On Mar 16, 9:58 am, c...@pobox.com (Chap Harrison) wrote:
> Oops, I misplaced the final closing parenthesis in the regex. But it doesn't
> seem to matter.
>
> - - - - -
>
> #!/usr/bin/perl
>
> use warnings;
> use strict;
> use feature ":5.10";
>
> #
> # $line, unless empty, should contain one or more white-space-separated
> # expressions of the form
> # FOO
> # or BAZ = BAR
> #
> # We need to parse them and set
> # $param{FOO} = 1 # default if value is omitted
> # $param{BAZ} = 'BAR'
> #
> # Valid input example:
> # MIN=2 MAX = 12 WEIGHTED TOTAL= 20
> # $param{MIN} = '2'
> # $param{MAX} = '12'
> # $param{WEIGHTED} = 1
> # $param{TOTAL} = '20'
> #
>
> my $line = 'min=2 max = 12 weighted total= 20';
> $line = 'min=2 max, = 12 weighted total= 20';
> say $line;
> my %param;
>
> if ( $line and
> ($line !~
> s/
> \G # Begin where prev. left off
> (?: # Either a parameter...
> (?: # Keyword clause:
> (\w+) # KEYWORD (captured $1)
> (?: # Value clause:
> \s* #
> = # equal sign
> \s* #
> (\w+) # VALUE (captured $2)
> )? # Value clause is optional
> )
> \s* # eat up any trailing ws
> ) ### <-- moved
> | # ... or ...
> $ # End of line.
> / # use captured to set %param
> $param{uc $1} = ( $2 ? $2 : 1 ) if defined $1;
> /xeg
> ) ) {
> say "Syntax error: '$line'";
> while (my ($x, $y) = each %param) {say "$x='$y'";}
> exit;}
>
> while (my ($x, $y) = each %param) {say "$x='$y'";}
I believe the problem is the "? # Value clause is optional"
since, in the case of your badline with a ",", the regex will
consume 'max' and then ignore the , since ? means 0 or 1
instance. Therefore the regex will still succeed and $2 will
be undefined. So the VALUE gets set to 1.
Rather than crafting a still more complicated regex, a
quick fix might be a pre-check to see if the line has any
character that's not a \w, =, or whitespace:
# disallow anything but equal, word, or whitespace
die "Syntax error: found disallowed char:$1"
if $line =~ /([^=\w\s])/);
# continue to process line...
if ( $line and $line !~ ....
--
Charles DeRykus
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