[CF 5456] v8 - Add XMLNamespaces option to XMLElement

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https://commitfest.postgresql.org/patch/5456

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Patch(es): https://www.postgresql.org/message-id/1b63f25a-276a-41b7-9284-260826afd906@uni-muenster.de
Author(s): Pavel Stehule, Jim Jones

Author: Commitfest Bot

doc/src/sgml/func.sgml

@@ -14730,7 +14730,10 @@ SELECT xmlconcat('<?xml version="1.1"?><foo/>', '<?xml version="1.1" standalone=
    </indexterm>
 
 <synopsis>
-<function>xmlelement</function> ( <literal>NAME</literal> <replaceable>name</replaceable> <optional>, <literal>XMLATTRIBUTES</literal> ( <replaceable>attvalue</replaceable> <optional> <literal>AS</literal> <replaceable>attname</replaceable> </optional> <optional>, ...</optional> ) </optional> <optional>, <replaceable>content</replaceable> <optional>, ...</optional></optional> ) <returnvalue>xml</returnvalue>
+<function>xmlelement</function> ( <literal>NAME</literal> <replaceable>name</replaceable>
+    <optional>, <literal>XMLATTRIBUTES</literal> ( <replaceable>attvalue</replaceable> <optional> <literal>AS</literal> <replaceable>attname</replaceable> </optional> <optional>, ...</optional> ) </optional>
+    <optional>, <literal>XMLNAMESPACES</literal> ( {<replaceable>regular-nsuri</replaceable> <literal>AS</literal> <replaceable>nsprefix</replaceable> | DEFAULT <replaceable>default-nsuri</replaceable> | NO DEFAULT} <optional>, ...</optional> ) </optional>
+<optional>, <replaceable>content</replaceable> <optional>, ...</optional></optional> ) <returnvalue>xml</returnvalue>
 </synopsis>
 
     <para>
@@ -14743,7 +14746,39 @@ SELECT xmlconcat('<?xml version="1.1"?><foo/>', '<?xml version="1.1" standalone=
      yield any <productname>PostgreSQL</productname> data type.  The
      argument(s) within <literal>XMLATTRIBUTES</literal> generate attributes
      of the XML element; the <replaceable>content</replaceable> value(s) are
-     concatenated to form its content.
+     concatenated to form its content. The arguments within <literal>XMLNAMESPACES</literal>
+     constuct namespace declarations from values provided in <replaceable>nsuri</replaceable>
+     and <replaceable>nsprefix</replaceable>, which correspond to the URI of a namespace and
+     its prefix, respectively. The option <literal>DEFAULT</literal> can be used to set the
+     default namespace declaration (without a prefix) to the URI provided in <replaceable>default-nsuri</replaceable>.
+     The option <literal>NO DEFAULT</literal> states that a namespace scope has no default namespace. A valid
+     <literal>XMLNAMESPACES</literal> item must fulfill the following conditions:
+
+    <itemizedlist>
+    <listitem>
+     <para>
+      Only a single <literal>DEFAULT</literal> declaration item within the same scope.
+     </para>
+    </listitem>
+    <listitem>
+     <para>
+      No two <replaceable>nsuri</replaceable> can be equal within the same scope.
+     </para>
+    </listitem>
+    <listitem>
+     <para>
+      No <replaceable>nsprefix</replaceable> can be equal to <literal>xml</literal> or <literal>xmlns</literal>,
+      and no <replaceable>nsuri</replaceable> can be equal to <literal>http://www.w3.org/2000/xmlns/</literal>
+      or to <literal>http://www.w3.org/XML/1998/namespace</literal>, as they are already bouned to standard XML declarations.
+     </para>
+    </listitem>
+    <listitem>
+     <para>
+      The value of a <replaceable>regular-nsuri</replaceable> cannot be a zero-length string.
+     </para>
+    </listitem>
+   </itemizedlist>
+
     </para>
 
     <para>
@@ -14766,6 +14801,24 @@ SELECT xmlelement(name foo, xmlattributes(current_date as bar), 'cont', 'ent');
              xmlelement
 -------------------------------------
  <foo bar="2007-01-26">content</foo>
+
+SELECT xmlelement(NAME "foo:root", xmlnamespaces('http:/foo.bar/' AS foo), 'content');
+
+                       xmlelement
+---------------------------------------------------------
+ <foo:root xmlns:foo="http:/foo.bar/">content</foo:root>
+
+ SELECT xmlelement(NAME "root", xmlnamespaces(DEFAULT 'http:/foo.bar/'), 'content');
+
+                 xmlelement
+---------------------------------------------
+ <root xmlns="http:/foo.bar/">content</root>
+
+ SELECT xmlelement(NAME "root", xmlnamespaces(NO DEFAULT), 'content');
+
+          xmlelement
+-------------------------------
+ <root xmlns="">content</root>
 ]]></screen>
     </para>
 

src/backend/parser/gram.y

@@ -136,6 +136,12 @@ typedef struct KeyActions
 	KeyAction *deleteAction;
 } KeyActions;
 
