Literal

Literal — RDF literals and RDF query-specific literals.

Synopsis

typedef             rasqal_literal;
enum                rasqal_literal_type;
rasqal_literal *    rasqal_new_typed_literal            (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         const unsigned char *string);
rasqal_literal *    rasqal_new_boolean_literal          (rasqal_world *world,
                                                         int value);
rasqal_literal *    rasqal_new_datetime_literal_from_datetime
                                                        (rasqal_world *world,
                                                         rasqal_xsd_datetime *dt);
rasqal_literal *    rasqal_new_decimal_literal          (rasqal_world *world,
                                                         const char *string);
rasqal_literal *    rasqal_new_decimal_literal_from_decimal
                                                        (rasqal_world *world,
                                                         const char *string,
                                                         rasqal_xsd_decimal *decimal);
rasqal_literal *    rasqal_new_double_literal           (rasqal_world *world,
                                                         double d);
rasqal_literal *    rasqal_new_float_literal            (rasqal_world *world,
                                                         float f);
rasqal_literal *    rasqal_new_floating_literal         (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         double d);
rasqal_literal *    rasqal_new_integer_literal          (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         int integer);
rasqal_literal *    rasqal_new_numeric_literal_from_long
                                                        (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         long value Param3);
rasqal_literal *    rasqal_new_pattern_literal          (rasqal_world *world,
                                                         const char *pattern,
                                                         const char *flags);
rasqal_literal *    rasqal_new_simple_literal           (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         const char *string);
rasqal_literal *    rasqal_new_string_literal           (rasqal_world *world,
                                                         const char *string,
                                                         const char *language,
                                                         raptor_uri *datatype,
                                                         const unsigned char *datatype_qname);
rasqal_literal *    rasqal_new_uri_literal              (rasqal_world *world,
                                                         raptor_uri *uri);
rasqal_literal *    rasqal_new_variable_literal         (rasqal_world *world,
                                                         rasqal_variable *variable);
rasqal_literal *    rasqal_new_literal_from_literal     (rasqal_literal *l);
void                rasqal_free_literal                 (rasqal_literal *l);
rasqal_literal *    rasqal_literal_as_node              (rasqal_literal *l);
const unsigned char * rasqal_literal_as_counted_string  (rasqal_literal *l,
                                                         size_t *len_p,
                                                         int flags,
                                                         int *error_p);
const unsigned char * rasqal_literal_as_string          (rasqal_literal *l);
const unsigned char * rasqal_literal_as_string_flags    (rasqal_literal *l,
                                                         int flags,
                                                         int *error_p);
rasqal_variable *   rasqal_literal_as_variable          (rasqal_literal *l);
int                 rasqal_literal_compare              (rasqal_literal *l1,
                                                         rasqal_literal *l2,
                                                         int flags,
                                                         int *error_p);
raptor_uri *        rasqal_literal_datatype             (rasqal_literal *l);
int                 rasqal_literal_equals               (rasqal_literal *l1,
                                                         rasqal_literal *l2);
char *              rasqal_literal_get_language         (rasqal_literal *l);
rasqal_literal_type rasqal_literal_get_rdf_term_type    (rasqal_literal *l);
rasqal_literal_type rasqal_literal_get_type             (rasqal_literal *l);
int                 rasqal_literal_is_rdf_literal       (rasqal_literal *l);
int                 rasqal_literal_print                (rasqal_literal *l,
                                                         FILE *fh);
void                rasqal_literal_print_type           (rasqal_literal *l,
                                                         FILE *fh);
const char *        rasqal_literal_type_label           (rasqal_literal_type type);
int                 rasqal_literal_same_term            (rasqal_literal *l1,
                                                         rasqal_literal *l2);
rasqal_literal *    rasqal_literal_value                (rasqal_literal *l);

Description

A class for handling RDF terms (URI, blank nodes, strings, datatyped literals) as well as those natively used in a query such as boolean, double, floating, integer, regex pattern and variables.

