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

Provided by: perltidy_20210717-1_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,
               teefile           => $teefile,
               debugfile         => $debugfile,
               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.

teefile
The teefile parameter allows the calling program to capture the tee stream. This stream is only
created if requested with one of the 'tee' parameters, a --tee-pod , --tee-block-comments,
--tee-side-commnts, or --tee-all-comments.

debugfile
The debugfile parameter allows the calling program to capture the stream produced by the --DEBUG
parameter. This parameter is mainly used for debugging perltidy itself.

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
parameters 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

       An exit value of 0, 1, or 2 is returned by perltidy to indicate the status of the result.

       A exit value of 0 indicates that perltidy ran to completion with no error messages.

       An  exit  value  of  1  indicates  that 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 for 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.

       An  exit value of 2 indicates that perltidy ran to completion but there there are warning messages in the
       stderr stream related to parameter errors or conflicts and/or 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 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

INSTALLATION

       The module 'Perl::Tidy' comes with a binary 'perltidy' which is installed when the module  is  installed.
       The  module  name  is case-sensitive.  For example, the basic command for installing with cpanm is 'cpanm
       Perl::Tidy'.

VERSION

       This man page documents Perl::Tidy version 20210717

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.

BUG REPORTS

       A     list     of     current    bugs    and    issues    can    be    found    at    the    CPAN    site
       <https://rt.cpan.org/Public/Dist/Display.html?Name=Perl-Tidy>

       To report a new bug or problem, use the link on this page.

       The source code repository is at <https://github.com/perltidy/perltidy>.