apacheGH-1615: Evaluation for lateral

jena-arq/src/main/java/org/apache/jena/sparql/algebra/optimize/TransformFilterImplicitJoin.java

@@ -120,10 +120,14 @@ private static Op apply(ExprList exprs, Op subOp) {
         // ---- Check if the subOp is the right shape to transform.
         Op op = subOp;
 
-        // Special case : deduce that the filter will always "eval unbound"
-        // hence eliminate all rows. Return the empty table.
+        // LATERAL : This is not longer true.
+//        // Special case : deduce that the filter will always "eval unbound"
+//        // hence eliminate all rows. Return the empty table.
+//        if (testSpecialCaseUnused(subOp, joins, remaining))
+//            return OpTable.empty();
+        // But simply skipping this causes (filter) to become (assign) which fails as (assign) does not handle errors.
         if (testSpecialCaseUnused(subOp, joins, remaining))
-            return OpTable.empty();
+            return null;
 
         // Special case: the deep left op of a OpConditional/OpLeftJoin is unit
         // table.

jena-arq/src/main/java/org/apache/jena/sparql/engine/iterator/QueryIter1.java

@@ -28,52 +28,49 @@
  * This class supports a QueryIter that takes one QueryIterator as input. */
 public abstract class QueryIter1 extends QueryIter
 {
-    private QueryIterator input ; 
-
-    public QueryIter1(QueryIterator input, ExecutionContext execCxt)
-    { 
-        super(execCxt) ;
-        this.input = input ;
+    private QueryIterator input;
+
+    public QueryIter1(QueryIterator input, ExecutionContext execCxt) {
+        super(execCxt);
+        this.input = input;
     }
-    
+
     protected QueryIterator getInput() { return input ; }
-    
+
     @Override
-    protected final
-    void closeIterator()
-    {
-        closeSubIterator() ;
-        performClose(input) ;
-        input = null ;
+    protected final void closeIterator() {
+        closeSubIterator();
+        performClose(input);
+        input = null;
     }
-    
+
     @Override
-    protected final
-    void requestCancel()
-    {
-        requestSubCancel() ;
-        performRequestCancel(input) ;
+    protected final void requestCancel() {
+        requestSubCancel();
+        performRequestCancel(input);
     }
-    
+
     /** Cancellation of the query execution is happening */
-    protected abstract void requestSubCancel() ;
-
-    /** Pass on the close method - no need to close the QueryIterator passed to the QueryIter1 constructor */
-    protected abstract void closeSubIterator() ;
-
+    protected abstract void requestSubCancel();
+
+    /**
+     * Pass on the close method - no need to close the QueryIterator passed to the
+     * QueryIter1 constructor
+     */
+    protected abstract void closeSubIterator();
+
     // Do better
     @Override
-    public void output(IndentedWriter out, SerializationContext sCxt)
-    {
+    public void output(IndentedWriter out, SerializationContext sCxt) {
         // Linear form.
         if ( getInput() != null )
             // Closed
-            getInput().output(out, sCxt) ;
+            getInput().output(out, sCxt);
         else
             out.println("Closed");
-        out.ensureStartOfLine() ;
-        details(out, sCxt) ;
-        out.ensureStartOfLine() ;
+        out.ensureStartOfLine();
+        details(out, sCxt);
+        out.ensureStartOfLine();
 
 //        details(out, sCxt) ;
 //        out.ensureStartOfLine() ;
@@ -83,9 +80,7 @@ public void output(IndentedWriter out, SerializationContext sCxt)
 //        out.ensureStartOfLine() ;
     }
 
-    protected void details(IndentedWriter out, SerializationContext sCxt)
-    {
-        out.println(Lib.className(this)) ;
+    protected void details(IndentedWriter out, SerializationContext sCxt) {
+        out.println(Lib.className(this));
     }
-
 }

jena-arq/src/main/java/org/apache/jena/sparql/engine/iterator/QueryIterLateral.java

