Changeset 4416 for trunk/examples

Timestamp:

08/10/08 06:25:36 (5 months ago)

Author:

pmoura

Message:

Added the SWI-Prolog constraint "queens" example.

Location:

trunk/examples/constraints/swipl

Files:

• queens.lgt (modified) (4 diffs)
• SCRIPT.txt (modified) (1 diff)

trunk/examples/constraints/swipl/queens.lgt

@@ -10 +10 @@
     :- use_module(clpfd, [ins/2, labeling/2, (#=)/2, (#\=)/2, (#<==>)/2]).
 
-    :- public(show/3).
+    :- public([n_queens/2, show/3]).
 
     /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -78 +78 @@
 
     postscript -->
-            "systemdict /.setlanguagelevel known { 2 .setlanguagelevel} if \
-     /init {  /N exch def 322 N div dup scale -1 -1 translate \
+        "systemdict /.setlanguagelevel known { 2 .setlanguagelevel} if \
+        /init {  /N exch def 322 N div dup scale -1 -1 translate \
               /Palatino-Roman findfont 0.8 scalefont setfont \
               0 setlinewidth \
               1 1 N { 1 1 N { 1 index c } for pop } for } bind def \
-     /showtext { 0.5 0.28 translate dup stringwidth pop -2 div 0 moveto \
+        /showtext { 0.5 0.28 translate dup stringwidth pop -2 div 0 moveto \
               1 setgray show} bind def \
-     /i { gsave translate .5 setgray 0 0 1 1 4 copy rectfill 0 setgray rectstroke \
-        grestore } bind def \
-     /q { gsave translate 0 0 1 1 rectfill (Q) showtext grestore } bind def \
-     /c { gsave translate 1 setgray 0 0 1 1 4 copy rectfill 0 setgray rectstroke \
-        grestore } bind def\n".
+        /i { gsave translate .5 setgray 0 0 1 1 4 copy rectfill 0 setgray rectstroke \
+            grestore } bind def \
+        /q { gsave translate 0 0 1 1 rectfill (Q) showtext grestore } bind def \
+        /c { gsave translate 1 setgray 0 0 1 1 4 copy rectfill 0 setgray rectstroke \
+            grestore } bind def\n".
 
 
@@ -97 +97 @@
 
     show(N, Options, Qs) :-
+        between(1, infinite, N),
         open(pipe('gs -dNOPAUSE -g680x680 -dGraphicsAlphaBits=2 -r151 -q -'), write,
-             Out, [buffer(false),alias(gs)]),
+            Out, [buffer(false),alias(gs)]),
         tell(Out),
-        integer(N), N > 0,
         phrase(postscript, Ps),
         format(Ps),
         format("~w init\n", [N]),
         n_queens(N, Qs),
-        animate(Qs),
-        labeling(Options, Qs),
-        finish.
-    show(_, _, _) :- finish, close(gs), fail.
+        call_cleanup(((animate(Qs),labeling(Options, Qs),finish)), close(gs)).
 
     finish :-
@@ -114 +111 @@
         % fill the buffer to make 'gs' process all generated output
         ignore((between(1,500,_),
-                format("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n"),
-                fail)),
+                format("%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\n"),
+                fail)),
         flush_output.
 
-
-    %?- between(0, inf, N), show(N, [ff], Qs).
+    %?- show(N, [ff], Qs).
 
     %?- show(8, [ff], Qs).

trunk/examples/constraints/swipl/SCRIPT.txt

@@ -61 +61 @@
 
 
+| ?- queens::n_queens(8, Qs), labeling([ff], Qs).
+Qs = [1, 5, 8, 6, 3, 7, 2, 4] ;
+Qs = [1, 6, 8, 3, 7, 4, 2, 5] ;
+Qs = [1, 7, 4, 6, 8, 2, 5, 3] ;
+(etc)
+
+
 % the following query implies that Ghostscript is available from the command-line:
 
 | ?- queens::show(8, [ff], Qs).
-
 Qs = [1, 5, 8, 6, 3, 7, 2, 4] ;
 Qs = [1, 6, 8, 3, 7, 4, 2, 5] ;
 Qs = [1, 7, 4, 6, 8, 2, 5, 3] ;
-Qs = [1, 7, 5, 8, 2, 4, 6, 3] ;
 (etc)
+
+
+| ?- queens::show(N, [ff], Qs).
+N = 1,
+Qs = [1] ;
+N = 4,
+Qs = [2, 4, 1, 3] ;
+N = 4,
+Qs = [3, 1, 4, 2] ;
+N = 5,
+Qs = [1, 3, 5, 2, 4] ;
+(etc)