Details

rasqal_literal

typedef struct rasqal_literal_s rasqal_literal;

Rasqal literal class.


enum rasqal_literal_type

typedef enum {
  /* internal */
  RASQAL_LITERAL_UNKNOWN,
  RASQAL_LITERAL_BLANK,
  RASQAL_LITERAL_URI,
  RASQAL_LITERAL_STRING,
  RASQAL_LITERAL_XSD_STRING,
  RASQAL_LITERAL_BOOLEAN,
  RASQAL_LITERAL_INTEGER,
  RASQAL_LITERAL_FLOAT,
  RASQAL_LITERAL_DOUBLE,
  RASQAL_LITERAL_DECIMAL,
  RASQAL_LITERAL_DATETIME,
  /* internal */
  RASQAL_LITERAL_FIRST_XSD = RASQAL_LITERAL_XSD_STRING,
  /* internal */
  RASQAL_LITERAL_LAST_XSD = RASQAL_LITERAL_DATETIME,
  RASQAL_LITERAL_UDT,
  RASQAL_LITERAL_PATTERN,
  RASQAL_LITERAL_QNAME,
  RASQAL_LITERAL_VARIABLE,
  /* internal */
  RASQAL_LITERAL_INTEGER_SUBTYPE,
  RASQAL_LITERAL_DATE,
  /* internal */
  RASQAL_LITERAL_LAST = RASQAL_LITERAL_DATE
} rasqal_literal_type;

Types of literal.

The order in the enumeration is significant as it encodes the SPARQL term ordering conditions:

Blank Nodes << IRIs << RDF literals << typed literals

which coresponds to in enum values

BLANK << URI << STRING << (BOOLEAN | INTEGER | DOUBLE | FLOAT | DECIMAL | DATETIME | XSD_STRING)

(RASQAL_LITERAL_FIRST_XSD ... RASQAL_LITERAL_LAST_XSD)

Not used (internal): PATTERN, QNAME, VARIABLE

See rasqal_literal_compare() when used with flags RASQAL_COMPARE_XQUERY

RASQAL_LITERAL_UNKNOWN

Internal.

RASQAL_LITERAL_BLANK

RDF blank node literal (SPARQL r:bNode)

RASQAL_LITERAL_URI

RDF URI Literal (SPARQL r:URI)

RASQAL_LITERAL_STRING

RDF Plain Literal - no datatype (SPARQL r:Literal)

RASQAL_LITERAL_XSD_STRING

String xsd:string

RASQAL_LITERAL_BOOLEAN

Boolean literal xsd:boolean.

RASQAL_LITERAL_INTEGER

Integer literal xsd:integer.

RASQAL_LITERAL_FLOAT

Floating point literal xsd:float.

RASQAL_LITERAL_DOUBLE

Double floating point literal xsd:double.

RASQAL_LITERAL_DECIMAL

Decimal integer xsd:decimal.

RASQAL_LITERAL_DATETIME

Date/Time literal xsd:dateTime.

RASQAL_LITERAL_FIRST_XSD

Internal.

RASQAL_LITERAL_LAST_XSD

Internal.

RASQAL_LITERAL_UDT

User defined typed literal with unknown datatype URI

RASQAL_LITERAL_PATTERN

Pattern literal for a regex.

RASQAL_LITERAL_QNAME

XML Qname literal.

RASQAL_LITERAL_VARIABLE

Variable literal.

RASQAL_LITERAL_INTEGER_SUBTYPE

Internal.

RASQAL_LITERAL_DATE

Date literal xsd:date.

RASQAL_LITERAL_LAST

Internal.

rasqal_new_typed_literal ()

rasqal_literal *    rasqal_new_typed_literal            (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         const unsigned char *string);

Constructor - Create a new Rasqal integer literal from a string

The integer decimal number is turned into a rasqal integer literal and given a datatype of xsd:integer

world :

rasqal world object

type :

Type of literal such as RASQAL_LITERAL_INTEGER or RASQAL_LITERAL_BOOLEAN

string :

lexical form - ownership not taken

Returns :

New rasqal_literal or NULL on failure

rasqal_new_boolean_literal ()

rasqal_literal *    rasqal_new_boolean_literal          (rasqal_world *world,
                                                         int value);

Constructor - Create a new Rasqal boolean literal.

world :

rasqal world object

value :

non-0 for true, 0 for false

Returns :

New rasqal_literal or NULL on failure

rasqal_new_datetime_literal_from_datetime ()

rasqal_literal *    rasqal_new_datetime_literal_from_datetime
                                                        (rasqal_world *world,
                                                         rasqal_xsd_datetime *dt);

Constructor - Create a new Rasqal datetime literal from an existing datetime.

