text: # -*- mode: cperl; tab-width: 8; indent-tabs-mode: nil; basic-offset: 2 -*-
  # vim:ts=8:sw=2:et:sta:sts=2
  package Module::Metadata; # git description: v1.000025-7-g47ca1b2
  
  # Adapted from Perl-licensed code originally distributed with
  # Module-Build by Ken Williams
  
  # This module provides routines to gather information about
  # perl modules (assuming this may be expanded in the distant
  # parrot future to look at other types of modules).
  
  sub __clean_eval { eval $_[0] }
  use strict;
  use warnings;
  
  our $VERSION = '1.000026';
  
  use Carp qw/croak/;
  use File::Spec;
  BEGIN {
         # Try really hard to not depend ony any DynaLoaded module, such as IO::File or Fcntl
         eval {
                 require Fcntl; Fcntl->import('SEEK_SET'); 1;
         } or *SEEK_SET = sub { 0 }
  }
  use version 0.87;
  BEGIN {
    if ($INC{'Log/Contextual.pm'}) {
      Log::Contextual->import('log_info');
    } else {
      *log_info = sub (&) { warn $_[0]->() };
    }
  }
  use File::Find qw(find);
  
  my $V_NUM_REGEXP = qr{v?[0-9._]+};  # crudely, a v-string or decimal
  
  my $PKG_FIRST_WORD_REGEXP = qr{ # the FIRST word in a package name
    [a-zA-Z_]                     # the first word CANNOT start with a digit
      (?:
        [\w']?                    # can contain letters, digits, _, or ticks
        \w                        # But, NO multi-ticks or trailing ticks
      )*
  }x;
  
  my $PKG_ADDL_WORD_REGEXP = qr{ # the 2nd+ word in a package name
    \w                           # the 2nd+ word CAN start with digits
      (?:
        [\w']?                   # and can contain letters or ticks
        \w                       # But, NO multi-ticks or trailing ticks
      )*
  }x;
  
  my $PKG_NAME_REGEXP = qr{ # match a package name
    (?: :: )?               # a pkg name can start with arisdottle
    $PKG_FIRST_WORD_REGEXP  # a package word
    (?:
      (?: :: )+             ### arisdottle (allow one or many times)
      $PKG_ADDL_WORD_REGEXP ### a package word
    )*                      # ^ zero, one or many times
    (?:
      ::                    # allow trailing arisdottle
    )?
  }x;
  
  my $PKG_REGEXP  = qr{   # match a package declaration
    ^[\s\{;]*             # intro chars on a line
    package               # the word 'package'
    \s+                   # whitespace
    ($PKG_NAME_REGEXP)    # a package name
    \s*                   # optional whitespace
    ($V_NUM_REGEXP)?        # optional version number
    \s*                   # optional whitesapce
    [;\{]                 # semicolon line terminator or block start (since 5.16)
  }x;
  
  my $VARNAME_REGEXP = qr{ # match fully-qualified VERSION name
    ([\$*])         # sigil - $ or *
    (
      (             # optional leading package name
        (?:::|\')?  # possibly starting like just :: (a la $::VERSION)
        (?:\w+(?:::|\'))*  # Foo::Bar:: ...
      )?
      VERSION
    )\b
  }x;
  
  my $VERS_REGEXP = qr{ # match a VERSION definition
    (?:
      \(\s*$VARNAME_REGEXP\s*\) # with parens
    |
      $VARNAME_REGEXP           # without parens
    )
    \s*
    =[^=~>]  # = but not ==, nor =~, nor =>
  }x;
  
  sub new_from_file {
    my $class    = shift;
    my $filename = File::Spec->rel2abs( shift );
  
    return undef unless defined( $filename ) && -f $filename;
    return $class->_init(undef, $filename, @_);
  }
  
  sub new_from_handle {
    my $class    = shift;
    my $handle   = shift;
    my $filename = shift;
    return undef unless defined($handle) && defined($filename);
    $filename = File::Spec->rel2abs( $filename );
  
    return $class->_init(undef, $filename, @_, handle => $handle);
  
