Implemented CaseExpressionWalker for different Dialects

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

@@ -28,6 +28,8 @@ import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.query.sqm.mutation.spi.SqmMultiTableMutationStrategy;
 import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.DerbyCaseFragment;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
+import org.hibernate.sql.ast.spi.DerbyCaseExpressionWalker;
 import org.hibernate.tool.schema.extract.internal.SequenceInformationExtractorDerbyDatabaseImpl;
 import org.hibernate.tool.schema.extract.internal.SequenceInformationExtractorNoOpImpl;
 import org.hibernate.tool.schema.extract.spi.SequenceInformationExtractor;
@@ -109,6 +111,11 @@ public class DerbyDialect extends DB2Dialect {
 		return new DerbyCaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return DerbyCaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public boolean dropConstraints() {
 		return true;

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

@@ -108,6 +108,8 @@ import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.ForUpdateFragment;
 import org.hibernate.sql.JoinFragment;
 import org.hibernate.sql.ast.SqlAstTranslatorFactory;
+import org.hibernate.sql.ast.spi.ANSICaseExpressionWalker;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
 import org.hibernate.sql.ast.spi.SqlAstWalker;
 import org.hibernate.sql.ast.spi.StandardSqlAstTranslatorFactory;
 import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
@@ -1785,32 +1787,15 @@ public abstract class Dialect implements ConversionContext {
 		return new ANSICaseFragment();
 	}
 
-	public void visitCaseSearchedExpression(
+	/**
-			CaseSearchedExpression caseSearchedExpression,
+	 * Create a {@link CaseExpressionWalker} responsible
-			StringBuilder sqlBuffer,
+	 * for handling this dialect's variations in how CASE statements are
-			SqlAstWalker sqlAstWalker) {
+	 * handled.
-		sqlBuffer.append( "case " );
+	 *
-
+	 * @return This dialect's {@link CaseFragment} strategy.
-		for ( CaseSearchedExpression.WhenFragment whenFragment : caseSearchedExpression.getWhenFragments() ) {
+	 */
-			sqlBuffer.append( " when " );
+	public CaseExpressionWalker getCaseExpressionWalker() {
-			whenFragment.getPredicate().accept( sqlAstWalker );
+		return ANSICaseExpressionWalker.INSTANCE;
-			sqlBuffer.append( " then " );
-			whenFragment.getResult().accept( sqlAstWalker );
-		}
-
-		Expression otherwise = caseSearchedExpression.getOtherwise();
-		if ( otherwise != null ) {
-			sqlBuffer.append( " else " );
-			otherwise.accept( sqlAstWalker );
-		}
-
-		sqlBuffer.append( " end" );
-
-		String columnExpression = caseSearchedExpression.getColumnExpression();
-
-		if ( columnExpression != null ) {
-			sqlBuffer.append( " as " ).append( columnExpression );
-		}
 	}
 
 	/**

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

@@ -22,6 +22,8 @@ import org.hibernate.dialect.lock.UpdateLockingStrategy;
 import org.hibernate.persister.entity.Lockable;
 import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.MckoiCaseFragment;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
+import org.hibernate.sql.ast.spi.MckoiCaseExpressionWalker;
 import org.hibernate.type.StandardBasicTypes;
 
 /**
@@ -108,6 +110,11 @@ public class MckoiDialect extends Dialect {
 		return new MckoiCaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return MckoiCaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public LockingStrategy getLockingStrategy(Lockable lockable, LockMode lockMode) {
 		// Mckoi has no known variation of a "SELECT ... FOR UPDATE" syntax...

hibernate-core/src/main/java/org/hibernate/dialect/Oracle8iDialect.java

@@ -43,6 +43,8 @@ import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.DecodeCaseFragment;
 import org.hibernate.sql.JoinFragment;
 import org.hibernate.sql.OracleJoinFragment;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
+import org.hibernate.sql.ast.spi.DecodeCaseExpressionWalker;
 import org.hibernate.tool.schema.extract.internal.SequenceInformationExtractorOracleDatabaseImpl;
 import org.hibernate.tool.schema.extract.spi.SequenceInformationExtractor;
 import org.hibernate.type.StandardBasicTypes;
@@ -298,6 +300,11 @@ public class Oracle8iDialect extends Dialect {
 		return new DecodeCaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return DecodeCaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public LimitHandler getLimitHandler() {
 		return LIMIT_HANDLER;

hibernate-core/src/main/java/org/hibernate/dialect/Oracle9iDialect.java

@@ -16,6 +16,8 @@ import org.hibernate.dialect.pagination.LimitHelper;
 import org.hibernate.engine.spi.RowSelection;
 import org.hibernate.sql.ANSICaseFragment;
 import org.hibernate.sql.CaseFragment;
+import org.hibernate.sql.ast.spi.ANSICaseExpressionWalker;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
 