Takes ownership of dt

world :

rasqal world object

dt :

rasqal XSD Datetime

Returns :

New rasqal_literal or NULL on failure

rasqal_new_decimal_literal ()

rasqal_literal *    rasqal_new_decimal_literal          (rasqal_world *world,
                                                         const char *string);

Constructor - Create a new Rasqal decimal literal.

world :

rasqal world object

string :

decimal literal

Returns :

New rasqal_literal or NULL on failure

rasqal_new_decimal_literal_from_decimal ()

rasqal_literal *    rasqal_new_decimal_literal_from_decimal
                                                        (rasqal_world *world,
                                                         const char *string,
                                                         rasqal_xsd_decimal *decimal);

Constructor - Create a new Rasqal decimal literal.

world :

rasqal world object

string :

decimal literal string

decimal :

rasqal XSD Decimal

Returns :

New rasqal_literal or NULL on failure

rasqal_new_double_literal ()

rasqal_literal *    rasqal_new_double_literal           (rasqal_world *world,
                                                         double d);

Constructor - Create a new Rasqal double literal.

world :

rasqal world object

d :

double literal

Returns :

New rasqal_literal or NULL on failure

rasqal_new_float_literal ()

rasqal_literal *    rasqal_new_float_literal            (rasqal_world *world,
                                                         float f);

Constructor - Create a new Rasqal float literal.

Deprecated: Use rasqal_new_floating_literal() with type RASQAL_LITERAL_FLOAT and double value.

world :

rasqal world object

f :

float literal

Returns :

New rasqal_literal or NULL on failure

rasqal_new_floating_literal ()

rasqal_literal *    rasqal_new_floating_literal         (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         double d);

Constructor - Create a new Rasqal float literal from a double.

world :

rasqal world object

type :

type - RASQAL_LITERAL_FLOAT or RASQAL_LITERAL_DOUBLE

d :

floating literal (double)

Returns :

New rasqal_literal or NULL on failure

rasqal_new_integer_literal ()

rasqal_literal *    rasqal_new_integer_literal          (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         int integer);

Constructor - Create a new Rasqal integer literal.

The integer decimal number is turned into a rasqal integer literal and given a datatype of xsd:integer

world :

rasqal world object

type :

Type of literal such as RASQAL_LITERAL_INTEGER or RASQAL_LITERAL_BOOLEAN

integer :

int value

Returns :

New rasqal_literal or NULL on failure

rasqal_new_numeric_literal_from_long ()

rasqal_literal *    rasqal_new_numeric_literal_from_long
                                                        (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         long value Param3);

Constructor - Create a new Rasqal numeric literal from a long.

The value is turned into a rasqal integer or decimal literal and given a datatype of xsd:integer

world :

rasqal world object

type :

Type of literal such as RASQAL_LITERAL_INTEGER or RASQAL_LITERAL_BOOLEAN

Returns :

New rasqal_literal or NULL on failure

rasqal_new_pattern_literal ()

rasqal_literal *    rasqal_new_pattern_literal          (rasqal_world *world,
                                                         const char *pattern,
                                                         const char *flags);

Constructor - Create a new Rasqal pattern literal.

The pattern and flags are input parameters and are stored in the literal, not copied. They are freed also on failure. The set of flags recognised depends on the regex library and the query language.

world :

rasqal world object

pattern :

regex pattern

flags :

regex flags

Returns :

New rasqal_literal or NULL on failure

rasqal_new_simple_literal ()

rasqal_literal *    rasqal_new_simple_literal           (rasqal_world *world,
                                                         rasqal_literal_type type,
                                                         const char *string);

Constructor - Create a new Rasqal simple literal.

The string is an input parameter and is stored in the literal, not copied. It is freed also on failure.

world :

rasqal world object

type :

RASQAL_LITERAL_BLANK or RASQAL_LITERAL_BLANK_QNAME

string :

the UTF-8 string value to store

Returns :

New rasqal_literal or NULL on failure

rasqal_new_string_literal ()

rasqal_literal *    rasqal_new_string_literal           (rasqal_world *world,
                                                         const char *string,
                                                         const char *language,
                                                         raptor_uri *datatype,
                                                         const unsigned char *datatype_qname);

Constructor - Create a new Rasqal string literal.

