=for Pod::Coverage empty

=head1 NAME

File::Globstar::ListMatch - Match File Names Against List Of Patterns

=head1 SYNOPSIS

    use File::Globstar::ListMatch;

    # Parse from file.
    $matcher = File::Globstar::ListMatch('.gitignore', 
                                         ignoreCase => 1,
                                         isExclude => 1);

    # Parse from file handle.
    $matcher = File::Globstar::ListMatch(STDIN, ignoreCase => 0);

    # Parse list of patterns.  Comments and blank lines are not
    # stripped!
    $matcher = File::Globstar::ListMatch([
        'src/**/*.o',
        '.*',
        '!.gitignore'
    ], filename => 'exclude.txt');

    # Parse string.
    $patterns = <<EOF;
    # Ignore all compiled object files.
    src/**/*.o
    # Ignore all hidden files.
    '.*'
    # But not this one.
    '.gitignore'
    EOF
    $matcher = File::Globstar::ListMatch(\$pattern);

    $filename = 'path/to/hello.o';
    if ($matcher->match($filename)) {
        print "Ignore '$filename'.\n";
    }

=head1 DESCRIPTION

Files containing list of files are very common as arguments to command-line options such
as "--ignore", "--exclude" or "--include".  A well-known example is the 
syntax used by L<git|https://git-scm.com/> as described in
L<https://git-scm.com/docs/gitignore>.

This module implements the same functionality in Perl.

While the module will normally be used for matching against filenames, no
file system operations are done.  Only strings are compared.  The reason for
this is that it should be possible to match names of deleted files as
well as existing files.

=head2 INPUT FILE FORMAT

Unless you pass a reference to an array of patterns as input, comments and 
blank lines are discarded.

=over 4

=item B<Comments>

Comments are lines that start with a hash-sign.  You can escape hash-signs that 
are part of the pattern with a backslash: "\#".

=item B<Blank Lines>

Blank lines are empty lines or lines consisting of whitespace only.  Whitespace
is a sequence of US-ASCII whitespace characters:  horizontal tabs 
(ASCII 9), line  feeds (ASCII 10), vertical tabs (ASCII 11), form feeds
(ASCII 12), carriage returns (ASCII 13), and space (ASCII 32).  Other
characters with the Unicode property "WSpace=Y" are not considered whitespace.

=back

Leading whitespace (see above) is I<not> removed!  Likewise, whitespace between
the leading negation "!" and the pattern is not removed!  On the other hand,
in order to ignore a file named "   " you have to backslash-escape
the first space character ("\   ").  Otherwise, the pattern will be interpreted
as a blank line and ignored.  This is consistent with the behavior of Git.

=head2 PATTERNS

Patterns undergo a little preprocessing:

=over 4

=item B<A leading exclamation is stripped off>

But the pattern is now negated.  It produces a match for all files that do
I<not> match the pattern.  A literal exclamation mark can be escaped with
a backslash.

=item B<A leading slash is stripped off>

But the pattern must match the entire significant "path" (actually string). 
For example "/foobar" matches for "/foobar" but not for "/sub/sub/foobar".

=item B<A trailing slash is stripped off>

But the pattern can only match "directories".  This is why the method
B<match()> below has an optional second argument that lets you specify, 
whether the string to be matched is considered a directory or not.

=back 

=head2 MATCHING ALGORITHM

The string (normally a filename) passed to the matcher is compared
subsequently to all patterns.  If none of the patterns match or if the last 
match was against a negated pattern, the overall result is false.  Otherwise it
is true.

If a patterrn contains a slash ("/"), the match is done against the full
path name, otherwise just against the basename of the file
with a leading "directory" part stripped off.

If a pattern starts with a leading slash, that slash is stripped off for
the purpose of comparison but the string must match relative to the 
base "directory".

The semantics of a match are the same as for B<fnmatchstar()> in
L<File::Globstar>.  But keep in mind that a leading exclamation mark (for
negation), a leading "directory" part, a leading slash, or a trailing slash
may be stripped off according to the rules outline above. 

=head1 METHODS

=over 4

=item B<new INPUT[, %OPTIONS]>

Creates a new B<File::Globstar::ListMatch> object.  B<INPUT> can be:

=over 8

=item B<FILE>

B<FILE> can be a filename, an open file handle, or a reference to an open
file handle.

