HHH-18497 Add xmlelement function

Author: beikov

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

@@ -7,6 +7,7 @@
 :example-dir-hql: {core-project-dir}/src/test/java/org/hibernate/orm/test/hql
 :array-example-dir-hql: {core-project-dir}/src/test/java/org/hibernate/orm/test/function/array
 :json-example-dir-hql: {core-project-dir}/src/test/java/org/hibernate/orm/test/function/json
+:xml-example-dir-hql: {core-project-dir}/src/test/java/org/hibernate/orm/test/function/xml
 :extrasdir: extras
 
 This chapter describes Hibernate Query Language (HQL) and Jakarta Persistence Query Language (JPQL).
@@ -2158,6 +2159,56 @@ include::{json-example-dir-hql}/JsonArrayInsertTest.java[tags=hql-json-array-ins
 
 WARNING: SAP HANA, DB2, H2 and HSQLDB do not support this function.
 
+[[hql-functions-xml]]
+==== Functions for dealing with XML
+
+The following functions deal with SQL XML types, which are not supported on every database.
+
+NOTE: The following functions are incubating/tech-preview and to use them in HQL,
+it is necessary to enable the `hibernate.query.hql.xml_functions_enabled` configuration setting.
+
+[[hql-xml-functions]]
+|===
+| Function | Purpose
+
+| `xmlelement()` | Constructs an XML element from arguments
+|===
+
+
+[[hql-xmlelement-function]]
+===== `xmlelement()`
+
+Constructs an XML element from the arguments.
+
+[[hql-xmlelement-bnf]]
+[source, antlrv4, indent=0]
+----
+include::{extrasdir}/xmlelement_bnf.txt[]
+----
+
+The identifier represents the XML element name and can be quoted by using backticks.
+
+[[hql-xmlelement-example]]
+====
+[source, java, indent=0]
+----
+include::{xml-example-dir-hql}/XmlElementTest.java[tags=hql-xmlelement-example]
+----
+====
+
+XML element attributes can be defined by using the `xmlattributes` function as second argument.
+All following arguments represent the XML content.
+
+[[hql-xmlelement-attributes-content-example]]
+====
+[source, java, indent=0]
+----
+include::{xml-example-dir-hql}/XmlElementTest.java[tags=hql-xmlelement-attributes-content-example]
+----
+====
+
+WARNING: SAP HANA, MySQL, MariaDB, H2 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/xmlelement_bnf.txt

@@ -0,0 +1,5 @@
+"xmlelement(name " identifier xmlattributes? ("," expressionOrPredicate)* ")"
+
+xmlattributes
+	: "xmlattributes(" expressionOrPredicate " as " identifier ("," expressionOrPredicate " as " identifier)* ")"
+	;

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

@@ -440,6 +440,8 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 				functionFactory.jsonObjectAgg_db2();
 			}
 		}
+
+		functionFactory.xmlelement();
 	}
 
 	@Override

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

@@ -417,6 +417,8 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 				// Use group_concat until 2.x as listagg was buggy
 				functionFactory.listagg_groupConcat();
 			}
+
+			functionFactory.xmlelement_h2();
 		}
 		else {
 			functionFactory.listagg_groupConcat();

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

@@ -325,6 +325,8 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 			functionFactory.jsonArrayAppend_oracle();
 			functionFactory.jsonArrayInsert_oracle();
 		}
+
+		functionFactory.xmlelement();
 	}
 
 	@Override

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

@@ -669,6 +669,8 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		functionFactory.jsonArrayAppend_postgresql( getVersion().isSameOrAfter( 13 ) );
 		functionFactory.jsonArrayInsert_postgresql();
 
+		functionFactory.xmlelement();
+
 		if ( getVersion().isSameOrAfter( 9, 4 ) ) {
 			functionFactory.makeDateTimeTimestamp();
 			// Note that PostgreSQL doesn't support the OVER clause for ordered set-aggregate functions

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

@@ -413,6 +413,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 			functionFactory.jsonArrayAppend_sqlserver( getVersion().isSameOrAfter( 16 ) );
 			functionFactory.jsonArrayInsert_sqlserver();
 		}
+		functionFactory.xmlelement_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

