General library facilities

## General library facilities General library facilities — Startup and shutdown, memory handling, version checks and misc functions. |

## Synopsis

    typedef             rasqal_world;
    void                rasqal_free_world                   (rasqal_world *world);
    rasqal_world *      rasqal_new_world                    (void);
    int                 rasqal_world_open                   (rasqal_world *world);
    void                rasqal_world_set_log_handler        (rasqal_world *world,
                                                             void *user_data,
                                                             raptor_log_handler handler);
    int                 rasqal_world_set_warning_level      (rasqal_world *world,
                                                             unsigned int warning_level);
    raptor_world *      rasqal_world_get_raptor             (rasqal_world *world);
    void                rasqal_world_set_raptor             (rasqal_world *world,
                                                             raptor_world *raptor_world_ptr);
    const raptor_syntax_description * rasqal_world_get_query_language_description
                                                            (rasqal_world *world,
                                                             unsigned int counter);
    const raptor_syntax_description * rasqal_world_get_query_results_format_description
                                                            (rasqal_world *world,
                                                             unsigned int counter);
    char *              (*rasqal_generate_bnodeid_handler)  (rasqal_world *world,
                                                             void *user_data,
                                                             unsigned char *user_bnodeid);
    int                 rasqal_world_set_generate_bnodeid_handler
                                                            (rasqal_world *world,
                                                             void *user_data,
                                                             rasqal_generate_bnodeid_handler handler);
    int                 rasqal_world_set_default_generate_bnodeid_parameters
                                                            (rasqal_world *world,
                                                             char *prefix,
                                                             int base);
    const char *        rasqal_world_guess_query_results_format_name
                                                            (rasqal_world *world,
                                                             raptor_uri *uri,
                                                             const char *mime_type,
                                                             const char *buffer,
                                                             size_t len,
                                                             const unsigned char *identifier);
    extern const unsigned int rasqal_version_decimal;
    extern const unsigned int rasqal_version_major;
    extern const unsigned int rasqal_version_minor;
    extern const unsigned int rasqal_version_release;
    extern const char * const rasqal_version_string;
    extern const char * const rasqal_copyright_string;
    extern const char * const rasqal_short_copyright_string;
    extern const char * const rasqal_home_url_string;
    extern const char * const rasqal_license_string;
    enum                rasqal_feature;
    int                 rasqal_language_name_check          (rasqal_world *world,
                                                             const char *name);
    int                 rasqal_languages_enumerate          (rasqal_world *world,
                                                             unsigned int counter,
                                                             const char **name,
                                                             const char **label,
                                                             const unsigned char **uri_string);
    void *              rasqal_alloc_memory                 (size_t size);
    void *              rasqal_calloc_memory                (size_t nmemb,
                                                             size_t size);
    void                rasqal_free_memory                  (void *ptr);
    rasqal_feature      rasqal_feature_from_uri             (rasqal_world *world,
                                                             raptor_uri *uri);
    int                 rasqal_feature_value_type           (const rasqal_feature feature);
    int                 rasqal_features_enumerate           (rasqal_world *world,
                                                             const rasqal_feature feature,
                                                             const char **name,
                                                             raptor_uri **uri,
                                                             const char **label);
    unsigned int        rasqal_get_feature_count            (void);
    #define             RASQAL_DEPRECATED
    #define             RASQAL_VERSION
    #define             RASQAL_VERSION_MAJOR
    #define             RASQAL_VERSION_MINOR
    #define             RASQAL_VERSION_RELEASE
    #define             RASQAL_VERSION_STRING
    #define             RASQAL_RAPTOR_VERSION

## Description

The functions in this section cover general library features such as startup and shutdown, checking the current library version and dealing with memory allocation and freeing. It also provides functions to enumerate and check the supported query languages, their names, labels and URI.

## Details

### rasqal_world

    rasqal_world* world;

Rasqal world class.

### rasqal_free_world ()

    void                rasqal_free_world                   (rasqal_world *world);

Terminate the rasqal library.

Destroys a rasqal_world object and all static information.

`world` : | rasqal_world object

### rasqal_new_world ()

    rasqal_world *      rasqal_new_world                    (void);

Allocate a new rasqal_world object.

