Function parseTypeString

src/backend/parser/parse_type.c:779–811

* Given a string that is supposed to be a SQL-compatible type declaration, * such as "int4" or "integer" or "character varying(32)", parse * the string and convert it to a type OID and type modifier. * If missing_ok is true, InvalidOid is returned rather than raising an error * when the type name is not found. */

 * when the type name is not found.
 */
void
parseTypeString(const char *str, Oid *typeid_p, int32 *typmod_p, bool missing_ok)
{
	TypeName   *typeName;
	Type		tup;

	typeName = typeStringToTypeName(str);

	tup = LookupTypeName(NULL, typeName, typmod_p, missing_ok);
	if (tup == NULL)
	{
		if (!missing_ok)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("type \"%s\" does not exist",
							TypeNameToString(typeName)),
					 parser_errposition(NULL, typeName->location)));
		*typeid_p = InvalidOid;
	}
	else
	{
		Form_pg_type typ = (Form_pg_type) GETSTRUCT(tup);

		if (!typ->typisdefined)
			ereport(ERROR,
					(errcode(ERRCODE_UNDEFINED_OBJECT),
					 errmsg("type \"%s\" is only a shell",
							TypeNameToString(typeName)),
					 parser_errposition(NULL, typeName->location)));
		*typeid_p = typ->oid;
		ReleaseSysCache(tup);
	}
}