Support for %TYPE in CREATE FUNCTION

This patch adds support for %TYPE in CREATE FUNCTION argument and
return types.

%TYPE is already supported by PL/pgSQL when declaring variables.
However, that does not help with the argument and return types in
CREATE FUNCTION.

Using %TYPE makes it easier to write a function which is independent
of the definition of a table. That is, minor changes to the types
used in the table may not require changes to the function.

For example, this trivial function will work whenever `table' which
has columns named `name' and `value', no matter what the types of the
columns are.

CREATE FUNCTION lookup (table.name%TYPE)
RETURNS table.value%TYPE
AS 'select value from table where name = $1'
LANGUAGE 'sql';

This patch includes changes to the testsuite and the documentation.

This work was sponsored by Zembu.

Ian

Index: src/include/nodes/parsenodes.h
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/include/nodes/parsenodes.h,v
retrieving revision 1.126
diff -p -u -r1.126 parsenodes.h
--- src/include/nodes/parsenodes.h 2001/03/23 04:49:56 1.126
+++ src/include/nodes/parsenodes.h 2001/04/28 03:38:21
@@ -945,6 +945,7 @@ typedef struct TypeName
bool setof; /* is a set? */
int32 typmod; /* type modifier */
List *arrayBounds; /* array bounds */
+ char *attrname; /* field name when using %TYPE */
} TypeName;

/*
Index: src/backend/parser/analyze.c
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/backend/parser/analyze.c,v
retrieving revision 1.183
diff -p -u -r1.183 analyze.c
--- src/backend/parser/analyze.c 2001/03/22 06:16:15 1.183
+++ src/backend/parser/analyze.c 2001/04/28 03:38:23
@@ -27,6 +27,7 @@
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "parser/parse_type.h"
+#include "parser/parse_expr.h"
#include "rewrite/rewriteManip.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
@@ -49,7 +50,10 @@ static Node *transformSetOperationTree(P
static Query *transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt);
static Query *transformCreateStmt(ParseState *pstate, CreateStmt *stmt);
static Query *transformAlterTableStmt(ParseState *pstate, AlterTableStmt *stmt);
+static Node *transformTypeRefs(ParseState *pstate, Node *stmt);

+static void transformTypeRefsList(ParseState *pstate, List *l);
+static void transformTypeRef(ParseState *pstate, TypeName *tn);
static List *getSetColTypes(ParseState *pstate, Node *node);
static void transformForUpdate(Query *qry, List *forUpdate);
static void transformFkeyGetPrimaryKey(FkConstraint *fkconstraint);
@@ -230,6 +234,18 @@ transformStmt(ParseState *pstate, Node *
(SelectStmt *) parseTree);
break;

+ /*
+ * Convert use of %TYPE in statements where it is permitted.
+ */
+ case T_ProcedureStmt:
+ case T_CommentStmt:
+ case T_RemoveFuncStmt:
+ case T_DefineStmt:
+ result = makeNode(Query);
+ result->commandType = CMD_UTILITY;
+ result->utilityStmt = transformTypeRefs(pstate, parseTree);
+ break;
+
default:

