perl/Git/SVN/Memoize/YAML.pm

   1 package Git::SVN::Memoize::YAML;
   2 use warnings $ENV{GIT_PERL_FATAL_WARNINGS} ? qw(FATAL all) : ();
   3 use strict;
   4 use YAML::Any ();
   5
   6 # based on Memoize::Storable.
   7
   8 sub TIEHASH {
   9         my $package = shift;
  10         my $filename = shift;
  11         my $truehash = (-e $filename) ? YAML::Any::LoadFile($filename) : {};
  12         my $self = {FILENAME => $filename, H => $truehash};
  13         bless $self => $package;
  14 }
  15
  16 sub STORE {
  17         my $self = shift;
  18         $self->{H}{$_[0]} = $_[1];
  19 }
  20
  21 sub FETCH {
  22         my $self = shift;
  23         $self->{H}{$_[0]};
  24 }
  25
  26 sub EXISTS {
  27         my $self = shift;
  28         exists $self->{H}{$_[0]};
  29 }
  30
  31 sub DESTROY {
  32         my $self = shift;
  33         YAML::Any::DumpFile($self->{FILENAME}, $self->{H});
  34 }
  35
  36 sub SCALAR {
  37         my $self = shift;
  38         scalar(%{$self->{H}});
  39 }
  40
  41 sub FIRSTKEY {
  42         'Fake hash from Git::SVN::Memoize::YAML';
  43 }
  44
  45 sub NEXTKEY {
  46         undef;
  47 }
  48
  49 1;
  50 __END__
  51
  52 =head1 NAME
  53
  54 Git::SVN::Memoize::YAML - store Memoized data in YAML format
  55
  56 =head1 SYNOPSIS
  57
  58     use Memoize;
  59     use Git::SVN::Memoize::YAML;
  60
  61     tie my %cache => 'Git::SVN::Memoize::YAML', $filename;
  62     memoize('slow_function', SCALAR_CACHE => [HASH => \%cache]);
  63     slow_function(arguments);
  64
  65 =head1 DESCRIPTION
  66
  67 This module provides a class that can be used to tie a hash to a
  68 YAML file.  The file is read when the hash is initialized and
  69 rewritten when the hash is destroyed.
  70
  71 The intent is to allow L<Memoize> to back its cache with a file in
  72 YAML format, just like L<Memoize::Storable> allows L<Memoize> to
  73 back its cache with a file in Storable format.  Unlike the Storable
  74 format, the YAML format is platform-independent and fairly stable.
  75
  76 Carps on error.
  77
  78 =head1 DIAGNOSTICS
  79
  80 See L<YAML::Any>.
  81
  82 =head1 DEPENDENCIES
  83
  84 L<YAML::Any> from CPAN.
  85
  86 =head1 INCOMPATIBILITIES
  87
  88 None reported.
  89
  90 =head1 BUGS
  91
  92 The entire cache is read into a Perl hash when loading the file,
  93 so this is not very scalable.