1
0
mirror of https://github.com/postgres/postgres.git synced 2025-08-27 07:42:10 +03:00

Add select_common_typmod()

This accompanies select_common_type() and select_common_collation().
Typmods were previously combined using hand-coded logic in several
places.  The logic in select_common_typmod() isn't very exciting, but
it makes the code more compact and readable in a few locations, and in
the future we can perhaps do more complicated things if desired.

As a small enhancement, the type unification of the direct and
aggregate arguments of hypothetical-set aggregates now unifies the
typmod as well using this new function, instead of just dropping it.

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://www.postgresql.org/message-id/flat/97df3af9-8b5e-fb7f-a029-3eb7e80d7af9@2ndquadrant.com
This commit is contained in:
Peter Eisentraut
2020-10-27 17:39:23 +01:00
parent 59ab4ac324
commit f893e68d76
5 changed files with 57 additions and 39 deletions

View File

@@ -1522,6 +1522,43 @@ coerce_to_common_type(ParseState *pstate, Node *node,
return node;
}
/*
* select_common_typmod()
* Determine the common typmod of a list of input expressions.
*
* common_type is the selected common type of the expressions, typically
* computed using select_common_type().
*/
int32
select_common_typmod(ParseState *pstate, List *exprs, Oid common_type)
{
ListCell *lc;
bool first = true;
int32 result = -1;
foreach(lc, exprs)
{
Node *expr = (Node *) lfirst(lc);
/* Types must match */
if (exprType(expr) != common_type)
return -1;
else if (first)
{
result = exprTypmod(expr);
first = false;
}
else
{
/* As soon as we see a non-matching typmod, fall back to -1 */
if (result != exprTypmod(expr))
return -1;
}
}
return result;
}
/*
* check_generic_type_consistency()
* Are the actual arguments potentially compatible with a