HHH-18497 Add xmlforest function

Author: beikov

documentation/src/main/asciidoc/userguide/chapters/query/hql/QueryLanguage.adoc

@@ -2173,6 +2173,7 @@ it is necessary to enable the `hibernate.query.hql.xml_functions_enabled` config
 
 | `xmlelement()` | Constructs an XML element from arguments
 | `xmlcomment()` | Constructs an XML comment from the single argument
+| `xmlforest()` | Constructs an XML forest from thearguments
 |===
 
 
@@ -2208,7 +2209,7 @@ include::{xml-example-dir-hql}/XmlElementTest.java[tags=hql-xmlelement-attribute
 ----
 ====
 
-WARNING: SAP HANA, MySQL, MariaDB, H2 and HSQLDB do not support this function.
+WARNING: SAP HANA, MySQL, MariaDB and HSQLDB do not support this function.
 
 [[hql-xmlcomment-function]]
 ===== `xmlcomment()`
@@ -2223,7 +2224,31 @@ include::{xml-example-dir-hql}/XmlCommentTest.java[tags=hql-xmlcomment-example]
 ----
 ====
 
-WARNING: SAP HANA, MySQL, MariaDB, H2 and HSQLDB do not support this function.
+WARNING: SAP HANA, MySQL, MariaDB and HSQLDB do not support this function.
+
+[[hql-xmlforest-function]]
+===== `xmlforest()`
+
+Constructs an XML forest from the arguments. A forest is a sequence of XML elements.
+
+[[hql-xmlforest-bnf]]
+[source, antlrv4, indent=0]
+----
+include::{extrasdir}/xmlforest_bnf.txt[]
+----
+
+The optional name specifies the XML element name to use for the content as produced by the expression.
+The name can be omitted if a path expression is passed, in which case the last attribute name is used as element name.
+
+[[hql-xmlforest-example]]
+====
+[source, java, indent=0]
+----
+include::{xml-example-dir-hql}/XmlForestTest.java[tags=hql-xmlforest-example]
+----
+====
+
+WARNING: SAP HANA, MySQL, MariaDB and HSQLDB do not support this function.
 
 [[hql-user-defined-functions]]
 ==== Native and user-defined functions

documentation/src/main/asciidoc/userguide/chapters/query/hql/extras/xmlforest_bnf.txt

@@ -0,0 +1 @@
+"xmlforest(expressionOrPredicate ("as" identifier)? ("," expressionOrPredicate ("as" identifier)?)* ")"

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/DB2LegacyDialect.java

@@ -443,6 +443,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 
 		functionFactory.xmlelement();
 		functionFactory.xmlcomment();
+		functionFactory.xmlforest();
 	}
 
 	@Override

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/H2LegacyDialect.java

@@ -420,6 +420,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 
 			functionFactory.xmlelement_h2();
 			functionFactory.xmlcomment();
+			functionFactory.xmlforest_h2();
 		}
 		else {
 			functionFactory.listagg_groupConcat();

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/OracleLegacyDialect.java

@@ -328,6 +328,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 
 		functionFactory.xmlelement();
 		functionFactory.xmlcomment();
+		functionFactory.xmlforest();
 	}
 
 	@Override

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/PostgreSQLLegacyDialect.java

@@ -671,6 +671,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 
 		functionFactory.xmlelement();
 		functionFactory.xmlcomment();
+		functionFactory.xmlforest();
 
 		if ( getVersion().isSameOrAfter( 9, 4 ) ) {
 			functionFactory.makeDateTimeTimestamp();

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/SQLServerLegacyDialect.java

@@ -415,6 +415,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		}
 		functionFactory.xmlelement_sqlserver();
 		functionFactory.xmlcomment_sqlserver();
+		functionFactory.xmlforest_sqlserver();
 		if ( getVersion().isSameOrAfter( 14 ) ) {
 			functionFactory.listagg_stringAggWithinGroup( "varchar(max)" );
 			functionFactory.jsonArrayAgg_sqlserver( getVersion().isSameOrAfter( 16 ) );

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlLexer.g4

@@ -332,6 +332,7 @@ WITHOUT				: [wW] [iI] [tT] [hH] [oO] [uU] [tT];
 WRAPPER				: [wW] [rR] [aA] [pP] [pP] [eE] [rR];
 XMLATTRIBUTES		: [xX] [mM] [lL] [aA] [tT] [tT] [rR] [iI] [bB] [uU] [tT] [eE] [sS];
 XMLELEMENT			: [xX] [mM] [lL] [eE] [lL] [eE] [mM] [eE] [nN] [tT];
+XMLFOREST			: [xX] [mM] [lL] [fF] [oO] [rR] [eE] [sS] [tT];
 YEAR				: [yY] [eE] [aA] [rR];
 ZONED				: [zZ] [oO] [nN] [eE] [dD];
 

hibernate-core/src/main/antlr/org/hibernate/grammars/hql/HqlParser.g4

@@ -1719,6 +1719,7 @@ jsonUniqueKeysClause
 
 xmlFunction
 	: xmlelementFunction
+	| xmlforestFunction
 	;
 
 /**
@@ -1735,6 +1736,13 @@ xmlattributesFunction
 	: XMLATTRIBUTES LEFT_PAREN expressionOrPredicate AS identifier (COMMA expressionOrPredicate AS identifier)* RIGHT_PAREN
 	;
 
+/**
+ * The 'xmlforest()' function
+ */
+xmlforestFunction
+	: XMLFOREST LEFT_PAREN expressionOrPredicate (AS identifier)? (COMMA expressionOrPredicate (AS identifier)?)* RIGHT_PAREN
+	;
+
 /**
  * Support for "soft" keywords which may be used as identifiers
  *
@@ -1943,6 +1951,7 @@ xmlattributesFunction
 	| WRAPPER
 	| XMLATTRIBUTES
 	| XMLELEMENT
+	| XMLFOREST
 	| YEAR
 	| ZONED) {
 		logUseOfReservedWordAsIdentifier( getCurrentToken() );

hibernate-core/src/main/java/org/hibernate/dialect/DB2Dialect.java

@@ -428,6 +428,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 
 		functionFactory.xmlelement();
 		functionFactory.xmlcomment();
+		functionFactory.xmlforest();
 	}
 
 	@Override