HHH-12196 Implement a naive limit handler for Sybase

It doesn't manage all the corner cases but it should be safe enough as
only triggered in the simple cases.

hibernate-core/src/main/java/org/hibernate/dialect/SybaseASE157Dialect.java

@@ -12,6 +12,8 @@ import java.util.Map;
 import org.hibernate.JDBCException;
 import org.hibernate.LockOptions;
 import org.hibernate.dialect.function.SQLFunctionTemplate;
+import org.hibernate.dialect.pagination.LimitHandler;
+import org.hibernate.dialect.pagination.SybaseASE157LimitHandler;
 import org.hibernate.exception.ConstraintViolationException;
 import org.hibernate.exception.LockTimeoutException;
 import org.hibernate.exception.spi.SQLExceptionConversionDelegate;
@@ -27,6 +29,8 @@ import org.hibernate.type.StandardBasicTypes;
  */
 public class SybaseASE157Dialect extends SybaseASE15Dialect {
 
+	private static final SybaseASE157LimitHandler LIMIT_HANDLER = new SybaseASE157LimitHandler();
+
 	/**
 	 * Constructs a SybaseASE157Dialect
 	 */
@@ -102,4 +106,19 @@ public class SybaseASE157Dialect extends SybaseASE15Dialect {
 			}
 		};
 	}
+
+	@Override
+	public boolean supportsLimit() {
+		return true;
+	}
+
+	@Override
+	public boolean supportsLimitOffset() {
+		return false;
+	}
+
+	@Override
+	public LimitHandler getLimitHandler() {
+		return LIMIT_HANDLER;
+	}
 }

hibernate-core/src/main/java/org/hibernate/dialect/pagination/SybaseASE157LimitHandler.java

@@ -0,0 +1,83 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.dialect.pagination;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.hibernate.engine.spi.RowSelection;
+
+/**
+ * This limit handler is very conservative and is only triggered in simple cases involving a select or select distinct.
+ * <p>
+ * Note that if the query already contains "top" just after the select or select distinct, we don't add anything to the
+ * query. It might just be a column name but, in any case, we just don't add the top clause and default to the previous
+ * behavior so it's not an issue.
+ */
+public class SybaseASE157LimitHandler extends AbstractLimitHandler {
+
+	private static final Pattern SELECT_DISTINCT_PATTERN = Pattern.compile( "^(\\s*select\\s+distinct\\s+).*",
+			Pattern.CASE_INSENSITIVE );
+	private static final Pattern SELECT_PATTERN = Pattern.compile( "^(\\s*select\\s+).*", Pattern.CASE_INSENSITIVE );
+	private static final Pattern TOP_PATTERN = Pattern.compile( "^\\s*top\\s+.*", Pattern.CASE_INSENSITIVE );
+
+	@Override
+	public String processSql(String sql, RowSelection selection) {
+		if ( selection.getMaxRows() == null ) {
+			return sql;
+		}
+
+		int top = getMaxOrLimit( selection );
+		if ( top == Integer.MAX_VALUE ) {
+			return sql;
+		}
+
+		Matcher selectDistinctMatcher = SELECT_DISTINCT_PATTERN.matcher( sql );
+		if ( selectDistinctMatcher.matches() ) {
+			return insertTop( selectDistinctMatcher, sql, top );
+		}
+
+		Matcher selectMatcher = SELECT_PATTERN.matcher( sql );
+		if ( selectMatcher.matches() ) {
+			return insertTop( selectMatcher, sql, top );
+		}
+
+		return sql;
+	}
+
+	@Override
+	public boolean supportsLimit() {
+		return true;
+	}
+
+	@Override
+	public boolean supportsLimitOffset() {
+		return false;
+	}
+
+	@Override
+	public boolean useMaxForLimit() {
+		return true;
+	}
+
+	@Override
+	public boolean supportsVariableLimit() {
+		return false;
+	}
+
+	private static String insertTop(Matcher matcher, String sql, int top) {
+		int end = matcher.end( 1 );
+
+		if ( TOP_PATTERN.matcher( sql.substring( end ) ).matches() ) {
+			return sql;
+		}
+
+		StringBuilder sb = new StringBuilder( sql );
+		sb.insert( end, "top " + top + " " );
+		return sb.toString();
+	}
+}

hibernate-core/src/test/java/org/hibernate/dialect/SybaseASE157LimitHandlerTest.java

@@ -0,0 +1,54 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.dialect;
+
+import static org.junit.Assert.assertEquals;
+
+import org.hibernate.dialect.pagination.SybaseASE157LimitHandler;
+import org.hibernate.engine.spi.RowSelection;
+import org.junit.Test;
+
+public class SybaseASE157LimitHandlerTest {
+
+	@Test
+	public void testLimitHandler() {
+		assertEquals( "select * from entity", processSql( "select * from entity", null, null ) );
+		assertEquals( "select * from entity", processSql( "select * from entity", 15, null ) );
+		assertEquals( "select top 15 * from entity", processSql( "select * from entity", null, 15 ) );
+		assertEquals( "select top 18 * from entity", processSql( "select * from entity", 3, 15 ) );
+		assertEquals( "SELECT top 18 * FROM entity", processSql( "SELECT * FROM entity", 3, 15 ) );
+		assertEquals( "		 select	 top 18 * from entity", processSql( "		 select	 * from entity", 3, 15 ) );
+		assertEquals( "selectand", processSql( "selectand", 3, 15 ) );
+		assertEquals( "select distinct top 15 id from entity",
+				processSql( "select distinct id from entity", null, 15 ) );
+		assertEquals( "select distinct top 18 id from entity", processSql( "select distinct id from entity", 3, 15 ) );
+		assertEquals( "		 select 	distinct	 top 18 id from entity",
+				processSql( "		 select 	distinct	 id from entity", 3, 15 ) );
+		assertEquals(
+				"WITH employee AS (SELECT * FROM Employees) SELECT * FROM employee WHERE ID < 20 UNION ALL SELECT * FROM employee WHERE Sex = 'M'",
+				processSql(
+						"WITH employee AS (SELECT * FROM Employees) SELECT * FROM employee WHERE ID < 20 UNION ALL SELECT * FROM employee WHERE Sex = 'M'",
+						3, 15 ) );
+
+		assertEquals( "select top 5 * from entity", processSql( "select top 5 * from entity", 3, 15 ) );
+		assertEquals( "select distinct top 7 * from entity", processSql( "select distinct top 7 * from entity", 3, 15 ) );
+		assertEquals( "select distinct top 18 top_column from entity", processSql( "select distinct top_column from entity", 3, 15 ) );
+	}
+
+	private String processSql(String sql, Integer offset, Integer limit) {
+		RowSelection rowSelection = new RowSelection();
+		if ( offset != null ) {
+			rowSelection.setFirstRow( offset );
+		}
+		if (limit != null) {
+			rowSelection.setMaxRows( limit );
+		}
+
+		SybaseASE157LimitHandler limitHandler = new SybaseASE157LimitHandler();
+		return limitHandler.processSql( sql, rowSelection );
+	}
+}