All parameters are input parameters and if present are stored in the literal, not copied. They are freed also on failure.

The datatype and datatype_qname parameters are alternatives; the qname is a datatype that cannot be resolved till later since the prefixes have not yet been declared or checked.

If the string literal is datatyped and of certain types recognised it may be converted to a different literal type.

world :

rasqal world object

string :

UTF-8 string lexical form

language :

RDF language (xml:lang) (or NULL)

datatype :

datatype URI (or NULL for plain literal)

datatype_qname :

datatype qname string (or NULL for plain literal)

Returns :

New rasqal_literal or NULL on failure

rasqal_new_uri_literal ()

rasqal_literal *    rasqal_new_uri_literal              (rasqal_world *world,
                                                         raptor_uri *uri);

Constructor - Create a new Rasqal URI literal from a raptor URI.

The uri is an input parameter and is stored in the literal, not copied. The uri is freed also on failure.

world :

rasqal world object

uri :

raptor_uri uri

Returns :

New rasqal_literal or NULL on failure

rasqal_new_variable_literal ()

rasqal_literal *    rasqal_new_variable_literal         (rasqal_world *world,
                                                         rasqal_variable *variable);

Constructor - Create a new Rasqal variable literal.

variable is an input parameter and stored in the literal, not copied.

world :

rasqal_world object

variable :

rasqal_variable to use

Returns :

New rasqal_literal or NULL on failure

rasqal_new_literal_from_literal ()

rasqal_literal *    rasqal_new_literal_from_literal     (rasqal_literal *l);

Copy Constructor - create a new rasqal_literal object from an existing rasqal_literal object.

l :

rasqal_literal object to copy or NULL

Returns :

a new rasqal_literal object or NULL if l was NULL.

rasqal_free_literal ()

void                rasqal_free_literal                 (rasqal_literal *l);

Destructor - destroy an rasqal_literal object.

l :

rasqal_literal object

rasqal_literal_as_node ()

rasqal_literal *    rasqal_literal_as_node              (rasqal_literal *l);

Turn a literal into a new RDF string, URI or blank literal.

l :

rasqal_literal object

Returns :

the new rasqal_literal or NULL on failure or if the literal was an unbound variable.

rasqal_literal_as_counted_string ()

const unsigned char * rasqal_literal_as_counted_string  (rasqal_literal *l,
                                                         size_t *len_p,
                                                         int flags,
                                                         int *error_p);

Return a counted string format of a literal according to flags.

flag bits affects conversion: RASQAL_COMPARE_XQUERY: use XQuery conversion rules

If error is not NULL, *error is set to non-0 on error

l :

rasqal_literal object

len_p :

pointer to store length of string (or NULL)

flags :

comparison flags

error_p :

pointer to error

Returns :

pointer to a shared string format of the literal.

rasqal_literal_as_string ()

const unsigned char * rasqal_literal_as_string          (rasqal_literal *l);

Return the string format of a literal.

l :

rasqal_literal object

Returns :

pointer to a shared string format of the literal.

rasqal_literal_as_string_flags ()

const unsigned char * rasqal_literal_as_string_flags    (rasqal_literal *l,
                                                         int flags,
                                                         int *error_p);

Return the string format of a literal according to flags.

flag bits affects conversion: RASQAL_COMPARE_XQUERY: use XQuery conversion rules

If error is not NULL, *error is set to non-0 on error

l :

rasqal_literal object

flags :

comparison flags

error_p :

pointer to error

Returns :

pointer to a shared string format of the literal.

rasqal_literal_as_variable ()

rasqal_variable *   rasqal_literal_as_variable          (rasqal_literal *l);

Get the variable inside a literal.

l :

rasqal_literal object

Returns :

the rasqal_variable or NULL if the literal is not a variable

rasqal_literal_compare ()

int                 rasqal_literal_compare              (rasqal_literal *l1,
                                                         rasqal_literal *l2,
                                                         int flags,
                                                         int *error_p);

Compare two literals with type promotion.

