Ubuntu Manpage: Perl::Tidy - Parses and beautifies perl source

Provided by: perltidy_20140328-1_all

NAME

       Perl::Tidy - Parses and beautifies perl source

SYNOPSIS

           use Perl::Tidy;

           my $error_flag = Perl::Tidy::perltidy(
               source            => $source,
               destination       => $destination,
               stderr            => $stderr,
               argv              => $argv,
               perltidyrc        => $perltidyrc,
               logfile           => $logfile,
               errorfile         => $errorfile,
               formatter         => $formatter,           # callback object (see below)
               dump_options      => $dump_options,
               dump_options_type => $dump_options_type,
               prefilter         => $prefilter_coderef,
               postfilter        => $postfilter_coderef,
           );

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 call to perltidy returns a scalar $error_flag which is TRUE if an error caused
premature termination, and FALSE if the process ran to normal completion. Additional
discuss of errors is contained below in the ERROR HANDLING section.

The module accepts input and output streams by a variety of methods. The following list
of parameters may be any of the following: a filename, 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
dump_options - ref to a hash to receive parameters (see below),
dump_options_type - controls contents of dump_options
dump_getopt_flags - ref to a hash to receive Getopt flags
dump_options_category - ref to a hash giving category of options
dump_abbreviations - ref to a hash giving all abbreviations

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. If an
input stream is defined with the source parameter then no other source filenames may
be specified in the @ARGV array or argv parameter.

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 redirect the stream that would
otherwise go to the standard error output device to any of the stream types listed
above. This stream contains important warnings and errors related to the parameters
passed to perltidy.

perltidyrc
If the perltidyrc file is given, it will be used instead of any .perltidyrc
configuration file that would otherwise be used.

errorfile
The errorfile parameter allows the calling program to capture the stream that would
otherwise go to either a .ERR file. This stream contains warnings or errors related
to the contents of one source file or stream.

The reason that this is different from the stderr stream is that when perltidy is
called to process multiple files there will be up to one .ERR file created for each
file and it would be very confusing if they were combined.

However if perltidy is called to process just a single perl script then it may be more
convenient to combine the errorfile stream with the stderr stream. This can be done
by setting the -se parameter, in which case this parameter is ignored.

logfile
The logfile parameter allows the calling program to capture the log stream. This
stream is only created if requested with a -g parameter. It contains detailed
diagnostic information about a script which may be useful for debugging.

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.

dump_options
If the dump_options parameter is given, it must be the reference to a hash. In this
case, the parameters contained in any perltidyrc configuration file will be placed in
this hash and perltidy will return immediately. This is equivalent to running
perltidy with --dump-options, except that the perameters are returned in a hash rather
than dumped to standard output. Also, by default only the parameters in the
perltidyrc file are returned, but this can be changed (see the next parameter). This
parameter provides a convenient method for external programs to read a perltidyrc
file. An example program using this feature, perltidyrc_dump.pl, is included in the
distribution.

Any combination of the dump_ parameters may be used together.

dump_options_type
This parameter is a string which can be used to control the parameters placed in the
hash reference supplied by dump_options. The possible values are 'perltidyrc'
(default) and 'full'. The 'full' parameter causes both the default options plus any
options found in a perltidyrc file to be returned.

dump_getopt_flags
If the dump_getopt_flags parameter is given, it must be the reference to a hash. This
hash will receive all of the parameters that perltidy understands and flags that are
passed to Getopt::Long. This parameter may be used alone or with the dump_options
flag. Perltidy will exit immediately after filling this hash. See the demo program
perltidyrc_dump.pl for example usage.

dump_options_category
If the dump_options_category parameter is given, it must be the reference to a hash.
This hash will receive a hash with keys equal to all long parameter names and values
equal to the title of the corresponding section of the perltidy manual. See the demo
program perltidyrc_dump.pl for example usage.

dump_abbreviations
If the dump_abbreviations parameter is given, it must be the reference to a hash.
This hash will receive all abbreviations used by Perl::Tidy. See the demo program
perltidyrc_dump.pl for example usage.

prefilter
A code reference that will be applied to the source before tidying. It is expected to
take the full content as a string in its input, and output the transformed content.

postfilter
A code reference that will be applied to the tidied result before outputting. It is
expected to take the full content as a string in its input, and output the transformed
content.