/*
@@ -2607,6 +2623,104 @@ transformAlterTableStmt(ParseState *psta
}
qry->utilityStmt = (Node *) stmt;
return qry;
+}
+
+/*
+ * Transform uses of %TYPE in a statement.
+ */
+static Node *
+transformTypeRefs(ParseState *pstate, Node *stmt)
+{
+ switch (nodeTag(stmt))
+ {
+ case T_ProcedureStmt:
+ {
+ ProcedureStmt *ps = (ProcedureStmt *) stmt;
+
+ transformTypeRefsList(pstate, ps->argTypes);
+ transformTypeRef(pstate, (TypeName *) ps->returnType);
+ transformTypeRefsList(pstate, ps->withClause);
+ }
+ break;
+
+ case T_CommentStmt:
+ {
+ CommentStmt *cs = (CommentStmt *) stmt;
+
+ transformTypeRefsList(pstate, cs->objlist);
+ }
+ break;
+
+ case T_RemoveFuncStmt:
+ {
+ RemoveFuncStmt *rs = (RemoveFuncStmt *) stmt;
+
+ transformTypeRefsList(pstate, rs->args);
+ }
+ break;
+
+ case T_DefineStmt:
+ {
+ DefineStmt *ds = (DefineStmt *) stmt;
+ List *ele;
+
+ foreach(ele, ds->definition)
+ {
+ DefElem *de = (DefElem *) lfirst(ele);
+
+ if (de->arg != NULL
+ && IsA(de->arg, TypeName))
+ {
+ transformTypeRef(pstate, (TypeName *) de->arg);
+ }
+ }
+ }
+ break;
+
+ default:
+ elog(ERROR, "Unsupported type %d in transformTypeRefs",
+ nodeTag(stmt));
+ break;
+ }
+
+ return stmt;
+}
+
+/*
+ * Transform uses of %TYPE in a list.
+ */
+static void
+transformTypeRefsList(ParseState *pstate, List *l)
+{
+ List *ele;
+
+ foreach(ele, l)
+ {
+ if (IsA(lfirst(ele), TypeName))
+ transformTypeRef(pstate, (TypeName *) lfirst(ele));
+ }
+}
+
+/*
+ * Transform a TypeName to not use %TYPE.
+ */
+static void
+transformTypeRef(ParseState *pstate, TypeName *tn)
+{
+ Attr *att;
+ Node *n;
+ Var *v;
+
+ if (tn->attrname == NULL)
+ return;
+ att = makeAttr(tn->name, tn->attrname);
+ n = transformExpr(pstate, (Node *) att, EXPR_COLUMN_FIRST);
+ if (! IsA(n, Var))
+ elog(ERROR, "unsupported expression in %%TYPE");
+ v = (Var *) n;
+ tn->name = typeidTypeName(v->vartype);
+ tn->typmod = v->vartypmod;
+ tn->attrname = NULL;
}

/* exported so planner can check again after rewriting, query pullup, etc */
Index: src/backend/parser/gram.y
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/backend/parser/gram.y,v
retrieving revision 2.221
diff -p -u -r2.221 gram.y
--- src/backend/parser/gram.y 2001/02/18 18:06:10 2.221
+++ src/backend/parser/gram.y 2001/04/28 03:38:26
@@ -192,7 +192,7 @@ static void doNegateFloat(Value *v);
def_list, opt_indirection, group_clause, TriggerFuncArgs,
select_limit, opt_select_limit

-%type <typnam> func_arg, func_return, aggr_argtype
+%type <typnam> func_arg, func_return, func_type, aggr_argtype

%type <boolean> opt_arg, TriggerForOpt, TriggerForType, OptTemp

@@ -2462,7 +2462,7 @@ func_args_list: func_arg
{ $$ = lappend($1, $3); }
;

-func_arg: opt_arg Typename
+func_arg: opt_arg func_type
{
/* We can catch over-specified arguments here if we want to,
* but for now better to silently swallow typmod, etc.
@@ -2470,7 +2470,7 @@ func_arg: opt_arg Typename
*/
$$ = $2;
}
- | Typename
+ | func_type
{
$$ = $1;
}
@@ -2498,7 +2498,7 @@ func_as: Sconst
{ $$ = makeList2(makeString($1), makeString($3)); }
;

-func_return: Typename
+func_return: func_type
{
/* We can catch over-specified arguments here if we want to,
* but for now better to silently swallow typmod, etc.
@@ -2508,6 +2508,18 @@ func_return: Typename
}
;

+func_type: Typename
+ {
+ $$ = $1;
+ }
+ | IDENT '.' ColId '%' TYPE_P
+ {
+ $$ = makeNode(TypeName);
+ $$->name = $1;
+ $$->typmod = -1;
+ $$->attrname = $3;
+ }
+ ;

/*****************************************************************************
*
Index: src/backend/parser/parse_expr.c
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/backend/parser/parse_expr.c,v
retrieving revision 1.92
diff -p -u -r1.92 parse_expr.c
--- src/backend/parser/parse_expr.c 2001/03/22 03:59:41 1.92
+++ src/backend/parser/parse_expr.c 2001/04/28 03:38:26
@@ -939,6 +939,7 @@ parser_typecast_expression(ParseState *p
char *
TypeNameToInternalName(TypeName *typename)
{
+ Assert(typename->attrname == NULL);
if (typename->arrayBounds != NIL)
{

Index: src/test/regress/input/create_function_2.source
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/test/regress/input/create_function_2.source,v
retrieving revision 1.12
diff -p -u -r1.12 create_function_2.source
--- src/test/regress/input/create_function_2.source 2000/11/20 20:36:54 1.12
+++ src/test/regress/input/create_function_2.source 2001/04/28 03:38:27
@@ -13,6 +13,12 @@ CREATE FUNCTION hobby_construct(text, te
LANGUAGE 'sql';