The two literals are compared across their range. If the types are not the same, they are promoted. If one is a double or float, the other is promoted to double, otherwise for integers, otherwise to strings (all literals have a string value).

The comparison returned is as for strcmp, first before second returns <0. equal returns 0, and first after second returns >0. For URIs, the string value is used for the comparsion.

flag bits affects comparisons: RASQAL_COMPARE_NOCASE: use case independent string comparisons RASQAL_COMPARE_XQUERY: use XQuery comparison and type promotion rules RASQAL_COMPARE_RDF: use RDF term comparison RASQAL_COMPARE_URI: allow comparison of URIs (typically for SPARQL ORDER)

If error is not NULL, *error is set to non-0 on error

l1 :

rasqal_literal first literal

l2 :

rasqal_literal second literal

flags :

comparison flags

error_p :

pointer to error

Returns :

<0, 0, or >0 as described above.

rasqal_literal_datatype ()

raptor_uri *        rasqal_literal_datatype             (rasqal_literal *l);

Get the datatype URI of a literal

l :

rasqal_literal object

Returns :

shared pointer to raptor_uri of datatype or NULL on failure or no value

rasqal_literal_equals ()

int                 rasqal_literal_equals               (rasqal_literal *l1,
                                                         rasqal_literal *l2);

Compare two literals with no type promotion.

If the l2 data literal value is a boolean, it will match the string "true" or "false" in the first literal l1.

l1 :

rasqal_literal literal

l2 :

rasqal_literal data literal

Returns :

non-0 if equal

rasqal_literal_get_language ()

char *              rasqal_literal_get_language         (rasqal_literal *l);

Get the language of a literal (if set)

l :

literal

Returns :

the literal language or NULL

rasqal_literal_get_rdf_term_type ()

rasqal_literal_type rasqal_literal_get_rdf_term_type    (rasqal_literal *l);

Get the RDF term type of a literal

An RDF term can be one of three choices: 1. URI: RASQAL_LITERAL_URI 2. literal: RASQAL_LITERAL_STRING 3. blank node: RASQAL_LITERAL_BLANK

Other non RDF-term cases include: NULL pointer, invalid literal, unknown type, a variable or other special cases (such as XML QName or Regex pattern) which all turn into RASQAL_LITERAL_UNKNOWN

l :

literal

Returns :

type or RASQAL_LITERAL_UNKNOWN if cannot be an RDF term

rasqal_literal_get_type ()

rasqal_literal_type rasqal_literal_get_type             (rasqal_literal *l);

Get the type of a literal

l :

literal

Returns :

the rasqal literal type or RASQAL_LITERAL_UNKNOWN if l is NULL

rasqal_literal_is_rdf_literal ()

int                 rasqal_literal_is_rdf_literal       (rasqal_literal *l);

Check if a literal is any RDF term literal - plain or typed literal

l :

rasqal_literal literal

Returns :

non-0 if the value is an RDF term literal

rasqal_literal_print ()

int                 rasqal_literal_print                (rasqal_literal *l,
                                                         FILE *fh);

Print a Rasqal literal in a debug format.

The print debug format may change in any release.

l :

the rasqal_literal object

fh :

the FILE handle to print to

Returns :

non-0 on failure

rasqal_literal_print_type ()

void                rasqal_literal_print_type           (rasqal_literal *l,
                                                         FILE *fh);

Print a string form for a rasqal literal type.

l :

the rasqal_literal object

fh :

the FILE* handle to print to

rasqal_literal_type_label ()

const char *        rasqal_literal_type_label           (rasqal_literal_type type);

Get a label for the rasqal literal type

type :

the rasqal_literal_type object

Returns :

the label (shared string) or NULL if type is out of range or unknown

rasqal_literal_same_term ()

int                 rasqal_literal_same_term            (rasqal_literal *l1,
                                                         rasqal_literal *l2);

Check if literals are same term (URI, literal, blank)

l1 :

rasqal_literal literal

l2 :

rasqal_literal data literal

Returns :

non-0 if same

rasqal_literal_value ()

rasqal_literal *    rasqal_literal_value                (rasqal_literal *l);

Get the literal value looking up any variables needed

l :

rasqal_literal object

Returns :

literal value or NULL if has no value


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