Allows to set BindingsIterator lifetime

Will allow to avoid a lot of copies

lib/src/sparql/algebra.rs

@@ -167,7 +167,7 @@ impl StaticBindings {
         self.values.iter()
     }
 
-    pub fn into_iterator(self) -> BindingsIterator {
+    pub fn into_iterator(self) -> BindingsIterator<'static> {
         BindingsIterator {
             variables: self.variables,
             iter: Box::new(self.values.into_iter().map(Ok)),
@@ -188,15 +188,15 @@ impl Default for StaticBindings {
     }
 }
 
-pub struct BindingsIterator {
+pub struct BindingsIterator<'a> {
     variables: Vec<Variable>,
-    iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>>>>,
+    iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a>,
 }
 
-impl BindingsIterator {
+impl<'a> BindingsIterator<'a> {
     pub fn new(
         variables: Vec<Variable>,
-        iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>>>>,
+        iter: Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a>,
     ) -> Self {
         Self { variables, iter }
     }
@@ -205,7 +205,7 @@ impl BindingsIterator {
         &*self.variables
     }
 
-    pub fn into_values_iter(self) -> Box<dyn Iterator<Item = Result<Vec<Option<Term>>>>> {
+    pub fn into_values_iter(self) -> Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a> {
         self.iter
     }
 
@@ -213,7 +213,7 @@ impl BindingsIterator {
         self,
     ) -> (
         Vec<Variable>,
-        Box<dyn Iterator<Item = Result<Vec<Option<Term>>>>>,
+        Box<dyn Iterator<Item = Result<Vec<Option<Term>>>> + 'a>,
     ) {
         (self.variables, self.iter)
     }
@@ -1574,8 +1574,8 @@ impl fmt::Display for Query {
     }
 }
 
-pub enum QueryResult {
-    Bindings(BindingsIterator),
+pub enum QueryResult<'a> {
+    Bindings(BindingsIterator<'a>),
     Boolean(bool),
     Graph(MemoryGraph),
 }

lib/src/sparql/eval.rs

@@ -21,7 +21,7 @@ use store::encoded::EncodedQuadsStore;
 use store::numeric_encoder::*;
 use Result;
 
-type EncodedTuplesIterator = Box<dyn Iterator<Item = Result<EncodedTuple>>>;
+type EncodedTuplesIterator<'a> = Box<dyn Iterator<Item = Result<EncodedTuple>> + 'a>;
 
 pub struct SimpleEvaluator<S: EncodedQuadsStore> {
     store: Arc<S>,
@@ -40,18 +40,18 @@ impl<S: EncodedQuadsStore> SimpleEvaluator<S> {
         Self { store }
     }
 
-    pub fn evaluate(&self, query: &Query) -> Result<QueryResult> {
-        match query {
-            Query::Select { algebra, dataset } => {
-                let (plan, variables) = PlanBuilder::build(&*self.store, algebra)?;
-                let iter = self.eval_plan(plan, vec![None; variables.len()]);
-                Ok(QueryResult::Bindings(self.decode_bindings(iter, variables)))
-            }
-            _ => unimplemented!(),
-        }
+    pub fn evaluate_select_plan<'a>(
+        &'a self,
+        plan: &PlanNode,
+        variables: &[Variable],
+    ) -> Result<QueryResult<'a>> {
+        let iter = self.eval_plan(plan.clone(), vec![None; variables.len()]);
+        Ok(QueryResult::Bindings(
+            self.decode_bindings(iter, variables.to_vec()),
+        ))
     }
 
-    fn eval_plan(&self, node: PlanNode, from: EncodedTuple) -> EncodedTuplesIterator {
+    fn eval_plan<'a>(&self, node: PlanNode, from: EncodedTuple) -> EncodedTuplesIterator<'a> {
         match node {
             PlanNode::Init => Box::new(once(Ok(from))),
             PlanNode::StaticBindings { tuples } => Box::new(tuples.into_iter().map(Ok)),
@@ -648,11 +648,11 @@ impl<S: EncodedQuadsStore> SimpleEvaluator<S> {
         }
     }
 
-    fn decode_bindings(
+    fn decode_bindings<'a>(
         &self,
-        iter: EncodedTuplesIterator,
+        iter: EncodedTuplesIterator<'a>,
         variables: Vec<Variable>,
-    ) -> BindingsIterator {
+    ) -> BindingsIterator<'a> {
         let store = self.store.clone();
         BindingsIterator::new(
             variables,
@@ -807,13 +807,13 @@ fn combine_tuples(a: &[Option<EncodedTerm>], b: &[Option<EncodedTerm>]) -> Optio
     }
 }
 
-struct JoinIterator {
+struct JoinIterator<'a> {
     left: Vec<EncodedTuple>,
-    right_iter: EncodedTuplesIterator,
+    right_iter: EncodedTuplesIterator<'a>,
     buffered_results: Vec<Result<EncodedTuple>>,
 }
 
-impl Iterator for JoinIterator {
+impl<'a> Iterator for JoinIterator<'a> {
     type Item = Result<EncodedTuple>;
 
     fn next(&mut self) -> Option<Result<EncodedTuple>> {
@@ -833,14 +833,14 @@ impl Iterator for JoinIterator {
     }
 }
 
-struct LeftJoinIterator<S: EncodedQuadsStore> {
+struct LeftJoinIterator<'a, S: EncodedQuadsStore> {
     eval: SimpleEvaluator<S>,
     right_plan: PlanNode,
-    left_iter: EncodedTuplesIterator,
-    current_right_iter: Option<EncodedTuplesIterator>,
+    left_iter: EncodedTuplesIterator<'a>,
+    current_right_iter: Option<EncodedTuplesIterator<'a>>,
 }
 