+CREATE FUNCTION hobbies_by_name(hobbies_r.name%TYPE)
+ RETURNS hobbies_r.person%TYPE
+ AS 'select person from hobbies_r where name = $1'
+ LANGUAGE 'sql';
+
+
CREATE FUNCTION equipment(hobbies_r)
RETURNS setof equipment_r
AS 'select * from equipment_r where hobby = $1.name'
Index: src/test/regress/input/misc.source
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/test/regress/input/misc.source,v
retrieving revision 1.14
diff -p -u -r1.14 misc.source
--- src/test/regress/input/misc.source 2000/11/20 20:36:54 1.14
+++ src/test/regress/input/misc.source 2001/04/28 03:38:28
@@ -214,6 +214,7 @@ SELECT user_relns() AS user_relns

--SELECT name(equipment(hobby_construct(text 'skywalking', text 'mer'))) AS equip_name;

+SELECT hobbies_by_name('basketball');

--
-- check that old-style C functions work properly with TOASTed values
Index: src/test/regress/output/create_function_2.source
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/test/regress/output/create_function_2.source,v
retrieving revision 1.13
diff -p -u -r1.13 create_function_2.source
--- src/test/regress/output/create_function_2.source 2000/11/20 20:36:54 1.13
+++ src/test/regress/output/create_function_2.source 2001/04/28 03:38:28
@@ -9,6 +9,10 @@ CREATE FUNCTION hobby_construct(text, te
RETURNS hobbies_r
AS 'select $1 as name, $2 as hobby'
LANGUAGE 'sql';
+CREATE FUNCTION hobbies_by_name(hobbies_r.name%TYPE)
+ RETURNS hobbies_r.person%TYPE
+ AS 'select person from hobbies_r where name = $1'
+ LANGUAGE 'sql';
CREATE FUNCTION equipment(hobbies_r)
RETURNS setof equipment_r
AS 'select * from equipment_r where hobby = $1.name'
Index: src/test/regress/output/misc.source
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/test/regress/output/misc.source,v
retrieving revision 1.27
diff -p -u -r1.27 misc.source
--- src/test/regress/output/misc.source 2000/11/20 20:36:54 1.27
+++ src/test/regress/output/misc.source 2001/04/28 03:38:28
@@ -656,6 +656,12 @@ SELECT user_relns() AS user_relns
(90 rows)

--SELECT name(equipment(hobby_construct(text 'skywalking', text 'mer'))) AS equip_name;
+SELECT hobbies_by_name('basketball');
+ hobbies_by_name
+-----------------
+ joe
+(1 row)
+
--
-- check that old-style C functions work properly with TOASTed values
--
Index: doc/src/sgml/ref/create_function.sgml
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/doc/src/sgml/ref/create_function.sgml,v
retrieving revision 1.21
diff -p -u -r1.21 create_function.sgml
--- doc/src/sgml/ref/create_function.sgml 2000/12/25 23:15:26 1.21
+++ doc/src/sgml/ref/create_function.sgml 2001/04/28 03:38:31
@@ -58,10 +58,16 @@ CREATE FUNCTION <replaceable class="para
<listitem>
<para>
The data type(s) of the function's arguments, if any.
- The input types may be base or complex types, or
- <firstterm>opaque</firstterm>.
+ The input types may be base or complex types,
+ <firstterm>opaque</firstterm>, or the same as the type of an
+ existing column.
<literal>Opaque</literal> indicates that the function
accepts arguments of a non-SQL type such as <type>char *</type>.
+ The type of a column is indicated using <replaceable
+ class="parameter">tablename</replaceable>.<replaceable
+ class="parameter">columnname</replaceable><literal>%TYPE</literal>;
+ using this can sometimes help make a function independent from
+ changes to the definition of a table.
</para>
</listitem>
</varlistentry>
@@ -72,7 +78,8 @@ CREATE FUNCTION <replaceable class="para
The return data type.
The output type may be specified as a base type, complex type,
<option>setof type</option>,
- or <option>opaque</option>.
+ <option>opaque</option>, or the same as the type of an
+ existing column.
The <option>setof</option>
modifier indicates that the function will return a set of items,
rather than a single item.