=item B<STRINGREF>

B<STRINGREF> is a reference to a string containing the patterns.

=item B<ARRAYREF>

You can also pass a list of patterns as an array reference.  Leading
exclamation marks ("!") followed by possible whitespace for negating patterns
are stripped off, but otherwise all patterns are taken as is, even blank
ones and patterns starting with a hash-sign ("#").

=back

The input source can be followed by optional named arguments passed as
key-value pairs.  Currently recogized:

=over 4

=item B<ignoreCase =E<gt> 0|1|undef>

Controls, whether to ignore case, when matching.  A true value will cause
case to be ignored.  The default value is false, so that matches are done
in a case-sensitive manner.  This is an appropriate setting for both
case-sensitive and case-preserving file systems.

=item B<filename =E<gt> FILENAME>

Use B<FILENAME> in messages for I/O errors.

=back

=item B<match STRING[, IS_DIRECTORY]>

Returns true if B<STRING> matches.  If you pass a true value for the
optional argument B<IS_DIRECTORY>, B<STRING> is considered to be the name
of a directory.

A leading slash in B<STRING> is stripped off and is ignored.

A trailing slash is also ignored but B<STRING> is then considered to
be a directory name and B<IS_DIRECTORY> is ignored.

When comparing against a pattern that contains a slash (except for a trailing
slash), the full string is taken into account.  Otherwise, only the part
after the last (non-trailing) slash is taken into account.

Note that B<match()> assumes that you are excluding or ignoring files.  This
I<exclude> mode implies that certain negations do not make sense and are
ignored.  Thake this example:

     /node_modules
     !/node_modules/foobar

The second line gets ignored.  In exclude mode it is assumed that you 
recurse a directory calling B<match()> for every file you visit.  If a file
matches it is always ignored.  And if it is a directory, it is not only
ignored but the recursion also stops here.

The exact rule is: You cannot re-include a file by negating a pattern if one
of the file's parent directories would be excluded.  

This is the  behavior of git, when evaluating ignore lists.  If you want to
avoid that behavior, see below for B<matchInclude()>.

On the other hand, the following is possible:

    docs/_*
    !docs/_posts

The only "parent directory" for the negation is F<docs> and that is not
excluded.  This is different to this example:

    docs/_*
    !docs/_posts/recent

The "parent directories" are F<docs> and F<docs/_posts> and F<docs/_posts>
matches against F<docs/_*>.  The negation is therefore invalid and ignored.

=item B<matchExclude STRING[, IS_DIRECTORY]>

This is an alias for B<match()>

=item B<matchInclude STRING[, IS_DIRECTORY]>

Does the same as B<match()> but all negations are valid.

The metaphor for include mode is different from exclude mode that is
assumed by B<match()> resp. B<matchExclude()>.  In include mode you would
interpret all patterns as globbing patterns.  A positive, non-negated
pattern would cause the matching files to be added to result list.  A
negated pattern will remove the matching files from the result list.  The
operation would happen recursively if a directory gets added or removed.

We take almost the same example as for B<match()> above:

    docs/_*
    !docs/_posts/archive

Imagine line 1 would produce the following list:

=over 4

=item * F<docs/_views/>

=item * F<docs/_views/main.html>

=item * F<docs/_views/head/>

=item * F<docs/_views/head/meta.html>

=item * F<docs/_posts/new/>

=item * F<docs/_posts/new/post4321.html>

=item * F<docs/_posts/archive/>

=item * F<docs/_posts/archive/post1.html>

=item * F<docs/_posts/archive/post2.html>

Line 2 would then kickout the last three matches from the result list.

=back

=item B<patterns>

Returns the patterns as a list of compiled regular expressions.  This is 
useful probably only for testing.

=back

=head1 BUGS AND CAVEATS

The module interprets backslashes only for escaping.  It does not assume any
path separator semantics for them.  This should normally not be a problem.

Git ignores all hidden files by default.  If you want the same behavior for
B<File::Globstar::ListMatch>, put a ".*" in front of the patterns.

=head1 COPYRIGHT

Copyright (C) 2016-2017 Guido Flohr <guido.flohr@cantanea.com>,
all rights reserved.

=head1 SEE ALSO

File::Globstar(3pm), File::Glob(3pm), glob(3), glob(7), fnmatch(3), glob(1), 
perl(1)
