create or replace type body ut_stack as

/*

utPLSQL - Version 3

Copyright 2016 - 2023 utPLSQL Project

Licensed under the Apache License, Version 2.0 (the "License"):

you may not use this file except in compliance with the License.

You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software

distributed under the License is distributed on an "AS IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and

limitations under the License.

*/

constructor function ut_stack( self in out nocopy ut_stack) return self as result is

begin

self.tokens := ut_varchar2_list();

self.top := 0;

return;

end ut_stack;

member function peek(self in out nocopy ut_stack) return varchar2 is

l_token varchar2(32767);

begin

if self.tokens.count =0 or self.tokens is null then

l_token := null;

else

l_token := self.tokens(self.tokens.last);

end if;

return l_token;

end;

member procedure push(self in out nocopy ut_stack, a_token varchar2) is

begin

self.tokens.extend;

self.tokens(self.tokens.last) := a_token;

self.top := self.tokens.count;

end push;

member procedure pop(self in out nocopy ut_stack,a_cnt in integer default 1) is

begin

self.tokens.trim(a_cnt);

self.top := self.tokens.count;

end pop;

member function pop(self in out nocopy ut_stack) return varchar2 is

l_token varchar2(32767) := self.tokens(self.tokens.last);

begin

self.pop();

return l_token;

end;

end;

/