HHH-19956: Add InterSystemsIRISLogFunction.java

Author: isc-service

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/function/InterSystemsIRISLogFunction.java

@@ -0,0 +1,53 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.community.dialect.function;
+
+import org.hibernate.query.sqm.function.AbstractSqmSelfRenderingFunctionDescriptor;
+import org.hibernate.query.sqm.produce.function.StandardArgumentsValidators;
+import org.hibernate.query.sqm.produce.function.StandardFunctionReturnTypeResolvers;
+import org.hibernate.sql.ast.SqlAstTranslator;
+import org.hibernate.sql.ast.spi.SqlAppender;
+import org.hibernate.sql.ast.tree.SqlAstNode;
+import org.hibernate.type.StandardBasicTypes;
+import org.hibernate.type.spi.TypeConfiguration;
+
+import java.util.List;
+
+public class InterSystemsIRISLogFunction extends AbstractSqmSelfRenderingFunctionDescriptor {
+
+	public InterSystemsIRISLogFunction(TypeConfiguration typeConfiguration) {
+		super(
+				"log",
+				StandardArgumentsValidators.between(1, 2),
+				StandardFunctionReturnTypeResolvers.invariant(
+						typeConfiguration.getBasicTypeRegistry()
+								.resolve( StandardBasicTypes.DOUBLE)
+				),
+				null
+		);
+	}
+
+	@Override
+	public void render(
+			SqlAppender sqlAppender,
+			List<? extends SqlAstNode> arguments,
+			SqlAstTranslator<?> walker) {
+
+		if (arguments.size() == 1) {
+			// LOG(x) → log(x)
+			sqlAppender.appendSql("log(");
+			arguments.get(0).accept(walker);
+			sqlAppender.appendSql(")");
+		}
+		else if (arguments.size() == 2) {
+			// LOG(base, value) → (log(value) / log(base))
+			sqlAppender.appendSql("(log(");
+			arguments.get(1).accept(walker);
+			sqlAppender.appendSql(")/log(");
+			arguments.get(0).accept(walker);
+			sqlAppender.appendSql("))");
+		}
+	}
+}