Tidy(3)
NAME
Perl::Tidy - Parses and beautifies perl source
SYNOPSIS
use Perl::Tidy;
Perl::Tidy::perltidy(
source => $source,
destination => $destination,
stderr => $stderr,
argv => $argv,
perltidyrc => $perltidyrc,
logfile => $logfile,
errorfile => $errorfile,
formatter => $formatter, # callback object (see below)
);
DESCRIPTION
This module makes the functionality of the perltidy utility available
to perl scripts. Any or all of the input parameters may be omitted, in
which case the @ARGV array will be used to provide input parameters as
described in the perltidy(1) man page.
For example, the perltidy script is basically just this:
use Perl::Tidy;
Perl::Tidy::perltidy();
The module accepts input and output streams by a variety of methods.
The following list of parameters may be any of a the following: a file-
name, an ARRAY reference, a SCALAR reference, or an object with either
a getline or print method, as appropriate.
source - the source of the script to be formatted
destination - the destination of the formatted output
stderr - standard error output
perltidyrc - the .perltidyrc file
logfile - the .LOG file stream, if any
errorfile - the .ERR file stream, if any
The following chart illustrates the logic used to decide how to treat a
parameter.
ref($param) $param is assumed to be:
----------- ---------------------
undef a filename
SCALAR ref to string
ARRAY ref to array
(other) object with getline (if source) or print method
If the parameter is an object, and the object has a close method, that
close method will be called at the end of the stream.
source
If the source parameter is given, it defines the source of the
input stream.
destination
If the destination parameter is given, it will be used to define
the file or memory location to receive output of perltidy.
stderr
The stderr parameter allows the calling program to capture the out-
put to what would otherwise go to the standard error output device.
perltidyrc
If the perltidyrc file is given, it will be used instead of any
.perltidyrc configuration file that would otherwise be used.
argv
If the argv parameter is given, it will be used instead of the
@ARGV array. The argv parameter may be a string, a reference to a
string, or a reference to an array. If it is a string or reference
to a string, it will be parsed into an array of items just as if it
were a command line string.
EXAMPLE
The following example passes perltidy a snippet as a reference to a
string and receives the result back in a reference to an array.
use Perl::Tidy;
# some messy source code to format
my $source = <<'EOM';
use strict;
my @editors=('Emacs', 'Vi '); my $rand = rand();
print "A poll of 10 random programmers gave these results:\n";
foreach(0..10) {
my $i=int ($rand+rand());
print " $editors[$i] users are from Venus" . ", " .
"$editors[1-$i] users are from Mars" .
"\n";
}
EOM
# We'll pass it as ref to SCALAR and receive it in a ref to ARRAY
my @dest;
perltidy( source => \$source, destination => \@dest );
foreach (@dest) {print}
Using the formatter Callback Object
The formatter parameter is an optional callback object which allows the
calling program to receive tokenized lines directly from perltidy for
further specialized processing. When this parameter is used, the two
formatting options which are built into perltidy (beautification or
html) are ignored. The following diagram illustrates the logical flow:
|-- (normal route) -> code beautification
caller->perltidy->|-- (-html flag ) -> create html
|-- (formatter given)-> callback to write_line
This can be useful for processing perl scripts in some way. The param-
eter $formatter in the perltidy call,
formatter => $formatter,
is an object created by the caller with a "write_line" method which
will accept and process tokenized lines, one line per call. Here is a
simple example of a "write_line" which merely prints the line number,
the line type (as determined by perltidy), and the text of the line:
sub write_line {
# This is called from perltidy line-by-line
my $self = shift;
my $line_of_tokens = shift;
my $line_type = $line_of_tokens->{_line_type};
my $input_line_number = $line_of_tokens->{_line_number};
my $input_line = $line_of_tokens->{_line_text};
print "$input_line_number:$line_type:$input_line";
}
The complete program, perllinetype, is contained in the examples sec-
tion of the source distribution. As this example shows, the callback
method receives a parameter $line_of_tokens, which is a reference to a
hash of other useful information. This example uses these hash
entries:
$line_of_tokens->{_line_number} - the line number (1,2,...)
