Re: Problem with a text-parsing regex

[tybalt89]

Different way to handle --

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11143647
use warnings;

while (my $x = <DATA>) {
    chomp $x;
    print "\n$x\n";
    my $out = '';
    while (
        $x =~ m/
        ([[:punct:]]*)      # $1: leading punct marks
        (                   # $2: a "word" consisting of
            [[:word:]]+     # word
            (?:
               (?: '-? | - )
               [[:word:]]+  # and ending in pure word characters
            )*
        )
        ( (?: --+ | [[:punct:]]* ) \ ? )   # $3: trailing punct marks 
+ending
                              # or multi-dashs
                              # with space (except at end of
                              # line?)
        /xxg
    )
    {
        $out .= sprintf "{%s|%s|%s} ",
            # make whitespace visible
            map {(my $y = $_ // '') =~ tr/ /_/; $y}  $1, $2, $3;
    }
print "$out\n" =~ s/ $//r =~ s/.{65}\K /\n/gr;
}
__DATA__
"'Uncouth' about sums it up."
The word they will use is 'uncouth'.
"It's the old story."
It's a will-o'-the-wisp--a two-fer--and Bob's-yer-uncle at four o'cloc
+k.
It's two o'clock--time for a nap.
Remember 45's?
What about (this)?
[Editor's note: blah blah] and so on...
A ... and B
I said--"What's the expression?"

Outputs (changed to be able to see all output without scrolling):

"'Uncouth' about sums it up."
{"'|Uncouth|'_} {|about|_} {|sums|_} {|it|_} {|up|."}

The word they will use is 'uncouth'.
{|The|_} {|word|_} {|they|_} {|will|_} {|use|_} {|is|_} {'|uncouth|'.}

"It's the old story."
{"|It's|_} {|the|_} {|old|_} {|story|."}

It's a will-o'-the-wisp--a two-fer--and Bob's-yer-uncle at four o'cloc
+k.
{|It's|_} {|a|_} {|will-o'-the-wisp|--} {|a|_} {|two-fer|--} {|and|_}
{|Bob's-yer-uncle|_} {|at|_} {|four|_} {|o'clock|.}

It's two o'clock--time for a nap.
{|It's|_} {|two|_} {|o'clock|--} {|time|_} {|for|_} {|a|_} {|nap|.}

Remember 45's?
{|Remember|_} {|45's|?}

What about (this)?
{|What|_} {|about|_} {(|this|)?}

[Editor's note: blah blah] and so on...
{[|Editor's|_} {|note|:_} {|blah|_} {|blah|]_} {|and|_} {|so|_} {|on|.
+..}

A ... and B
{|A|_} {|and|_} {|B|}

I said--"What's the expression?"
{|I|_} {|said|--} {"|What's|_} {|the|_} {|expression|?"}

Did get every thing right?

[hv]

The instructions were that "--" was to be treated like a space, so presumably should not be part of the punctuation runs - I think it should print {|o'clock|}, for example, not {|o'clock|--}.

I do prefer your version of the word parsing to mine, but I suspect (?: '-? | -'? ) is what's intended. (There aren't any examples of "word-'word" in the test cases though - I could probably come up with one in Dutch, but I imagine they're pretty rare in English.)

[ibm1620]

I grepped my collection of text files (all English-language downloads from gutenberg.org) for -' and only found forty-'leven and fellow-'prentice. I've updated tybalt89's solution with your improvement.

The contents of $3 will contain a final space if one is present, so {|o'clock|--} is consistent with the instructions.

[ibm1620]

Yes! Beautiful. Makes perfect sense. Thank you.

Your final print is a real head-scratcher, but I like what it does and I'll noodle on it some more....

[kcott]

G'day ibm1620,

"Your final print is a real head-scratcher, but I like what it does and I'll noodle on it some more...."

I'm assuming "final print" refers to:

print "$out\n" =~ s/ $//r =~ s/.{65}\K /\n/gr;

I don't know which bit, or bits, you're having difficulties with. One, or both, of these references might help:

perlop: Regexp Quote-Like Operators: s/PATTERN/REPLACEMENT/msixpodualngcer

• The /r option indicates non-destructive substitution.
• These can be chained; e.g. s///r =~ s///r =~ s///r
• The same option also exists for transliteration: "perlop: Quote-Like Operators: y/SEARCHLIST/REPLACEMENTLIST/cdsr".
• These can also be chained; e.g. y///r =~ y///r =~ y///r
• You can also mix chaining; e.g. s///r =~ y///r =~ s///r =~ y///r
• Introduced in 5.14: "perl5140delta: Non-destructive substitution".

perlrebackslash: Misc: \K

• The \K escape sequence indicates that everything to its left should be kept.
• See also "perlre: Extended Patterns: Lookaround Assertions: \K".
• Introduced in 5.10: "perl5100delta: Core Enhancements: Regular expressions: \K escape".

I've shown the versions where /r and \K were introduced. With your stated 5.34.1 version, both of these will be available to you. I included this information for those using older versions of Perl.