# -*- perl -*- ############################################################### # # MiniMemoize.pm # # Memoizing demonstration module # Copyright 1999 M-J. Dominus (mjd-tpj-memoize@plover.com) # For details and explanation, see # http://www.plover.com/~mjd/perl/MiniMemoize/ # # For a full-strength memoization module, see # http://www.plover.com/~mjd/perl/Memoize/ # ############################################################### package MiniMemoize; use Exporter; @ISA = qw(Exporter); @EXPORT = qw(memoize); use strict; my %memotable; sub memoize { my $function = shift; my $caller = caller; my $funcname; if (ref $function eq '') { # Convert to code reference $function = $caller . "::$function" unless $function =~ /::/; $funcname = $function; no strict 'refs'; $function = \&$function; } my $wrapper = eval qq{sub { _check_cache("$function", \@_) }}; $memotable{$function} = { original => $function, memoized => $wrapper, cache => { }, }; { no strict 'refs'; *{$funcname} = $wrapper if defined $funcname; } 1; } sub _check_cache { my $what_func = shift; unless (exists $memotable{$what_func}) { # This `should never happen' croak("Tried to check cache of non-memoized function `$what_func'; aborting"); } my $cache = $memotable{$what_func}{cache}; my $argstr = join $;, @_; if (exists $cache->{$argstr}) { return $cache->{$argstr} } my $real_function = $memotable{$what_func}{original}; $cache->{$argstr} = $real_function->(@_); } 1;