section-expression

section-expression

Functions

Types and Values

Description

Functions

rasqal_new_0op_expression ()

rasqal_expression *
rasqal_new_0op_expression (rasqal_world *world,
                           rasqal_op op);

Constructor - create a new 0-operand (constant) expression.

The operators are: RASQAL_EXPR_VARSTAR

The only operator here is the '*' in COUNT(*) as used by LAQRS.

Parameters

world

rasqal_world object

 

op

Expression operator

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_1op_expression ()

rasqal_expression *
rasqal_new_1op_expression (rasqal_world *world,
                           rasqal_op op,
                           rasqal_expression *arg);

Constructor - create a new 1-operand expression. Takes ownership of the operand expression.

The operators are: RASQAL_EXPR_TILDE RASQAL_EXPR_BANG RASQAL_EXPR_UMINUS RASQAL_EXPR_BOUND RASQAL_EXPR_STR RASQAL_EXPR_LANG RASQAL_EXPR_LANGMATCHES RASQAL_EXPR_DATATYPE RASQAL_EXPR_ISURI RASQAL_EXPR_ISBLANK RASQAL_EXPR_ISLITERAL RASQAL_EXPR_ORDER_COND_ASC RASQAL_EXPR_ORDER_COND_DESC RASQAL_EXPR_COUNT RASQAL_EXPR_SUM RASQAL_EXPR_AVG RASQAL_EXPR_MIN RASQAL_EXPR_MAX

The operator RASQAL_EXPR_TILDE is not used by SPARQL (formerly RDQL).

Parameters

world

rasqal_world object

 

op

Expression operator

 

arg

Operand 1

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_2op_expression ()

rasqal_expression *
rasqal_new_2op_expression (rasqal_world *world,
                           rasqal_op op,
                           rasqal_expression *arg1,
                           rasqal_expression *arg2);

Constructor - create a new 2-operand expression. Takes ownership of the operand expressions.

The operators are: RASQAL_EXPR_AND RASQAL_EXPR_OR RASQAL_EXPR_EQ RASQAL_EXPR_NEQ RASQAL_EXPR_LT RASQAL_EXPR_GT RASQAL_EXPR_LE RASQAL_EXPR_GE RASQAL_EXPR_PLUS RASQAL_EXPR_MINUS RASQAL_EXPR_STAR RASQAL_EXPR_SLASH RASQAL_EXPR_REM RASQAL_EXPR_STR_EQ RASQAL_EXPR_STR_NEQ

RASQAL_EXPR_REM RASQAL_EXPR_STR_EQ , RASQAL_EXPR_STR_NEQ and RASQAL_EXPR_REM are unused (formerly RDQL).

Parameters

world

rasqal_world object

 

op

Expression operator

 

arg1

Operand 1

 

arg2

Operand 2

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_3op_expression ()

rasqal_expression *
rasqal_new_3op_expression (rasqal_world *world,
                           rasqal_op op,
                           rasqal_expression *arg1,
                           rasqal_expression *arg2,
                           rasqal_expression *arg3);

Constructor - create a new 3-operand expression. Takes ownership of the operands.

The operators are: RASQAL_EXPR_REGEX RASQAL_EXPR_IF RASQAL_EXPR_SUBSTR

Parameters

world

rasqal_world object

 

op

Expression operator

 

arg1

Operand 1

 

arg2

Operand 2

 

arg3

Operand 3 (may be NULL)

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_4op_expression ()

rasqal_expression *
rasqal_new_4op_expression (rasqal_world *world,
                           rasqal_op op,
                           rasqal_expression *arg1,
                           rasqal_expression *arg2,
                           rasqal_expression *arg3,
                           rasqal_expression *arg4);

Constructor - create a new 4-operand expression. Takes ownership of the operands.