The rasqal_world is initialized with `rasqal_world_open()`. Allocation and initialization are decoupled to allow changing settings on the world object before init.

Returns : | rasqal_world object or NULL on failure

### rasqal_world_open ()

    int                 rasqal_world_open                   (rasqal_world *world);

Initialise the rasqal library.

Initializes a rasqal_world object created by `rasqal_new_world()`. Allocation and initialization are decoupled to allow changing settings on the world object before init. These settings include e.g. the raptor library instance set with `rasqal_world_set_raptor()`.

The initialized world object is used with subsequent rasqal API calls.

`world` : | rasqal_world object
Returns : | non-0 on failure

### rasqal_world_set_log_handler ()

    void                rasqal_world_set_log_handler        (rasqal_world *world,
                                                             void *user_data,
                                                             raptor_log_handler handler);

Set the log handler for this rasqal_world.

Also sets the raptor log handler to the same `user_data` and `handler` via `raptor_world_set_log_handler()`. (Rasqal 0.9.26+)

`world` : | rasqal_world object
`user_data` : | user data for log handler function
`handler` : | log handler function

### rasqal_world_set_warning_level ()

    int                 rasqal_world_set_warning_level      (rasqal_world *world,
                                                             unsigned int warning_level);

Set the rasqal warning reporting level

The warning levels used are as follows:

1. Level 10 is used for serious warnings that may be errors.

2. Level 30 is used for moderate style warnings.

3. Level 90 is used for strict conformance warnings.

When this method is called to set a warning level, only warnings of less than `warning_level` are reported. The default warning level is 50.

`world` : | world
`warning_level` : | warning level 0..100
Returns : | non-0 on failure

### rasqal_world_get_raptor ()

    raptor_world *      rasqal_world_get_raptor             (rasqal_world *world);

Get the raptor_world instance used by this rasqal_world.

`world` : | rasqal_world object
Returns : | raptor_world object or NULL on failure (e.g. not initialized)

### rasqal_world_set_raptor ()

    void                rasqal_world_set_raptor             (rasqal_world *world,
                                                             raptor_world *raptor_world_ptr);

Set the raptor_world instance to be used with this rasqal_world.

If no raptor_world instance is set with this function, `rasqal_world_open()` creates a new instance.

Ownership of the raptor_world is not taken. If the raptor library instance is set with this function, `rasqal_free_world()` will not free it.

`world` : | rasqal_world object
`raptor_world_ptr` : | raptor_world object

### rasqal_world_get_query_language_description ()

    const raptor_syntax_description * rasqal_world_get_query_language_description
                                                            (rasqal_world *world,
                                                             unsigned int counter);

Get query language descriptive information

`world` : | world object
`counter` : | index into the list of query languages
Returns : | description or NULL if counter is out of range

### rasqal_world_get_query_results_format_description ()

    const raptor_syntax_description * rasqal_world_get_query_results_format_description
                                                            (rasqal_world *world,
                                                             unsigned int counter);

Get query result format descriptive syntax information

`world` : | world object
`counter` : | index into the list of query result formats
Returns : | description or NULL if counter is out of range

### rasqal_generate_bnodeid_handler ()

    char *              (*rasqal_generate_bnodeid_handler)  (rasqal_world *world,
                                                             void *user_data,
                                                             unsigned char *user_bnodeid);

User handler used with `rasqal_world_set_generate_bnodeid_handler()` to set method for generating a blank node ID.

`world` : | world arg
`user_data` : | user data given to
`user_bnodeid` : | user blank node ID string passed in
Returns : | blank node ID string or NULL on failure.

### rasqal_world_set_generate_bnodeid_handler ()

    int                 rasqal_world_set_generate_bnodeid_handler
                                                            (rasqal_world *world,
                                                             void *user_data,
                                                             rasqal_generate_bnodeid_handler handler);

Set the generate blank node ID handler function

Sets the function to generate blank node IDs. The handler is called with a pointer to the rasqal_world, the `user_data` pointer and a user_bnodeid which is the value of a user-provided blank node identifier (may be NULL). It can either be returned directly as the generated value when present or modified. The passed in value must be `free()`d if it is not used.

