class QueryResultIterator |
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\class QueryResultIterator queryresultiterator.h Soprano/QueryResultIterator
An iterator for query results. %Query results in %Soprano are wrapped in a QueryResultIterator. %Query iterators are returned by Model.executeQuery(). In contrast to NodeIterator or StatementIterator %QueryResultIterator has a set of different access methods for the current dataset which can be one of three things:
Example:
QueryResultIterator it = model->executeQuery( someGraphQuery ); while( it.next() ) { doSomething( it.currentStatement() ); } Many backends do lock the underlying Model during iteration. Thus, it is always a good idea to cache the results if they are to be used to modify the model to prevent a deadlock:
Soprano.QueryResultIterator it = model->executeQuery( someTupleQuery ); QList For further details on %Soprano iterators see Iterator. Be aware that iterators in Soprano are shared objects which means that copies of one iterator object work on the same data.
Author Daniele Galdi |
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Creates and empty, invalid iterator. |
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Copy constructor. Copies of iterators share their data. |
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Create a new QueryResultIterator which uses qr as backend. QueryResultIterator will take ownership of the QueryResultIteratorBackend. |
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Convenience method that collects all binding sets that are left in the iterator. |
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Get the current binding for a variable.
name - The name of the requested variable. This method does only make sense for tuple queries. Returns The binding for the requested variable or and invalid node if the bindings do not contain the variable. |
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Get the current binding for a variable by index.
offset - The index of the requested variable. This method does only make sense for tuple queries. Returns The binding for the requested variable or and invalid node if offset is out of bounds, i.e. bigger or equal to bindingCount(). |
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The number of bindings in this query result.
This method does only make sense for tuple queries. Returns The number of bindings. |
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This method does only make sense for tuple queries.
Returns The names of the bound variables in this query result. |
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This method does only make sense for boolean queries.
Returns The result of a boolean query (SPARQL ASK). See also isBool() |
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Convenience method that puts all current bindings into one map. This method does only make sense for tuple queries. |
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Retrieve the current Statement after a call to next. This method does only make sense for graph queries. |
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Check if this is a tuple result.
Returns true if this result refers to a tuple query, i.e. currentBindings(), binding(), bindingCount(), bindingNames(), and allBindings() return valid values. |
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Check if this is a boolean result.
There is no need to call next() for boolean results. However, for internal reasons backends need to always return true for boolean queries. Returns true if this result refers to a boolean query (SPARQL ASK), i.e. boolValue() returns a valid value. |
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Check if this is a graph result.
Returns true if this result refers to a graph query, i.e. currentStatement() and iterateStatements() return valid values. |
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Convenience method that creates an iterator over one column of bindings in this query result.
This method does only make sense for tuple queries.
variableName - The name of the requested variable. The new iterator is just a wrapper around this one. Thus, changing it will also change this one. Returns A wrapper iterator over one column in a tuple query or an invalid iterator if the result does not contain bindings for variableName. |
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Convenience method that creates an iterator over one column of bindings in this query result.
This method does only make sense for tuple queries.
offset - The index of the requested variable. The new iterator is just a wrapper around this one. Thus, changing it will also change this one. Returns A wrapper iterator over one column in a tuple query or an invalid iterator if offset is out of bounds, i.e. bigger or equal to bindingCount(). |
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Convenience method that creates an iterator over the statements in this query result.
This method does only make sense for graph queries.
The new iterator is just a wrapper around this one. Thus, changing it will also change this one. Returns A wrapper iterator over the statements in a graph query. |