  }
  
  
  sub new_from_module {
    my $class   = shift;
    my $module  = shift;
    my %props   = @_;
  
    $props{inc} ||= \@INC;
    my $filename = $class->find_module_by_name( $module, $props{inc} );
    return undef unless defined( $filename ) && -f $filename;
    return $class->_init($module, $filename, %props);
  }
  
  {
  
    my $compare_versions = sub {
      my ($v1, $op, $v2) = @_;
      $v1 = version->new($v1)
        unless UNIVERSAL::isa($v1,'version');
  
      my $eval_str = "\$v1 $op \$v2";
      my $result   = eval $eval_str;
      log_info { "error comparing versions: '$eval_str' $@" } if $@;
  
      return $result;
    };
  
    my $normalize_version = sub {
      my ($version) = @_;
      if ( $version =~ /[=<>!,]/ ) { # logic, not just version
        # take as is without modification
      }
      elsif ( ref $version eq 'version' ) { # version objects
        $version = $version->is_qv ? $version->normal : $version->stringify;
      }
      elsif ( $version =~ /^[^v][^.]*\.[^.]+\./ ) { # no leading v, multiple dots
        # normalize string tuples without "v": "1.2.3" -> "v1.2.3"
        $version = "v$version";
      }
      else {
        # leave alone
      }
      return $version;
    };
  
    # separate out some of the conflict resolution logic
  
    my $resolve_module_versions = sub {
      my $packages = shift;
  
      my( $file, $version );
      my $err = '';
        foreach my $p ( @$packages ) {
          if ( defined( $p->{version} ) ) {
            if ( defined( $version ) ) {
              if ( $compare_versions->( $version, '!=', $p->{version} ) ) {
                $err .= "  $p->{file} ($p->{version})\n";
              } else {
                # same version declared multiple times, ignore
              }
            } else {
              $file    = $p->{file};
              $version = $p->{version};
            }
          }
        $file ||= $p->{file} if defined( $p->{file} );
      }
  
      if ( $err ) {
        $err = "  $file ($version)\n" . $err;
      }
  
      my %result = (
        file    => $file,
        version => $version,
        err     => $err
      );
  
      return \%result;
    };
  
    sub provides {
      my $class = shift;
  
      croak "provides() requires key/value pairs \n" if @_ % 2;
      my %args = @_;
  
      croak "provides() takes only one of 'dir' or 'files'\n"
        if $args{dir} && $args{files};
  
      croak "provides() requires a 'version' argument"
        unless defined $args{version};
  
      croak "provides() does not support version '$args{version}' metadata"
          unless grep { $args{version} eq $_ } qw/1.4 2/;
  
      $args{prefix} = 'lib' unless defined $args{prefix};
  
      my $p;
      if ( $args{dir} ) {
        $p = $class->package_versions_from_directory($args{dir});
      }
      else {
        croak "provides() requires 'files' to be an array reference\n"
          unless ref $args{files} eq 'ARRAY';
        $p = $class->package_versions_from_directory($args{files});
      }
  
      # Now, fix up files with prefix
      if ( length $args{prefix} ) { # check in case disabled with q{}
        $args{prefix} =~ s{/$}{};
        for my $v ( values %$p ) {
          $v->{file} = "$args{prefix}/$v->{file}";
        }
      }
  
      return $p
    }
  
    sub package_versions_from_directory {
      my ( $class, $dir, $files ) = @_;
  
      my @files;
  
      if ( $files ) {
        @files = @$files;
      } else {
        find( {
          wanted => sub {
            push @files, $_ if -f $_ && /\.pm$/;
          },
          no_chdir => 1,
        }, $dir );
      }
  
      # First, we enumerate all packages & versions,
      # separating into primary & alternative candidates
      my( %prime, %alt );
      foreach my $file (@files) {
        my $mapped_filename = File::Spec::Unix->abs2rel( $file, $dir );
        my @path = split( /\//, $mapped_filename );
        (my $prime_package = join( '::', @path )) =~ s/\.pm$//;
  
        my $pm_info = $class->new_from_file( $file );
  
        foreach my $package ( $pm_info->packages_inside ) {
          next if $package eq 'main';  # main can appear numerous times, ignore
          next if $package eq 'DB';    # special debugging package, ignore
          next if grep /^_/, split( /::/, $package ); # private package, ignore
  
          my $version = $pm_info->version( $package );
  
