http://qs321.pair.com?node_id=1225550


in reply to Re^2: Pattern matching
in thread Pattern matching

... can you explain to me how to read the patterns ...

Because parv's regex contains nothing that is not supported by Perl version 5.6, the YAPE::Regex::Explain module can help. 

c:\@Work\Perl\monks>perl -wMstrict -le
"use YAPE::Regex::Explain;
 ;;
 my $rx = qr{ \b (MODULE \s+ [A-Z]+[0-9]+) \s* [(] .+? [)] }x;
 ;;
 print YAPE::Regex::Explain->new($rx)->explain;
"
The regular expression:

(?x-ims: \b (MODULE \s+ [A-Z]+[0-9]+) \s* [(] .+? [)] )

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?x-ims:                 group, but do not capture (disregarding
                         whitespace and comments) (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n):
----------------------------------------------------------------------
  \b                       the boundary between a word char (\w) and
                           something that is not a word char
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    MODULE                   'MODULE'
----------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
----------------------------------------------------------------------
    [A-Z]+                   any character of: 'A' to 'Z' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
----------------------------------------------------------------------
  [(]                      any character of: '('
----------------------------------------------------------------------
  .+?                      any character except \n (1 or more times
                           (matching the least amount possible))
----------------------------------------------------------------------
  [)]                      any character of: ')'
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------

[download]

Give a man a fish:  <%-{-{-{-<

Replies are listed 'Best First'.
Re^4: Pattern matching
by parv (Parson) on Nov 11, 2018 at 01:46 UTC

    Thanks to you & kevbot for posting about YAPE::Regex::Explain. That was what I wanted to do too before posting my explanation.

    Read more... (Y::R::E install was too much work consuming too much time in order to avoid the work) (1177 Bytes)

    In order to use the Y::R::E module installed in my own directory with system perl, I needed to set $PREL5LIB obviously. But ... 

    export PERL5LIB="/dir/lib/perl5"

    [download]

    ... was not enough. I had to add 2 more sub-directories ... 

    export PERL5LIB="/dir/lib/perl5:/dir/lib/perl5/site_perl:/dir/lib/perl
+5/site_perl/mach"

    [download]

    ... why could perl not find the last two directory paths by itself in year 2018? (Yes, I am aware the virtues of installing, compiling my own perl. And I love that; had built multiple times on FreeBSD & CentOS.)

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom