HHH-15518 bless degrees() and radians() as standard

- add a test
- emulate them on HANA and Oracle

documentation/src/main/asciidoc/userguide/chapters/query/hql/QueryLanguage.adoc

@@ -1002,6 +1002,8 @@ Of course, we also have a number of functions for working with numeric values.
 | `pi` | π | `pi` | ✗
 | `sin()`, `cos()`, `tan()`, `asin()`, `acos()`, `atan()`, `atan2()`
 | Basic trigonometric functions | `sin(theta)`, `cos(theta)`, `atan2(opposite, adjacent)` | ✗
+| `degrees()` | Convert radians to degrees | `degrees(x)` | ✗
+| `radians()` | Convert degrees to radians | `radians(x)` | ✗
 | `least()` | Return the smallest of the given arguments | `least(x, y, z)` |✗
 | `greatest()` | Return the largest of the given arguments | `greatest(x, y, z)` | ✗
 |===

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

@@ -377,6 +377,9 @@ public abstract class AbstractHANADialect extends Dialect {
 		functionFactory.inverseDistributionOrderedSetAggregates();
 		functionFactory.hypotheticalOrderedSetAggregates_windowEmulation();
 
+		functionFactory.radians_acos();
+		functionFactory.degrees_acos();
+
 		queryEngine.getSqmFunctionRegistry().register( "timestampadd",
 				new IntegralTimestampaddFunction( this, typeConfiguration ) );
 	}

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

@@ -787,6 +787,8 @@ public abstract class Dialect implements ConversionContext {
 	 * <li> <code>round(arg0, arg1)</code>
 	 * <li> <code>least(arg0, arg1, ...)</code>
 	 * <li> <code>greatest(arg0, arg1, ...)</code>
+	 * <li> <code>degrees(arg)</code>
+	 * <li> <code>radians(arg)</code>
 	 * </ul>
 	 *
 	 * <ul>

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

@@ -174,6 +174,9 @@ public class OracleDialect extends Dialect {
 		functionFactory.monthsBetween();
 		functionFactory.everyAny_minMaxCase();
 
+		functionFactory.radians_acos();
+		functionFactory.degrees_acos();
+
 		functionFactory.median();
 		functionFactory.stddev();
 		functionFactory.stddevPopSamp();

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

@@ -80,14 +80,6 @@ public class CommonFunctionFactory {
 				.register();
 	}
 
-	public void degrees() {
-		functionRegistry.namedDescriptorBuilder( "degrees" )
-				.setExactArgumentCount( 1 )
-				.setParameterTypes(NUMERIC)
-				.setInvariantType(doubleType)
-				.register();
-	}
-
 	/**
 	 * For databases where the first parameter is the base
 	 */
@@ -178,6 +170,36 @@ public class CommonFunctionFactory {
 				.register();
 	}
 
+	/**
+	 * For Oracle, HANA
+	 */
+	public void radians_acos() {
+		functionRegistry.patternDescriptorBuilder( "radians", "(?1*acos(-1)/180)" )
+				.setInvariantType(doubleType)
+				.setExactArgumentCount(1)
+				.setParameterTypes(NUMERIC)
+				.register();
+	}
+
+	public void degrees() {
+		functionRegistry.namedDescriptorBuilder( "degrees" )
+				.setExactArgumentCount( 1 )
+				.setParameterTypes(NUMERIC)
+				.setInvariantType(doubleType)
+				.register();
+	}
+
+	/**
+	 * For Oracle, HANA
+	 */
+	public void degrees_acos() {
+		functionRegistry.patternDescriptorBuilder( "degrees", "(?1/acos(-1)*180)" )
+				.setInvariantType(doubleType)
+				.setExactArgumentCount(1)
+				.setParameterTypes(NUMERIC)
+				.register();
+	}
+
 	public void sinh() {
 		functionRegistry.namedDescriptorBuilder( "sinh" )
 				.setExactArgumentCount( 1 )

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

@@ -27,7 +27,6 @@ import org.hibernate.sql.ast.spi.SqlAppender;
 import org.hibernate.sql.ast.tree.SqlAstNode;
 import org.hibernate.sql.ast.tree.expression.Distinct;
 import org.hibernate.sql.ast.tree.expression.Expression;
-import org.hibernate.sql.ast.tree.expression.FunctionExpression;
 import org.hibernate.sql.ast.tree.expression.SqlTuple;
 import org.hibernate.sql.ast.tree.expression.SqlTupleContainer;
 import org.hibernate.sql.ast.tree.expression.Star;

hibernate-core/src/test/java/org/hibernate/orm/test/query/hql/StandardFunctionTests.java

@@ -921,6 +921,22 @@ public class StandardFunctionTests {
 		);
 	}
 
+	@Test
+	public void testDegreesRadians(SessionFactoryScope scope) {
+		scope.inTransaction(
+				session -> {
+					assertThat(
+							session.createQuery("select degrees(pi)", Double.class).getSingleResult(),
+							IsCloseTo.closeTo( 180.0, 1e-9 )
+					);
+					assertThat(
+							session.createQuery("select radians(180.0)", Double.class).getSingleResult(),
+							IsCloseTo.closeTo( Math.PI, 1e-9 )
+					);
+				}
+		);
+	}
+
 	@Test
 	public void testLog(SessionFactoryScope scope) {
 		scope.inTransaction(