          $prime_package = $package if lc($prime_package) eq lc($package);
          if ( $package eq $prime_package ) {
            if ( exists( $prime{$package} ) ) {
              croak "Unexpected conflict in '$package'; multiple versions found.\n";
            } else {
              $mapped_filename = "$package.pm" if lc("$package.pm") eq lc($mapped_filename);
              $prime{$package}{file} = $mapped_filename;
              $prime{$package}{version} = $version if defined( $version );
            }
          } else {
            push( @{$alt{$package}}, {
                                      file    => $mapped_filename,
                                      version => $version,
                                     } );
          }
        }
      }
  
      # Then we iterate over all the packages found above, identifying conflicts
      # and selecting the "best" candidate for recording the file & version
      # for each package.
      foreach my $package ( keys( %alt ) ) {
        my $result = $resolve_module_versions->( $alt{$package} );
  
        if ( exists( $prime{$package} ) ) { # primary package selected
  
          if ( $result->{err} ) {
          # Use the selected primary package, but there are conflicting
          # errors among multiple alternative packages that need to be
          # reported
            log_info {
              "Found conflicting versions for package '$package'\n" .
              "  $prime{$package}{file} ($prime{$package}{version})\n" .
              $result->{err}
            };
  
          } elsif ( defined( $result->{version} ) ) {
          # There is a primary package selected, and exactly one
          # alternative package
  
          if ( exists( $prime{$package}{version} ) &&
               defined( $prime{$package}{version} ) ) {
            # Unless the version of the primary package agrees with the
            # version of the alternative package, report a conflict
          if ( $compare_versions->(
                   $prime{$package}{version}, '!=', $result->{version}
                 )
               ) {
  
              log_info {
                "Found conflicting versions for package '$package'\n" .
                "  $prime{$package}{file} ($prime{$package}{version})\n" .
                "  $result->{file} ($result->{version})\n"
              };
            }
  
          } else {
            # The prime package selected has no version so, we choose to
            # use any alternative package that does have a version
            $prime{$package}{file}    = $result->{file};
            $prime{$package}{version} = $result->{version};
          }
  
          } else {
          # no alt package found with a version, but we have a prime
          # package so we use it whether it has a version or not
          }
  
        } else { # No primary package was selected, use the best alternative
  
          if ( $result->{err} ) {
            log_info {
              "Found conflicting versions for package '$package'\n" .
              $result->{err}
            };
          }
  
          # Despite possible conflicting versions, we choose to record
          # something rather than nothing
          $prime{$package}{file}    = $result->{file};
          $prime{$package}{version} = $result->{version}
            if defined( $result->{version} );
        }
      }
  
      # Normalize versions.  Can't use exists() here because of bug in YAML::Node.
      # XXX "bug in YAML::Node" comment seems irrelevant -- dagolden, 2009-05-18
      for (grep defined $_->{version}, values %prime) {
        $_->{version} = $normalize_version->( $_->{version} );
      }
  
      return \%prime;
    }
  }
  
  
  sub _init {
    my $class    = shift;
    my $module   = shift;
    my $filename = shift;
    my %props = @_;
  
    my $handle = delete $props{handle};
    my( %valid_props, @valid_props );
    @valid_props = qw( collect_pod inc );
    @valid_props{@valid_props} = delete( @props{@valid_props} );
    warn "Unknown properties: @{[keys %props]}\n" if scalar( %props );
  
    my %data = (
      module       => $module,
      filename     => $filename,
      version      => undef,
      packages     => [],
      versions     => {},
      pod          => {},
      pod_headings => [],
      collect_pod  => 0,
  
      %valid_props,
    );
  
    my $self = bless(\%data, $class);
  
    if ( not $handle ) {
      my $filename = $self->{filename};
      open $handle, '<', $filename
        or croak( "Can't open '$filename': $!" );
  