 /**
  * A dialect for Oracle 9i databases.
@@ -102,6 +104,11 @@ public class Oracle9iDialect extends Oracle8iDialect {
 		return new ANSICaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return ANSICaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public LimitHandler getLimitHandler() {
 		return LIMIT_HANDLER;

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

@@ -14,6 +14,8 @@ import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.DecodeCaseFragment;
 import org.hibernate.sql.JoinFragment;
 import org.hibernate.sql.OracleJoinFragment;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
+import org.hibernate.sql.ast.spi.DecodeCaseExpressionWalker;
 
 import org.jboss.logging.Logger;
 
@@ -54,6 +56,11 @@ public class OracleDialect extends Oracle9Dialect {
 		return new DecodeCaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return DecodeCaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public String getLimitString(String sql, boolean hasOffset) {
 

hibernate-core/src/main/java/org/hibernate/dialect/RDMSOS2200Dialect.java

@@ -28,6 +28,8 @@ import org.hibernate.internal.CoreMessageLogger;
 import org.hibernate.persister.entity.Lockable;
 import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.DecodeCaseFragment;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
+import org.hibernate.sql.ast.spi.DecodeCaseExpressionWalker;
 import org.hibernate.type.StandardBasicTypes;
 
 import org.jboss.logging.Logger;
@@ -363,6 +365,11 @@ public class RDMSOS2200Dialect extends Dialect {
 		return new DecodeCaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return DecodeCaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public LimitHandler getLimitHandler() {
 		if ( isLegacyLimitHandlerBehaviorEnabled() ) {

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

@@ -19,6 +19,8 @@ import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.query.sqm.mutation.spi.SqmMultiTableMutationStrategy;
 import org.hibernate.sql.CaseFragment;
 import org.hibernate.sql.DecodeCaseFragment;
+import org.hibernate.sql.ast.spi.CaseExpressionWalker;
+import org.hibernate.sql.ast.spi.DecodeCaseExpressionWalker;
 import org.hibernate.tool.schema.extract.internal.SequenceInformationExtractorSAPDBDatabaseImpl;
 import org.hibernate.tool.schema.extract.spi.SequenceInformationExtractor;
 import org.hibernate.type.StandardBasicTypes;
@@ -218,6 +220,11 @@ public class SAPDBDialect extends Dialect {
 		return new DecodeCaseFragment();
 	}
 
+	@Override
+	public CaseExpressionWalker getCaseExpressionWalker() {
+		return DecodeCaseExpressionWalker.INSTANCE;
+	}
+
 	@Override
 	public SqmMultiTableMutationStrategy getFallbackSqmMutationStrategy(EntityPersister runtimeRootEntityDescriptor) {
 		throw new NotYetImplementedFor6Exception( getClass() );

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/ANSICaseExpressionWalker.java

@@ -0,0 +1,46 @@
+/*
+ * 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.sql.ast.spi;
+
+import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
+import org.hibernate.sql.ast.tree.expression.Expression;
+
+/**
+ * @author Andrea Boriero
+ */
+public class ANSICaseExpressionWalker implements CaseExpressionWalker {
+
+	public static ANSICaseExpressionWalker INSTANCE = new ANSICaseExpressionWalker();
+
+	public void visitCaseSearchedExpression(
+			CaseSearchedExpression caseSearchedExpression,
+			StringBuilder sqlBuffer,
+			SqlAstWalker sqlAstWalker){
+		sqlBuffer.append( "case " );
+
+		for ( CaseSearchedExpression.WhenFragment whenFragment : caseSearchedExpression.getWhenFragments() ) {
+			sqlBuffer.append( " when " );
+			whenFragment.getPredicate().accept( sqlAstWalker );
+			sqlBuffer.append( " then " );
+			whenFragment.getResult().accept( sqlAstWalker );
+		}
+
+		Expression otherwise = caseSearchedExpression.getOtherwise();
+		if ( otherwise != null ) {
+			sqlBuffer.append( " else " );
+			otherwise.accept( sqlAstWalker );
+		}
+
+		sqlBuffer.append( " end" );
+
+		final String columnExpression = caseSearchedExpression.getColumnExpression();
+
+		if ( columnExpression != null ) {
+			sqlBuffer.append( " as " ).append( columnExpression );
+		}
+	}
+}

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/AbstractSqlAstWalker.java

@@ -742,7 +742,7 @@ public abstract class AbstractSqlAstWalker
 
 	@Override
 	public void visitCaseSearchedExpression(CaseSearchedExpression caseSearchedExpression) {
-		dialect.visitCaseSearchedExpression( caseSearchedExpression, sqlBuffer, this );
+		dialect.getCaseExpressionWalker().visitCaseSearchedExpression( caseSearchedExpression, sqlBuffer, this );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/CaseExpressionWalker.java

