Help perlifying this string parse-o-rama

balt has asked for the wisdom of the Perl Monks concerning the following question:

Oh enlightened ones, I have this string of a thing that needs parsed. Parts of it vary in length, but there are some anchors to go by. This example code sums it all up. Can anyone suggest a more elegant (=regexish and perlish) way to parse this? While my method works, it's not pretty. This is all about parsing backwards and forwards from a known middle anchor. Valid assumptions are: - only a single space between fields - the second field can have several space separated words - the fourth field comprises everything left to the right. :-)

#!/usr/bin/perl -w
use strict;

my $string = "firstfield second field KNOWNWORD alwaysOneWord then one
+ or more make the last field";

my $field1 = ( split / /, $string)[0];
my $field2 = substr($string, length("$field1 "), index($string, "KNOWN
+WORD") - length("$field1 "));
my @temp = split / /, substr($string,  index($string, "KNOWNWORD")+len
+gth("KNOWNWORD"));
my $field3 = $temp[1];
my $field4 = join ' ', @temp[2..$#temp];

print "field1: $field1\n";
print "field2: $field2\n";
print "field3: $field3\n";
print "field4: $field4\n";
[download]

This prints the expected result:

field1: firstfield
field2: second field 
field3: alwaysOneWord
field4: then one or more make the last field
[download]

Comment on Help perlifying this string parse-o-rama Select or Download Code

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Re: Help perlifying this string parse-o-rama by hdb (Monsignor) on Oct 22, 2015 at 12:48 UTC
split has a third parameter to provide the maximum number of parts to split in. This could be used like this: `my @fields = map { split / /, $_, 2 } split /\s+KNOWNWORD\s+/, $string +;` [download]	[reply] [d/l]
Re: Help perlifying this string parse-o-rama by choroba (Cardinal) on Oct 22, 2015 at 12:27 UTC
A regexish solution: `#!/usr/bin/perl use warnings; use strict; my $string = 'firstfield second field KNOWNWORD alwaysOneWord then one + or more make the last field'; my (@fields) = $string =~ / ^ (\S+) [ ] (.?) [ ] KNOWNWORD [ ] (\S+) +[ ] (.) /x; for my $i (0 .. $#fields) { print "$i:$fields[$i]\n"; }` [download] Note that it might not work if KNOWNWORD is one of the words in the second field. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re: Help perlifying this string parse-o-rama by BrowserUk (Patriarch) on Oct 22, 2015 at 12:26 UTC
Relatively straight forward: `$s = "firstfield second field KNOWNWORD alwaysOneWord then one or more + make the last field";; @fields = $s =~ m[(\S+)\s(.+)\sKNOWNWORD\s(\S+)\s(.+)];; print join '\|', @fields;; firstfield\|second field\|alwaysOneWord\|then one or more make the last f +ield` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]