      $self->_handle_bom($handle, $filename);
    }
    $self->_parse_fh($handle);
  
    unless($self->{module} and length($self->{module})) {
      my ($v, $d, $f) = File::Spec->splitpath($self->{filename});
      if($f =~ /\.pm$/) {
        $f =~ s/\..+$//;
        my @candidates = grep /$f$/, @{$self->{packages}};
        $self->{module} = shift(@candidates); # punt
      }
      else {
        if(grep /main/, @{$self->{packages}}) {
          $self->{module} = 'main';
        }
        else {
          $self->{module} = $self->{packages}[0] || '';
        }
      }
    }
  
    $self->{version} = $self->{versions}{$self->{module}}
        if defined( $self->{module} );
  
    return $self;
  }
  
  # class method
  sub _do_find_module {
    my $class   = shift;
    my $module  = shift || croak 'find_module_by_name() requires a package name';
    my $dirs    = shift || \@INC;
  
    my $file = File::Spec->catfile(split( /::/, $module));
    foreach my $dir ( @$dirs ) {
      my $testfile = File::Spec->catfile($dir, $file);
      return [ File::Spec->rel2abs( $testfile ), $dir ]
        if -e $testfile and !-d _;  # For stuff like ExtUtils::xsubpp
      $testfile .= '.pm';
      return [ File::Spec->rel2abs( $testfile ), $dir ]
        if -e $testfile;
    }
    return;
  }
  
  # class method
  sub find_module_by_name {
    my $found = shift()->_do_find_module(@_) or return;
    return $found->[0];
  }
  
  # class method
  sub find_module_dir_by_name {
    my $found = shift()->_do_find_module(@_) or return;
    return $found->[1];
  }
  
  
  # given a line of perl code, attempt to parse it if it looks like a
  # $VERSION assignment, returning sigil, full name, & package name
  sub _parse_version_expression {
    my $self = shift;
    my $line = shift;
  
    my( $sigil, $variable_name, $package);
    if ( $line =~ /$VERS_REGEXP/o ) {
      ( $sigil, $variable_name, $package) = $2 ? ( $1, $2, $3 ) : ( $4, $5, $6 );
      if ( $package ) {
        $package = ($package eq '::') ? 'main' : $package;
        $package =~ s/::$//;
      }
    }
  
    return ( $sigil, $variable_name, $package );
  }
  
  # Look for a UTF-8/UTF-16BE/UTF-16LE BOM at the beginning of the stream.
  # If there's one, then skip it and set the :encoding layer appropriately.
  sub _handle_bom {
    my ($self, $fh, $filename) = @_;
  
    my $pos = tell $fh;
    return unless defined $pos;
  
    my $buf = ' ' x 2;
    my $count = read $fh, $buf, length $buf;
    return unless defined $count and $count >= 2;
  
    my $encoding;
    if ( $buf eq "\x{FE}\x{FF}" ) {
      $encoding = 'UTF-16BE';
    } elsif ( $buf eq "\x{FF}\x{FE}" ) {
      $encoding = 'UTF-16LE';
    } elsif ( $buf eq "\x{EF}\x{BB}" ) {
      $buf = ' ';
      $count = read $fh, $buf, length $buf;
      if ( defined $count and $count >= 1 and $buf eq "\x{BF}" ) {
        $encoding = 'UTF-8';
      }
    }
  
    if ( defined $encoding ) {
      if ( "$]" >= 5.008 ) {
        binmode( $fh, ":encoding($encoding)" );
      }
    } else {
      seek $fh, $pos, SEEK_SET
        or croak( sprintf "Can't reset position to the top of '$filename'" );
    }
  
    return $encoding;
  }
  
  sub _parse_fh {
    my ($self, $fh) = @_;
  
    my( $in_pod, $seen_end, $need_vers ) = ( 0, 0, 0 );
    my( @packages, %vers, %pod, @pod );
    my $package = 'main';
    my $pod_sect = '';
    my $pod_data = '';
    my $in_end = 0;
  
    while (defined( my $line = <$fh> )) {
      my $line_num = $.;
  
      chomp( $line );
  
