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72 lines
1.3 KiB
Plaintext
72 lines
1.3 KiB
Plaintext
6 years ago
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unit stack;
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interface
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type
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link = ^node;
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fixed_string = String[20];
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node = record
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data : fixed_string;
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next : link
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end;
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stack_obj = record
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alement : link;
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zlement : link
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end;
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procedure push(s: stack_obj;v: fixed_string);
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function pop(s: stack_obj) : fixed_string;
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function top(s: stack_obj) : fixed_string;
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function is_empty(s: stack_obj) : Boolean;
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function init_stack : stack_obj;
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implementation
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procedure push(s: stack_obj; v: fixed_string);
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var
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t : link;
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begin
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t := GetMem(SizeOf(node));
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t^.data := v;
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t^.next := s.alement^.next;
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s.alement^.next := t;
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end;
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function pop(s: stack_obj): fixed_string;
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var
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t: link;
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begin
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if is_empty(s) = false then
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begin
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t := s.alement^.next;
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s.alement^.next := t^.next;
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pop := t^.data;
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FreeMem(t);
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end;
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end;
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function top(s: stack_obj): fixed_string;
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begin
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top := s.alement^.next^.data;
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end;
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function is_empty(s: stack_obj): Boolean;
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begin
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if s.alement^.next = s.zlement then
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is_empty := true
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else
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is_empty := false;
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end;
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function init_stack: stack_obj;
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var
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s : stack_obj;
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begin
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s.alement := GetMem(SizeOf(node));
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s.zlement := GetMem(SizeOf(node));
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s.alement^.next := s.zlement;
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s.zlement^.next := s.zlement;
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init_stack := s;
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end;
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begin
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{ Main Body }
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end.
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