If handler is NULL, the default method is used

`world` : | rasqal_world object
`user_data` : | user data pointer for callback
`handler` : | generate blank ID callback function
Returns : | non-0 on failure

### rasqal_world_set_default_generate_bnodeid_parameters ()

    int                 rasqal_world_set_default_generate_bnodeid_parameters
                                                            (rasqal_world *world,
                                                             char *prefix,
                                                             int base);

Set default bnodeid generation parameters

Sets the parameters for the default algorithm used to generate blank node IDs. The default algorithm uses both `prefix` and `base` to generate a new identifier. The exact identifier generated is not guaranteed to be a strict concatenation of `prefix` and `base` but will use both parts.

For finer control of the generated identifiers, use `rasqal_world_set_generate_bnodeid_handler()`

If prefix is NULL, the default prefix is used (currently "bnodeid") If base is less than 1, it is initialised to 1.

`world` : | rasqal_world object
`prefix` : | prefix string
`base` : | integer base identifier
Returns : | non-0 on failure

### rasqal_world_guess_query_results_format_name ()

    const char *        rasqal_world_guess_query_results_format_name
                                                            (rasqal_world *world,
                                                             raptor_uri *uri,
                                                             const char *mime_type,
                                                             const char *buffer,
                                                             size_t len,
                                                             const unsigned char *identifier);

Guess a query results format name for content.

Find a query results format by scoring recognition of the syntax by a block of characters, the content identifier or a mime type. The content identifier is typically a filename or URI or some other identifier.

`world` : | world object
`uri` : | URI identifying the syntax (or NULL)
`mime_type` : | mime type identifying the content (or NULL)
`buffer` : | buffer of content to guess (or NULL)
`len` : | length of buffer
`identifier` : | identifier of content (or NULL)
Returns : | a query results format name or NULL if no guess could be made

### rasqal_version_decimal

    extern const unsigned int rasqal_version_decimal;

Rasqal version as a decimal number.

Format: major * 10000 + minor * 100 + release

### rasqal_version_major

    extern const unsigned int rasqal_version_major;

Rasqal major version number.

### rasqal_version_minor

    extern const unsigned int rasqal_version_minor;

Rasqal minor version number.

### rasqal_version_release

    extern const unsigned int rasqal_version_release;

Rasqal release version number.

### rasqal_version_string

    extern const char * const rasqal_version_string;

Rasqal version as a string.

### rasqal_copyright_string

    extern const char * const rasqal_copyright_string;

Copyright string (multiple lines).

### rasqal_short_copyright_string

    extern const char * const rasqal_short_copyright_string;

Short copyright string (one line).

### rasqal_home_url_string

    extern const char * const rasqal_home_url_string;

Rasqal home page URL.

### rasqal_license_string

    extern const char * const rasqal_license_string;

Rasqal license string.

### enum rasqal_feature

    typedef enum {
      RASQAL_FEATURE_NO_NET,
      RASQAL_FEATURE_RAND_SEED,
      RASQAL_FEATURE_LAST = RASQAL_FEATURE_RAND_SEED
    } rasqal_feature;

Query features.

None currently defined.

`RASQAL_FEATURE_NO_NET` | Deny network requests.
`RASQAL_FEATURE_RAND_SEED` | Set `rand()` / `rand_r()` seed
`RASQAL_FEATURE_LAST` | Internal.

### rasqal_language_name_check ()

    int                 rasqal_language_name_check          (rasqal_world *world,
                                                             const char *name);

Check name of a query language.

`world` : | rasqal_world object
`name` : | the query language name
Returns : | non 0 if name is a known query language

### rasqal_languages_enumerate ()

    int                 rasqal_languages_enumerate          (rasqal_world *world,
                                                             unsigned int counter,
                                                             const char **name,
                                                             const char **label,
                                                             const unsigned char **uri_string);

`deprecated`: Use `rasqal_world_get_query_language_description()` instead.

Get information on query languages.

