Next(3)

NAME
File::Next - File-finding iterator

VERSION
Version 1.16

SYNOPSIS
File::Next is a lightweight, taint-safe file-finding module. It's lightweight and has no non-core prerequisites.

    use File::Next;

    my $files = File::Next::files( '/tmp' );

    while ( defined ( my $file = $files->() ) ) {
        # do something...
    }

OPERATIONAL THEORY
The two major functions, files() and dirs(), return an iterator that will walk through a directory tree. The simplest use case is:

    use File::Next;

    my $iter = File::Next::files( '/tmp' );

    while ( defined ( my $file = $iter->() ) ) {
        print $file, "\n";
    }

    # Prints...
    /tmp/foo.txt
    /tmp/bar.pl
    /tmp/baz/1
    /tmp/baz/2.txt
    /tmp/baz/wango/tango/purple.txt

Note that only files are returned by "files()"'s iterator. Directories are ignored.

In list context, the iterator returns a list containing $dir, $file and $fullpath, where $fullpath is what would get returned in scalar context.

The first parameter to any of the iterator factory functions may be a hashref of options.

ITERATORS
For the three iterators, the \%options are optional.

  files( [ \%options, ] @starting_points )
Returns an iterator that walks directories starting with the items in @starting_points. Each call to the iterator returns another regular file.

  dirs( [ \%options, ] @starting_points )
Returns an iterator that walks directories starting with the items in @starting_points. Each call to the iterator returns another directory.

  everything( [ \%options, ] @starting_points )
Returns an iterator that walks directories starting with the items in @starting_points. Each call to the iterator returns another file, whether it's a regular file, directory, symlink, socket, or whatever.

  from_file( [ \%options, ] $filename )
Returns an iterator that iterates over each of the files specified in $filename. If $filename is "-", then the files are read from STDIN.

The files are assumed to be in the file one filename per line. If $nul_separated is passed, then the files are assumed to be NUL-separated, as by "find -print0".

If there are blank lines or empty filenames in the input stream, they are ignored.

Each filename is checked to see that it is a regular file or a named pipe. If the file does not exists or is a directory, then a warning is thrown to warning_handler, and the file is skipped.

The following options have no effect in "from_files": descend_filter, sort_files, follow_symlinks.

SUPPORT FUNCTIONS

  sort_standard( $a, $b )
A sort function for passing as a "sort_files" option:

    my $iter = File::Next::files( {
        sort_files => \&File::Next::sort_standard,
    }, 't/swamp' );

This function is the default, so the code above is identical to:

    my $iter = File::Next::files( {
        sort_files => 1,
    }, 't/swamp' );

  sort_reverse( $a, $b )
Same as "sort_standard", but in reverse.

  reslash( $path )
Takes a path with all forward slashes and rebuilds it with whatever is appropriate for the platform. For example 'foo/bar/bat' will become 'foo\bar\bat' on Windows.

This is really just a convenience function. I'd make it private, but ack wants it, too.

CONSTRUCTOR PARAMETERS

  file_filter -> \&file_filter
The file_filter lets you check to see if it's really a file you want to get back. If the file_filter returns a true value, the file will be returned; if false, it will be skipped.

The file_filter function takes no arguments but rather does its work through a collection of variables.

•   $_ is the current filename within that directory

•   $File::Next::dir is the current directory name

•   $File::Next::name is the complete pathname to the file

These are analogous to the same variables in File::Find.

    my $iter = File::Next::files( { file_filter => sub { /\.txt$/ } }, '/tmp' );

By default, the file_filter is "sub {1}", or "all files".

This filter has no effect if your iterator is only returning directories.

  descend_filter => \&descend_filter
The descend_filter lets you check to see if the iterator should descend into a given directory. Maybe you want to skip CVS and .svn directories.

    my $descend_filter = sub { $_ ne "CVS" && $_ ne ".svn" }

The descend_filter function takes no arguments but rather does its work through a collection of variables.

•   $_ is the current filename of the directory

•   $File::Next::dir is the complete directory name

The descend filter is NOT applied to any directory names specified as @starting_points in the constructor. For example,

    my $iter = File::Next::files( { descend_filter => sub{0} }, '/tmp' );

always descends into /tmp, as you would expect.