The operators are: RASQAL_EXPR_REPLACE

Parameters

world

rasqal_world object

 

op

Expression operator

 

arg1

Operand 1

 

arg2

Operand 2

 

arg3

Operand 3

 

arg4

Operand 4 (may be NULL)

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_aggregate_function_expression ()

rasqal_expression *
rasqal_new_aggregate_function_expression
                               (rasqal_world *world,
                                rasqal_op op,
                                rasqal_expression *arg1,
                                raptor_sequence *params,
                                unsigned int flags);

Constructor - create a new 1-arg aggregate function expression for a builtin aggregate function

Takes ownership of the args and params

Parameters

world

rasqal_world object

 

op

built-in aggregate function expression operator

 

arg1

rasqal_expression argument to aggregate function

 

params

sequence of rasqal_expression function parameters (or NULL)

 

flags

extension function bitflags

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_cast_expression ()

rasqal_expression *
rasqal_new_cast_expression (rasqal_world *world,
                            raptor_uri *name,
                            rasqal_expression *value);

Constructor - create a new expression for casting and expression to a datatype. Takes ownership of the datatype uri and expression value.

Parameters

world

rasqal_world object

 

name

cast datatype URI

 

value

expression value to cast to datatype type

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_function_expression ()

rasqal_expression *
rasqal_new_function_expression (rasqal_world *world,
                                raptor_uri *name,
                                raptor_sequence *args,
                                raptor_sequence *params,
                                unsigned int flags);

Constructor - create a new expression for a URI-named function with arguments and optional parameters.

Takes ownership of the name , args and params arguments.

Parameters

world

rasqal_world object

 

name

function name

 

args

sequence of rasqal_expression function arguments

 

params

sequence of rasqal_expression function parameters (or NULL)

 

flags

extension function bitflags

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_group_concat_expression ()

rasqal_expression *
rasqal_new_group_concat_expression (rasqal_world *world,
                                    unsigned int flags,
                                    raptor_sequence *args,
                                    rasqal_literal *separator);

Constructor - create a new SPARQL group concat expression

Takes an optional distinct flag, a list of expressions and an optional separator string.

Takes ownership of the args and separator

Parameters

world

rasqal_world object

 

flags

bitset of flags. Only RASQAL_EXPR_FLAG_DISTINCT is defined

 

args

sequence of rasqal_expression list arguments

 

separator

SEPARATOR string literal or NULL

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_literal_expression ()

rasqal_expression *
rasqal_new_literal_expression (rasqal_world *world,
                               rasqal_literal *literal);

Constructor - create a new expression for a rasqal_literal Takes ownership of the operand literal.

Parameters

world

rasqal_world object

 

literal

Literal operand 1

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_set_expression ()

rasqal_expression *
rasqal_new_set_expression (rasqal_world *world,
                           rasqal_op op,
                           rasqal_expression *arg1,
                           raptor_sequence *args);

Constructor - create a new set IN/NOT IN operation with expression arguments.

Takes ownership of the arg1 and args

Parameters

world

rasqal_world object

 

op

list operation

 

arg1

expression to look for in list

 

args

sequence of rasqal_expression list arguments

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_string_op_expression ()

rasqal_expression *
rasqal_new_string_op_expression (rasqal_world *world,
                                 rasqal_op op,
                                 rasqal_expression *arg1,
                                 rasqal_literal *literal);

Constructor - create a new expression with one expression and one string operand. Takes ownership of the operands.

The operators are: RASQAL_EXPR_STR_MATCH and RASQAL_EXPR_STR_NMATCH (unused: formerly for RDQL)

Parameters

world

rasqal_world object

 

op

Expression operator

 

arg1

Operand 1

 

literal

Literal operand 2

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_new_expression_from_expression ()

rasqal_expression *
rasqal_new_expression_from_expression (rasqal_expression *e);

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

Parameters

e

rasqal_expression object to copy or NULL

 

Returns

a new rasqal_expression object or NULL if e is NULL


rasqal_new_expr_seq_expression ()

rasqal_expression *
rasqal_new_expr_seq_expression (rasqal_world *world,
                                rasqal_op op,
                                raptor_sequence *args);

Constructor - create a new expression with a sequence of expression arguments.

