HHH-1689 - Support subqueries in HQL as CASE statement alternatives;

SQM-30 - test

(cherry picked from commit 57401b9aa8)

hibernate-core/src/main/antlr/hql-sql.g

@@ -611,10 +611,36 @@ arithmeticExpr
 	;
 
 caseExpr
-	: #(CASE { inCase = true; } (#(WHEN logicalExpr expr))+ (#(ELSE expr))?) { inCase = false; }
+	: simpleCaseExpression
-	| #(CASE2 { inCase = true; } expr (#(WHEN expr expr))+ (#(ELSE expr))?) { inCase = false; }
+	| searchedCaseExpression
 	;
 
+expressionOrSubQuery
+	: expr
+	| query
+	;
+
+simpleCaseExpression
+	: #(CASE2 {inCase=true;} expressionOrSubQuery (simpleCaseWhenClause)+ (elseClause)?) {inCase=false;}
+	;
+
+simpleCaseWhenClause
+	: #(WHEN expressionOrSubQuery expressionOrSubQuery)
+	;
+
+elseClause
+	: #(ELSE expressionOrSubQuery)
+	;
+
+searchedCaseExpression
+	: #(CASE {inCase = true;} (searchedCaseWhenClause)+ (elseClause)?) {inCase = false;}
+	;
+
+searchedCaseWhenClause
+	: #(WHEN logicalExpr expressionOrSubQuery)
+	;
+
+
 //TODO: I don't think we need this anymore .. how is it different to 
 //      maxelements, etc, which are handled by functionCall
 collectionFunction

hibernate-core/src/main/antlr/hql.g

@@ -641,15 +641,18 @@ unaryExpression
 	;
 
 caseExpression
-	: CASE^ (whenClause)+ (elseClause)? END! 
+	// NOTE : the unaryExpression rule contains the subQuery rule
-	| CASE^ { #CASE.setType(CASE2); } unaryExpression (altWhenClause)+ (elseClause)? END!
+	: simpleCaseStatement
+	| searchedCaseStatement
 	;
 
-whenClause
+simpleCaseStatement
-	: (WHEN^ logicalExpression THEN! unaryExpression)
+	: CASE^ unaryExpression (simpleCaseWhenClause)+ (elseClause)? END! {
+		#simpleCaseStatement.setType(CASE2);
+	}
 	;
 
-altWhenClause
+simpleCaseWhenClause
 	: (WHEN^ unaryExpression THEN! unaryExpression)
 	;
 
@@ -657,6 +660,14 @@ elseClause
 	: (ELSE^ unaryExpression)
 	;
 
+searchedCaseStatement
+	: CASE^ (searchedCaseWhenClause)+ (elseClause)? END!
+	;
+
+searchedCaseWhenClause
+	: (WHEN^ logicalExpression THEN! unaryExpression)
+	;
+	
 quantifiedExpression
 	: ( SOME^ | EXISTS^ | ALL^ | ANY^ ) 
 	( identifier | collectionExpr | (OPEN! ( subQuery ) CLOSE!) )

hibernate-core/src/test/java/org/hibernate/test/hql/SubQueryTest.java

@@ -17,6 +17,7 @@ import javax.persistence.Table;
 
 import org.hibernate.Session;
 
+import org.hibernate.testing.FailureExpected;
 import org.hibernate.testing.TestForIssue;
 import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
 import org.junit.Test;
@@ -155,4 +156,64 @@ public class SubQueryTest extends BaseCoreFunctionalTestCase {
 		s.close();
 
 	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-1689, SQM-30" )
+	public void testSubQueryAsSearchedCaseResultExpression() {
+		final String query = "SELECT CASE WHEN l.id IS NOT NULL THEN (SELECT COUNT(r.id) FROM Root r) ELSE 0 END FROM Leaf l";
+		// simple syntax check
+		Session s = openSession();
+		s.beginTransaction();
+		s.createQuery( query ).list();
+		s.getTransaction().commit();
+		s.close();
+	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-1689, SQM-30" )
+	public void testSubQueryAsSearchedCaseExpression() {
+		final String query = "SELECT CASE WHEN (SELECT COUNT(r.id) FROM Root r) > 1 THEN 1 ELSE 0 END FROM Leaf l";
+		// simple syntax check
+		Session s = openSession();
+		s.beginTransaction();
+		s.createQuery( query ).list();
+		s.getTransaction().commit();
+		s.close();
+	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-1689, SQM-30" )
+	public void testSubQueryAsCaseElseResultExpression() {
+		final String query = "SELECT CASE WHEN  l.id > 1 THEN 1 ELSE (SELECT COUNT(r.id) FROM Root r) END FROM Leaf l";
+		// simple syntax check
+		Session s = openSession();
+		s.beginTransaction();
+		s.createQuery( query ).list();
+		s.getTransaction().commit();
+		s.close();
+	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-1689, SQM-30" )
+	public void testSubQueryAsSimpleCaseTestExpression() {
+		final String query = "SELECT CASE (SELECT COUNT(r.id) FROM Root r) WHEN  1 THEN 1 ELSE 0 END FROM Leaf l";
+		// simple syntax check
+		Session s = openSession();
+		s.beginTransaction();
+		s.createQuery( query ).list();
+		s.getTransaction().commit();
+		s.close();
+	}
+
+	@Test
+	@TestForIssue( jiraKey = "HHH-1689, SQM-30" )
+	public void testSubQueryAsSimpleCaseWhenExpression() {
+		final String query = "SELECT CASE l.id WHEN (SELECT COUNT(r.id) FROM Root r) THEN 1 ELSE 0 END FROM Leaf l";
+		// simple syntax check
+		Session s = openSession();
+		s.beginTransaction();
+		s.createQuery( query ).list();
+		s.getTransaction().commit();
+		s.close();
+	}
 }