By default, the descend_filter is "sub {1}", or "always descend".

  error_handler => \&error_handler
If error_handler is set, then any errors will be sent through it. If the error is OS-related (ex. file not found, not permissions), the native error code is passed as a second argument. By default, this value is "CORE::die". This function must NOT return.

  warning_handler => \&warning_handler
If warning_handler is set, then any errors will be sent through it. By default, this value is "CORE::warn". Unlike the error_handler, this function must return.

  sort_files => [ 0 | 1 | \&sort_sub]
If you want files sorted, pass in some true value, as in "sort_files => 1".

If you want a special sort order, pass in a sort function like "sort_files => sub { $a->[1] cmp $b->[1] }". Note that the parms passed in to the sub are arrayrefs, where $a->[0] is the directory name, $a->[1] is the file name and $a->[2] is the full path. Typically you're going to be sorting on $a->[2].

  follow_symlinks => [ 0 | 1 ]
If set to false, the iterator will ignore any files and directories that are actually symlinks. This has no effect on non-Unixy systems such as Windows. By default, this is true.

Note that this filter does not apply to any of the @starting_points passed in to the constructor.

You should not set "follow_symlinks => 0" unless you specifically need that behavior. Setting "follow_symlinks => 0" can be a speed hit, because File::Next must check to see if the file or directory you're about to follow is actually a symlink.

  nul_separated => [ 0 | 1 ]
Used by the "from_file" iterator. Specifies that the files listed in the input file are separated by NUL characters, as from the "find" command with the "-print0" argument.

PRIVATE FUNCTIONS

  _setup( $default_parms, @whatever_was_passed_to_files() )
Handles all the scut-work for setting up the parms passed in.

Returns a hashref of operational options, combined between $passed_parms and $defaults, plus the queue.

The queue prep stuff takes the strings in @starting_points and puts them in the format that queue needs.

The @queue that gets passed around is an array that has three elements for each of the entries in the queue: $dir, $file and $fullpath. Items must be pushed and popped off the queue three at a time (spliced, really).

  _candidate_files( $parms, $dir )
Pulls out the files/dirs that might be worth looking into in $dir. If $dir is the empty string, then search the current directory.

$parms is the hashref of parms passed into File::Next constructor.

DIAGNOSTICS

"File::Next::files must not be invoked as File::Next->files"
"File::Next::dirs must not be invoked as File::Next->dirs"
"File::Next::everything must not be invoked as File::Next->everything"

The interface functions do not allow for the method invocation syntax and throw errors with the messages above. You can work around this limitation with "can" in UNIVERSAL.

    for my $file_system_feature (qw(dirs files)) {
        my $iterator = File::Next->can($file_system_feature)->($options, $target_directory);
        while (defined(my $name = $iterator->())) {
            # ...
        }
    }

SPEED TWEAKS

•   Don't set "follow_symlinks => 0" unless you need it.

AUTHOR
Andy Lester, "<andy at petdance.com>"

BUGS
Please report any bugs or feature requests to <http://github.com/petdance/file-next/issues>.

Note that File::Next does NOT use <http://rt.cpan.org> for bug tracking.

SUPPORT
You can find documentation for this module with the perldoc command.

    perldoc File::Next

You can also look for information at:

•   File::Next's bug queue

    <http://github.com/petdance/file-next/issues>

•   AnnoCPAN: Annotated CPAN documentation

    <http://annocpan.org/dist/File-Next>

•   CPAN Ratings

    <http://cpanratings.perl.org/d/File-Next>

•   Search CPAN

    <http://search.cpan.org/dist/File-Next>

•   Source code repository

    <http://github.com/petdance/file-next/tree/master>

ACKNOWLEDGEMENTS
All file-finding in this module is adapted from Mark Jason Dominus' marvelous Higher Order Perl, page 126.

Thanks also for bug fixes and typo finding to Gerhard Poul, Brian Fraser, Todd Rinaldo, Bruce Woodward, Christopher J. Madsen, Bernhard Fisseni and Rob Hoelz.

COPYRIGHT & LICENSE
Copyright 2005-2016 Andy Lester.

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.