SQM-1 - Created a unified alias registry

hibernate-query-interpreter/src/main/antlr/org/hibernate/query/parser/internal/hql/antlr/HqlParser.g4

@@ -139,7 +139,11 @@ selection
 	// I have noticed that without this predicate, Antlr will sometimes
 	// interpret `select a.b from Something ...` as `from` being the
 	// select-expression alias
-	: selectExpression (asKeyword? {!doesUpcomingTokenMatchAny("from")}? IDENTIFIER)?
+	: selectExpression (asKeyword? {!doesUpcomingTokenMatchAny("from")}? alias)?
+	;
+
+alias
+	: IDENTIFIER
 	;
 
 selectExpression
@@ -201,23 +205,23 @@ fromElementSpaceRoot
 	;
 
 mainEntityPersisterReference
-	: dotIdentifierSequence (asKeyword? {!doesUpcomingTokenMatchAny("where","join")}? IDENTIFIER)?
+	: dotIdentifierSequence (asKeyword? {!doesUpcomingTokenMatchAny("where","join")}? alias)?
 	;
 
 crossJoin
 	: crossKeyword joinKeyword mainEntityPersisterReference
 	;
 
 jpaCollectionJoin
-	:	inKeyword LEFT_PAREN path RIGHT_PAREN (asKeyword? IDENTIFIER)?
+	:	inKeyword LEFT_PAREN path RIGHT_PAREN (asKeyword? alias)?
 	;
 
 qualifiedJoin
 	: ( innerKeyword | ((leftKeyword|rightKeyword|fullKeyword)? outerKeyword) )? joinKeyword fetchKeyword? qualifiedJoinRhs (qualifiedJoinPredicate)?
 	;
 
 qualifiedJoinRhs
-	: path (asKeyword? IDENTIFIER)?
+	: path (asKeyword? alias)?
 	;
 
 qualifiedJoinPredicate

hibernate-query-interpreter/src/main/java/org/hibernate/query/parser/AliasCollisionException.java

@@ -0,0 +1,20 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: Apache License, Version 2.0
+ * See the LICENSE file in the root directory or visit http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.hibernate.query.parser;
+
+/**
+ * @author Andrea Boriero
+ */
+public class AliasCollisionException extends SemanticException {
+	public AliasCollisionException(String message) {
+		super( message );
+	}
+
+	public AliasCollisionException(String message, Throwable cause) {
+		super( message, cause );
+	}
+}

hibernate-query-interpreter/src/main/java/org/hibernate/query/parser/internal/AliasRegistry.java

@@ -0,0 +1,30 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: Apache License, Version 2.0
+ * See the LICENSE file in the root directory or visit http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.hibernate.query.parser.internal;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.hibernate.query.parser.AliasCollisionException;
+
+/**
+ * @author Andrea Boriero
+ */
+public class AliasRegistry {
+	Set<String> aliases;
+
+	public AliasRegistry() {
+		this.aliases = new HashSet<String>();
+	}
+
+	public void registerAlias(String alias) {
+		if ( aliases.contains( alias ) ) {
+			throw new AliasCollisionException( "Alias collision, alias " + alias + " is used in a different clause" );
+		}
+		aliases.add( alias );
+	}
+}

hibernate-query-interpreter/src/main/java/org/hibernate/query/parser/internal/ParsingContext.java

@@ -16,6 +16,7 @@
 public class ParsingContext {
 	private final ConsumerContext consumerContext;
 	private final ImplicitAliasGenerator aliasGenerator = new ImplicitAliasGenerator();
+	private final AliasRegistry aliasRegistry = new AliasRegistry();
 
 	public ParsingContext(ConsumerContext consumerContext) {
 		this.consumerContext = consumerContext;
@@ -28,4 +29,8 @@ public ConsumerContext getConsumerContext() {
 	public ImplicitAliasGenerator getImplicitAliasGenerator() {
 		return aliasGenerator;
 	}
+
+	public AliasRegistry getAliasRegistry(){
+		return aliasRegistry;
+	}
 }

hibernate-query-interpreter/src/main/java/org/hibernate/query/parser/internal/hql/AbstractHqlParseTreeVisitor.java

@@ -243,10 +243,19 @@ public SelectClause visitSelectClause(HqlParser.SelectClauseContext ctx) {
 	public Selection visitSelection(HqlParser.SelectionContext ctx) {
 		return new Selection(
 				visitSelectExpression( ctx.selectExpression() ),
-				ctx.IDENTIFIER() == null ? null : ctx.IDENTIFIER().getText()
+				visitAlias( ctx.alias() )
 		);
 	}
 
+	@Override
+	public String visitAlias(HqlParser.AliasContext ctx) {
+		if(ctx == null){
+			return null;
+		}
+		parsingContext.getAliasRegistry().registerAlias( ctx.IDENTIFIER().getText() );
+		return ctx.IDENTIFIER().getText();
+	}
+
 	@Override
 	public Expression visitSelectExpression(HqlParser.SelectExpressionContext ctx) {
 		if ( ctx.dynamicInstantiation() != null ) {

hibernate-query-interpreter/src/main/java/org/hibernate/query/parser/internal/hql/phase1/FromClauseProcessor.java