Takes ownership of the args

Parameters

world

rasqal_world object

 

op

expression operation

 

args

sequence of rasqal_expression arguments

 

Returns

a new rasqal_expression object or NULL on failure


rasqal_free_expression ()

void
rasqal_free_expression (rasqal_expression *e);

Destructor - destroy a rasqal_expression object.

Parameters

e

rasqal_expression object

 

rasqal_expression_compare ()

int
rasqal_expression_compare (rasqal_expression *e1,
                           rasqal_expression *e2,
                           int flags,
                           int *error_p);

Compare two expressions

The two literals are compared. 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.

See rasqal_literal_compare() for comparison flags.

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

Parameters

e1

rasqal_expression first expression

 

e2

rasqal_expression second expression

 

flags

comparison flags: see rasqal_literal_compare()

 

error_p

pointer to error

 

Returns

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


rasqal_expression_evaluate ()

rasqal_literal *
rasqal_expression_evaluate (rasqal_world *world,
                            raptor_locator *locator,
                            rasqal_expression *e,
                            int flags);

rasqal_expression_evaluate is deprecated and should not be used in newly-written code.

Evaluate a rasqal_expression tree to give a rasqal_literal result or error.

Deprecated : use rasqal_expression_evaluate2() using a rasqal_evaluation_context

Parameters

world

rasqal_world

 

locator

error locator (or NULL)

 

e

The expression to evaluate.

 

flags

Flags for rasqal_literal_compare() and RASQAL_COMPARE_NOCASE for string matches.

 

Returns

a rasqal_literal value or NULL on failure.


rasqal_expression_evaluate2 ()

rasqal_literal *
rasqal_expression_evaluate2 (rasqal_expression *e,
                             rasqal_evaluation_context *eval_context,
                             int *error_p);

Evaluate a rasqal_expression tree in the context of a rasqal_evaluation_context to give a rasqal_literal result or error.

Parameters

e

The expression to evaluate.

 

eval_context

expression context

 

error_p

pointer to error return flag

 

Returns

a rasqal_literal value or NULL (a valid value). error_p is set to non-0 on failure.


rasqal_expression_op_label ()

const char *
rasqal_expression_op_label (rasqal_op op);

Get a label for the rasqal expression operator

Parameters

op

the rasqal_expression_op object

 

Returns

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


rasqal_expression_print ()

int
rasqal_expression_print (rasqal_expression *e,
                         FILE *fh);

Print a Rasqal expression in a debug format.

The print debug format may change in any release.

Parameters

e

rasqal_expression object.

 

fh

The FILE* handle to print to.

 

Returns

non-0 on failure


rasqal_expression_print_op ()

void
rasqal_expression_print_op (rasqal_expression *e,
                            FILE *fh);

Print a rasqal expression operator in a debug format.

The print debug format may change in any release.

Parameters

e

the rasqal_expression object

 

fh

the FILE* handle to print to

 

rasqal_expression_visit_fn ()

int
(*rasqal_expression_visit_fn) (void *user_data,
                               rasqal_expression *e);

User function to visit an expression and operate on it with rasqal_expression_visit()

Parameters

user_data

user data passed in with rasqal_expression_visit()

 

e

current expression

 

Returns

non-0 to truncate the visit


rasqal_expression_visit ()

int
rasqal_expression_visit (rasqal_expression *e,
                         rasqal_expression_visit_fn fn,
                         void *user_data);

Visit a user function over a rasqal_expression

If the user function fn returns non-0, the visit is truncated and the value is returned.

Parameters

e

rasqal_expression to visit

 

fn

visit function

 

user_data

user data to pass to visit function

 

Returns

non-0 if the visit was truncated.


rasqal_new_evaluation_context ()

rasqal_evaluation_context *
rasqal_new_evaluation_context (rasqal_world *world,
                               raptor_locator *locator,
                               int flags);

Constructor - create a rasqal_evaluation_context for use with rasqal_expression_evaluate2()

Parameters

world

rasqal world

 

locator

locator or NULL

 

flags

expression comparison flags

 

Returns

non-0 on failure


rasqal_free_evaluation_context ()

void
rasqal_free_evaluation_context (rasqal_evaluation_context *eval_context);

Destructor - destroy a rasqal_evaluation_context object.

