X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FSub%2FNary.pm;h=de42e73576a67eba931eca0956f58f4a9ccc08d5;hb=790ba71f0305951a6d7bb04ca02a1dad7563f439;hp=1406d6695dbde7f89ce4e62c52177c039a34cef4;hpb=429a59ef0920be32c4263b67fc0a32b542ae34be;p=perl%2Fmodules%2FSub-Nary.git diff --git a/lib/Sub/Nary.pm b/lib/Sub/Nary.pm index 1406d66..de42e73 100644 --- a/lib/Sub/Nary.pm +++ b/lib/Sub/Nary.pm @@ -1,13 +1,13 @@ package Sub::Nary; -use 5.008001; +use 5.008_001; use strict; use warnings; -use Carp qw/croak/; +use Carp qw; -use B qw/class ppname svref_2object OPf_KIDS/; +use B qw; =head1 NAME @@ -28,30 +28,41 @@ BEGIN { use Sub::Nary; - my $sn = Sub::Nary->new(); + my $sn = Sub::Nary->new; my $r = $sn->nary(\&hlagh); =head1 DESCRIPTION -This module uses the L framework to walk into subroutines and try to guess how many scalars are likely to be returned in list context. It's not always possible to give a definitive answer to this question at compile time, so the results are given in terms of "probability of return" (to be understood in a sense described below). +This module uses the L framework to walk into subroutines and try to guess how many scalars are likely to be returned in list context. +It's not always possible to give a definitive answer to this question at compile time, so the results are given in terms of "probability of return" (to be understood in a sense described below). =head1 METHODS =head2 C -The usual constructor. Currently takes no argument. + my $sn = Sub::Nary->new; -=head2 C +The usual constructor. +Currently takes no argument. -Takes a code reference to a named or anonymous subroutine, and returns a hash reference whose keys are the possible numbers of returning scalars, and the corresponding values the "probability" to get them. The special key C<'list'> is used to denote a possibly infinite number of returned arguments. The return value hence would look at +=head2 C + + my $res = $sn->nary($coderef); + +Takes a reference to a named or anonymous subroutine, and returns a hash reference whose keys are the possible numbers of returning scalars, and the corresponding values the "probability" to get them. +The special key C<'list'> is used to denote a possibly infinite number of returned arguments. +The return value hence would look at { 1 => 0.2, 2 => 0.4, 4 => 0.3, list => 0.1 } -that is, we should get C<1> scalar C<1> time over C<5> and so on. The sum of all values is C<1>. The returned result, and all the results obtained from intermediate subs, are cached into the object. +that is, we should get C<1> scalar C<1> time over C<5> and so on. +The sum of all values is C<1>. +The returned result, and all the results obtained from intermediate subs, are cached into the object. =head2 C -Flushes the L object cache. Returns the object itself. +Flushes the L object cache. +Returns the object itself. =head1 PROBABILITY OF RETURN @@ -59,7 +70,9 @@ The probability is computed as such : =over 4 -=item * When branching, each branch is considered equally possible. +=item * + +When branching, each branch is considered equally possible. For example, the subroutine @@ -85,9 +98,11 @@ As for it is considered to return C<3> scalars with probability C<1/2>, C<2> with probability C<1/2 * 1/2 = 1/4> and C<1> (when the two tests fail, the last computed value is returned, which here is C<< $x > 0.9 >> evaluated in the scalar context of the test) with remaining probability C<1/4>. -=item * The total probability law for a given returning point is the convolution product of the probabilities of its list elements. +=item * + +The total probability law for a given returning point is the convolution product of the probabilities of its list