      # From toke.c : any line that begins by "=X", where X is an alphabetic
      # character, introduces a POD segment.
      my $is_cut;
      if ( $line =~ /^=([a-zA-Z].*)/ ) {
        my $cmd = $1;
        # Then it goes back to Perl code for "=cutX" where X is a non-alphabetic
        # character (which includes the newline, but here we chomped it away).
        $is_cut = $cmd =~ /^cut(?:[^a-zA-Z]|$)/;
        $in_pod = !$is_cut;
      }
  
      if ( $in_pod ) {
  
        if ( $line =~ /^=head[1-4]\s+(.+)\s*$/ ) {
          push( @pod, $1 );
          if ( $self->{collect_pod} && length( $pod_data ) ) {
            $pod{$pod_sect} = $pod_data;
            $pod_data = '';
          }
          $pod_sect = $1;
  
        } elsif ( $self->{collect_pod} ) {
          $pod_data .= "$line\n";
  
        }
  
      } elsif ( $is_cut ) {
  
        if ( $self->{collect_pod} && length( $pod_data ) ) {
          $pod{$pod_sect} = $pod_data;
          $pod_data = '';
        }
        $pod_sect = '';
  
      } else {
  
        # Skip after __END__
        next if $in_end;
  
        # Skip comments in code
        next if $line =~ /^\s*#/;
  
        # Would be nice if we could also check $in_string or something too
        if ($line eq '__END__') {
          $in_end++;
          next;
        }
        last if $line eq '__DATA__';
  
        # parse $line to see if it's a $VERSION declaration
        my( $version_sigil, $version_fullname, $version_package ) =
            index($line, 'VERSION') >= 1
                ? $self->_parse_version_expression( $line )
                : ();
  
        if ( $line =~ /$PKG_REGEXP/o ) {
          $package = $1;
          my $version = $2;
          push( @packages, $package ) unless grep( $package eq $_, @packages );
          $need_vers = defined $version ? 0 : 1;
  
          if ( not exists $vers{$package} and defined $version ){
            # Upgrade to a version object.
            my $dwim_version = eval { _dwim_version($version) };
            croak "Version '$version' from $self->{filename} does not appear to be valid:\n$line\n\nThe fatal error was: $@\n"
                unless defined $dwim_version;  # "0" is OK!
            $vers{$package} = $dwim_version;
          }
  
        # VERSION defined with full package spec, i.e. $Module::VERSION
        } elsif ( $version_fullname && $version_package ) {
          push( @packages, $version_package ) unless grep( $version_package eq $_, @packages );
          $need_vers = 0 if $version_package eq $package;
  
          unless ( defined $vers{$version_package} && length $vers{$version_package} ) {
          $vers{$version_package} = $self->_evaluate_version_line( $version_sigil, $version_fullname, $line );
        }
  
        # first non-comment line in undeclared package main is VERSION
        } elsif ( $package eq 'main' && $version_fullname && !exists($vers{main}) ) {
          $need_vers = 0;
          my $v = $self->_evaluate_version_line( $version_sigil, $version_fullname, $line );
          $vers{$package} = $v;
          push( @packages, 'main' );
  
        # first non-comment line in undeclared package defines package main
        } elsif ( $package eq 'main' && !exists($vers{main}) && $line =~ /\w/ ) {
          $need_vers = 1;
          $vers{main} = '';
          push( @packages, 'main' );
  
        # only keep if this is the first $VERSION seen
        } elsif ( $version_fullname && $need_vers ) {
          $need_vers = 0;
          my $v = $self->_evaluate_version_line( $version_sigil, $version_fullname, $line );
  
          unless ( defined $vers{$package} && length $vers{$package} ) {
            $vers{$package} = $v;
          }
        }
      }
    }
  
    if ( $self->{collect_pod} && length($pod_data) ) {
      $pod{$pod_sect} = $pod_data;
    }
  
    $self->{versions} = \%vers;
    $self->{packages} = \@packages;
    $self->{pod} = \%pod;
    $self->{pod_headings} = \@pod;
  }
  