+typedef struct XmlElementOpts
+{
+	List	   *xml_attributes;
+	List	   *xml_namespaces;
+} XmlElementOpts;
+
 /* ConstraintAttributeSpec yields an integer bitmask of these flags: */
 #define CAS_NOT_DEFERRABLE			0x01
 #define CAS_DEFERRABLE				0x02
@@ -186,7 +192,7 @@ static Node *makeNotExpr(Node *expr, int location);
 static Node *makeAArrayExpr(List *elements, int location, int end_location);
 static Node *makeSQLValueFunction(SQLValueFunctionOp op, int32 typmod,
 								  int location);
-static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args,
+static Node *makeXmlExpr(XmlExprOp op, char *name, XmlElementOpts *opts,
 						 List *args, int location);
 static List *mergeTableFuncParameters(List *func_args, List *columns, core_yyscan_t yyscanner);
 static TypeName *TableFuncTypeName(List *columns);
@@ -266,6 +272,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	MergeWhenClause *mergewhen;
 	struct KeyActions *keyactions;
 	struct KeyAction *keyaction;
+	struct XmlElementOpts *xmlelementopts;
 	ReturningClause *retclause;
 	ReturningOptionKind retoptionkind;
 }
@@ -617,8 +624,9 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <list>	xmltable_column_list xmltable_column_option_list
 %type <node>	xmltable_column_el
 %type <defelt>	xmltable_column_option_el
-%type <list>	xml_namespace_list
+%type <list>	xml_namespace_list xml_namespaces
 %type <target>	xml_namespace_el
+%type <xmlelementopts> xmlelement_opts
 
 %type <node>	func_application func_expr_common_subexpr
 %type <node>	func_expr func_expr_windowless
@@ -14292,6 +14300,15 @@ xml_namespace_el:
 					$$->val = $2;
 					$$->location = @1;
 				}
+			| NO DEFAULT
+				{
+					$$ = makeNode(ResTarget);
+					$$->name = NULL;
+					$$->indirection = NIL;
+					$$->val = NULL;
+					$$->location = @1;
+				}
+
 		;
 
 json_table:
@@ -15346,12 +15363,12 @@ a_expr:		c_expr									{ $$ = $1; }
 				}
 			| a_expr IS DOCUMENT_P					%prec IS
 				{
-					$$ = makeXmlExpr(IS_DOCUMENT, NULL, NIL,
+					$$ = makeXmlExpr(IS_DOCUMENT, NULL, NULL,
 									 list_make1($1), @2);
 				}
 			| a_expr IS NOT DOCUMENT_P				%prec IS
 				{
-					$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NIL,
+					$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NULL,
 												 list_make1($1), @2),
 									 @2);
 				}
@@ -15493,12 +15510,12 @@ b_expr:		c_expr
 				}
 			| b_expr IS DOCUMENT_P					%prec IS
 				{
-					$$ = makeXmlExpr(IS_DOCUMENT, NULL, NIL,
+					$$ = makeXmlExpr(IS_DOCUMENT, NULL, NULL,
 									 list_make1($1), @2);
 				}
 			| b_expr IS NOT DOCUMENT_P				%prec IS
 				{
-					$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NIL,
+					$$ = makeNotExpr(makeXmlExpr(IS_DOCUMENT, NULL, NULL,
 												 list_make1($1), @2),
 									 @2);
 				}
@@ -16033,21 +16050,21 @@ func_expr_common_subexpr:
 				}
 			| XMLCONCAT '(' expr_list ')'
 				{
-					$$ = makeXmlExpr(IS_XMLCONCAT, NULL, NIL, $3, @1);
+					$$ = makeXmlExpr(IS_XMLCONCAT, NULL, NULL, $3, @1);
 				}
 			| XMLELEMENT '(' NAME_P ColLabel ')'
 				{
-					$$ = makeXmlExpr(IS_XMLELEMENT, $4, NIL, NIL, @1);
+					$$ = makeXmlExpr(IS_XMLELEMENT, $4, NULL, NIL, @1);
 				}
-			| XMLELEMENT '(' NAME_P ColLabel ',' xml_attributes ')'
+			| XMLELEMENT '(' NAME_P ColLabel ',' xmlelement_opts ')'
 				{
 					$$ = makeXmlExpr(IS_XMLELEMENT, $4, $6, NIL, @1);
 				}
 			| XMLELEMENT '(' NAME_P ColLabel ',' expr_list ')'
 				{
-					$$ = makeXmlExpr(IS_XMLELEMENT, $4, NIL, $6, @1);
+					$$ = makeXmlExpr(IS_XMLELEMENT, $4, NULL, $6, @1);
 				}
-			| XMLELEMENT '(' NAME_P ColLabel ',' xml_attributes ',' expr_list ')'
+			| XMLELEMENT '(' NAME_P ColLabel ',' xmlelement_opts ',' expr_list ')'
 				{
 					$$ = makeXmlExpr(IS_XMLELEMENT, $4, $6, $8, @1);
 				}
@@ -16062,12 +16079,17 @@ func_expr_common_subexpr:
 				}
 			| XMLFOREST '(' xml_attribute_list ')'
 				{
-					$$ = makeXmlExpr(IS_XMLFOREST, NULL, $3, NIL, @1);
+					XmlElementOpts opts;
+
+					opts.xml_attributes = $3;
+					opts.xml_namespaces = NIL;
+
+					$$ = makeXmlExpr(IS_XMLFOREST, NULL, &opts, NIL, @1);
 				}
 			| XMLPARSE '(' document_or_content a_expr xml_whitespace_option ')'
 				{
 					XmlExpr *x = (XmlExpr *)
-						makeXmlExpr(IS_XMLPARSE, NULL, NIL,
+						makeXmlExpr(IS_XMLPARSE, NULL, NULL,
 									list_make2($4, makeBoolAConst($5, -1)),
 									@1);
 
