refactor(query): extract DescribeQueryCompiler and split pipeline executor tests

src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/CoreseAstQueryBuilder.java

@@ -146,8 +146,7 @@ public Query toNextQuery(DescribeQueryAst describeQueryAst) {
                 describeQueryAst.valuesClause(),
                 compiler);
         applyOrderBy(query, describeQueryAst.solutionModifier(), compiler);
-        List<Node> describedNodes = describeNodes(query, describeQueryAst, compiler);
-        lowerDescribeToConstructQuery(query, describedNodes);
+        DescribeQueryCompiler.compile(query, describeQueryAst, compiler);
         query.setAST(describeQueryAst);
         return query;
     }
@@ -365,78 +364,6 @@ private Node groupByNode(Query query, String name) {
         return null;
     }
 
-    /**
-     * Resolves the resources of a {@code DESCRIBE} against the compiled body.
-     *
-     * <p>{@code DESCRIBE *} reuses the in-scope nodes of the body (like {@code SELECT *}).
-     * A described variable reuses its runtime node (so it is the one bound by the body) and
-     * fails fast when it is not visible; a described IRI becomes a fresh constant node.</p>
-     */
-    private List<Node> describeNodes(
-            Query query, DescribeQueryAst describeQueryAst, WhereCompiler compiler) {
-        if (describeQueryAst.isDescribeAll()) {
-            return query.selectNodesFromPattern();
-        }
-        List<Node> nodes = new ArrayList<>();
-        for (TermAst term : describeQueryAst.described()) {
-            if (term instanceof VarAst(String name)) {
-                Node node = visibleBodyNode(query, name);
-                if (node == null) {
-                    throw new IllegalArgumentException(
-                            "DESCRIBE variable ?" + name + " is not visible in the compiled query body");
-                }
-                nodes.add(node);
-            } else {
-                nodes.add(compiler.termResolver().toNode(term));
-            }
-        }
-        return nodes;
-    }
-
-    /**
-     * Lowers {@code DESCRIBE} to the construct-like shape expected by the current
-     * KGRAM-next runtime.
-     *
-     * <p>This keeps the current KGRAM contract, inherited from the historical pipeline:
-     * {@code DESCRIBE} is executed through the construct runtime path.</p>
-     */
-    private void lowerDescribeToConstructQuery(Query query, List<Node> describedNodes) {
-        Exp constructTemplate = Exp.create(Type.BGP);
-        int syntheticIndex = 0;
-        for (Node describedNode : describedNodes) {
-            DescribePattern describePattern = describePattern(describedNode, syntheticIndex++);
-            // KGRAM-next currently represents DESCRIBE with outgoing and incoming construct triples.
-            constructTemplate.add(describePattern.outgoing().getEdge());
-            constructTemplate.add(describePattern.incoming().getEdge());
-            query.getBody().add(Exp.create(Type.OPTIONAL, Exp.create(Type.AND), describePattern.optionalBody()));
-        }
-        query.setConstruct(constructTemplate);
-        query.setConstruct(true);
-        query.setConstructNodes(constructTemplate.getNodes());
-    }
-
-    private DescribePattern describePattern(Node describedNode, int index) {
-        Node outgoingPredicate = createSyntheticDescribeNode("p", index, 0);
-        Node outgoingValue = createSyntheticDescribeNode("v", index, 0);
-        Node incomingPredicate = createSyntheticDescribeNode("p", index, 1);
-        Node incomingValue = createSyntheticDescribeNode("v", index, 1);
-
-        Exp outgoing = Exp.create(Type.EDGE, new AstBackedEdge(describedNode, outgoingPredicate, outgoingValue));
-        Exp incoming = Exp.create(Type.EDGE, new AstBackedEdge(incomingValue, incomingPredicate, describedNode));
-        Exp outgoingBgp = Exp.create(Type.BGP);
-        outgoingBgp.add(outgoing);
-        Exp incomingBgp = Exp.create(Type.BGP);
-        incomingBgp.add(incoming);
-        return new DescribePattern(outgoing, incoming, Exp.create(Type.UNION, outgoingBgp, incomingBgp));
-    }
-
-    private Node createSyntheticDescribeNode(String role, int describedIndex, int directionIndex) {
-        return NodeImpl.forVariable("__describe_" + role + "_" + describedIndex + "_" + directionIndex);
-    }
-
-    private record DescribePattern(Exp outgoing, Exp incoming, Exp optionalBody) {
-    }
-
     /**
      * Maps {@code ORDER BY} conditions that are already expressible in runtime KGRAM terms.
      *

src/main/java/fr/inria/corese/core/next/query/impl/sparql/bridge/DescribeQueryCompiler.java

