mirror of
https://github.com/Mercury-Language/mercury.git
synced 2026-04-17 10:23:46 +00:00
7cb525fde3
Estimated hours taken: 0.5 library/*.m: compiler/*.m: Undo Zoltan's bogus update of all the copyright dates. The dates in the copyright header should reflect the years in which the file was modified (and no, changes to the copyright header itself don't count as modifications).
118 lines
3.3 KiB
Mathematica
118 lines
3.3 KiB
Mathematica
%---------------------------------------------------------------------------%
|
|
% Copyright (C) 1994-1995, 1997 The University of Melbourne.
|
|
% This file may only be copied under the terms of the GNU Library General
|
|
% Public License - see the file COPYING.LIB in the Mercury distribution.
|
|
%---------------------------------------------------------------------------%
|
|
|
|
% File: stack.m.
|
|
% Main author: fjh.
|
|
% Stability: high.
|
|
|
|
% This file contains a `stack' ADT.
|
|
% Stacks are implemented here using lists.
|
|
|
|
%--------------------------------------------------------------------------%
|
|
|
|
:- module stack.
|
|
:- interface.
|
|
:- import_module list.
|
|
|
|
:- type stack(_T).
|
|
|
|
% `stack__init(Stack)' is true iff `Stack' is an empty stack.
|
|
|
|
:- pred stack__init(stack(_T)).
|
|
:- mode stack__init(out) is det.
|
|
|
|
% `stack__is_empty(Stack)' is true iff `Stack' is an empty stack.
|
|
|
|
:- pred stack__is_empty(stack(_T)).
|
|
:- mode stack__is_empty(in) is semidet.
|
|
|
|
% `stack__is_full(Stack)' is intended to be true iff `Stack'
|
|
% is a stack whose capacity is exhausted. This
|
|
% implement allows arbitrary-sized stacks, so stack__is_full
|
|
% always fails.
|
|
|
|
:- pred stack__is_full(stack(_T)).
|
|
:- mode stack__is_full(in) is semidet.
|
|
|
|
% `stack__push(Stack0, Elem, Stack)' is true iff `Stack' is
|
|
% the stack which results from pushing `Elem' onto the top
|
|
% of `Stack0'.
|
|
|
|
:- pred stack__push(stack(T), T, stack(T)).
|
|
:- mode stack__push(in, in, out) is det.
|
|
|
|
% `stack__push_list(Stack0, Elems, Stack)' is true iff `Stack'
|
|
% is the stack which results from pushing the elements of the
|
|
% list `Elems' onto the top of `Stack0'.
|
|
|
|
:- pred stack__push_list(stack(T), list(T), stack(T)).
|
|
:- mode stack__push_list(in, in, out) is det.
|
|
|
|
% `stack__top(Stack, Elem)' is true iff `Stack' is a non-empty
|
|
% stack whose top element is `Elem'.
|
|
|
|
:- pred stack__top(stack(T), T).
|
|
:- mode stack__top(in, out) is semidet.
|
|
|
|
% `stack__pop(Stack0, Elem, Stack)' is true iff `Stack0' is
|
|
% a non-empty stack whose top element is `Elem', and `Stack'
|
|
% the stack which results from popping `Elem' off `Stack0'.
|
|
|
|
:- pred stack__pop(stack(T), T, stack(T)).
|
|
:- mode stack__pop(in, out, out) is semidet.
|
|
|
|
% `stack__pop_det' is like `stack__pop' except that it will
|
|
% call error/1 rather than failing if given an empty stack.
|
|
|
|
:- pred stack__pop_det(stack(T), T, stack(T)).
|
|
:- mode stack__pop_det(in, out, out) is det.
|
|
|
|
% `stack__depth(Stack, Depth)' is true iff `Stack' is a stack
|
|
% containing `Depth' elements.
|
|
|
|
:- pred stack__depth(stack(_T), int).
|
|
:- mode stack__depth(in, out) is det.
|
|
:- mode stack__depth(in, in) is semidet. % implied
|
|
|
|
%--------------------------------------------------------------------------%
|
|
|
|
:- implementation.
|
|
|
|
:- import_module list, require, std_util.
|
|
|
|
:- type stack(T) == list(T).
|
|
|
|
stack__init([]).
|
|
|
|
stack__is_empty([]).
|
|
|
|
stack__is_full(_) :-
|
|
semidet_fail.
|
|
|
|
stack__push(Stack, Elem, [Elem | Stack]).
|
|
|
|
stack__push_list(Stack, [], Stack).
|
|
stack__push_list(Stack0, [Elem | Elems], Stack1) :-
|
|
stack__push(Stack0, Elem, Stack2),
|
|
stack__push_list(Stack2, Elems, Stack1).
|
|
|
|
stack__top([Elem | _], Elem).
|
|
|
|
stack__pop([Elem | Stack], Elem, Stack).
|
|
|
|
stack__pop_det(Stack0, Elem, Stack) :-
|
|
( Stack0 = [Elem1 | Stack1] ->
|
|
Elem = Elem1,
|
|
Stack = Stack1
|
|
;
|
|
error("stack__pop_det: pop from empty stack")
|
|
).
|
|
|
|
stack__depth(Stack, Depth) :-
|
|
list__length(Stack, Depth).
|
|
|
|
%--------------------------------------------------------------------------%
|