Expressions

Expressions — Query language expressions.

Synopsis

typedef             rasqal_expression;
enum                rasqal_expression_flags;
                    rasqal_evaluation_context;
enum                rasqal_op;
enum                rasqal_compare_flags;
enum                rasqal_pattern_flags;
rasqal_expression * rasqal_new_0op_expression           (rasqal_world *world,
                                                         rasqal_op op);
rasqal_expression * rasqal_new_1op_expression           (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg);
rasqal_expression * rasqal_new_2op_expression           (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg1,
                                                         rasqal_expression *arg2);
rasqal_expression * rasqal_new_3op_expression           (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg1,
                                                         rasqal_expression *arg2,
                                                         rasqal_expression *arg3);
rasqal_expression * rasqal_new_4op_expression           (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg1,
                                                         rasqal_expression *arg2,
                                                         rasqal_expression *arg3,
                                                         rasqal_expression *arg4);
rasqal_expression * rasqal_new_aggregate_function_expression
                                                        (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg1,
                                                         raptor_sequence *params,
                                                         unsigned int flags);
rasqal_expression * rasqal_new_cast_expression          (rasqal_world *world,
                                                         raptor_uri *name,
                                                         rasqal_expression *value);
rasqal_expression * rasqal_new_function_expression      (rasqal_world *world,
                                                         raptor_uri *name,
                                                         raptor_sequence *args,
                                                         raptor_sequence *params,
                                                         unsigned int flags);
rasqal_expression * rasqal_new_group_concat_expression  (rasqal_world *world,
                                                         unsigned int flags,
                                                         raptor_sequence *args,
                                                         rasqal_literal *separator);
rasqal_expression * rasqal_new_literal_expression       (rasqal_world *world,
                                                         rasqal_literal *literal);
rasqal_expression * rasqal_new_set_expression           (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg1,
                                                         raptor_sequence *args);
rasqal_expression * rasqal_new_string_op_expression     (rasqal_world *world,
                                                         rasqal_op op,
                                                         rasqal_expression *arg1,
                                                         rasqal_literal *literal);
rasqal_expression * rasqal_new_expression_from_expression
                                                        (rasqal_expression *e);
rasqal_expression * rasqal_new_expr_seq_expression      (rasqal_world *world,
                                                         rasqal_op op,
                                                         raptor_sequence *args);
void                rasqal_free_expression              (rasqal_expression *e);
int                 rasqal_expression_compare           (rasqal_expression *e1,
                                                         rasqal_expression *e2,
                                                         int flags,
                                                         int *error_p);
rasqal_literal *    rasqal_expression_evaluate          (rasqal_world *world,
                                                         raptor_locator *locator,
                                                         rasqal_expression *e,
                                                         int flags);
rasqal_literal *    rasqal_expression_evaluate2         (rasqal_expression *e,
                                                         rasqal_evaluation_context *eval_context,
                                                         int *error_p);
const char *        rasqal_expression_op_label          (rasqal_op op);
int                 rasqal_expression_print             (rasqal_expression *e,
                                                         FILE *fh);
void                rasqal_expression_print_op          (rasqal_expression *e,
                                                         FILE *fh);
int                 (*rasqal_expression_visit_fn)       (void *user_data,
                                                         rasqal_expression *e);
int                 rasqal_expression_visit             (rasqal_expression *e,
                                                         rasqal_expression_visit_fn fn,
                                                         void *user_data);
rasqal_evaluation_context * rasqal_new_evaluation_context
                                                        (rasqal_world *world,
                                                         raptor_locator *locator,
                                                         int flags);
void                rasqal_free_evaluation_context      (rasqal_evaluation_context *eval_context);
int                 rasqal_evaluation_context_set_base_uri
                                                        (rasqal_evaluation_context *eval_context,
                                                         raptor_uri *base_uri);
int                 rasqal_evaluation_context_set_rand_seed
                                                        (rasqal_evaluation_context *eval_context,
                                                         unsigned int seed);

Description

Expressions form an expression tree that can be evaluated using rasqal_expression_evaluate() over rasqal_op operators, rasqal_literal constants and rasqal_variable values bound in some rasqal_query_result. The result is a rasqal_literal value.

Details

rasqal_expression

typedef struct rasqal_expression_s rasqal_expression;

Expression with arguments


enum rasqal_expression_flags

typedef enum {
  RASQAL_EXPR_FLAG_DISTINCT = 1,
  RASQAL_EXPR_FLAG_AGGREGATE = 2
} rasqal_expression_flags;

Flags for expressions.