@@ -172,7 +172,7 @@ public void enterFromElementSpaceRoot(HqlParser.FromElementSpaceRootContext ctx)
 		final RootEntityFromElement rootEntityFromElement = fromElementBuilder.makeRootEntityFromElement(
 				currentFromElementSpace,
 				resolveEntityReference( ctx.mainEntityPersisterReference().dotIdentifierSequence() ),
-				interpretAlias( ctx.mainEntityPersisterReference().IDENTIFIER() )
+				interpretAlias( ctx.mainEntityPersisterReference().alias() )
 		);
 		fromElementMap.put( ctx.getText(), rootEntityFromElement );
 	}
@@ -188,11 +188,13 @@ private EntityTypeDescriptor resolveEntityReference(HqlParser.DotIdentifierSeque
 		return entityTypeDescriptor;
 	}
 
-	private String interpretAlias(TerminalNode aliasNode) {
-		if ( aliasNode == null ) {
+	private String interpretAlias(HqlParser.AliasContext ctx) {
+		if ( ctx == null ) {
 			return parsingContext.getImplicitAliasGenerator().buildUniqueImplicitAlias();
 		}
+		final TerminalNode aliasNode = ctx.IDENTIFIER();
 		assert aliasNode.getSymbol().getType() == HqlParser.IDENTIFIER;
+		parsingContext.getAliasRegistry().registerAlias( aliasNode.getText() );
 		return aliasNode.getText();
 	}
 
@@ -212,7 +214,7 @@ public void enterCrossJoin(HqlParser.CrossJoinContext ctx) {
 		final CrossJoinedFromElement join = fromElementBuilder.makeCrossJoinedFromElement(
 				currentFromElementSpace,
 				entityTypeDescriptor,
-				interpretAlias( ctx.mainEntityPersisterReference().IDENTIFIER() )
+				interpretAlias( ctx.mainEntityPersisterReference().alias() )
 		);
 		fromElementMap.put( ctx.getText(), join );
 	}
@@ -226,7 +228,7 @@ public void enterJpaCollectionJoin(HqlParser.JpaCollectionJoinContext ctx) {
 				currentFromElementSpace,
 				currentFromClauseStackNode,
 				JoinType.INNER,
-				interpretAlias( ctx.IDENTIFIER() ),
+				interpretAlias( ctx.alias() ),
 				false
 		);
 
@@ -259,7 +261,7 @@ public void enterQualifiedJoin(HqlParser.QualifiedJoinContext ctx) {
 				currentFromElementSpace,
 				currentFromClauseStackNode,
 				joinType,
-				interpretAlias( ctx.qualifiedJoinRhs().IDENTIFIER() ),
+				interpretAlias( ctx.qualifiedJoinRhs().alias() ),
 				ctx.fetchKeyword() != null
 		);
 

hibernate-query-interpreter/src/test/java/org/hibernate/query/parser/hql/SimpleSemanticQueryBuilderTest.java

@@ -8,6 +8,7 @@
 
 import java.util.Collection;
 
+import org.hibernate.query.parser.AliasCollisionException;
 import org.hibernate.query.parser.SemanticException;
 import org.hibernate.query.parser.SemanticQueryInterpreter;
 import org.hibernate.query.parser.internal.hql.HqlParseTreeBuilder;
@@ -325,6 +326,33 @@ public void testSimpleDynamicInstantiation() throws Exception {
 		assertNotNull( querySpec );
 	}
 
+	@Test(expected = AliasCollisionException.class)
+	public void testAliasCollision(){
+		final String query = "select a.address as a from Anything as a";
+		final SelectStatement selectStatement = (SelectStatement) SemanticQueryInterpreter.interpret(
+				query,
+				new ConsumerContextTestingImpl()
+		);
+	}
+
+	@Test(expected = AliasCollisionException.class)
+	public void testAliasCollisionInSubquery() throws Exception {
+		final String query = "Select a from Something a where a.b in ( select a from SomethingElse a where a.basic = 5) and a.c in ( select c from SomethingElse2 c where c.basic1 = 6)";
+		final SelectStatement selectStatement = (SelectStatement) SemanticQueryInterpreter.interpret(
+				query,
+				new ConsumerContextTestingImpl()
+		);
+	}
+
+	@Test(expected = AliasCollisionException.class)
+	public void testAliasCollisionInJoin() throws Exception {
+		final String query = "select a from Something a left outer join a.entity a on a.basic1 > 5 and a.basic2 < 20";
+		final SelectStatement selectStatement = (SelectStatement) SemanticQueryInterpreter.interpret(
+				query,
+				new ConsumerContextTestingImpl()
+		);
+	}
+
 	private static class DTO {
 	}
 }