Parameters

eval_context

rasqal_evaluation_context object

 

rasqal_evaluation_context_set_base_uri ()

int
rasqal_evaluation_context_set_base_uri
                               (rasqal_evaluation_context *eval_context,
                                raptor_uri *base_uri);

Set the URI for a rasqal_evaluation_context

Parameters

eval_context

rasqal_evaluation_context object

 

base_uri

base URI

 

Returns

non-0 on failure


rasqal_evaluation_context_set_rand_seed ()

int
rasqal_evaluation_context_set_rand_seed
                               (rasqal_evaluation_context *eval_context,
                                unsigned int seed);

Set the random seed for a rasqal_evaluation_context

Parameters

eval_context

rasqal_evaluation_context object

 

seed

random seed

 

Returns

non-0 on failure

Types and Values

rasqal_expression

typedef struct rasqal_expression_s rasqal_expression;

Expression with arguments


enum rasqal_expression_flags

Flags for expressions.

Members

RASQAL_EXPR_FLAG_DISTINCT

Distinct

 

RASQAL_EXPR_FLAG_AGGREGATE

Aggregate function expression

 

rasqal_evaluation_context

typedef struct {
  rasqal_world *world;
  raptor_uri* base_uri;
  raptor_locator *locator;
  int flags;
  unsigned int seed;
  rasqal_random* random;
} rasqal_evaluation_context;

A context for evaluating an expression such as with rasqal_expression_evaluate2()

Members

rasqal_world *world;

rasqal world

 

raptor_uri *base_uri;

base URI of expression context (or NULL)

 

raptor_locator *locator;

locator or NULL

 

int flags;

expression comparison flags

 

unsigned int seed;

random seeed

 

rasqal_random *random;

random number generator object

 

enum rasqal_op

Rasqal expression operators. A mixture of unary, binary and tertiary operators (string matches). Also includes casting and two ordering operators from ORDER BY in SPARQL.

Members

RASQAL_EXPR_UNKNOWN

Internal

 

RASQAL_EXPR_AND

Expression for AND(A, B)

 

RASQAL_EXPR_OR

Expression for OR(A, B)

 

RASQAL_EXPR_EQ

Expression for A equals B

 

RASQAL_EXPR_NEQ

Expression for A not equals B.

 

RASQAL_EXPR_LT

Expression for A less than B.

 

RASQAL_EXPR_GT

Expression for A greather than B.

 

RASQAL_EXPR_LE

Expression for A less than or equal to B.

 

RASQAL_EXPR_GE

Expression for A greater than or equal to B.

 

RASQAL_EXPR_UMINUS

Expression for -A.

 

RASQAL_EXPR_PLUS

Expression for +A.

 

RASQAL_EXPR_MINUS

Expression for A-B.

 

RASQAL_EXPR_STAR

Expression for A*B.

 

RASQAL_EXPR_SLASH

Expression for A/B.

 

RASQAL_EXPR_REM

Expression for A/B remainder.

 

RASQAL_EXPR_STR_EQ

Expression for A string equals B.

 

RASQAL_EXPR_STR_NEQ

Expression for A string not-equals B.

 

RASQAL_EXPR_STR_MATCH

Expression for string A matches literal regex B with flags.

 

RASQAL_EXPR_STR_NMATCH

Expression for string A not-matches literal regex B with flags.

 

RASQAL_EXPR_TILDE

Expression for binary not A.

 

RASQAL_EXPR_BANG

Expression for logical not A.

 

RASQAL_EXPR_LITERAL

Expression for a rasqal_literal.

 

RASQAL_EXPR_FUNCTION

Expression for a function A with arguments (B...).

 

RASQAL_EXPR_BOUND

Expression for SPARQL ISBOUND(A).

