(*
Copyright 2018, 2020 Anton Krotov
This file is part of fb2read.
fb2read is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
fb2read is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with fb2read. If not, see <http://www.gnu.org/licenses/>.
*)
MODULE LISTS;
TYPE
LIST* = POINTER TO rLIST;
ITEM* = POINTER TO rITEM;
rITEM* = RECORD
prev*, next*: ITEM;
destroy*: PROCEDURE (VAR item: ITEM)
END;
rLIST* = RECORD
first*, last*: ITEM
END;
PROCEDURE push* (list: LIST; item: ITEM);
BEGIN
ASSERT(list # NIL);
ASSERT(item # NIL);
IF list.first = NIL THEN
list.first := item;
list.last := item;
item.prev := NIL;
item.next := NIL
ELSE
ASSERT(list.last # NIL);
item.prev := list.last;
list.last.next := item;
item.next := NIL;
list.last := item
END
END push;
PROCEDURE get* (list: LIST; n: INTEGER): ITEM;
VAR
cur: ITEM;
BEGIN
cur := list.first;
WHILE (cur # NIL) & (n > 0) DO
cur := cur.next;
DEC(n)
END
RETURN cur
END get;
PROCEDURE idx* (list: LIST; item: ITEM): INTEGER;
VAR
cur: ITEM;
n: INTEGER;
BEGIN
ASSERT(item # NIL);
n := 0;
cur := list.first;
WHILE (cur # NIL) & (cur # item) DO
cur := cur.next;
INC(n)
END;
IF cur = NIL THEN
n := -1
END
RETURN n
END idx;
PROCEDURE create* (list: LIST): LIST;
BEGIN
IF list = NIL THEN
NEW(list)
END;
list.first := NIL;
list.last := NIL
RETURN list
END create;
PROCEDURE destroy* (VAR list: LIST);
VAR
item, next: ITEM;
BEGIN
IF list # NIL THEN
item := list.first;
WHILE item # NIL DO
next := item.next;
IF item.destroy # NIL THEN
item.destroy(item)
ELSE
DISPOSE(item)
END;
item := next
END;
DISPOSE(list)
END
END destroy;
END LISTS.