apacheGH-1615: ElementLateral: Parse and visit

jena-arq/Grammar/arq.jj

@@ -35,6 +35,8 @@ import org.apache.jena.sparql.expr.aggregate.lib.* ;
 import org.apache.jena.update.* ;
 import org.apache.jena.sparql.modify.request.* ;
 import org.apache.jena.sparql.core.Quad ;
+import java.util.List;
+import java.util.ArrayList;
 public class ARQParser extends ARQParserBase
 {}
 PARSER_END(ARQParser)
@@ -612,6 +614,8 @@ Element GraphPatternNotTriples() : { Element el = null ; }
    el = GroupOrUnionGraphPattern()
  |
    el = OptionalGraphPattern()
+ |
+   el = LateralGraphPattern()
  |
    el = MinusGraphPattern()
  |
@@ -637,6 +641,10 @@ Element OptionalGraphPattern() : { Element el ; }
 { <OPTIONAL> el = GroupGraphPattern()
     { return new ElementOptional(el) ; }
 }
+Element LateralGraphPattern() : { Element el ; }
+{ <LATERAL> el = GroupGraphPattern()
+    { return new ElementLateral(el) ; }
+}
 Element GraphGraphPattern() : { Element el ; Node n ;}
 {
   <GRAPH> n = VarOrIri() el = GroupGraphPattern()
@@ -1783,6 +1791,7 @@ TOKEN [IGNORE_CASE] :
 | < SUBJECT: "SUBJECT" >
 | < PREDICATE: "PREDICATE" >
 | < OBJECT: "OBJECT" >
+| < LATERAL: "LATERAL" >
 | < EXISTS: "exists" >
 | < NOT: "not" >
 | < AS: "as" >

jena-arq/Grammar/main.jj

@@ -99,6 +99,8 @@ import org.apache.jena.sparql.modify.request.* ;
 #endif
 #ifdef ARQ
 import org.apache.jena.sparql.core.Quad ;
+import java.util.List;
+import java.util.ArrayList;
 #endif
 
 public class CLASS extends PARSERBASE
@@ -879,6 +881,10 @@ Element GraphPatternNotTriples() : { Element el = null ; }
    el = GroupOrUnionGraphPattern()
  |
    el = OptionalGraphPattern()
+#ifdef ARQ
+ |
+   el = LateralGraphPattern()
+#endif
  |
    el = MinusGraphPattern()
  |
@@ -910,13 +916,19 @@ Element OptionalGraphPattern() : { Element el ; }
     { return new ElementOptional(el) ; }
 }
 
+#ifdef ARQ
+Element LateralGraphPattern() : { Element el ; }
+{ <LATERAL> el = GroupGraphPattern()
+    { return new ElementLateral(el) ; }
+}
+#endif
+
 Element GraphGraphPattern() : { Element el ; Node n ;}
 {
   <GRAPH> n = VarOrIri() el = GroupGraphPattern()
     { return new ElementNamedGraph(n, el) ; }
 }
 
-
 Element ServiceGraphPattern() : { Element el ; Node n ; boolean silent = false ; }
 {
   <SERVICE> 
@@ -2522,6 +2534,7 @@ TOKEN [IGNORE_CASE] :
 |  < SUBJECT:     "SUBJECT" >
 |  < PREDICATE:   "PREDICATE" >
 |  < OBJECT:      "OBJECT" >
+|  < LATERAL:     "LATERAL" >
 #endif
 |  < EXISTS:      "exists" >
 |  < NOT:         "not" >

jena-arq/Grammar/tokens.txt

@@ -104,6 +104,7 @@
 [<GRAPH>]      ::= 'GRAPH'
 [<UNION>]      ::= 'UNION'
 [<OPTIONAL>]   ::= 'OPTIONAL'
+[<LATERAL>]    ::= 'LATERAL'
 [<BOUND>]      ::= 'BOUND'
 [<COALESCE>]   ::= 'COALESCE'
 [<IF>]         ::= 'IF'

