CQDB: CQDB Reader API

The memory-passing interface has several advantages. Firstly, one can choose an efficient way for their application to load a database image to a memory block, e.g., to read the whole image from a file, to use the Memory Mapped File (mmap) API, etc. Secondaly, one can design the file format freely only if the memory block for a database is extracted from the file.

The most fundamental operation on the CQDB reader API is forward lookup through the use of cqdb_to_id() function, which retrieves integer identifiers from strings. Reverse lookup (retrieving strings from integer identifiers) with cqdb_to_string() function is not supported if the database has been created with CQDB_ONEWAY flag.


Typedefs
typedef tag_cqdb	cqdb_t
	Typedef of a CQDB reader.
Functions
cqdb_t *	cqdb_reader (void *buffer, size_t size)
	Open a new CQDB reader on a memory block.
void	cqdb_delete (cqdb_t *db)
	Delete the CQDB reader.
int	cqdb_to_id (cqdb_t db, const char str)
	Retrieve the identifier associated with a string.
const char *	cqdb_to_string (cqdb_t *db, int id)
	Retrieve the string associated with an identifier.
int	cqdb_num (cqdb_t *db)
	Get the number of associations in the database.

Function Documentation

void cqdb_delete ( cqdb_t * db )

Delete the CQDB reader.

This function frees the work area allocated by cqdb_reader() function.

Parameters:

The pointer to the cqdb_t instance.

int cqdb_num ( cqdb_t * db )

Get the number of associations in the database.

This function returns the number of associations in the database.

Parameters:

The pointer to the cqdb_t instance.

Return values:

int

The number of string/identifier associations.

cqdb_t* cqdb_reader	(	void *	buffer,
		size_t	size
	)

Open a new CQDB reader on a memory block.

This function initializes a database on a memory block and returns the pointer to a cqdb_t instance to access the database.

Parameters:

	buffer	The pointer to the memory block.
	size	The size of the memory block.

Return values:

cqdb_t*

The pointer to the cqdb_t instance.

int cqdb_to_id	(	cqdb_t *	db,
		const char *	str
	)

Retrieve the identifier associated with a string.

This function returns the identifier associated with a string.

Parameters:

	db	The pointer to the cqdb_t instance.
	str	The pointer to a string.

Return values:

int

The non-negative identifier if successful, negative status code otherwise.

const char* cqdb_to_string	(	cqdb_t *	db,
		int	id
	)

Retrieve the string associated with an identifier.

This function returns the string associated with an identifier.

Parameters:

	db	The pointer to the cqdb_t instance.
	id	The id.

Return values:

const char* The pointer to the string associated with the identifier if successful; otherwise NULL.

CQDB Reader API

Detailed Description

Typedefs

Functions

Function Documentation