  {
  my $pn = 0;
  sub _evaluate_version_line {
    my $self = shift;
    my( $sigil, $variable_name, $line ) = @_;
  
    # We compile into a local sub because 'use version' would cause
    # compiletime/runtime issues with local()
    $pn++; # everybody gets their own package
    my $eval = qq{ my \$dummy = q#  Hide from _packages_inside()
      #; package Module::Metadata::_version::p${pn};
      use version;
      sub {
        local $sigil$variable_name;
        $line;
        \$$variable_name
      };
    };
  
    $eval = $1 if $eval =~ m{^(.+)}s;
  
    local $^W;
    # Try to get the $VERSION
    my $vsub = __clean_eval($eval);
    # some modules say $VERSION <equal sign> $Foo::Bar::VERSION, but Foo::Bar isn't
    # installed, so we need to hunt in ./lib for it
    if ( $@ =~ /Can't locate/ && -d 'lib' ) {
      local @INC = ('lib',@INC);
      $vsub = __clean_eval($eval);
    }
    warn "Error evaling version line '$eval' in $self->{filename}: $@\n"
      if $@;
  
    (ref($vsub) eq 'CODE') or
      croak "failed to build version sub for $self->{filename}";
  
    my $result = eval { $vsub->() };
    # FIXME: $eval is not the right thing to print here
    croak "Could not get version from $self->{filename} by executing:\n$eval\n\nThe fatal error was: $@\n"
      if $@;
  
    # Upgrade it into a version object
    my $version = eval { _dwim_version($result) };
  
    # FIXME: $eval is not the right thing to print here
    croak "Version '$result' from $self->{filename} does not appear to be valid:\n$eval\n\nThe fatal error was: $@\n"
      unless defined $version; # "0" is OK!
  
    return $version;
  }
  }
  
  # Try to DWIM when things fail the lax version test in obvious ways
  {
    my @version_prep = (
      # Best case, it just works
      sub { return shift },
  
      # If we still don't have a version, try stripping any
      # trailing junk that is prohibited by lax rules
      sub {
        my $v = shift;
        $v =~ s{([0-9])[a-z-].*$}{$1}i; # 1.23-alpha or 1.23b
        return $v;
      },
  
      # Activestate apparently creates custom versions like '1.23_45_01', which
      # cause version.pm to think it's an invalid alpha.  So check for that
      # and strip them
      sub {
        my $v = shift;
        my $num_dots = () = $v =~ m{(\.)}g;
        my $num_unders = () = $v =~ m{(_)}g;
        my $leading_v = substr($v,0,1) eq 'v';
        if ( ! $leading_v && $num_dots < 2 && $num_unders > 1 ) {
          $v =~ s{_}{}g;
          $num_unders = () = $v =~ m{(_)}g;
        }
        return $v;
      },
  
      # Worst case, try numifying it like we would have before version objects
      sub {
        my $v = shift;
        no warnings 'numeric';
        return 0 + $v;
      },
  
    );
  
    sub _dwim_version {
      my ($result) = shift;
  
      return $result if ref($result) eq 'version';
  
      my ($version, $error);
      for my $f (@version_prep) {
        $result = $f->($result);
        $version = eval { version->new($result) };
        $error ||= $@ if $@; # capture first failure
        last if defined $version;
      }
  
      croak $error unless defined $version;
  
      return $version;
    }
  }
  
  ############################################################
  
  # accessors
  sub name            { $_[0]->{module}            }
  
  sub filename        { $_[0]->{filename}          }
  sub packages_inside { @{$_[0]->{packages}}       }
  sub pod_inside      { @{$_[0]->{pod_headings}}   }
  sub contains_pod    { 0+@{$_[0]->{pod_headings}} }
  
  sub version {
      my $self = shift;
      my $mod  = shift || $self->{module};
      my $vers;
      if ( defined( $mod ) && length( $mod ) &&
           exists( $self->{versions}{$mod} ) ) {
          return $self->{versions}{$mod};
      } else {
          return undef;
      }
  }
  
  sub pod {
      my $self = shift;
      my $sect = shift;
      if ( defined( $sect ) && length( $sect ) &&
           exists( $self->{pod}{$sect} ) ) {
          return $self->{pod}{$sect};
      } else {
          return undef;
      }
  }
  
  sub is_indexable {
    my ($self, $package) = @_;
  
    my @indexable_packages = grep { $_ ne 'main' } $self->packages_inside;
  