@@ -258,6 +258,7 @@ MINELEMENT			: [mM] [iI] [nN] [eE] [lL] [eE] [mM] [eE] [nN] [tT];
 MININDEX			: [mM] [iI] [nN] [iI] [nN] [dD] [eE] [xX];
 MINUTE				: [mM] [iI] [nN] [uU] [tT] [eE];
 MONTH				: [mM] [oO] [nN] [tT] [hH];
+NAME				: [nN] [aA] [mM] [eE];
 NANOSECOND			: [nN] [aA] [nN] [oO] [sS] [eE] [cC] [oO] [nN] [dD];
 NEW					: [nN] [eE] [wW];
 NEXT				: [nN] [eE] [xX] [tT];
@@ -329,6 +330,8 @@ WITH				: [wW] [iI] [tT] [hH];
 WITHIN				: [wW] [iI] [tT] [hH] [iI] [nN];
 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];
 YEAR				: [yY] [eE] [aA] [rR];
 ZONED				: [zZ] [oO] [nN] [eE] [dD];
 

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

@@ -1110,6 +1110,7 @@ function
 	| jpaNonstandardFunction
 	| columnFunction
 	| jsonFunction
+	| xmlFunction
 	| genericFunction
 	;
 
@@ -1716,6 +1717,24 @@ jsonUniqueKeysClause
 	: (WITH|WITHOUT) UNIQUE KEYS
 	;
 
+xmlFunction
+	: xmlelementFunction
+	;
+
+/**
+ * The 'xmlelement()' function
+ */
+xmlelementFunction
+	: XMLELEMENT LEFT_PAREN NAME identifier (COMMA xmlattributesFunction)? (COMMA expressionOrPredicate)* RIGHT_PAREN
+	;
+
+/**
+ * The 'xmlattributes()' function
+ */
+xmlattributesFunction
+	: XMLATTRIBUTES LEFT_PAREN expressionOrPredicate AS identifier (COMMA expressionOrPredicate AS identifier)* RIGHT_PAREN
+	;
+
 /**
  * Support for "soft" keywords which may be used as identifiers
  *
@@ -1847,6 +1866,7 @@ jsonUniqueKeysClause
 	| MININDEX
 	| MINUTE
 	| MONTH
+	| NAME
 	| NANOSECOND
 	| NATURALID
 	| NEW
@@ -1921,6 +1941,8 @@ jsonUniqueKeysClause
 	| WITHIN
 	| WITHOUT
 	| WRAPPER
+	| XMLATTRIBUTES
+	| XMLELEMENT
 	| YEAR
 	| ZONED) {
 		logUseOfReservedWordAsIdentifier( getCurrentToken() );

hibernate-core/src/main/java/org/hibernate/boot/internal/SessionFactoryOptionsBuilder.java

@@ -131,6 +131,7 @@
 import static org.hibernate.cfg.QuerySettings.DEFAULT_NULL_ORDERING;
 import static org.hibernate.cfg.QuerySettings.JSON_FUNCTIONS_ENABLED;
 import static org.hibernate.cfg.QuerySettings.PORTABLE_INTEGER_DIVISION;
+import static org.hibernate.cfg.QuerySettings.XML_FUNCTIONS_ENABLED;
 import static org.hibernate.engine.config.spi.StandardConverters.BOOLEAN;
 import static org.hibernate.internal.CoreLogging.messageLogger;
 import static org.hibernate.internal.log.DeprecationLogger.DEPRECATION_LOGGER;
@@ -276,6 +277,7 @@ public class SessionFactoryOptionsBuilder implements SessionFactoryOptions {
 
 	private final boolean portableIntegerDivisionEnabled;
 	private final boolean jsonFunctionsEnabled;
+	private final boolean xmlFunctionsEnabled;
 
 	private final int queryStatisticsMaxSize;
 
@@ -614,6 +616,10 @@ else if ( jdbcTimeZoneValue != null ) {
 				JSON_FUNCTIONS_ENABLED,
 				configurationSettings
 		);
+		this.xmlFunctionsEnabled = getBoolean(
+				XML_FUNCTIONS_ENABLED,
+				configurationSettings
+		);
 
 		this.queryStatisticsMaxSize = getInt(
 				QUERY_STATISTICS_MAX_SIZE,
@@ -1244,6 +1250,11 @@ public boolean isJsonFunctionsEnabled() {
 		return jsonFunctionsEnabled;
 	}
 
+	@Override
+	public boolean isXmlFunctionsEnabled() {
+		return xmlFunctionsEnabled;
+	}
+
 	@Override
 	public boolean isPortableIntegerDivisionEnabled() {
 		return portableIntegerDivisionEnabled;