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comparison bin/shove @ 2114:7914d7e0b500

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<ais523> revert 87c64ef250a0
author HackBot
date Wed, 13 Feb 2013 00:17:51 +0000
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2113:1c1429d055bc 2114:7914d7e0b500
1 #!/usr/bin/env perl
2 # -*- cperl -*-
3 # Shove interpreter. By Alex Smith.
4
5 # Commands:
6 # ' " Quote a string ('' strings nest inside "" strings and vice versa)
7 # < v > ^ Change direction of execution
8 # A V ( ) Pop a string onto the playfield
9 # space NOP
10
11 # ! NOP, but tells the compiler that everything behind the IP will
12 # never be used (a useful optimisation)
13 # S NOP, but outputs TOS (without popping) on systems with output
14 # n NOP, but outputs a newline on systems with output
15
16 use strict;
17
18 # Read in the program
19
20 my $debug = ($#ARGV >= 0 and $ARGV[0] eq '-d' and shift and 1);
21 my @program = ($#ARGV >= 0 and ($ARGV[0] ne '-f' or (shift and 0)))
22 ? @ARGV : <>;
23 chomp for @program;
24
25 my $x = 0;
26 my $y = 0;
27 my $width = 0; $width = ($width < length $_ ? length $_ : $width) for @program;
28 my $height = scalar @program;
29 my $totalrotation = 0;
30 my @stack = ();
31 # always going right, we rotate the program if necessary to ensure this
32
33 # Pads its argument to width $width.
34 sub widthpad {
35 my $s = shift;
36 return $s . (' ' x ($width - length $s));
37 }
38
39 # Rotates the program clockwise (arg = 1), 180 degrees (arg = 2),
40 # or anticlockwise (arg = 3)
41 sub rotateprogram {
42 my $amount = shift;
43 $amount or return;
44 $totalrotation += $amount;
45 $totalrotation %= 4;
46 if ($amount >= 2) {
47 @program = reverse @program;
48 $_ = reverse widthpad $_ for @program;
49 $x = $width - 1 - $x;
50 $y = $height - 1 - $y;
51 tr/<v>^AV()/>^<vVA)(/ for @program;
52 $amount == 2 and return;
53 } else {
54 $_ = widthpad $_ for @program;
55 }
56 my @newprog = ();
57 # We repeatedly move the leftmost column of @program to the top row
58 # of @newprog.
59 while (length $program[0]) {
60 my $build='';
61 $build = (substr $_, 0, 1, '') . $build for @program;
62 push @newprog, $build;
63 }
64 @program = @newprog;
65 tr/<^>v(A)V/^>v<A)V(/ for @program;
66 ($width, $height) = ($height, $width);
67 ($x, $y) = ($width - 1 - $y, $x);
68 }
69
70 sub shove {
71 my $sx = shift;
72 my $sy = shift;
73 if($sx < 0) {
74 $_ = ' '.$_ for @program;
75 $x++;
76 $sx++;
77 $width++;
78 }
79 if($sx >= $width) {
80 $width++;
81 }
82 if($sy < 0) {
83 unshift @program, "";
84 $y++;
85 $sy++;
86 $height++;
87 }
88 if($sy >= $height) {
89 push @program, "";
90 $height++;
91 }
92 scalar @stack or die "Empty stack when shoving.";
93 $program[$sy] = widthpad $program[$sy];
94 ($x > $sx && $y == $sy) and $x += length $stack[0];
95 substr $program[$sy], $sx, 0, shift @stack;
96 $program[$sy] =~ s/\ +$//;
97 $width < length $program[$sy] and $width = length $program[$sy];
98 }
99
100 sub showprogram {
101 my $tr = $totalrotation;
102 print "\nactual size: ($width, $height), pos: ($x, $y)\n";
103 rotateprogram ((4-$tr)%4);
104 $program[$y] = widthpad $program[$y];
105 my $c = substr $program[$y], $x, 1, '*';
106 print "rotated for viewing; pos: ($x, $y), dir: $tr\n";
107 print "stack: ";
108 print "{$_} " for @stack;
109 print "\n";
110 print "$_\n" for @program;
111 substr $program[$y], $x, 1, $c;
112 rotateprogram $tr;
113 scalar <STDIN>;
114 }
115
116 while ($x < $width && $y < $height && $x >= 0 && $y >= 0) {
117 showprogram if $debug;
118 my $cmd = substr $program[$y], $x, 1;
119 # $cmd eq '>' is a nop
120 $cmd eq '^' and rotateprogram 1;
121 $cmd eq '<' and rotateprogram 2;
122 $cmd eq 'v' and rotateprogram 3;
123 $cmd eq '(' and shove $x-1, $y;
124 $cmd eq ')' and shove $x+1, $y;
125 $cmd eq 'A' and shove $x, $y-1;
126 $cmd eq 'V' and shove $x, $y+1;
127 $cmd eq 'S' and print $stack[0];
128 $cmd eq 'n' and print '\n';
129 if ($cmd eq '!') {
130 substr $_, 0, $x, '' for @program;
131 $width -= $x;
132 $x = 0;
133 }
134 if ($cmd eq '"' || $cmd eq "'") {
135 my $quotecount = 1;
136 my $lws = $cmd eq "'";
137 my $newpush = "";
138 while($quotecount) {
139 $x++;
140 $x < $width or die "Unterminated string.";
141 $cmd = substr $program[$y], $x, 1;
142 $cmd eq "'" and ($quotecount += ($lws ? -1 : 1)), ($lws = !$lws);
143 $cmd eq '"' and ($quotecount += ($lws ? 1 : -1)), ($lws = !$lws);
144 $quotecount and $newpush .= $cmd;
145 }
146 unshift @stack, $newpush;
147 }
148 $x++; # move to next command
149 }