Note: A convenient way to check the function of your custom prefilter and postfilter
code is to use the --notidy option, first with just the prefilter and then with both
the prefilter and postfilter. See also the file filter_example.pl in the perltidy
distribution.

ERROR HANDLING

       Perltidy will return with an error flag indicating if the process had to be terminated
       early due to errors in the input parameters.  This can happen for example if a parameter
       is misspelled or given an invalid value.  The calling program should check this flag
       because if it is set the destination stream will be empty or incomplete and should be
       ignored.  Error messages in the stderr stream will indicate the cause of any problem.

       If the error flag is not set then perltidy ran to completion.   However there may still be
       warning messages in the stderr stream related to control parameters, and there may be
       warning messages in the errorfile stream relating to possible syntax errors in the source
       code being tidied.

       In the event of a catastrophic error for which recovery is not possible perltidy
       terminates by making calls to croak or confess to help the programmer localize the
       problem.  These should normally only occur during program development.

NOTES ON FORMATTING PARAMETERS

       Parameters which control formatting may be passed in several ways: in a .perltidyrc
       configuration file, in the perltidyrc parameter, and in the argv parameter.

       The -syn (--check-syntax) flag may be used with all source and destination streams except
       for standard input and output.  However data streams which are not associated with a
       filename will be copied to a temporary file before being be passed to Perl.  This use of
       temporary files can cause somewhat confusing output from Perl.

       If the -pbp style is used it will typically be necessary to also specify a -nst flag.
       This is necessary to turn off the -st flag contained in the -pbp parameter set which
       otherwise would direct the output stream to the standard output.

EXAMPLES

       The following example uses string references to hold the input and output code and error
       streams, and illustrates checking for errors.

         use Perl::Tidy;

         my $source_string = <<'EOT';
         my$error=Perl::Tidy::perltidy(argv=>$argv,source=>\$source_string,
           destination=>\$dest_string,stderr=>\$stderr_string,
         errorfile=>\$errorfile_string,);
         EOT

         my $dest_string;
         my $stderr_string;
         my $errorfile_string;
         my $argv = "-npro";   # Ignore any .perltidyrc at this site
         $argv .= " -pbp";     # Format according to perl best practices
         $argv .= " -nst";     # Must turn off -st in case -pbp is specified
         $argv .= " -se";      # -se appends the errorfile to stderr
         ## $argv .= " --spell-check";  # uncomment to trigger an error

         print "<<RAW SOURCE>>\n$source_string\n";

         my $error = Perl::Tidy::perltidy(
             argv        => $argv,
             source      => \$source_string,
             destination => \$dest_string,
             stderr      => \$stderr_string,
             errorfile   => \$errorfile_string,    # ignored when -se flag is set
             ##phasers   => 'stun',                # uncomment to trigger an error
         );

         if ($error) {

             # serious error in input parameters, no tidied output
             print "<<STDERR>>\n$stderr_string\n";
             die "Exiting because of serious errors\n";
         }

         if ($dest_string)      { print "<<TIDIED SOURCE>>\n$dest_string\n" }
         if ($stderr_string)    { print "<<STDERR>>\n$stderr_string\n" }
         if ($errorfile_string) { print "<<.ERR file>>\n$errorfile_string\n" }

       Additional examples are given in examples section of the perltidy distribution.

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 parameter $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 section 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 (identifiers), so the for
       loop skips past all other types.  When an identifier 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 number.

       The formatter feature is relatively new in perltidy, and further documentation 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 peculiar 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 filename.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 20140328.

LICENSE

       This package is free software; you can redistribute it and/or modify it under the terms of
       the "GNU General Public License".

       Please refer to the file "COPYING" for details.

AUTHOR

        Steve Hancock
        perltidy at users.sourceforge.net