view release on metacpan or  search on metacpan

lib/App/Tailor.pm  view on Meta::CPAN

  my ($regex, $replacement) = @_;
  push @RULES, [MODIFY, $regex, $replacement];
}

sub colorize ($@) {
  my ($regex, @colors) = @_;
  my $color = color @colors;
  push @RULES, [COLORIZE, $regex, $color];
}

1;

__END__

=pod

=encoding UTF-8

=head1 NAME

App::Tailor - easily tailor terminal output to meet your needs

=head1 VERSION

version 0.02

=head1 SYNOPSIS

  #-------------------------------------------------------------------------------
  # file: my-filter.pl
  #-------------------------------------------------------------------------------
  use App::Tailor;
  use JSON::XS qw(decode_json);

  # ignore lines containing /ping
  ignore qr/\/ping/;

  # parse JSON-encoded lines
  modify qr/^{/ => sub{
    my $data = decode_json $_;
    my $msg  = $data->{message};
    my $ts   = $data->{timestamp};
    my $pri  = $data->{priority};
    return "[$ts] [$pri] $msg";
  };

  # make error lines white on red
  colorize qr/\[ERROR\]/ => qw(white on_red);

  # tail STDIN
  tail;

  #-------------------------------------------------------------------------------
  # using your filter
  #-------------------------------------------------------------------------------
  $ tail /var/log/some-log-file | my-filter.pl

=head1 DESCRIPTION

There are a number of programs available to filter, colorize, and modify
streaming output. Generating exactly the desired output often requires
pipe-chaining many calls to grep, cut, cols, jq, et al, or using an inflexible
config file or files, often in tandem with a long chain of piped commands.

C<App::Tailor> makes it easier to do this by making it trivial to write quick
scripts to filter, alter, and colorize output exactly as needed.

=head1 EXPORTS

=head2 ignore

Accepts a regex which, when matched, will cause a line of input to be ignored.

  ignore qr/foo/;       # ignore any line containing 'foo'
  ignore qr/foo(?=bar)  # ignore any line containing 'foo' followed by 'bar'

Ignored rules are applied to each line of input B<FIRST>.

=head2 modify

Accepts a regex which, when matched, will cause a the first capture in the
input to by modified. If the second argument is a string, it will replace the
first capture in the matching regex. If the second argument is a function, it
will be called on the first capture's matching text and its return value will
replace the captured text in the line's output. For convenience, C<$_> is
assigned to the value of the captured text.

If multiple matching rules exist, they are applied in the order in which they
were defined.

  modify qr/foo/ => sub{ uc $_ };   # foo => FOO
  modify qr/FOO/ => 'FOOL';         # FOO => 'FOOL';

Modifier rules are applied to each line of input B<SECOND>.

=head2 colorize

Accepts a regex which, when matched, will cause the entire match to be
colorized using ANSI color escapes. The second argument is a list of color
labels to be applied. See L<Term::ANSIColor/Function-Interface> for acceptable
labels.

  # "foo" has fg:red, bg:white
  colorize qr/foo/ => qw(red on_white);

  # "foo" when followed by "bar" will become painful to look at;
  # "bar" itself is not colorized.
  colorize qr/foo(?=bar) => qw(bright_white on_bright_magenta);

Colorizing rules are applied to each line of input B<LAST>.

=head2 tail

Tails an input stream. By default, reads from C<STDIN> and prints to C<STDOUT>,
applying any rules defined with L</ignore>, L</modify>, and L</colorize> to the
emitted output.

Input and output streams may be overridden by passing positional parameters,
both of which are optional:

  tail $in, $out;