add some rudimentary error detection...

1 files changed, 23 insertions, 12 deletions

diff --git a/challenge-119/james-smith/cesil/cesil.pl b/challenge-119/james-smith/cesil/cesil.pl
index 61c724ca9c..0bbd61888e 100644
--- a/challenge-119/james-smith/cesil/cesil.pl
+++ b/challenge-119/james-smith/cesil/cesil.pl
@@ -2,33 +2,44 @@ use strict;
 use warnings;
 
 $| = 1;
-my( $ptr, @in, %mem, @code, %ptrs, $reg ) = 0;
+my( $ptr, $reg, @in, %mem, @code, %ptrs ) = 0;
+
+my %messages = (
+  'i' => 'No further input',
+  'm' => 'Unitialized memory at ',
+  'l' => 'Unknown pointer ',
+);
 
 my %commands = (
 'LINE'    ,sub{print "\n"},
 'OUT'     ,sub{print $reg},
 'PRINT'   ,sub{print $_[0]=~s{^"}{}r=~s{"$}{}r;},
-'IN'      ,sub{die 'OUT OF INPUT' unless @in;$reg=shift@in},
+'IN'      ,sub{_err('i') unless @in;$reg=shift@in},
 'STORE'   ,sub{$mem{$_[0]}=$reg},
-'LOAD'    ,sub{$reg=$mem{$_[0]}},
-'ADD'     ,sub{$reg+=$_[0]=~m{^-?\d+$}?$_[0]:$mem{$_[0]}},
-'SUBTRACT',sub{$reg-=$_[0]=~m{^-?\d+$}?$_[0]:$mem{$_[0]}},
-'MULTIPLY',sub{$reg*=$_[0]=~m{^-?\d+$}?$_[0]:$mem{$_[0]}},
-'DIVIDE'  ,sub{$reg/=$_[0]=~m{^-?\d+$}?$_[0]:$mem{$_[0]};$reg=int$reg},
-'JINEG'   ,sub{$ptr=$ptrs{$_[0]}-1 if $reg<0},
-'JIZERO'  ,sub{$ptr=$ptrs{$_[0]}-1 if $reg==0},
-'JUMP'    ,sub{$ptr=$ptrs{$_[0]}-1},
+'LOAD'    ,sub{_err('m') unless exists$mem{$_[0]};$reg=$mem{$_[0]}},
+'ADD'     ,sub{$reg+=$_[0]=~m{^-?\d+$}?$_[0]:exists$mem{$_[0]}?$mem{$_[0]}:(_err('m'))},
+'SUBTRACT',sub{$reg-=$_[0]=~m{^-?\d+$}?$_[0]:exists$mem{$_[0]}?$mem{$_[0]}:(_err('m'))},
+'MULTIPLY',sub{$reg*=$_[0]=~m{^-?\d+$}?$_[0]:exists$mem{$_[0]}?$mem{$_[0]}:(_err('m'))},
+'DIVIDE'  ,sub{$reg/=$_[0]=~m{^-?\d+$}?$_[0]:exists$mem{$_[0]}?$mem{$_[0]}:(_err('m'));$reg=int$reg},
+'JINEG'   ,sub{_err('l') unless exists $ptrs{$_[0]}; $ptr=$ptrs{$_[0]}-1 if $reg<0},
+'JIZERO'  ,sub{_err('l') unless exists $ptrs{$_[0]}; $ptr=$ptrs{$_[0]}-1 if $reg==0},
+'JUMP'    ,sub{_err('l') unless exists $ptrs{$_[0]}; $ptr=$ptrs{$_[0]}-1},
 'HALT'    ,sub{exit},
 );
 
 while(<>) {
   ((@in = map { 0+$_ } <> ),last) if m{^ {8}%};
   ($ptrs{$1},$_)=(scalar @code,$2) if m{^(\S{1,7})\s+(.*)};
-  push @code, [ split m{\s+}, s{^\s+}{}r=~s{\s+$}{}r, 2 ];
+  my($cmd,$data) = split m{\s+}, s{^\s+}{}r=~s{\s+$}{}r, 2;
+  die "Unknown command [cmd $cmd - line ",1+@code,"]\n" unless exists $commands{$cmd};
+  push @code, [$cmd,$data||''];
 }
 
 my $MAX_LOOPS = 1e6;
 ($commands{$code[$ptr][0]}($code[$ptr][1]),$ptr++)
   while --$MAX_LOOPS && $ptr<@code;
 
-
+sub _err {
+  my $flag = shift;
+  die sprintf "\n%s%s [cmd %s - line %d]\n", $messages{$flag}, $code[$ptr][1], $code[$ptr][0], 1+$ptr;
+}