    # check for specific package, if provided
    return !! grep { $_ eq $package } @indexable_packages if $package;
  
    # otherwise, check for any indexable packages at all
    return !! @indexable_packages;
  }
  
  1;
  
  =head1 NAME
  
  Module::Metadata - Gather package and POD information from perl module files
  
  =head1 SYNOPSIS
  
    use Module::Metadata;
  
    # information about a .pm file
    my $info = Module::Metadata->new_from_file( $file );
    my $version = $info->version;
  
    # CPAN META 'provides' field for .pm files in a directory
    my $provides = Module::Metadata->provides(
      dir => 'lib', version => 2
    );
  
  =head1 DESCRIPTION
  
  This module provides a standard way to gather metadata about a .pm file through
  (mostly) static analysis and (some) code execution.  When determining the
  version of a module, the C<$VERSION> assignment is C<eval>ed, as is traditional
  in the CPAN toolchain.
  
  =head1 USAGE
  
  =head2 Class methods
  
  =over 4
  
  =item C<< new_from_file($filename, collect_pod => 1) >>
  
  Constructs a C<Module::Metadata> object given the path to a file.  Returns
  undef if the filename does not exist.
  
  C<collect_pod> is a optional boolean argument that determines whether POD
  data is collected and stored for reference.  POD data is not collected by
  default.  POD headings are always collected.
  
  If the file begins by an UTF-8, UTF-16BE or UTF-16LE byte-order mark, then
  it is skipped before processing, and the content of the file is also decoded
  appropriately starting from perl 5.8.
  
  =item C<< new_from_handle($handle, $filename, collect_pod => 1) >>
  
  This works just like C<new_from_file>, except that a handle can be provided
  as the first argument.
  
  Note that there is no validation to confirm that the handle is a handle or
  something that can act like one.  Passing something that isn't a handle will
  cause a exception when trying to read from it.  The C<filename> argument is
  mandatory or undef will be returned.
  
  You are responsible for setting the decoding layers on C<$handle> if
  required.
  
  =item C<< new_from_module($module, collect_pod => 1, inc => \@dirs) >>
  
  Constructs a C<Module::Metadata> object given a module or package name.
  Returns undef if the module cannot be found.
  
  In addition to accepting the C<collect_pod> argument as described above,
  this method accepts a C<inc> argument which is a reference to an array of
  directories to search for the module.  If none are given, the default is
  @INC.
  
  If the file that contains the module begins by an UTF-8, UTF-16BE or
  UTF-16LE byte-order mark, then it is skipped before processing, and the
  content of the file is also decoded appropriately starting from perl 5.8.
  
  =item C<< find_module_by_name($module, \@dirs) >>
  
  Returns the path to a module given the module or package name. A list
  of directories can be passed in as an optional parameter, otherwise
  @INC is searched.
  
  Can be called as either an object or a class method.
  
  =item C<< find_module_dir_by_name($module, \@dirs) >>
  
  Returns the entry in C<@dirs> (or C<@INC> by default) that contains
  the module C<$module>. A list of directories can be passed in as an
  optional parameter, otherwise @INC is searched.
  
  Can be called as either an object or a class method.
  
  =item C<< provides( %options ) >>
  
  This is a convenience wrapper around C<package_versions_from_directory>
  to generate a CPAN META C<provides> data structure.  It takes key/value
  pairs.  Valid option keys include:
  
  =over
  
  =item version B<(required)>
  
  Specifies which version of the L<CPAN::Meta::Spec> should be used as
  the format of the C<provides> output.  Currently only '1.4' and '2'
  are supported (and their format is identical).  This may change in
  the future as the definition of C<provides> changes.
  
  The C<version> option is required.  If it is omitted or if
  an unsupported version is given, then C<provides> will throw an error.
  
