#453 [BRIDGE] Add EXISTS/NOT EXISTS to filter conversion

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

@@ -0,0 +1,54 @@
+package fr.inria.corese.core.next.query.impl.sparql.bridge;
+
+import fr.inria.corese.core.next.query.impl.sparql.ast.GroupGraphPatternAst;
+import fr.inria.corese.core.next.query.kgram.api.core.ExprType;
+import fr.inria.corese.core.next.query.kgram.core.Exp;
+import fr.inria.corese.core.sparql.triple.parser.ASTBuffer;
+import fr.inria.corese.core.sparql.triple.parser.Term;
+
+import java.util.Objects;
+
+final class AstBackedExistTerm extends Term {
+
+    private final GroupGraphPatternAst patternAst;
+    private Exp compiledPattern;
+
+    AstBackedExistTerm(GroupGraphPatternAst patternAst) {
+        super("exists");
+        setOper(ExprType.EXIST);
+        this.patternAst = Objects.requireNonNull(patternAst, "patternAst");
+    }
+
+    GroupGraphPatternAst patternAst() {
+        return patternAst;
+    }
+
+    void setCompiledPattern(Exp compiledPattern) {
+        this.compiledPattern = compiledPattern;
+    }
+
+    Exp compiledPattern() {
+        return compiledPattern;
+    }
+
+    /**
+     * The legacy {@code Term} reports an existence test through {@code getExist() != null}, but this
+     * bridge carries the pattern as a next-KGRAM {@link Exp} instead. Reporting it here keeps
+     * {@code isRecExist()} true, which the engine relies on to place FILTER EXISTS correctly
+     * (QuerySorter, in-scope filters of OPTIONAL/MINUS).
+     */
+    @Override
+    public boolean isTermExist() {
+        return true;
+    }
+
+    @Override
+    public boolean isExist() {
+        return true;
+    }
+
+    @Override
+    public ASTBuffer toString(ASTBuffer sb) {
+        return sb.append("exists {...}");
+    }
+}