Variables

Variables — Variable with names and literal value.

Synopsis

                    rasqal_variable;
rasqal_variable *   rasqal_new_variable_from_variable   (rasqal_variable *v);
void                rasqal_free_variable                (rasqal_variable *v);
int                 rasqal_variable_print               (rasqal_variable *v,
                                                         FILE *fh);
void                rasqal_variable_set_value           (rasqal_variable *v,
                                                         rasqal_literal *l);
enum                rasqal_variable_type;

Description

A class to hold a variable with optional name and a rasqal_literal value. The name is not required for SPARQL anonymous variables.

Details

rasqal_variable

typedef struct {
  rasqal_variables_table* vars_table;
  const char * name;
  rasqal_literal* value;
  int offset;
  rasqal_variable_type type;
  struct rasqal_expression_s* expression;
  void *user_data;
  int usage;
} rasqal_variable;

Binding between a variable name and a value.

Includes internal field offset for recording the offset into the (internal) rasqal_query variables array.

rasqal_variables_table *`vars_table`;	variables table that owns this variable
const char *`name`;	Variable name.
rasqal_literal *`value`;	Variable value or NULL if unbound.
int `offset`;	Internal.
rasqal_variable_type `type`;	Variable type.
struct rasqal_expression_s *`expression`;	Expression when the variable is a computed SELECT expression
void *`user_data`;	Pointer to user data associated with a variable. This is not used by rasqal.
int `usage`;	reference count

rasqal_new_variable_from_variable ()

rasqal_variable *   rasqal_new_variable_from_variable   (rasqal_variable *v);

Copy Constructor - Create a new Rasqal variable from an existing one

This adds a new reference to the variable, it does not do a deep copy

`v` :	rasqal_variable to copy
Returns :	a new rasqal_variable or NULL on failure.

rasqal_free_variable ()

void                rasqal_free_variable                (rasqal_variable *v);

Destructor - Destroy a Rasqal variable object.

v :

rasqal_variable object

rasqal_variable_print ()

int                 rasqal_variable_print               (rasqal_variable *v,
                                                         FILE *fh);

Print a Rasqal variable in a debug format.

The print debug format may change in any release.

`v` :	the rasqal_variable object
`fh` :	the FILE* handle to print to
Returns :	non-0 on failure

rasqal_variable_set_value ()

void                rasqal_variable_set_value           (rasqal_variable *v,
                                                         rasqal_literal *l);

Set the value of a Rasqal variable.

The variable value is an input parameter and is copied in, not shared. If the variable value is NULL, any existing value is deleted.

`v` :	the rasqal_variable object
`l` :	the rasqal_literal value to set (or NULL)

enum rasqal_variable_type

typedef enum {
  RASQAL_VARIABLE_TYPE_UNKNOWN   = 0,
  RASQAL_VARIABLE_TYPE_NORMAL    = 1,
  RASQAL_VARIABLE_TYPE_ANONYMOUS = 2
} rasqal_variable_type;

Rasqal variable types.

ANONYMOUS can be used in queries but cannot be returned in a result.

`RASQAL_VARIABLE_TYPE_UNKNOWN`	Internal.
`RASQAL_VARIABLE_TYPE_NORMAL`	The regular variable type.
`RASQAL_VARIABLE_TYPE_ANONYMOUS`	Anonymous variable type.

			Rasqal RDF Query Library Manual
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