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=head1 NAME |
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|
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Coro::Cont - continuations in perl |
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|
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=head1 SYNOPSIS |
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|
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use Coro::Cont; |
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|
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# multiply all hash keys by 2 |
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my $cont = csub { |
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yield $_*2; |
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yield $_; |
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}; |
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my %hash2 = map &$cont, %hash1; |
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|
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# dasselbe in grün (as the germans say) |
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sub mul2 : Cont { |
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yield $_[0]*2; |
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yield $_[0]; |
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} |
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|
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my %hash2 = map mul2($_), %hash1; |
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|
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=head1 DESCRIPTION |
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|
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=over 4 |
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|
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=cut |
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|
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package Coro::Cont; |
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|
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BEGIN { eval { require warnings } && warnings->unimport } |
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|
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use Carp qw(croak); |
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|
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use Coro::State; |
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|
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use vars qw($return); |
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|
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use base 'Exporter'; |
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|
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$VERSION = 1.9; |
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@EXPORT = qw(csub yield); |
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|
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{ |
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my @csub; |
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|
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# this way of handling attributes simply is NOT scalable ;() |
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sub import { |
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Coro::Cont->export_to_level(1, @_); |
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my $old = *{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"}{CODE}; |
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*{(caller)[0]."::MODIFY_CODE_ATTRIBUTES"} = sub { |
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my ($package, $ref) = (shift, shift); |
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my @attrs; |
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for (@_) { |
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if ($_ eq "Cont") { |
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push @csub, [$package, $ref]; |
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} else { |
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push @attrs, $_; |
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} |
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} |
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return $old ? $old->($package, $ref, @attrs) : @attrs; |
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}; |
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} |
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|
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sub findsym { |
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my ($pkg, $ref) = @_; |
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my $type = ref $ref; |
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for my $sym (values %{$pkg."::"}) { |
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return \$sym if *{$sym}{$type} == $ref; |
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} |
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(); |
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} |
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|
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sub INIT { |
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# prototypes are currently being ignored |
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for (@csub) { |
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my $ref = findsym(@$_) |
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or croak "package $package: cannot declare non-global subs as 'Cont'"; |
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*$ref = &csub($_->[1]); |
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} |
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@csub = (); |
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} |
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} |
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|
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=item csub { ... } |
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|
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Create a new "continuation" (when the sub falls off the end it is being |
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terminated). |
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|
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=cut |
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|
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sub csub(&) { |
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my $code = $_[0]; |
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my $prev = new Coro::State; |
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|
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my $coro = new Coro::State sub { |
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# we do this superfluous switch just to |
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# avoid the parameter passing problem |
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# on the first call |
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&yield; |
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&$code while 1; |
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}; |
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|
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# call it once |
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push @{ $Coro::current->{yieldstack} }, [$coro, $prev]; |
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Coro::State::transfer ($prev, $coro, 0); |
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|
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sub { |
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push @{ $Coro::current->{yieldstack} }, [$coro, $prev]; |
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Coro::State::transfer ($prev, $coro, 0); |
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wantarray ? @_ : $_[0]; |
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}; |
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} |
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|
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=item @_ = yield [list] |
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|
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Return the given list/scalar as result of the continuation. Also returns |
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the new arguments given to the subroutine on the next call. |
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|
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=cut |
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|
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# implemented in Coro/State.xs |
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#sub yield(@) { |
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# &Coro::State::transfer(@{pop @$$return}, 0); |
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# wantarray ? @_ : $_[0]; |
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#} |
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|
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1; |
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|
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=back |
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|
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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|
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=cut |
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|