 

RASQAL_EXPR_STR

Expression for SPARQL STR(A).

 

RASQAL_EXPR_LANG

Expression for SPARQL LANG(A).

 

RASQAL_EXPR_DATATYPE

Expression for SPARQL DATATYPE(A).

 

RASQAL_EXPR_ISURI

Expression for SPARQL ISURI(A).

 

RASQAL_EXPR_ISBLANK

Expression for SPARQL ISBLANK(A).

 

RASQAL_EXPR_ISLITERAL

Expression for SPARQL ISLITERAL(A).

 

RASQAL_EXPR_CAST

Expression for cast literal A to type B.

 

RASQAL_EXPR_ORDER_COND_ASC

Expression for SPARQL order condition ascending.

 

RASQAL_EXPR_ORDER_COND_DESC

Expression for SPARQL order condition descending.

 

RASQAL_EXPR_LANGMATCHES

Expression for SPARQL LANGMATCHES(A, B).

 

RASQAL_EXPR_REGEX

Expression for string A matches expression regex B with flags.

 

RASQAL_EXPR_GROUP_COND_ASC

Obsolete - not used

 

RASQAL_EXPR_GROUP_COND_DESC

Obsolete - not used

 

RASQAL_EXPR_COUNT

Expression for LAQRS select COUNT() aggregate function

 

RASQAL_EXPR_VARSTAR

Expression for LAQRS select Variable *

 

RASQAL_EXPR_SAMETERM

Expression for SPARQL sameTerm

 

RASQAL_EXPR_SUM

Expression for LAQRS select SUM() aggregate function

 

RASQAL_EXPR_AVG

Expression for LAQRS select AVG() aggregate function

 

RASQAL_EXPR_MIN

Expression for LAQRS select MIN() aggregate function

 

RASQAL_EXPR_MAX

Expression for LAQRS select MAX() aggregate function

 

RASQAL_EXPR_COALESCE

Expression for LAQRS COALESCE(Expr+)

 

RASQAL_EXPR_IF

Expression for LAQRS IF(expr, expr, expr)

 

RASQAL_EXPR_URI

Expression for LAQRS URI(expr)

 

RASQAL_EXPR_IRI

Expression for LAQRS IRI(expr)

 

RASQAL_EXPR_STRLANG

Expression for LAQRS STRLANG(expr, expr)

 

RASQAL_EXPR_STRDT

Expression for LAQRS STRDT(expr, expr)

 

RASQAL_EXPR_BNODE

Expression for LAQRS BNODE() and BNODE(expr)

 

RASQAL_EXPR_GROUP_CONCAT

Expression for LAQRS GROUP_CONCAT(arglist) aggregate function

 

RASQAL_EXPR_SAMPLE

Expression for LAQRS SAMPLE(expr) aggregate function

 

RASQAL_EXPR_IN

Expression for LAQRS expr IN ( list of expr )

 

RASQAL_EXPR_NOT_IN

Expression for LAQRS expr NOT IN ( list of expr )

 

RASQAL_EXPR_ISNUMERIC

Expression for SPARQL 1.1 isNUMERIC(expr)

 

RASQAL_EXPR_YEAR

Expression for SPARQL 1.1 YEAR(datetime)

 

RASQAL_EXPR_MONTH

Expression for SPARQL 1.1 MONTH(datetime)

 

RASQAL_EXPR_DAY

Expression for SPARQL 1.1 DAY(datetime)

 

RASQAL_EXPR_HOURS

Expression for SPARQL 1.1 HOURS(datetime)

 

RASQAL_EXPR_MINUTES

Expression for SPARQL 1.1 MINUTES(datetime)

 

RASQAL_EXPR_SECONDS

Expression for SPARQL 1.1 SECONDS(datetime)

 

RASQAL_EXPR_TIMEZONE

Expression for SPARQL 1.1 TIMEZONE(datetime)

 

RASQAL_EXPR_CURRENT_DATETIME

Expression for LAQRS CURRENT_DATETIME( void )

