Re: [PATCH 6/8] gitweb: Highlight interesting parts of diff

> Jakub Narebski <jnareb@gmail.com> writes:
> > Michał Kiedrowicz <michal.kiedrowicz@gmail.com> writes:
>  
> > > +# Highlight characters from $prefix to $suffix and escape HTML.
> > > +# $str is a reference to the array of characters.
> > > +sub esc_html_mark_range {
> > > +	my ($str, $prefix, $suffix) = @_;
> > > +
> > > +	# Don't generate empty <span> element.
> > > +	if ($prefix == $suffix + 1) {
> > > +		return esc_html(join('', @$str), -nbsp=>1);
> > > +	}
> > > +
> > > +	my $before = join('', @{$str}[0..($prefix - 1)]);
> > > +	my $marked = join('', @{$str}[$prefix..$suffix]);
> > > +	my $after = join('', @{$str}[($suffix + 1)..$#{$str}]);
> > 
> > Eeeeeek!  First you split into letters, in caller at that, then
> > join? Why not pass striung ($str suggests string not array of
> > characters), and use substr instead?
> > 
> > [Please disregard this and the next paragraph at first reading]
> > 
> > > +
> > > +	return esc_html($before, -nbsp=>1) .
> > > +		$cgi->span({-class=>'marked'}, esc_html($marked,
> > > -nbsp=>1)) .
> > > +		esc_html($after,-nbsp=>1);
> > > +}
> > 
> > Anyway I have send to git mailing list a patch series, which in one
> > of patches adds esc_html_match_hl($str, $regexp) to highlight
> > matches in a string.  

> > 
> >    # Highlight selected fragments of string, using given CSS class,
> >    # and escape HTML.  It is assumed that fragments do not overlap.
> >    # Regions are passed as list of pairs (array references).
> >    sub esc_html_hl {
> >         my ($str, $css_class, @sel) = @_;
> >         return esc_html($str) unless @sel;
> >    
> >         my $out = '';
> >         my $pos = 0;
> >    
> >         for my $s (@sel) {
> >                 $out .= esc_html(substr($str, $pos, $s->[0] - $pos))
> >                         if ($s->[0] - $pos > 0);
> >                 $out .= $cgi->span({-class => $css_class},
> >                                    esc_html(substr($str, $s->[0],
> > $s->[1] - $s->[0])));
> > 
> >                 $pos = $m->[1];
> >         }
> >         $out .= esc_html(substr($str, $pos))
> >                 if ($pos < length($str));
> >    
> >         return $out;
> >    }
> 
> Actually we can accomodate both operating on string and operating on
> array of characters in a single subroutine.  Though it can be left for
> later commit, anyway...

> 
>      # Highlight selected fragments of string, using given CSS class,
>      # and escape HTML.  It is assumed that fragments do not overlap.
>      # Regions are passed as list of pairs (array references).
>      sub esc_html_hl {
>           my ($sth, $css_class, @sel) = @_;
> 
>           if (!@sel) {
>                 if (ref($sth) eq "ARRAY") {
>                         return esc_html(join('', @$sth), -nbsp=>1);
>                 } else {
>                         return esc_html($sth, -nbsp=>1);
>           }
> 
>           if (ref($sth) eq "ARRAY") {
>                 return esc_html_hl_gen($sth,
>                         sub { 
>                                 my ($arr, $from, $to) = @_;
>                                 return join('', @{$arr}[$from..$to]);
>                         },
>                         scalar @{$arr}, $css_class, @sel);
>            } else {
>                 return esc_html_hl_gen($sth,
>                         sub {
>                                 my ($str, $from, $to) = @_;
>                                 if ($to < 0) { $to += lenght($str); };
>                                 return substr($str, $from, $to -
> $from); },
>                         length($sth), $css_class, @sel);
>            }
>      }
> 
>      # Highlight selected fragments of string or array of characters
>      # with given length, using provided $extr subroutine to extract
>      # fragment (substring)
>      sub esc_html_hl_gen {
>           my ($sth, $extr, $len, $css_class, @sel) = @_;
>      
>           my $out = '';
>           my $pos = 0;
>      
>           for my $s (@sel) {
>                 $out .= esc_html($extr->($str, $pos, $s->[0]))
>                         if ($s->[0] - $pos > 0);
>                 $out .= $cgi->span({-class => $css_class},
>                                    esc_html($extr->($str, $s->[0],
> $s->[1]))); 
>                 $pos = $s->[1];
>           }
>           $out .= esc_html($extr->($str, $pos, $len))
>                   if ($pos < $len);
>      
>           return $out;
>      }
> 
> Or maybe I have read "Higher-Order Perl" one time too many ;-))))
>