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<?php
namespace SMW\SPARQLStore\QueryEngine;
use Iterator;
use SMWExpLiteral as ExpLiteral;
/**
* Class for accessing SPARQL query results in a unified form. The data is
* structured in tabular form, with each cell containing some SMWExpElement.
* Rows should always have the same number of columns, but the datatype of the
* cells in each column may not be uniform throughout the result.
*
* @ingroup Sparql
*
* @license GNU GPL v2+
* @since 1.6
*
* @author Markus Krötzsch
*/
class RepositoryResult implements Iterator {
/// Error code: no errors occurred.
const ERROR_NOERROR = 0;
/// Error code: service unreachable; result will be empty
const ERROR_UNREACHABLE = 1;
/// Error code: results might be incomplete (e.g. due to some resource limit being reached)
const ERROR_INCOMPLETE = 2;
/**
* Associative array mapping SPARQL variable names to column indices.
* @var array of integer
*/
protected $header;
/**
* List of result rows. Individual entries can be null if a cell in the
* SPARQL result table is empty (this is different from finding a blank
* node).
* @var array of array of (SMWExpElement or null)
*/
protected $data;
/**
* List of comment strings found in the XML file (without surrounding
* markup, i.e. the actual string only).
* @var array of string
*/
protected $comments;
/**
* Error code.
* @var integer
*/
protected $errorCode;
/**
* Initialise a result set from a result string in SPARQL XML format.
*
* @param $header array mapping SPARQL variable names to column indices
* @param $data array of array of (SMWExpElement or null)
* @param $comments array of string comments if the result contained any
* @param $errorCode integer an error code
*/
public function __construct( array $header = [], array $data = [], array $comments = [], $errorCode = self::ERROR_NOERROR ) {
$this->header = $header;
$this->data = $data;
$this->comments = $comments;
$this->errorCode = $errorCode;
reset( $this->data );
}
/**
* Get the number of rows in the result object.
*
* @return integer number of result rows
*/
public function numRows() {
return count( $this->data );
}
/**
* Return error code. SMWSparqlResultWrapper::ERROR_NOERROR (0)
* indicates that no error occurred.
*
* @return integer error code
*/
public function getErrorCode() {
return $this->errorCode;
}
/**
* Set the error code of this result set. This is used for allowing
* callers to add additional errors discovered only later on. It does
* not allow removing existing errors, since it will not accept
* SMWSparqlResultWrapper::ERROR_NOERROR as a parameter.
*
* @param $errorCode integer error code
*/
public function setErrorCode( $errorCode ) {
if ( $errorCode != self::ERROR_NOERROR ) {
$this->errorCode = $errorCode;
}
}
/**
* Return a list of comment strings found in the SPARQL result. Comments
* are used by some RDF stores to provide additional information or
* warnings that can thus be accessed.
*
* @return array of string
*/
public function getComments() {
return $this->comments;
}
/**
* Check if the result is what one would get for a SPARQL ASK query
* that returned true. Returns false in all other cases (including
* the case that the results do not look at all like the result of
* an ASK query).
*
* @return boolean
*/
public function isBooleanTrue() {
if ( count( $this->data ) == 1 ) {
$row = reset( $this->data );
$expElement = reset( $row );
if ( ( count( $row ) == 1 ) && ( $expElement instanceof ExpLiteral ) &&
( $expElement->getLexicalForm() == 'true' ) &&
( $expElement->getDatatype() == 'http://www.w3.org/2001/XMLSchema#boolean' ) ) {
return true;
}
}
return false;
}
/**
* Check if the result is what one would get for a SPARQL SELECT COUNT
* query, and return the corresponding integer value. Returns 0 in all
* other cases (including the case that the results do not look at all
* like the result of a SELECT COUNT query).
*
* @return integer
*/
public function getNumericValue() {
if ( count( $this->data ) == 1 ) {
$row = reset( $this->data );
$expElement = reset( $row );
if ( ( count( $row ) == 1 ) && ( $expElement instanceof ExpLiteral ) &&
( $expElement->getDatatype() == 'http://www.w3.org/2001/XMLSchema#integer' ) ) {
return (int)$expElement->getLexicalForm();
}
}
return 0;
}
/**
* Reset iterator to position 0. Standard method of Iterator.
*/
public function rewind() {
reset( $this->data );
}
/**
* Return the current result row. Standard method of Iterator.
*
* @return array of (SMWExpElement or null), or false at end of data
*/
public function current() {
return current( $this->data );
}
/**
* Return the next result row and advance the internal pointer.
* Standard method of Iterator.
*
* @return array of (SMWExpElement or null), or false at end of data
*/
public function next() {
return next( $this->data );
}
/**
* Return the next result row and advance the internal pointer.
* Standard method of Iterator.
*
* @return array of (SMWExpElement or null), or false at end of data
*/
public function key() {
return key( $this->data );
}
/**
* Return true if the internal pointer refers to a valid element.
* Standard method of Iterator.
*
* @return boolean
*/
public function valid() {
return ( current( $this->data ) !== false );
}
}
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