 

RASQAL_EXPR_NOW

Expression for LAQRS NOW( void )

 

RASQAL_EXPR_FROM_UNIXTIME

Expression for LAQRS FROM_UNIXTIME(int)

 

RASQAL_EXPR_TO_UNIXTIME

Expression for LAQRS TO_UNIXTIME(datetime)

 

RASQAL_EXPR_CONCAT

Expression for SPARQL 1.1 CONCAT(strings)

 

RASQAL_EXPR_STRLEN

Expression for SPARQL 1.1 STRLEN(str)

 

RASQAL_EXPR_SUBSTR

Expression for SPARQL 1.1 SUBSTR(str, start[,offset])

 

RASQAL_EXPR_UCASE

Expression for SPARQL 1.1 UCASE(str)

 

RASQAL_EXPR_LCASE

Expression for SPARQL 1.1 LCASE(str)

 

RASQAL_EXPR_STRSTARTS

Expression for SPARQL 1.1 STRSTARTS(str, str)

 

RASQAL_EXPR_STRENDS

Expression for SPARQL 1.1 STRENDS(str, str)

 

RASQAL_EXPR_CONTAINS

Expression for SPARQL 1.1 CONTAINS(str, str)

 

RASQAL_EXPR_ENCODE_FOR_URI

Expression for SPARQL 1.1 ENCODE_FOR_URI(str)

 

RASQAL_EXPR_TZ

Expression for SPARQL 1.1 TZ()

 

RASQAL_EXPR_RAND

Expression for SPARQL 1.1 RAND()

 

RASQAL_EXPR_ABS

Expression for SPARQL 1.1 ABS()

 

RASQAL_EXPR_ROUND

Expression for SPARQL 1.1 ROUND()

 

RASQAL_EXPR_CEIL

Expression for SPARQL 1.1 CEIL()

 

RASQAL_EXPR_FLOOR

Expression for SPARQL 1.1 FLOOR()

 

RASQAL_EXPR_MD5

Expression for SPARQL 1.1 MD5()

 

RASQAL_EXPR_SHA1

Expression for SPARQL 1.1 SHA1()

 

RASQAL_EXPR_SHA224

Expression for SPARQL 1.1 SHA224()

 

RASQAL_EXPR_SHA256

Expression for SPARQL 1.1 SHA256()

 

RASQAL_EXPR_SHA384

Expression for SPARQL 1.1 SHA384()

 

RASQAL_EXPR_SHA512

Expression for SPARQL 1.1 SHA512()

 

RASQAL_EXPR_STRBEFORE

Expression for SPARQL 1.1 STRBEFORE()

 

RASQAL_EXPR_STRAFTER

Expression for SPARQL 1.1 STRAFTER()

 

RASQAL_EXPR_REPLACE

Expression for SPARQL 1.1 REPLACE()

 

RASQAL_EXPR_UUID

Expression for SPARQL 1.1 UUID()

 

RASQAL_EXPR_STRUUID

Expression for SPARQL 1.1 STRUUID()

 

RASQAL_EXPR_LAST

Internal

 

enum rasqal_compare_flags

Flags for rasqal_expression_evaluate(), rasqal_literal_compare() or rasqal_literal_as_string_flags()

Members

RASQAL_COMPARE_NOCASE

String comparisons are case independent.

 

RASQAL_COMPARE_XQUERY

XQuery comparsion rules apply.

 

RASQAL_COMPARE_RDF

RDF Term comparsion rules apply.

 

RASQAL_COMPARE_URI

Allow comparison of URIs and allow strings to have a boolean value (unused; was for RDQL)

 

RASQAL_COMPARE_SAMETERM

SPARQL sameTerm() builtin rules apply.

 

enum rasqal_pattern_flags

Flags for rasqal_graph_pattern.

Members

RASQAL_PATTERN_FLAGS_OPTIONAL

True when the graph pattern is an optional match.

 

RASQAL_PATTERN_FLAGS_LAST

Internal