ch18ex09.pro

来自「prolog,人工智能推理程序,运行环境prolog」· PRO 代码 · 共 41 行

/*
   Turbo Prolog 2.0 Chapter 18, Example Program 9
   
   Copyright (c) 1986, 88 by Borland International, Inc
   
*/
   
include "CH18EX08.pro" /* CH18EX08.PRO, excluding the goal */

domains
   row, col, length = integer
   field = f(row, col, length)
   position = pos(row, col)

predicates
   scr(field, position, key)

goal
   Row=10, Col=10, Length=30, cursor(Row, Col),
   makewindow(1, 23, 1, "Example Editor", 0, 0, 25, 80),
   write("Edit the text. Use the arrow keys to move"),
   readkey(Key),
   field_attr(Row, Col, Length, 112),
   scr(f(Row, Col, Length), pos(Row, Col), Key), nl, nl,
   field_str(Row, Col, Length, Contents),
   write("Edited contents: ", Contents).

clauses
   scr(_, _, esc) :- !, fail.
   scr(_, _, fkey(10)) :- !.
   scr(f(Row, Col, L), pos(R, C), char(Ch)) :-
      scr_char(R, C, Ch), C1=C+1, C1<Col+L, cursor(R, C1),
   readkey(Key), scr(f(Row, Col, L), pos(R, C1), Key).
   scr(f(Row, Col, L), pos(R, C), Key) :- 
      C1=C+1, C1<Col+L, cursor(R, C1), readkey(Key),
      scr(f(Row, Col, L), pos(R, C1), Key).
   scr(f(Row, Col, L), pos(R, C), Key) :- 
      C1=C-1, C1>=Col, cursor(R, C1),
      readkey(Key), scr(f(Row, Col, L), pos(R, C1), Key).
   scr(Field, Pos, _) :- beep, readkey(Key), scr(Field, Pos, Key).