Adds QueryTriplesIterator

lib/src/sparql/eval.rs

@@ -89,22 +89,26 @@ impl<S: ReadableEncodedStore + 'static> SimpleEvaluator<S> {
         construct: Rc<Vec<TripleTemplate>>,
     ) -> Result<QueryResult> {
         let from = EncodedTuple::with_capacity(plan.maybe_bound_variables().len());
-        Ok(QueryResult::Graph(Box::new(ConstructIterator {
-            eval: self.clone(),
-            iter: self.eval_plan(plan, from),
-            template: construct,
-            buffered_results: Vec::default(),
-            bnodes: Vec::default(),
-        })))
+        Ok(QueryResult::Graph(QueryTriplesIterator {
+            iter: Box::new(ConstructIterator {
+                eval: self.clone(),
+                iter: self.eval_plan(plan, from),
+                template: construct,
+                buffered_results: Vec::default(),
+                bnodes: Vec::default(),
+            }),
+        }))
     }
 
     pub fn evaluate_describe_plan(&self, plan: &PlanNode) -> Result<QueryResult> {
         let from = EncodedTuple::with_capacity(plan.maybe_bound_variables().len());
-        Ok(QueryResult::Graph(Box::new(DescribeIterator {
-            eval: self.clone(),
-            iter: self.eval_plan(plan, from),
-            quads: Box::new(empty()),
-        })))
+        Ok(QueryResult::Graph(QueryTriplesIterator {
+            iter: Box::new(DescribeIterator {
+                eval: self.clone(),
+                iter: self.eval_plan(plan, from),
+                quads: Box::new(empty()),
+            }),
+        }))
     }
 
     fn eval_plan(&self, node: &PlanNode, from: EncodedTuple) -> EncodedTuplesIterator {

lib/src/sparql/mod.rs

@@ -21,6 +21,7 @@ use crate::Result;
 
 pub use crate::sparql::model::QuerySolution;
 pub use crate::sparql::model::QuerySolutionsIterator;
+pub use crate::sparql::model::QueryTriplesIterator;
 #[deprecated(note = "Please directly use QuerySolutionsIterator type instead")]
 pub type BindingsIterator<'a> = QuerySolutionsIterator;
 pub use crate::sparql::model::QueryResult;

lib/src/sparql/model.rs

@@ -19,7 +19,7 @@ pub enum QueryResult {
     /// Result of a [ASK](https://www.w3.org/TR/sparql11-query/#ask) query
     Boolean(bool),
     /// Results of a [CONSTRUCT](https://www.w3.org/TR/sparql11-query/#construct) or [DESCRIBE](https://www.w3.org/TR/sparql11-query/#describe) query
-    Graph(Box<dyn Iterator<Item = Result<Triple>>>),
+    Graph(QueryTriplesIterator),
 }
 
 impl QueryResult {
@@ -112,11 +112,9 @@ impl QueryResult {
     }
 }
 
-impl<E: Into<Error>, I: Iterator<Item = std::result::Result<Triple, E>> + 'static> From<I>
-    for QueryResult
-{
-    fn from(iter: I) -> Self {
-        QueryResult::Graph(Box::new(iter.map(|e| e.map_err(|e| e.into()))))
+impl From<QuerySolutionsIterator> for QueryResult {
+    fn from(value: QuerySolutionsIterator) -> Self {
+        QueryResult::Solutions(value)
     }
 }
 
@@ -365,6 +363,43 @@ impl VariableSolutionIndex for Variable {
     }
 }
 
+/// An iterator over the triples that compose a graph solution
+///
+/// ```
+/// use oxigraph::MemoryStore;
+/// use oxigraph::sparql::{QueryResult, QueryOptions};
+///
+/// let store = MemoryStore::new();
+/// if let QueryResult::Graph(triples) = store.query("CONSTRUCT WHERE { ?s ?p ?o }", QueryOptions::default())? {
+///     for triple in triples {
+///         println!("{}", triple?);
+///     }
+/// }
+/// # oxigraph::Result::Ok(())
+/// ```
+pub struct QueryTriplesIterator {
+    pub(crate) iter: Box<dyn Iterator<Item = Result<Triple>>>,
+}
+
+impl Iterator for QueryTriplesIterator {
+    type Item = Result<Triple>;
+
+    fn next(&mut self) -> Option<Result<Triple>> {
+        self.iter.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+
+    fn fold<Acc, G>(self, init: Acc, mut g: G) -> Acc
+    where
+        G: FnMut(Acc, Self::Item) -> Acc,
+    {
+        self.iter.fold(init, |acc, elt| g(acc, elt))
+    }
+}
+
 /// A SPARQL query variable
 ///
 /// ```

python/src/store_utils.rs

@@ -1,7 +1,6 @@
 use crate::model::*;
 use oxigraph::model::*;
-use oxigraph::sparql::{QueryResult, QuerySolution, QuerySolutionsIterator};
-use oxigraph::Result;
+use oxigraph::sparql::{QueryResult, QuerySolution, QuerySolutionsIterator, QueryTriplesIterator};
 use pyo3::exceptions::{IOError, TypeError, ValueError};
 use pyo3::prelude::*;
 use pyo3::{PyIterProtocol, PyMappingProtocol, PyNativeType, PyObjectProtocol};
@@ -121,7 +120,7 @@ impl PyIterProtocol for QuerySolutionIter {
 
 #[pyclass(unsendable)]
 pub struct TripleResultIter {
-    inner: Box<dyn Iterator<Item = Result<Triple>>>,
+    inner: QueryTriplesIterator,
 }
 
 #[pyproto]