  =item dir
  
  Directory to search recursively for F<.pm> files.  May not be specified with
  C<files>.
  
  =item files
  
  Array reference of files to examine.  May not be specified with C<dir>.
  
  =item prefix
  
  String to prepend to the C<file> field of the resulting output. This defaults
  to F<lib>, which is the common case for most CPAN distributions with their
  F<.pm> files in F<lib>.  This option ensures the META information has the
  correct relative path even when the C<dir> or C<files> arguments are
  absolute or have relative paths from a location other than the distribution
  root.
  
  =back
  
  For example, given C<dir> of 'lib' and C<prefix> of 'lib', the return value
  is a hashref of the form:
  
    {
      'Package::Name' => {
        version => '0.123',
        file => 'lib/Package/Name.pm'
      },
      'OtherPackage::Name' => ...
    }
  
  =item C<< package_versions_from_directory($dir, \@files?) >>
  
  Scans C<$dir> for .pm files (unless C<@files> is given, in which case looks
  for those files in C<$dir> - and reads each file for packages and versions,
  returning a hashref of the form:
  
    {
      'Package::Name' => {
        version => '0.123',
        file => 'Package/Name.pm'
      },
      'OtherPackage::Name' => ...
    }
  
  The C<DB> and C<main> packages are always omitted, as are any "private"
  packages that have leading underscores in the namespace (e.g.
  C<Foo::_private>)
  
  Note that the file path is relative to C<$dir> if that is specified.
  This B<must not> be used directly for CPAN META C<provides>.  See
  the C<provides> method instead.
  
  =item C<< log_info (internal) >>
  
  Used internally to perform logging; imported from Log::Contextual if
  Log::Contextual has already been loaded, otherwise simply calls warn.
  
  =back
  
  =head2 Object methods
  
  =over 4
  
  =item C<< name() >>
  
  Returns the name of the package represented by this module. If there
  is more than one package, it makes a best guess based on the
  filename. If it's a script (i.e. not a *.pm) the package name is
  'main'.
  
  =item C<< version($package) >>
  
  Returns the version as defined by the $VERSION variable for the
  package as returned by the C<name> method if no arguments are
  given. If given the name of a package it will attempt to return the
  version of that package if it is specified in the file.
  
  =item C<< filename() >>
  
  Returns the absolute path to the file.
  
  =item C<< packages_inside() >>
  
  Returns a list of packages. Note: this is a raw list of packages
  discovered (or assumed, in the case of C<main>).  It is not
  filtered for C<DB>, C<main> or private packages the way the
  C<provides> method does.  Invalid package names are not returned,
  for example "Foo:Bar".  Strange but valid package names are
  returned, for example "Foo::Bar::", and are left up to the caller
  on how to handle.
  
  =item C<< pod_inside() >>
  
  Returns a list of POD sections.
  
  =item C<< contains_pod() >>
  
  Returns true if there is any POD in the file.
  
  =item C<< pod($section) >>
  
  Returns the POD data in the given section.
  
  =item C<< is_indexable($package) >> or C<< is_indexable() >>
  
  Returns a boolean indicating whether the package (if provided) or any package
  (otherwise) is eligible for indexing by PAUSE, the Perl Authors Upload Server.
  Note This only checks for valid C<package> declarations, and does not take any
  ownership information into account.
  
  =back
  
  =head1 AUTHOR
  
  Original code from Module::Build::ModuleInfo by Ken Williams
  <kwilliams@cpan.org>, Randy W. Sims <RandyS@ThePierianSpring.org>
  
  Released as Module::Metadata by Matt S Trout (mst) <mst@shadowcat.co.uk> with
  assistance from David Golden (xdg) <dagolden@cpan.org>.
  
  =head1 COPYRIGHT & LICENSE
  
  Original code Copyright (c) 2001-2011 Ken Williams.
  Additional code Copyright (c) 2010-2011 Matt Trout and David Golden.
  All rights reserved.
  
  This library is free software; you can redistribute it and/or
  modify it under the same terms as Perl itself.
  
  =cut
  
  