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

@@ -301,6 +301,11 @@ protected Op compileOneInGroup(Element elt, Op current, Deque<Op> acc) {
             return compileElementOptional(eltOpt, current);
         }
 
+        if ( elt instanceof ElementLateral ) {
+            ElementLateral eltLateral = (ElementLateral)elt;
+            return compileElementLateral(eltLateral, current);
+        }
+
         if ( elt instanceof ElementMinus ) {
             ElementMinus elt2 = (ElementMinus)elt;
             Op op = compileElementMinus(current, elt2);
@@ -397,6 +402,12 @@ protected Op compileElementOptional(ElementOptional eltOpt, Op current) {
         return current;
     }
 
+    protected Op compileElementLateral(ElementLateral eltLateral, Op current) {
+        Element subElt = eltLateral.getLateralElement();
+        Op op = compileElement(subElt);
+        return OpLateral.create(current, op);
+    }
+
     protected Op compileBasicPattern(BasicPattern pattern) {
         return new OpBGP(pattern);
     }

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

@@ -24,7 +24,7 @@
 
 /**
  * Special purpose base class for a single transformation.
- *  
+ *
  * When writing {@link Transform}s to be applied to a tree,
  * extend {@link TransformCopy}, not this class.
  */
@@ -76,6 +76,8 @@ public class TransformSingle implements Transform
     @Override
     public Op transform(OpUnion opUnion, Op left, Op right)         { return opUnion ; }
     @Override
+    public Op transform(OpLateral opCopLateral, Op left, Op right)  { return opCopLateral ; }
+    @Override
     public Op transform(OpConditional opCond, Op left, Op right)    { return opCond ; }
 
     @Override

jena-arq/src/main/java/org/apache/jena/sparql/algebra/op/OpLateral.java

@@ -18,50 +18,20 @@
 
 package org.apache.jena.sparql.algebra.op;
 
-import java.util.List;
-
-import org.apache.jena.atlas.lib.InternalErrorException;
 import org.apache.jena.sparql.algebra.Op;
 import org.apache.jena.sparql.algebra.OpVisitor;
 import org.apache.jena.sparql.algebra.Transform;
-import org.apache.jena.sparql.core.Var;
 import org.apache.jena.sparql.sse.Tags;
 import org.apache.jena.sparql.util.NodeIsomorphismMap;
 
 public class OpLateral extends Op2
 {
     public static Op create(Op left, Op right) {
-        return new OpLateral(left, right, null, false);
-    }
-
-    public static Op create(Op left, Op right, List<Var> vars) {
-        return new OpLateral(left, right, vars, false);
-    }
-
-    public static Op create(Op left, Op right, boolean withStar) {
-        return new OpLateral(left, right, null, true);
+        return new OpLateral(left, right);
     }
 
-    private final List<Var> vars;
-    /// Was it LATERAL(*) / LATERAL * (as opposed to LATERAL { ... }
-    // which means the same.
-    private final boolean withStar;
-
-    private OpLateral(Op left, Op right, List<Var> vars, boolean withStar) {
+    private OpLateral(Op left, Op right) {
         super(left, right);
-        if ( vars != null && withStar )
-            throw new InternalErrorException("Inconsistent: OpLateral: Both a variable list and has a *");
-        this.vars = vars;
-        this.withStar = withStar;
-    }
-
-    /** LATERAL(vars) - null means "no vars" */
-    public List<Var> vars() {
-        return vars;
-    }
-
-    public boolean withStar() {
-        return withStar;
     }
 
     @Override
@@ -76,7 +46,7 @@ public Op apply(Transform transform, Op left, Op right)
 
     @Override
     public Op2 copy(Op newLeft, Op newRight)
-    { return new OpLateral(newLeft, newRight, List.copyOf(vars), withStar); }
+    { return new OpLateral(newLeft, newRight); }
 
     @Override
     public boolean equalTo(Op op2, NodeIsomorphismMap labelMap) {