@@ -0,0 +1,19 @@
+/*
+ * 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.sql.ast.spi;
+
+import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
+
+/**
+ * @author Andrea Boriero
+ */
+public interface CaseExpressionWalker {
+	void visitCaseSearchedExpression(
+			CaseSearchedExpression caseSearchedExpression,
+			StringBuilder sqlBuffer,
+			SqlAstWalker sqlAstWalker);
+}

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/DecodeCaseExpressionWalker.java

@@ -0,0 +1,52 @@
+/*
+ * 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.sql.ast.spi;
+
+import java.util.List;
+
+import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
+import org.hibernate.sql.ast.tree.expression.Expression;
+
+/**
+ * @author Andrea Boriero
+ */
+public class DecodeCaseExpressionWalker implements CaseExpressionWalker {
+
+	public static final DecodeCaseExpressionWalker INSTANCE = new DecodeCaseExpressionWalker();
+
+	@Override
+	public void visitCaseSearchedExpression(
+			CaseSearchedExpression caseSearchedExpression, StringBuilder sqlBuffer, SqlAstWalker sqlAstWalker) {
+		sqlBuffer.append( "decode( " );
+
+		List<CaseSearchedExpression.WhenFragment> whenFragments = caseSearchedExpression.getWhenFragments();
+		int caseNumber = whenFragments.size();
+		for ( int i = 0; i < caseNumber; i++ ) {
+			final CaseSearchedExpression.WhenFragment whenFragment = whenFragments.get( i );
+			if ( i != 0 ) {
+				sqlBuffer.append( ", " );
+			}
+			whenFragment.getPredicate().getLeftHandExpression().accept( sqlAstWalker );
+			sqlBuffer.append( ", " );
+			whenFragment.getResult().accept( sqlAstWalker );
+		}
+
+		Expression otherwise = caseSearchedExpression.getOtherwise();
+		if ( otherwise != null ) {
+			sqlBuffer.append( ", " );
+			otherwise.accept( sqlAstWalker );
+		}
+
+		sqlBuffer.append( "')'" );
+
+		final String columnExpression = caseSearchedExpression.getColumnExpression();
+
+		if ( columnExpression != null ) {
+			sqlBuffer.append( " as " ).append( columnExpression );
+		}
+	}
+}

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/DerbyCaseExpressionWalker.java

@@ -0,0 +1,61 @@
+/*
+ * 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.sql.ast.spi;
+
+import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
+import org.hibernate.sql.ast.tree.expression.Expression;
+import org.hibernate.sql.ast.tree.expression.QueryLiteral;
+
+/**
+ * @author Andrea Boriero
+ */
+public class DerbyCaseExpressionWalker implements CaseExpressionWalker {
+
+	public static DerbyCaseExpressionWalker INSTANCE = new DerbyCaseExpressionWalker();
+
+	@Override
+	public void visitCaseSearchedExpression(
+			CaseSearchedExpression caseSearchedExpression,
+			StringBuilder sqlBuffer,
+			SqlAstWalker sqlAstWalker) {
+
+		sqlBuffer.append( "case " );
+
+		for ( CaseSearchedExpression.WhenFragment whenFragment : caseSearchedExpression.getWhenFragments() ) {
+			sqlBuffer.append( " when " );
+			whenFragment.getPredicate().accept( sqlAstWalker );
+			sqlBuffer.append( " then " );
+			whenFragment.getResult().accept( sqlAstWalker );
+		}
+
+		// TODO (6.0) : not sure this is the correct way to managed the otherwise expression
+		Expression otherwise = caseSearchedExpression.getOtherwise();
+		if ( otherwise != null ) {
+			sqlBuffer.append( " else " );
+			if ( otherwise instanceof QueryLiteral ) {
+				Object value = ( (QueryLiteral) otherwise ).getValue();
+				if ( value == null ) {
+					// null is not considered the same type as Integer.
+					sqlBuffer.append( "-1" );
+				}
+				else {
+					otherwise.accept( sqlAstWalker );
+				}
+			}
+			else {
+				otherwise.accept( sqlAstWalker );
+			}
+		}
+		sqlBuffer.append( " end" );
+
+		final String columnExpression = caseSearchedExpression.getColumnExpression();
+
+		if ( columnExpression != null ) {
+			sqlBuffer.append( " as " ).append( columnExpression );
+		}
+	}
+}

hibernate-core/src/main/java/org/hibernate/sql/ast/spi/MckoiCaseExpressionWalker.java

