use strict;
use warnings;
use YAPE::Regex::Explain;
my $regexp = qr/^(.*?)((=<)|[<=>])(.*)/;
my $exp = YAPE::Regex::Explain->new($regexp);
print $exp->explain;
####
NODE EXPLANATION
----------------------------------------------------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
^ the beginning of the string
----------------------------------------------------------------------
( group and capture to \1:
----------------------------------------------------------------------
.*? any character except \n (0 or more times
(matching the least amount possible))
----------------------------------------------------------------------
) end of \1
----------------------------------------------------------------------
( group and capture to \2:
----------------------------------------------------------------------
( group and capture to \3:
----------------------------------------------------------------------
=< '=<'
----------------------------------------------------------------------
) end of \3
----------------------------------------------------------------------
| OR
----------------------------------------------------------------------
[<=>] any character of: '<', '=', '>'
----------------------------------------------------------------------
) end of \2
----------------------------------------------------------------------
( group and capture to \4:
----------------------------------------------------------------------
.* any character except \n (0 or more times
(matching the most amount possible))
----------------------------------------------------------------------
) end of \4
----------------------------------------------------------------------
) end of grouping
----------------------------------------------------------------------
##
##
my $re = qr{
^(.*?)
(
(=<)
|
[<=>]
)
(.*)
}x;
##
##
my $re = qr{
^ # Beginning of line
\s* # Optional whitespace
([a-zA-Z0-9_]+) # Capture(1) Alphanumeric LHS
\s* # Optional whitespace
( # Capture(2) either:
[<>!]= # <=, >=, !=
|
[<>=] # <, >, =
)
\s* # Optional whitespace
([a-zA-Z0-9_]+) # Capture(3) Alphanumeric RHS
}x;
##
##
my $operand = '[a-zA-Z0-9_]+' ;
my $re = qr{
\A # Beginning of line
\s* # Optional whitespace
($operand) # Capture(1) Alphanumeric LHS
\s* # Optional whitespace
( # Capture(2) either:
[<>!]= # <=, >=, !=
|
[<>=] # <, >, =
)
\s* # Optional whitespace
($operand) # Capture(3) Alphanumeric LHS
}x;
##
##
use strict;
use warnings;
my $operand = '[a-zA-Z0-9_]+' ;
my $re = qr{
^ # Beginning of string
\s* # Optional whitespace
($operand) # Capture(1) Alphanumeric LHS
\s* # Optional whitespace
( # Capture(2) either:
[<>!]= # <=, >=, !=
|
[<>=] # <, >, =
)
\s* # Optional whitespace
($operand) # Capture(1) Alphanumeric LHS
}x;
while (my $line = ) {
my ($lhs,$operator,$rhs) = $line =~ $re;
if ($line =~ $re) {
my ($lhs,$operator,$rhs) = ($1,$2,$3);
printf " (%4s) (%2s) (%4s)\n", $lhs, $operator, $rhs;
}
}
__DATA__
a=b
a!=b
ab
a=>b
a=