`world` : | rasqal_world object
`counter` : | index into the list of syntaxes
`name` : | pointer to store the name of the syntax (or NULL)
`label` : | pointer to store syntax readable label (or NULL)
`uri_string` : | pointer to store syntax URI string (or NULL)
Returns : | non 0 on failure of if counter is out of range

### rasqal_alloc_memory ()

    void *              rasqal_alloc_memory                 (size_t size);

Allocate memory inside rasqal.

Some systems require memory allocated in a library to be deallocated in that library. This function allows memory to be allocated inside the rasqal shared library that can be freed inside rasqal either internally or via `rasqal_free_memory()`.

`size` : | size of memory to allocate
Returns : | the address of the allocated memory or NULL on failure

### rasqal_calloc_memory ()

    void *              rasqal_calloc_memory                (size_t nmemb,
                                                             size_t size);

Allocate zeroed array of items inside rasqal.

Some systems require memory allocated in a library to be deallocated in that library. This function allows memory to be allocated inside the rasqal shared library that can be freed inside rasqal either internally or via `rasqal_free_memory()`.

`nmemb` : | number of members
`size` : | size of item
Returns : | the address of the allocated memory or NULL on failure

### rasqal_free_memory ()

    void                rasqal_free_memory                  (void *ptr);

Free memory allocated inside rasqal.

Some systems require memory allocated in a library to be deallocated in that library. This function allows memory allocated by rasqal to be freed.

`ptr` : | memory pointer

### rasqal_feature_from_uri ()

    rasqal_feature      rasqal_feature_from_uri             (rasqal_world *world,
                                                             raptor_uri *uri);

Turn a feature URI into an feature enum.

The allowed feature URIs are available via `rasqal_features_enumerate()`.

`world` : | rasqal_world object
`uri` : | feature URI
Returns : | < 0 if the feature is unknown

### rasqal_feature_value_type ()

    int                 rasqal_feature_value_type           (const rasqal_feature feature);

Get the type of a features.

The type of the `feature` is 0=integer , 1=string. Other values are undefined. Most features are integer values and use rasqal_query_set_feature `rasqal_query_get_feature()`

`feature` : | rasqal query feature
Returns : | the type of the feature or <0 if `feature` is unknown

### rasqal_features_enumerate ()

    int                 rasqal_features_enumerate           (rasqal_world *world,
                                                             const rasqal_feature feature,
                                                             const char **name,
                                                             raptor_uri **uri,
                                                             const char **label);

Get list of rasqal features.

If uri is not NULL, a pointer to a new raptor_uri is returned that must be freed by the caller with `raptor_free_uri()`.

`world` : | rasqal_world object
`feature` : | feature enumeration (0+)
`name` : | pointer to store feature short name (or NULL)
`uri` : | pointer to store feature URI (or NULL)
`label` : | pointer to feature label (or NULL)
Returns : | 0 on success, <0 on failure, >0 if feature is unknown

### rasqal_get_feature_count ()

    unsigned int        rasqal_get_feature_count            (void);

Get the count of features defined.

This is prefered to the compile time-only symbol RASQAL_FEATURE_LAST and returns a count of the number of features which is RASQAL_FEATURE_LAST+1.

Returns : | count of features in the rasqal_feature enumeration

### RASQAL_DEPRECATED

    #define RASQAL_DEPRECATED __attribute__((deprecated))

When defined before a function, indicates that the function has been deprecated and may be replaced in a future release. With some versions of gcc this may give a compilation warning.

### RASQAL_VERSION

    #define RASQAL_VERSION 933

Rasqal library version number

Format: major * 10000 + minor * 100 + release

### RASQAL_VERSION_MAJOR

    #define RASQAL_VERSION_MAJOR 0

Rasqal library major version

### RASQAL_VERSION_MINOR

    #define RASQAL_VERSION_MINOR 9

Rasqal library minor version

### RASQAL_VERSION_RELEASE

    #define RASQAL_VERSION_RELEASE 33

Rasqal library release

### RASQAL_VERSION_STRING

    #define RASQAL_VERSION_STRING "0.9.33"

Rasqal library version string

### RASQAL_RAPTOR_VERSION

    #define RASQAL_RAPTOR_VERSION 20015

Version of Raptor that Rasqal was configured against.