@@ -16084,7 +16106,7 @@ func_expr_common_subexpr:
 				}
 			| XMLROOT '(' a_expr ',' xml_root_version opt_xml_root_standalone ')'
 				{
-					$$ = makeXmlExpr(IS_XMLROOT, NULL, NIL,
+					$$ = makeXmlExpr(IS_XMLROOT, NULL, NULL,
 									 list_make3($3, $5, $6), @1);
 				}
 			| XMLSERIALIZE '(' document_or_content a_expr AS SimpleTypename xml_indent_option ')'
@@ -16288,6 +16310,9 @@ opt_xml_root_standalone: ',' STANDALONE_P YES_P
 xml_attributes: XMLATTRIBUTES '(' xml_attribute_list ')'	{ $$ = $3; }
 		;
 
+xml_namespaces: XMLNAMESPACES '(' xml_namespace_list ')'	{ $$ = $3; }
+		;
+
 xml_attribute_list:	xml_attribute_el					{ $$ = list_make1($1); }
 			| xml_attribute_list ',' xml_attribute_el	{ $$ = lappend($1, $3); }
 		;
@@ -16324,6 +16349,44 @@ xml_whitespace_option: PRESERVE WHITESPACE_P		{ $$ = true; }
 			| /*EMPTY*/								{ $$ = false; }
 		;
 
+xmlelement_opts: xml_attributes
+				{
+					XmlElementOpts *n = palloc(sizeof(XmlElementOpts));
+
+					n->xml_attributes = $1;
+					n->xml_namespaces = NIL;
+					$$ = n;
+				}
+			| xml_namespaces
+				{
+					XmlElementOpts *n = palloc(sizeof(XmlElementOpts));
+
+					n->xml_attributes = NIL;
+					n->xml_namespaces = $1;
+					$$ = n;
+				}
+			| xmlelement_opts ',' xml_attributes
+				{
+					if ($$->xml_attributes)
+						ereport(ERROR,
+							(errcode(ERRCODE_DUPLICATE_OBJECT),
+							 errmsg("duplicate XMLATTRIBUTES specified"),
+							 parser_errposition(@3)));
+
+					$$->xml_attributes = $3;
+				}
+			| xmlelement_opts ',' xml_namespaces
+				{
+					if ($$->xml_namespaces)
+						ereport(ERROR,
+							(errcode(ERRCODE_DUPLICATE_OBJECT),
+							 errmsg("duplicate XMLNAMESACES specified"),
+							 parser_errposition(@3)));
+
+					$$->xml_namespaces = $3;
+				}
+		;
+
 /* We allow several variants for SQL and other compatibility. */
 xmlexists_argument:
 			PASSING c_expr
@@ -19246,7 +19309,7 @@ makeSQLValueFunction(SQLValueFunctionOp op, int32 typmod, int location)
 }
 
 static Node *
-makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args,
+makeXmlExpr(XmlExprOp op, char *name, XmlElementOpts *opts, List *args,
 			int location)
 {
 	XmlExpr    *x = makeNode(XmlExpr);
@@ -19258,7 +19321,12 @@ makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args,
 	 * named_args is a list of ResTarget; it'll be split apart into separate
 	 * expression and name lists in transformXmlExpr().
 	 */
-	x->named_args = named_args;
+	if (opts)
+	{
+		x->named_args = opts->xml_attributes;
+		x->xmlnamespaces = opts->xml_namespaces;
+	}
+
 	x->arg_names = NIL;
 	x->args = args;
 	/* xmloption, if relevant, must be filled in by caller */

src/backend/parser/parse_clause.c

@@ -842,7 +842,12 @@ transformRangeTableFunc(ParseState *pstate, RangeTableFunc *rtf)
 			Node	   *ns_uri;
 
 			Assert(IsA(r, ResTarget));
-			ns_uri = transformExpr(pstate, r->val, EXPR_KIND_FROM_FUNCTION);
+			/* Create an empty String for NO DEFAULT namespaces */
+			if (!r->name && !r->val)
+				ns_uri = transformExpr(pstate, makeStringConst("", r->location), EXPR_KIND_FROM_FUNCTION);
+			else
+				ns_uri = transformExpr(pstate, r->val, EXPR_KIND_FROM_FUNCTION);
+
 			ns_uri = coerce_to_specific_type(pstate, ns_uri,
 											 TEXTOID, constructName);
 			assign_expr_collations(pstate, ns_uri);