@@ -0,0 +1,49 @@
+/*
+ * 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.sql.ast.spi;
+
+import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
+import org.hibernate.sql.ast.tree.expression.Expression;
+import org.hibernate.sql.ast.tree.predicate.NullnessPredicate;
+
+/**
+ * @author Andrea Boriero
+ */
+public class MckoiCaseExpressionWalker implements CaseExpressionWalker {
+
+	public static final MckoiCaseExpressionWalker INSTANCE = new MckoiCaseExpressionWalker();
+
+	@Override
+	public void visitCaseSearchedExpression(
+			CaseSearchedExpression caseSearchedExpression, StringBuilder sqlBuffer, SqlAstWalker sqlAstWalker) {
+		sqlBuffer.append( "case " );
+		StringBuilder buf2= new StringBuilder( );
+
+		for ( CaseSearchedExpression.WhenFragment whenFragment : caseSearchedExpression.getWhenFragments() ) {
+			sqlBuffer.append( " if( " );
+			whenFragment.getPredicate().accept( sqlAstWalker );
+			sqlBuffer.append( ", " );
+			whenFragment.getResult().accept( sqlAstWalker );
+			sqlBuffer.append(", ");
+			buf2.append(")");
+		}
+		Expression otherwise = caseSearchedExpression.getOtherwise();
+		if ( otherwise != null ) {
+			otherwise.accept( sqlAstWalker );
+		}
+		else {
+			sqlBuffer.append( "null" );
+		}
+		sqlBuffer.append(buf2);
+
+		final String columnExpression = caseSearchedExpression.getColumnExpression();
+
+		if ( columnExpression != null ) {
+			sqlBuffer.append( " as " ).append( columnExpression );
+		}
+	}
+}

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/expression/CaseSearchedExpression.java

@@ -14,7 +14,7 @@ import org.hibernate.metamodel.mapping.MappingModelExpressable;
 import org.hibernate.query.sqm.sql.internal.DomainResultProducer;
 import org.hibernate.sql.ast.spi.SqlAstWalker;
 import org.hibernate.sql.ast.spi.SqlSelection;
-import org.hibernate.sql.ast.tree.predicate.Predicate;
+import org.hibernate.sql.ast.tree.predicate.CasePredicate;
 import org.hibernate.sql.results.internal.SqlSelectionImpl;
 import org.hibernate.sql.results.internal.domain.basic.BasicResult;
 import org.hibernate.sql.results.spi.DomainResult;
@@ -53,7 +53,7 @@ public class CaseSearchedExpression implements Expression, DomainResultProducer
 		return otherwise;
 	}
 
-	public void when(Predicate predicate, Expression result) {
+	public void when(CasePredicate predicate, Expression result) {
 		whenFragments.add( new WhenFragment( predicate, result ) );
 	}
 
@@ -109,15 +109,15 @@ public class CaseSearchedExpression implements Expression, DomainResultProducer
 	}
 
 	public static class WhenFragment {
-		private final Predicate predicate;
+		private final CasePredicate predicate;
 		private final Expression result;
 
-		public WhenFragment(Predicate predicate, Expression result) {
+		public WhenFragment(CasePredicate predicate, Expression result) {
 			this.predicate = predicate;
 			this.result = result;
 		}
 
-		public Predicate getPredicate() {
+		public CasePredicate getPredicate() {
 			return predicate;
 		}
 

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/predicate/CasePredicate.java

@@ -0,0 +1,17 @@
+/*
+ * 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.sql.ast.tree.predicate;
+
+import org.hibernate.sql.ast.tree.expression.Expression;
+
+/**
+ * @author Andrea Boriero
+ */
+public interface CasePredicate extends Predicate {
+	Expression getLeftHandExpression();
+}
+

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/predicate/ComparisonPredicate.java

@@ -13,7 +13,7 @@ import org.hibernate.sql.ast.tree.expression.Expression;
 /**
  * @author Steve Ebersole
  */
-public class ComparisonPredicate implements Predicate {
+public class ComparisonPredicate implements Predicate, CasePredicate {
 	private final Expression leftHandExpression;
 	private ComparisonOperator operator;
 	private final Expression rightHandExpression;
@@ -27,6 +27,7 @@ public class ComparisonPredicate implements Predicate {
 		this.rightHandExpression = rightHandExpression;
 	}
 
+	@Override
 	public Expression getLeftHandExpression() {
 		return leftHandExpression;
 	}

hibernate-core/src/main/java/org/hibernate/sql/ast/tree/predicate/NullnessPredicate.java

@@ -12,7 +12,7 @@ import org.hibernate.sql.ast.tree.expression.Expression;
 /**
  * @author Steve Ebersole
  */
-public class NullnessPredicate implements Predicate {
+public class NullnessPredicate implements Predicate, CasePredicate {
 	private final Expression expression;
 	private final boolean negated;
 
@@ -38,4 +38,9 @@ public class NullnessPredicate implements Predicate {
 	public void accept(SqlAstWalker sqlTreeWalker) {
 		sqlTreeWalker.visitNullnessPredicate( this );
 	}
+
+	@Override
+	public Expression getLeftHandExpression() {
+		return expression;
+	}
 }