$line_of_tokens->{_line_text} - the text of the line
$line_of_tokens->{_line_type} - the type of the line, one of:
SYSTEM - system-specific code before hash-bang line
CODE - line of perl code (including comments)
POD_START - line starting pod, such as '=head'
POD - pod documentation text
POD_END - last line of pod section, '=cut'
HERE - text of here-document
HERE_END - last line of here-doc (target word)
FORMAT - format section
FORMAT_END - last line of format section, '.'
DATA_START - __DATA__ line
DATA - unidentified text following __DATA__
END_START - __END__ line
END - unidentified text following __END__
ERROR - we are in big trouble, probably not a perl script
Most applications will be only interested in lines of type CODE. For
another example, let's write a program which checks for one of the so-
called naughty matching variables "&`", $&, and $', which can slow down
processing. Here is a write_line, from the example program
find_naughty.pl, which does that:
sub write_line {
# This is called back from perltidy line-by-line
# We're looking for $`, $&, and $'
my ( $self, $line_of_tokens ) = @_;
# pull out some stuff we might need
my $line_type = $line_of_tokens->{_line_type};
my $input_line_number = $line_of_tokens->{_line_number};
my $input_line = $line_of_tokens->{_line_text};
my $rtoken_type = $line_of_tokens->{_rtoken_type};
my $rtokens = $line_of_tokens->{_rtokens};
chomp $input_line;
# skip comments, pod, etc
return if ( $line_type ne 'CODE' );
# loop over tokens looking for $`, $&, and $'
for ( my $j = 0 ; $j < @$rtoken_type ; $j++ ) {
# we only want to examine token types 'i' (identifier)
next unless $$rtoken_type[$j] eq 'i';
# pull out the actual token text
my $token = $$rtokens[$j];
# and check it
if ( $token =~ /^\$[\`\&\']$/ ) {
print STDERR
"$input_line_number: $token\n";
}
}
}
This example pulls out these tokenization variables from the
$line_of_tokens hash reference:
$rtoken_type = $line_of_tokens->{_rtoken_type};
$rtokens = $line_of_tokens->{_rtokens};
The variable $rtoken_type is a reference to an array of token type
codes, and $rtokens is a reference to a corresponding array of token
text. These are obviously only defined for lines of type CODE.
Perltidy classifies tokens into types, and has a brief code for each
type. You can get a complete list at any time by running perltidy from
the command line with
perltidy --dump-token-types
In the present example, we are only looking for tokens of type i (iden-
tifiers), so the for loop skips past all other types. When an identi-
fier is found, its actual text is checked to see if it is one being
sought. If so, the above write_line prints the token and its line num-
ber.
The formatter feature is relatively new in perltidy, and further docu-
mentation needs to be written to complete its description. However,
several example programs have been written and can be found in the
examples section of the source distribution. Probably the best way to
get started is to find one of the examples which most closely matches
your application and start modifying it.
For help with perltidy's pecular way of breaking lines into tokens, you
might run, from the command line,
perltidy -D filename
where filename is a short script of interest. This will produce file-
name.DEBUG with interleaved lines of text and their token types. The
-D flag has been in perltidy from the beginning for this purpose. If
you want to see the code which creates this file, it is
"write_debug_entry" in Tidy.pm.
EXPORT
&perltidy
CREDITS
Thanks to Hugh Myers who developed the initial modular interface to
perltidy.
VERSION
This man page documents Perl::Tidy version 20031021.
AUTHOR
Steve Hancock
perltidy at users.sourceforge.net
SEE ALSO
The perltidy(1) man page describes all of the features of perltidy. It
can be found at http://perltidy.sourceforge.net.
perl v5.8.6 2003-10-21 Perl::Tidy(3)
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