Re^2: Comparing two text files and marking differences

I appreciate all of the answers, and found that I was able to make some modifications to this one in particular which seems to be yielding most of what I want. I'm still doing a few post-subroutine substitutions to clear up some text formatting issues, but the following subroutine does the bulk of what needed to be done.

sub comparator {
my $str1 = shift @_;
my $str2 = shift @_;
my $original = '';
my $revised  = '';

my @from = split(/((?:<[^>]+>)+|(?:\s)+|(?:\w[A-Za-z'-]*\w*)+|(?:\W|\P
+{IsWord})|(?:\p{IsDigit}))/, $str1);
my @to   = split(/((?:<[^>]+>)+|(?:\s)+|(?:\w[A-Za-z'-]*\w*)+|(?:\W|\P
+{IsWord})|(?:\p{IsDigit}))/, $str2);

my $OS = qq|<span class="m">|;
my $OE = qq|</span> |;
my $RS = qq|<span class="hl">|;
my $RE = qq|</span> |;

  traverse_sequences( \@from, \@to,
    {
    MATCH     => sub { my $oldtext = $from[shift()]; $original .= $old
+text; $revised .= $oldtext },
    DISCARD_A => sub { my $oldtext = $from[shift()]; if ($oldtext =~ m
+/(?:\p{IsPunct})|(?:\s)/) {$original .= $oldtext } else { $original .
+= $OS.$oldtext.$OE } },
    DISCARD_B => sub { my $newtext = $to[pop()];     if ($newtext =~ m
+/(?:\p{IsPunct})|(?:\s)/) {$revised  .= $newtext } else { $revised  .
+= $RS.$newtext.$RE } },
    } );
    
    return ($original, $revised);
    
} #END SUB comparator
[download]

I have never found the output of a standard diff to be very enlightening. I'm sure it works well to change files, patch-style, but it isn't very readable for someone simply wanting to see what happened to the text in a side-by-side format. This procedure is making a visual inspection much easier, with the help of some HTML markup.

Thank you!

Blessings,

~Polyglot~

Comment on Re^2: Comparing two text files and marking differences Download Code

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Re^3: Comparing two text files and marking differences by afoken (Chancellor) on Jan 31, 2021 at 14:35 UTC
I have never found the output of a standard diff to be very enlightening. I'm sure it works well to change files, patch-style, but it isn't very readable for someone simply wanting to see what happened to the text in a side-by-side format. Plain old diff (in the GNU version) has at least four output formats: ed script: `/tmp>diff foo bar 1,2c1,2 < Bla bla. Foo bar baz. < Nada nada nada. Nada? --- > Bla bar. Foo bar baz. > Nada na-da nada. Nada? 4c4 < bar. Bla. Bar bla. --- > bar. Bla bar bla.` [download] Unified: `/tmp>diff -u foo bar --- foo 2021-01-31 15:13:16.892239748 +0100 +++ bar 2021-01-31 15:13:43.403869518 +0100 @@ -1,6 +1,6 @@ -Bla bla. Foo bar baz. -Nada nada nada. Nada? +Bla bar. Foo bar baz. +Nada na-da nada. Nada? Foo foo foo! Bar. Foo -bar. Bla. Bar bla. +bar. Bla bar bla. Foo bla bla nada bar.` [download] Side by side (also available via sdiff) `/tmp>diff -y foo bar Bla bla. Foo bar baz. \| Bla ba +r. Foo bar baz. Nada nada nada. Nada? \| Nada n +a-da nada. Nada? Foo foo foo! Bar. Foo Foo fo +o foo! Bar. Foo bar. Bla. Bar bla. \| bar. B +la bar bla. Foo bla bla nada bar. Foo bl +a bla nada bar.` [download] rcs `/tmp>diff -n foo bar d1 2 a2 2 Bla bar. Foo bar baz. Nada na-da nada. Nada? d4 1 a4 1 bar. Bla bar bla.` [download] TortoiseSVN comes with a diff and merge tool called TortoiseMerge that can show changes side by side, highlighting not only changed lines, but also changes within the lines. Side note: `sub comparator { my $str1 = shift @_; #... my $RE = qq\|</span> \|; traverse_sequences( \@from, \@to, { # ... } ); return ($original, $revised); } #END SUB comparator` [download] Proper indenting would make the "#END SUB comparator" redundant: `sub comparator { my $str1 = shift @_; #... my $RE = qq\|</span> \|; traverse_sequences( \@from, \@to, { # ... } ); return ($original, $revised); }` [download] Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re^4: Comparing two text files and marking differences by Polyglot (Chaplain) on Jan 31, 2021 at 15:53 UTC
Regarding the proper indenting making my comment "redundant": I use indenting as well, but I tend to have subroutines that extend well beyond one screen's worth of code. I like having that note at the bottom just to help guide me in locating my position within the file as I'm scanning. I've developed a habit for doing it this way, and it's not going to change! Remember, TMTOWTDI. This is my way. Blessings, ~Polyglot~	[reply]