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.jena.sparql.engine.iterator;
+
+import org.apache.jena.sparql.algebra.Op;
+import org.apache.jena.sparql.algebra.op.OpTable;
+import org.apache.jena.sparql.core.Substitute;
+import org.apache.jena.sparql.engine.ExecutionContext;
+import org.apache.jena.sparql.engine.QueryIterator;
+import org.apache.jena.sparql.engine.binding.Binding;
+import org.apache.jena.sparql.engine.main.QC;
+
+public class QueryIterLateral extends QueryIterRepeatApply {
+
+    private final Op lateralOp;
+    private final boolean isUnit;
+
+    public QueryIterLateral(QueryIterator input, Op lateralOp, ExecutionContext execCxt) {
+        super(input, execCxt);
+        this.lateralOp = lateralOp;
+        this.isUnit = isJoinIdentity(lateralOp);
+    }
+
+    private boolean isJoinIdentity(Op op) {
+        if( ! ( op instanceof OpTable ) )
+            return false;
+        OpTable table = (OpTable)lateralOp;
+        return table.isJoinIdentity();
+    }
+
+    @Override
+    protected QueryIterator nextStage(Binding binding) {
+        if ( isUnit )
+            return QueryIterSingleton.create(binding, super.getExecContext());
+        Op op = Substitute.substitute(lateralOp, binding);
+        return QC.execute(op, binding, super.getExecContext());
+    }
+}

jena-arq/src/main/java/org/apache/jena/sparql/engine/main/ExecutionDispatch.java

@@ -21,7 +21,6 @@
 import java.util.ArrayDeque;
 import java.util.Deque;
 
-import org.apache.jena.atlas.lib.NotImplemented;
 import org.apache.jena.atlas.logging.Log;
 import org.apache.jena.sparql.algebra.Op;
 import org.apache.jena.sparql.algebra.OpVisitor;
@@ -156,8 +155,6 @@ public void visit(OpUnion opUnion) {
 
     @Override
     public void visit(OpLateral opLateral) {
-        if ( true )
-            throw new NotImplemented("EvaluatorDispatch.visit(OpLateral)");
         QueryIterator input = pop();
         QueryIterator qIter = opExecutor.execute(opLateral, input);
         push(qIter);

jena-arq/src/main/java/org/apache/jena/sparql/engine/main/OpExecutor.java

@@ -24,7 +24,6 @@
 import java.util.Set;
 
 import org.apache.jena.atlas.iterator.Iter;
-import org.apache.jena.atlas.lib.NotImplemented;
 import org.apache.jena.graph.Node;
 import org.apache.jena.query.ARQ;
 import org.apache.jena.query.QueryExecException;
@@ -41,7 +40,9 @@
 import org.apache.jena.sparql.engine.binding.Binding;
 import org.apache.jena.sparql.engine.iterator.*;
 import org.apache.jena.sparql.engine.join.Join;
-import org.apache.jena.sparql.engine.main.iterator.*;
+import org.apache.jena.sparql.engine.main.iterator.QueryIterGraph;
+import org.apache.jena.sparql.engine.main.iterator.QueryIterOptionalIndex;
+import org.apache.jena.sparql.engine.main.iterator.QueryIterUnion;
 import org.apache.jena.sparql.expr.Expr;
 import org.apache.jena.sparql.expr.ExprList;
 import org.apache.jena.sparql.procedure.ProcEval;
@@ -235,11 +236,8 @@ protected QueryIterator execute(OpLeftJoin opLeftJoin, QueryIterator input) {
 
     protected QueryIterator execute(OpLateral opLateral, QueryIterator input) {
         QueryIterator left = exec(opLateral.getLeft(), input);
-        if ( true )
-            throw new NotImplemented();
-        // QueryIterator qIter = new QueryIterOptionalIndex(left,
-        // opCondition.getRight(), execCxt) ;
-        QueryIterator qIter = null;
+        // For each row, substitute and execute.
+        QueryIterator qIter = new QueryIterLateral(left, opLateral.getRight(), execCxt);
         return qIter;
     }
 

jena-arq/src/main/java/org/apache/jena/sparql/engine/main/VarFinder.java

@@ -226,7 +226,6 @@ private static void combinefilterMentions(VarUsageVisitor usage, Set<Var> mentio
 
         @Override
         public void visit(OpLateral opLateral) {
-            // [LATERAL] ???
             mergeVars(opLateral.getLeft());
             mergeVars(opLateral.getRight());
         }