@@ -0,0 +1,106 @@
+package fr.inria.corese.core.next.query.impl.sparql.bridge;
+
+import fr.inria.corese.core.next.query.impl.engine.model.ExpType.Type;
+import fr.inria.corese.core.next.query.impl.engine.model.Node;
+import fr.inria.corese.core.next.query.impl.engine.model.NodeImpl;
+import fr.inria.corese.core.next.query.impl.engine.pattern.Exp;
+import fr.inria.corese.core.next.query.impl.engine.pattern.Query;
+import fr.inria.corese.core.next.query.impl.sparql.ast.DescribeQueryAst;
+import fr.inria.corese.core.next.query.impl.sparql.ast.TermAst;
+import fr.inria.corese.core.next.query.impl.sparql.ast.VarAst;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/** Compiles DESCRIBE resources into incoming and outgoing graph construction patterns. */
+final class DescribeQueryCompiler {
+    private DescribeQueryCompiler() {
+    }
+
+    /**
+     * Adds the DESCRIBE patterns to an initialized query shell.
+     *
+     * @param query query with its body, dataset and modifiers already compiled
+     * @param description resources requested by DESCRIBE
+     * @param compiler compiler carrying the query prologue
+     * @throws IllegalArgumentException if a described variable is not visible
+     */
+    static void compile(Query query, DescribeQueryAst description, WhereCompiler compiler) {
+        lowerDescribeToConstructQuery(query, describeNodes(query, description, compiler));
+    }
+
+    /**
+     * Resolves the resources of a {@code DESCRIBE} against the compiled body.
+     *
+     * <p>{@code DESCRIBE *} reuses the in-scope nodes of the body (like {@code SELECT *}).
+     * A described variable reuses its runtime node (so it is the one bound by the body) and
+     * fails fast when it is not visible; a described IRI becomes a fresh constant node.</p>
+     */
+    private static List<Node> describeNodes(
+            Query query, DescribeQueryAst describeQueryAst, WhereCompiler compiler) {
+        if (describeQueryAst.isDescribeAll()) {
+            return query.selectNodesFromPattern();
+        }
+        List<Node> nodes = new ArrayList<>();
+        for (TermAst term : describeQueryAst.described()) {
+            if (term instanceof VarAst(String name)) {
+                Node node = query.selectNodesFromPattern().stream()
+                        .filter(candidate -> candidate.getLabel().equals(name))
+                        .findFirst().orElse(null);
+                if (node == null) {
+                    throw new IllegalArgumentException(
+                            "DESCRIBE variable ?" + name + " is not visible in the compiled query body");
+                }
+                nodes.add(node);
+            } else {
+                nodes.add(compiler.termResolver().toNode(term));
+            }
+        }
+        return nodes;
+    }
+
+    /**
+     * Lowers {@code DESCRIBE} to the construct-like shape expected by the current
+     * KGRAM-next runtime.
+     *
+     * <p>This keeps the current KGRAM contract, inherited from the historical pipeline:
+     * {@code DESCRIBE} is executed through the construct runtime path.</p>
+     */
+    private static void lowerDescribeToConstructQuery(Query query, List<Node> describedNodes) {
+        Exp constructTemplate = Exp.create(Type.BGP);
+        int syntheticIndex = 0;
+        for (Node describedNode : describedNodes) {
+            DescribePattern describePattern = describePattern(describedNode, syntheticIndex++);
+            // KGRAM-next currently represents DESCRIBE with outgoing and incoming construct triples.
+            constructTemplate.add(describePattern.outgoing().getEdge());
+            constructTemplate.add(describePattern.incoming().getEdge());
+            query.getBody().add(Exp.create(Type.OPTIONAL, Exp.create(Type.AND), describePattern.optionalBody()));
+        }
+        query.setConstruct(constructTemplate);
+        query.setConstruct(true);
+        query.setConstructNodes(constructTemplate.getNodes());
+    }
+
+    private static DescribePattern describePattern(Node describedNode, int index) {
+        Node outgoingPredicate = createSyntheticDescribeNode("p", index, 0);
+        Node outgoingValue = createSyntheticDescribeNode("v", index, 0);
+        Node incomingPredicate = createSyntheticDescribeNode("p", index, 1);
+        Node incomingValue = createSyntheticDescribeNode("v", index, 1);
+
+        Exp outgoing = Exp.create(Type.EDGE, new AstBackedEdge(describedNode, outgoingPredicate, outgoingValue));
+        Exp incoming = Exp.create(Type.EDGE, new AstBackedEdge(incomingValue, incomingPredicate, describedNode));
+        Exp outgoingBgp = Exp.create(Type.BGP);
+        outgoingBgp.add(outgoing);
+        Exp incomingBgp = Exp.create(Type.BGP);
+        incomingBgp.add(incoming);
+        return new DescribePattern(outgoing, incoming, Exp.create(Type.UNION, outgoingBgp, incomingBgp));
+    }
+
+    private static Node createSyntheticDescribeNode(String role, int describedIndex, int directionIndex) {
+        return NodeImpl.forVariable("__describe_" + role + "_" + describedIndex + "_" + directionIndex);
+    }
+
+    private record DescribePattern(Exp outgoing, Exp incoming, Exp optionalBody) {
+    }
+
+}