-impl<S: EncodedQuadsStore> Iterator for LeftJoinIterator<S> {
+impl<'a, S: EncodedQuadsStore> Iterator for LeftJoinIterator<'a, S> {
     type Item = Result<EncodedTuple>;
 
     fn next(&mut self) -> Option<Result<EncodedTuple>> {
@@ -867,13 +867,13 @@ impl<S: EncodedQuadsStore> Iterator for LeftJoinIterator<S> {
     }
 }
 
-struct BadLeftJoinIterator<S: EncodedQuadsStore> {
+struct BadLeftJoinIterator<'a, S: EncodedQuadsStore> {
     input: EncodedTuple,
-    iter: LeftJoinIterator<S>,
+    iter: LeftJoinIterator<'a, S>,
     problem_vars: Vec<usize>,
 }
 
-impl<S: EncodedQuadsStore> Iterator for BadLeftJoinIterator<S> {
+impl<'a, S: EncodedQuadsStore> Iterator for BadLeftJoinIterator<'a, S> {
     type Item = Result<EncodedTuple>;
 
     fn next(&mut self) -> Option<Result<EncodedTuple>> {
@@ -903,14 +903,14 @@ impl<S: EncodedQuadsStore> Iterator for BadLeftJoinIterator<S> {
     }
 }
 
-struct UnionIterator<S: EncodedQuadsStore> {
+struct UnionIterator<'a, S: EncodedQuadsStore> {
     eval: SimpleEvaluator<S>,
     children_plan: Vec<PlanNode>,
-    input_iter: EncodedTuplesIterator,
-    current_iters: Vec<EncodedTuplesIterator>,
+    input_iter: EncodedTuplesIterator<'a>,
+    current_iters: Vec<EncodedTuplesIterator<'a>>,
 }
 
-impl<S: EncodedQuadsStore> Iterator for UnionIterator<S> {
+impl<'a, S: EncodedQuadsStore> Iterator for UnionIterator<'a, S> {
     type Item = Result<EncodedTuple>;
 
     fn next(&mut self) -> Option<Result<EncodedTuple>> {

lib/src/sparql/mod.rs

@@ -4,10 +4,12 @@
 use model::Dataset;
 use sparql::algebra::Query;
 use sparql::algebra::QueryResult;
+use sparql::algebra::Variable;
 use sparql::eval::SimpleEvaluator;
 use sparql::parser::read_sparql_query;
+use sparql::plan::PlanBuilder;
+use sparql::plan::PlanNode;
 use std::io::Read;
-use std::sync::Arc;
 use store::encoded::EncodedQuadsStore;
 use store::encoded::StoreDataset;
 use Result;
@@ -31,20 +33,37 @@ impl<S: EncodedQuadsStore> SparqlDataset for StoreDataset<S> {
     type PreparedQuery = SimplePreparedQuery<S>;
 
     fn prepare_query(&self, query: impl Read) -> Result<SimplePreparedQuery<S>> {
-        Ok(SimplePreparedQuery {
-            query: read_sparql_query(query, None)?,
-            store: self.encoded(),
+        Ok(match read_sparql_query(query, None)? {
+            Query::Select { algebra, dataset } => {
+                let store = self.encoded();
+                let (plan, variables) = PlanBuilder::build(&*store, &algebra)?;
+                SimplePreparedQuery::Select {
+                    plan,
+                    variables,
+                    evaluator: SimpleEvaluator::new(store),
+                }
+            }
+            _ => unimplemented!(),
         })
     }
 }
 
-pub struct SimplePreparedQuery<S: EncodedQuadsStore> {
-    query: Query,
-    store: Arc<S>,
+pub enum SimplePreparedQuery<S: EncodedQuadsStore> {
+    Select {
+        plan: PlanNode,
+        variables: Vec<Variable>,
+        evaluator: SimpleEvaluator<S>,
+    },
 }
 
 impl<S: EncodedQuadsStore> PreparedQuery for SimplePreparedQuery<S> {
     fn exec(&self) -> Result<QueryResult> {
-        SimpleEvaluator::new(self.store.clone()).evaluate(&self.query)
+        match self {
+            SimplePreparedQuery::Select {
+                plan,
+                variables,
+                evaluator,
+            } => evaluator.evaluate_select_plan(&plan, &variables),
+        }
     }
 }

lib/src/sparql/xml_results.rs

@@ -10,7 +10,7 @@ use std::iter::empty;
 use std::str::FromStr;
 use Result;
 
-pub fn read_xml_results(source: impl BufRead + 'static) -> Result<QueryResult> {
+pub fn read_xml_results(source: impl BufRead + 'static) -> Result<QueryResult<'static>> {
     enum State {
         Start,
         Sparql,

lib/tests/sparql_test_cases.rs

@@ -211,15 +211,18 @@ fn sparql_w3c_query_evaluation_testsuite() {
                     .unwrap()
                     .for_each(|triple| named_graph.insert(&triple.unwrap()).unwrap());
             }
-            match data
-                .prepare_query(client.get(&test.query).unwrap())
-                .and_then(|p| p.exec())
-            {
+            match data.prepare_query(client.get(&test.query).unwrap()) {
                 Err(error) => assert!(
                     false,
                     "Failure to parse query of {} with error: {}",
                     test, error
                 ),
+                Ok(query) => match query.exec() {
+                    Err(error) => assert!(
+                        false,
+                        "Failure to execute query of {} with error: {}",
+                        test, error
+                    ),
                     Ok(result) => {
                         let actual_graph = to_graph(result).unwrap();
                         let expected_graph = client
@@ -235,6 +238,7 @@ fn sparql_w3c_query_evaluation_testsuite() {
                             data
                         )
                     }
+                },
             }
         } else {
             assert!(false, "Not supported test: {}", test);