◆ VOLK_CodecFeatures

enum VOLK_CodecFeatures

Feature flags applicable to a codec.

Enumerator
VOLK_CODEC_FEAT_ENCODE_TERM	Supports encoding a single term.
VOLK_CODEC_FEAT_DECODE_TERM	Supports decoding a single term.
VOLK_CODEC_FEAT_ENCODE_GR	Supports encoding a graph.
VOLK_CODEC_FEAT_DECODE_GR	Supports decoding a graph.
VOLK_CODEC_FEAT_ENCODE_DS	Supports encoding a data set.
VOLK_CODEC_FEAT_DECODE_DS	Supports decoding a data set.
VOLK_CODEC_FEAT_ENCODE_STORE	Supports encoding a whole store.
VOLK_CODEC_FEAT_DECODE_STORE	Supports decoding a whole store.

Definition at line 104 of file codec_interface.h.

◆ VOLK_CodecFlags

enum VOLK_CodecFlags

Parse error information.

Option flags passed to codec function calls.

Enumerator
VOLK_CODEC_NO_PROLOG	Do not generate prolog.
CODEC_EXT_TXN	The iterator is using an externally provided transaction that must not be freed. This is set internally.
VOLK_CODEC_INDENT	Indent each output line by four spaces. Used by TTL writer when encoding a graph for TriG.

Definition at line 93 of file codec_interface.h.

Function Documentation

◆ escape_lit()

VOLK_rc escape_lit	(	const char *	in,
		char **	out )

Add escape character (backslash) to illegal literal characters.

Parameters

[in]	in	Input string.
[out]	out	Output string.

Returns: VOLK_OK on success; VOLK_MEM_ERR on memory error.

Definition at line 81 of file codec_interface.c.

◆ fmt_header()

char * fmt_header ( char * pfx )

Format an informational header.

The information includes software version and current date. It is terminated by a newline + NUL and prefixed with the string specified in pfx. It is NOT prefixed by any comment characters.

Parameters

[in] pfx Prefix to add to the string. It may be a comment starter, such as # .

Definition at line 116 of file codec_interface.c.

◆ uint8_dup()

uint8_t * uint8_dup ( const uint8_t * str )

inline

strdup() for unsigned char.

This is to be used with uint8_t sequences considered to be UTF-8 sequences, requird by re2c (it won't work with byte sequences containing NUL).

Definition at line 128 of file codec_interface.h.

◆ uint8_ndup()

uint8_t * uint8_ndup	(	const uint8_t *	str,
		size_t	size )

inline

strndup() for unsigned char.

This is to be used with uint8_t sequences considered to be UTF-8 sequences, requird by re2c (it won't work with byte sequences containing NUL).

Definition at line 138 of file codec_interface.h.

◆ unescape_char()

char unescape_char ( const char c )

inline

Unescape a single character.

Convert escaped special characters such as \t, \n, etc. into their corresponding code points.

Non-special characters are returned unchanged.

Parameters

[in] c Character to unescape. Note that this is the single character after \\endiskip.

Returns: Code point corresponding to the escaped character.

Definition at line 184 of file codec_interface.h.

◆ unescape_unicode()

uint8_t * unescape_unicode	(	const uint8_t *	esc_str,
		size_t	size )

Replace \uxxxx and \Uxxxxxxxx with Unicode bytes.

Parameters

[in]	esc_str	Escaped string.
[in]	size	Maximum number of characters to scan, à la strncpy().

Returns: String with escape sequences replaced by Unicode bytes.

Definition at line 11 of file codec_interface.c.

Volksdata 1.0b7 RDF library

Data Structures

Macros

Typedefs

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ CHUNK_SIZE

Typedef Documentation

◆ decode_ds_fn_t

◆ decode_gr_fn_t

◆ decode_term_fn_t

◆ encode_ds_done_fn_t

◆ encode_ds_init_fn_t

◆ encode_ds_iter_fn_t

◆ encode_gr_done_fn_t

◆ encode_gr_init_fn_t

◆ encode_gr_iter_fn_t

◆ encode_store_done_fn_t

◆ encode_store_init_fn_t

◆ encode_store_iter_fn_t

◆ encode_term_fn_t

Enumeration Type Documentation

◆ VOLK_CodecFeatures

◆ VOLK_CodecFlags

Function Documentation

◆ escape_lit()

◆ fmt_header()

◆ uint8_dup()

◆ uint8_ndup()

◆ unescape_char()

◆ unescape_unicode()