| 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
| ///////////////////////////////////////////////////////////////////////////
// //
// Copyright (c) 2015 by Charta Software B.V. //
// All rights reserved //
// //
// Version: 1.7.0.83525 //
// Web site: https://pascal.chartasoftware.com/ //
// //
// This code and information are provided "as is" without warranty of //
// any kind. Dissemination of this information or reproduction of //
// this material is strictly forbidden unless prior written permission //
// is obtained from Charta Software B.V.. //
// //
///////////////////////////////////////////////////////////////////////////
unit Collection.Stack;
interface
uses
Boolean,
Collection;
type
TStack<TElement> = class(TCollection<TElement>)
protected
function GetTop(): TElement; virtual; abstract;
public
function Add(Element: TElement): TBoolean; override;
function Extract(Element: TElement): TElement; override;
function Dequeue(): TElement; override;
procedure Push(Element: TElement); virtual; abstract;
function ExtractTop(): TElement; virtual; abstract;
function Pop(): TElement; virtual;
property Top: TElement read GetTop;
end;
implementation
uses
Mathematics.Sign;
{ TStack<TElement> }
function TStack<TElement>.Add(Element: TElement): TBoolean;
begin
Result := True;
Push(Element);
end;
function TStack<TElement>.Dequeue(): TElement;
begin
Result := ExtractTop();
end;
function TStack<TElement>.Extract(Element: TElement): TElement;
begin
if (Count > 0) and (Comparator.Compare(Element, Top) = sZero) then
Result := ExtractTop()
else
Result := Unassigned;
end;
function TStack<TElement>.Pop(): TElement;
begin
Result := ExtractTop();
ReleaseElement(Result);
end;
end.
|