HHH-6686 fix JQL exception in face of 'empty'

hibernate-core/src/main/java/org/hibernate/hql/internal/ast/HqlParser.java

@@ -18,7 +18,6 @@ import java.util.Set;
 import org.hibernate.QueryException;
 import org.hibernate.hql.internal.antlr.HqlBaseParser;
 import org.hibernate.hql.internal.antlr.HqlTokenTypes;
-import org.hibernate.hql.internal.ast.util.ASTPrinter;
 import org.hibernate.hql.internal.ast.util.ASTUtil;
 import org.hibernate.hql.internal.ast.util.TokenPrinters;
 import org.hibernate.internal.CoreLogging;
@@ -116,7 +115,7 @@ public final class HqlParser extends HqlBaseParser {
 	 * @param token The token.
 	 * @param ex The recognition exception.
 	 *
-	 * @return AST - The new AST.
+	 * @return The new AST.
 	 *
 	 * @throws antlr.RecognitionException if the substitution was not possible.
 	 * @throws antlr.TokenStreamException if the substitution was not possible.
@@ -159,7 +158,7 @@ public final class HqlParser extends HqlBaseParser {
 	 *
 	 * @param x The sub tree to transform, the parent is assumed to be NOT.
 	 *
-	 * @return AST - The equivalent sub-tree.
+	 * @return The equivalent sub-tree.
 	 */
 	@Override
 	public AST negateNode(AST x) {
@@ -286,7 +285,7 @@ public final class HqlParser extends HqlBaseParser {
 	 *
 	 * @param x The equality expression.
 	 *
-	 * @return AST - The clean sub-tree.
+	 * @return The clean sub-tree.
 	 */
 	@Override
 	public AST processEqualityExpression(AST x) {
@@ -348,6 +347,10 @@ public final class HqlParser extends HqlBaseParser {
 	private AST createSubquery(AST node) {
 		AST ast = ASTUtil.createParent( astFactory, RANGE, "RANGE", node );
 		ast = ASTUtil.createParent( astFactory, FROM, "from", ast );
+
+		AST alias = ASTUtil.createSibling( astFactory, ALIAS, "_", node );
+		ASTUtil.insertChild( ASTUtil.createSibling( astFactory, SELECT, "select", ast ), astFactory.create(IDENT, alias.getText() ) );
+		
 		ast = ASTUtil.createParent( astFactory, SELECT_FROM, "SELECT_FROM", ast );
 		ast = ASTUtil.createParent( astFactory, QUERY, "QUERY", ast );
 		return ast;
@@ -489,12 +492,12 @@ public final class HqlParser extends HqlBaseParser {
 		LOG.debugf( "Registering discovered request to treat(%s as %s)", path, subclassName );
 
 		if ( treatMap == null ) {
-			treatMap = new HashMap<String, Set<String>>();
+			treatMap = new HashMap<>();
 		}
 
 		Set<String> subclassNames = treatMap.get( path );
 		if ( subclassNames == null ) {
-			subclassNames = new HashSet<String>();
+			subclassNames = new HashSet<>();
 			treatMap.put( path, subclassNames );
 		}
 		subclassNames.add( subclassName );
@@ -512,11 +515,11 @@ public final class HqlParser extends HqlBaseParser {
 	}
 
 	public Map<String, Set<String>> getTreatMap() {
-		return treatMap == null ? Collections.<String, Set<String>>emptyMap() : treatMap;
+		return treatMap == null ? Collections.emptyMap() : treatMap;
 	}
 
 	public static void panic() {
-		//overriden to avoid System.exit
+		//overridden to avoid System.exit
 		throw new QueryException( "Parser: panic" );
 	}
 }

hibernate-core/src/test/java/org/hibernate/jpa/test/criteria/paths/PluralAttributeExpressionsTest.java

@@ -72,7 +72,6 @@ public class PluralAttributeExpressionsTest extends AbstractMetamodelSpecificTes
 
