[HHH-16861] HQL ordinal() function

`ordinal(field)` is equivalent to `cast(enum as Integer`, implementation taken from CastStrEmulation

Added new rule in both Lexer and parser (remember to add nakedidentifier)

Author: lucamolteni

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlLexer.g4

@@ -273,6 +273,7 @@ ON					: [oO] [nN];
 ONLY				: [oO] [nN] [lL] [yY];
 OR					: [oO] [rR];
 ORDER				: [oO] [rR] [dD] [eE] [rR];
+ORDINAL				: [oO] [rR] [dD] [iI] [nN] [aA] [lL];
 OTHERS				: [oO] [tT] [hH] [eE] [rR] [sS];
 OUTER				: [oO] [uU] [tT] [eE] [rR];
 OVER				: [oO] [vV] [eE] [rR];

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlParser.g4

@@ -1863,6 +1863,7 @@ jsonUniqueKeysClause
 	| ONLY
 	| OR
 	| ORDER
+	| ORDINAL
 	| OTHERS
 //	| OUTER
 	| OVER

hibernate-core/src/main/java/org/hibernate/dialect/Dialect.java

@@ -68,6 +68,7 @@
 import org.hibernate.dialect.function.LpadRpadPadEmulation;
 import org.hibernate.dialect.function.SqlFunction;
 import org.hibernate.dialect.function.TrimFunction;
+import org.hibernate.dialect.function.OrdinalFunction;
 import org.hibernate.dialect.identity.IdentityColumnSupport;
 import org.hibernate.dialect.identity.IdentityColumnSupportImpl;
 import org.hibernate.dialect.lock.LockingStrategy;
@@ -1226,6 +1227,11 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		functionContributions.getFunctionRegistry().register( "str",
 				new CastStrEmulation( typeConfiguration ) );
 
+		// Function to convert enum mapped as Ordinal to their ordinal value
+
+		functionContributions.getFunctionRegistry().register( "ordinal",
+				new OrdinalFunction( typeConfiguration ) );
+
 		//format() function for datetimes, emulated on many databases using the
 		//Oracle-style to_char() function, and on others using their native
 		//formatting functions

hibernate-core/src/main/java/org/hibernate/dialect/function/OrdinalFunction.java

@@ -0,0 +1,71 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.dialect.function;
+
+import org.hibernate.query.ReturnableType;
+import org.hibernate.query.spi.QueryEngine;
+import org.hibernate.query.sqm.function.AbstractSqmFunctionDescriptor;
+import org.hibernate.query.sqm.function.SelfRenderingSqmFunction;
+import org.hibernate.query.sqm.produce.function.ArgumentsValidator;
+import org.hibernate.query.sqm.produce.function.FunctionReturnTypeResolver;
+import org.hibernate.query.sqm.produce.function.StandardArgumentsValidators;
+import org.hibernate.query.sqm.produce.function.StandardFunctionReturnTypeResolvers;
+import org.hibernate.query.sqm.tree.SqmTypedNode;
+import org.hibernate.query.sqm.tree.expression.SqmCastTarget;
+import org.hibernate.type.StandardBasicTypes;
+import org.hibernate.type.spi.TypeConfiguration;
+
+import java.util.List;
+
+import static java.util.Arrays.asList;
+
+/**
+ * The HQL {@code ordinal()} function is now considered a synonym for {@code cast(x as Integer)}.
+ * Same as {@link CastStrEmulation} but for Integer.
+ * This is useful for enum types mapped as ORDINAL.
+ *
+ * @author Luca Molteni
+ */
+public class OrdinalFunction
+		extends AbstractSqmFunctionDescriptor {
+
+	public OrdinalFunction(TypeConfiguration typeConfiguration) {
+		super(
+				"ordinal",
+				StandardArgumentsValidators.exactly( 1 ),
+				StandardFunctionReturnTypeResolvers.invariant(
+						typeConfiguration.getBasicTypeRegistry().resolve( StandardBasicTypes.INTEGER )
+				),
+				null
+		);
+	}
+
+	protected OrdinalFunction(
+			String name,
+			ArgumentsValidator argumentsValidator,
+			FunctionReturnTypeResolver returnTypeResolver) {
+		super( name, argumentsValidator, returnTypeResolver, null );
+	}
+
+	@Override
+	protected <T> SelfRenderingSqmFunction<T> generateSqmFunctionExpression(
+			List<? extends SqmTypedNode<?>> arguments,
+			ReturnableType<T> impliedResultType,
+			QueryEngine queryEngine) {
+		final SqmTypedNode<?> argument = arguments.get( 0 );
+		return queryEngine.getSqmFunctionRegistry().findFunctionDescriptor( "cast" )
+				.generateSqmExpression(
+						asList(
+								argument,
+								new SqmCastTarget<>(
+										queryEngine.getTypeConfiguration().getBasicTypeRegistry().resolve( StandardBasicTypes.INTEGER ),
+										queryEngine.getCriteriaBuilder()
+								)
+						),
+						impliedResultType,
+						queryEngine
+				);
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/hql/EnumTest.java

@@ -0,0 +1,67 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.orm.test.hql;
+
+import org.hibernate.testing.orm.domain.gambit.Shirt;
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@DomainModel(annotatedClasses = {
+		Shirt.class,
+		Shirt.Size.class})
+@SessionFactory
+@Jira("https://hibernate.atlassian.net/browse/HHH-16861")
+public class EnumTest {
+
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction(session -> {
+			Shirt largeShirt = new Shirt();
+			largeShirt.setId(10_000_000);
+			largeShirt.setSize(Shirt.Size.LARGE); // Ordinal 2
+
+			Shirt smallShirt = new Shirt();
+			smallShirt.setId(10_000_001);
+			smallShirt.setSize(Shirt.Size.SMALL); // Ordinal 0
+
+			session.persist(largeShirt);
+			session.persist(smallShirt);
+		});
+	}
+
+	@Test
+	public void testOrdinalFunctionOnEnum(SessionFactoryScope scope) {
+		scope.inTransaction(session -> {
+			List<Integer> largeShirtsOrdinalFunction = session.createQuery(
+							"select ordinal(size)" +
+									"from Shirt s " +
+									"where s.size = :size",
+							Integer.class)
+					.setParameter("size", Shirt.Size.LARGE)
+					.getResultList();
+
+			List<Integer> largeShirtsOrdinal = session.createQuery(
+							"select cast(s.size as Integer)" +
+									"from Shirt s " +
+									"where s.size = :size",
+							Integer.class)
+					.setParameter("size", Shirt.Size.LARGE)
+					.getResultList();
+
+			assertThat(largeShirtsOrdinal).hasSize(1);
+			assertThat(largeShirtsOrdinal).hasSameElementsAs(largeShirtsOrdinalFunction);
+		});
+
+	}
+
+}