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()

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

typedef enum {
  /* internal */
  RASQAL_EXPR_UNKNOWN,
  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_UMINUS,
  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_STR_MATCH,
  RASQAL_EXPR_STR_NMATCH,
  RASQAL_EXPR_TILDE,
  RASQAL_EXPR_BANG,
  RASQAL_EXPR_LITERAL,
  RASQAL_EXPR_FUNCTION,
  RASQAL_EXPR_BOUND,
  RASQAL_EXPR_STR,
  RASQAL_EXPR_LANG,
  RASQAL_EXPR_DATATYPE,
  RASQAL_EXPR_ISURI,
  RASQAL_EXPR_ISBLANK,
  RASQAL_EXPR_ISLITERAL,
  RASQAL_EXPR_CAST,
  RASQAL_EXPR_ORDER_COND_ASC,
  RASQAL_EXPR_ORDER_COND_DESC,
  RASQAL_EXPR_LANGMATCHES,
  RASQAL_EXPR_REGEX,
  RASQAL_EXPR_GROUP_COND_ASC,
  RASQAL_EXPR_GROUP_COND_DESC,
  RASQAL_EXPR_COUNT,
  RASQAL_EXPR_VARSTAR,
  RASQAL_EXPR_SAMETERM,
  RASQAL_EXPR_SUM,
  RASQAL_EXPR_AVG,
  RASQAL_EXPR_MIN,
  RASQAL_EXPR_MAX,
  RASQAL_EXPR_COALESCE,
  RASQAL_EXPR_IF,
  RASQAL_EXPR_URI,
  RASQAL_EXPR_IRI,
  RASQAL_EXPR_STRLANG,
  RASQAL_EXPR_STRDT,
  RASQAL_EXPR_BNODE,
  RASQAL_EXPR_GROUP_CONCAT,
  RASQAL_EXPR_SAMPLE,
  RASQAL_EXPR_IN,
  RASQAL_EXPR_NOT_IN,
  RASQAL_EXPR_ISNUMERIC,
  RASQAL_EXPR_YEAR,
  RASQAL_EXPR_MONTH,
  RASQAL_EXPR_DAY,
  RASQAL_EXPR_HOURS,
  RASQAL_EXPR_MINUTES,
  RASQAL_EXPR_SECONDS,
  RASQAL_EXPR_TIMEZONE,
  RASQAL_EXPR_CURRENT_DATETIME,
  RASQAL_EXPR_NOW,
  RASQAL_EXPR_FROM_UNIXTIME,
  RASQAL_EXPR_TO_UNIXTIME,
  RASQAL_EXPR_CONCAT,
  RASQAL_EXPR_STRLEN,
  RASQAL_EXPR_SUBSTR,
  RASQAL_EXPR_UCASE,
  RASQAL_EXPR_LCASE,
  RASQAL_EXPR_STRSTARTS,
  RASQAL_EXPR_STRENDS,
  RASQAL_EXPR_CONTAINS,
  RASQAL_EXPR_ENCODE_FOR_URI,
  RASQAL_EXPR_TZ,
  RASQAL_EXPR_RAND,
  RASQAL_EXPR_ABS,
  RASQAL_EXPR_ROUND,
  RASQAL_EXPR_CEIL,
  RASQAL_EXPR_FLOOR,
  RASQAL_EXPR_MD5,
  RASQAL_EXPR_SHA1,
  RASQAL_EXPR_SHA224,
  RASQAL_EXPR_SHA256,
  RASQAL_EXPR_SHA384,
  RASQAL_EXPR_SHA512,
  RASQAL_EXPR_STRBEFORE,
  RASQAL_EXPR_STRAFTER,
  RASQAL_EXPR_REPLACE,
  RASQAL_EXPR_UUID,
  RASQAL_EXPR_STRUUID,
  /* internal */
  RASQAL_EXPR_LAST = RASQAL_EXPR_STRUUID
} 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.

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

typedef enum {
  RASQAL_COMPARE_NOCASE = 1,
  RASQAL_COMPARE_XQUERY = 2,
  RASQAL_COMPARE_RDF    = 4,
  RASQAL_COMPARE_URI    = 8,
  RASQAL_COMPARE_SAMETERM = 16
} rasqal_compare_flags;

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

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

typedef enum {
  RASQAL_PATTERN_FLAGS_OPTIONAL = 1,

  RASQAL_PATTERN_FLAGS_LAST     = RASQAL_PATTERN_FLAGS_OPTIONAL
} rasqal_pattern_flags;

Flags for rasqal_graph_pattern.

RASQAL_PATTERN_FLAGS_OPTIONAL

True when the graph pattern is an optional match.

RASQAL_PATTERN_FLAGS_LAST

Internal

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.

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).

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).

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

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

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

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.

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.

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

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.

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

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)

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.

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

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.

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

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);

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

Deprecated: use rasqal_expression_evaluate2() using a rasqal_evaluation_context

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.

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

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.

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.

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()

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.

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()

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.

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

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

eval_context :

rasqal_evaluation_context object

seed :

random seed

Returns :

non-0 on failure


Navigation: Redland Home Page

Copyright 2000-2014 Dave Beckett