 	@Test
 	@TestForIssue( jiraKey = "HHH-11225" )
-	@FailureExpected( jiraKey = "HHH-6686")
 	public void testElementMapIsEmptyHql() {
 		doInJPA( this::entityManagerFactory, entityManager -> {
 			entityManager.createQuery( "select m from MapEntity m where m.localized is empty" ).getResultList();
@@ -81,7 +80,6 @@ public class PluralAttributeExpressionsTest extends AbstractMetamodelSpecificTes
 
 	@Test
 	@TestForIssue( jiraKey = "HHH-11225" )
-	@FailureExpected( jiraKey = "HHH-6686")
 	public void testElementMapIsEmptyCriteria() {
 		doInJPA( this::entityManagerFactory, entityManager -> {
 			final HibernateCriteriaBuilder cb = (HibernateCriteriaBuilder) entityManager.getCriteriaBuilder();

hibernate-core/src/test/java/org/hibernate/query/IsEmptyJQLTest.java

@@ -0,0 +1,97 @@
+package org.hibernate.query;
+
+import org.hibernate.jpa.test.BaseEntityManagerFunctionalTestCase;
+import org.hibernate.testing.TestForIssue;
+import org.junit.Test;
+
+import javax.persistence.*;
+import java.util.*;
+import java.util.stream.Collectors;
+
+import static org.hibernate.testing.transaction.TransactionUtil.doInJPA;
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author Nathan Xu
+ */
+@TestForIssue(jiraKey = "HHH-6686")
+public class IsEmptyJQLTest extends BaseEntityManagerFunctionalTestCase {
+
+	private Long personWithoutNicknameId = 1L;
+	private Long personaWithSingleNicknameId = 2L;
+	private Long personWithMultipleNicknamesId = 3L;
+	
+	@Override
+	public Class<?>[] getAnnotatedClasses() {
+		return new Class[] { Person.class };
+	}
+	
+	@Test
+	public void testJQLContainingEmpty() {
+		List<Person> personWithNicknames = doInJPA( this::entityManagerFactory, entityManager -> {
+			return entityManager.createQuery(
+					"select p from Person p where p.nicknames is not empty", Person.class )
+					.getResultList();
+		});
+		
+		assertEquals( new HashSet<>( Arrays.asList(personaWithSingleNicknameId, personWithMultipleNicknamesId)), 
+				personWithNicknames.stream().map( Person::getId ).collect( Collectors.toSet() ));
+
+		List<Person> personWithOutNickname = doInJPA( this::entityManagerFactory, entityManager -> {
+			return entityManager.createQuery(
+					"select p from Person p where p.nicknames is empty", Person.class )
+					.getResultList();
+		});
+
+		assertEquals( Collections.singleton(personWithoutNicknameId), 
+				personWithOutNickname.stream().map( Person::getId ).collect( Collectors.toSet() ));
+	}
+
+	@Override
+	protected void afterEntityManagerFactoryBuilt() {
+		doInJPA( this::entityManagerFactory, entityManager -> {
+			Person personaWithoutNickname = new Person();
+			personaWithoutNickname.setId(personWithoutNicknameId);
+			
+			Person personaWithSingleNickname = new Person();
+			personaWithSingleNickname.getNicknames().add( "nickname" );
+			personaWithSingleNickname.setId(personaWithSingleNicknameId);
+			
+			Person personWithMultipleNicknames = new Person();
+			personWithMultipleNicknames.getNicknames().addAll( Arrays.asList( "nickName1", "nickName2" ) );
+			personWithMultipleNicknames.setId(personWithMultipleNicknamesId);
+			
+			entityManager.persist( personaWithoutNickname );
+			entityManager.persist( personaWithSingleNickname );
+			entityManager.persist( personWithMultipleNicknames );
+		} );
+	}
+
+	@Entity(name = "Person")
+	public static class Person {
+
+		@Id
+		private Long id;
+		
+		@ElementCollection
+		private List<String> nicknames = new ArrayList<>();
+
+		public Long getId() {
+			return id;
+		}
+
+		public void setId(Long id) {
+			this.id = id;
+		}
+
+		public List<String> getNicknames() {
+			return nicknames;
+		}
+
+		public void setNicknames(List<String> nicknames) {
+			this.nicknames = nicknames;
+		}
+	}
+}
+
+