elements. -As such, +As such, sub notsosimple { return 1, simple(), 2 @@ -101,11 +116,16 @@ returns C<3> or C<4> arguments with probability C<1/2> ; and never returns C<1> argument but returns C<2> with probability C<1/2 * 1/2 = 1/4>, C<3> with probability C<1/2 * 1/2 + 1/2 * 1/2 = 1/2> and C<4> with probability C<1/4> too. -=item * If a core function may return different numbers of scalars, each kind is considered equally possible. +=item * -For example, C returns C<13> elements on success and C<0> on error. The according probability will then be C<< { 0 => 0.5, 13 => 0.5 } >>. +If a core function may return different numbers of scalars, each kind is considered equally possible. -=item * The C state is absorbing in regard of all the other ones. +For example, C returns C<13> elements on success and C<0> on error. +The according probability will then be C<< { 0 => 0.5, 13 => 0.5 } >>. + +=item * + +The C state is absorbing in regard of all the other ones. This is just a pedantic way to say that "list + fixed length = list". That's why @@ -191,12 +211,12 @@ sub power { my %ops; $ops{$_} = 1 for scalops; -$ops{$_} = 0 for qw/stub nextstate pushmark iter unstack/; -$ops{$_} = 1 for qw/padsv/; -$ops{$_} = 'list' for qw/padav/; -$ops{$_} = 'list' for qw/padhv rv2hv/; -$ops{$_} = 'list' for qw/padany/; -$ops{$_} = 'list' for qw/match entereval readline/; +$ops{$_} = 0 for qw; +$ops{$_} = 1 for qw; +$ops{$_} = 'list' for qw; +$ops{$_} = 'list' for qw; +$ops{$_} = 'list' for qw; +$ops{$_} = 'list' for qw; $ops{each} = { 0 => 0.5, 2 => 0.5 }; $ops{stat} = { 0 => 0.5, 13 => 0.5 }; @@ -205,12 +225,12 @@ $ops{caller} = sub { my @a = caller 0; scalar @a }->(); $ops{localtime} = do { my @a = localtime; scalar @a }; $ops{gmtime} = do { my @a = gmtime; scalar @a }; -$ops{$_} = { 0 => 0.5, 10 => 0.5 } for map "gpw$_", qw/nam uid ent/; -$ops{$_} = { 0 => 0.5, 4 => 0.5 } for map "ggr$_", qw/nam gid ent/; -$ops{$_} = 'list' for qw/ghbyname ghbyaddr ghostent/; -$ops{$_} = { 0 => 0.5, 4 => 0.5 } for qw/gnbyname gnbyaddr gnetent/; -$ops{$_} = { 0 => 0.5, 3 => 0.5 } for qw/gpbyname gpbynumber gprotoent/; -$ops{$_} = { 0 => 0.5, 4 => 0.5 } for qw/gsbyname gsbyport gservent/; +$ops{$_} = { 0 => 0.5, 10 => 0.5 } for map "gpw$_", qw; +$ops{$_} = { 0 => 0.5, 4 => 0.5 } for map "ggr$_", qw; +$ops{$_} = 'list' for qw; +$ops{$_} = { 0 => 0.5, 4 => 0.5 } for qw; +$ops{$_} = { 0 => 0.5, 3 => 0.5 } for qw; +$ops{$_} = { 0 => 0.5, 4 => 0.5 } for qw; sub enter { my ($self, $cv) = @_; @@ -366,8 +386,8 @@ sub pp_entersub { $next = $next->sibling; } $n = name($op) - } while ($op->flags & OPf_KIDS and { map { $_ => 1 } qw/null leave/ }->{$n}); - return 'list', undef unless { map { $_ => 1 } qw/gv refgen/ }->{$n}; + } while ($op->flags & OPf_KIDS and { map { $_ => 1 } qw }->{$n}); + return 'list', undef unless { map { $_ => 1 } qw }->{$n}; local $self->{sub} = 1; my ($rc, $lc) = $self->inspect($op); return $r, scale $c, $lc; @@ -592,17 +612,21 @@ C isn't specialized when encountered in the optree. L 5.8.1. -L (standard since perl 5), L (since perl 5.005) and L (since perl 5.006). +A C compiler. +This module may happen to build with a C++ compiler as well, but don't rely on it, as no guarantee is made in this regard. + +L (standard since perl 5), L (since perl 5.005) and L (since perl 5.6.0). =head1 AUTHOR Vincent Pit, C<< >>, L. -You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince). +You can contact me by mail or on C (vincent). =head1 BUGS -Please report any bugs or feature requests to C, or through the web interface at L. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. +Please report any bugs or feature requests to C, or through the web interface at L. +I will be notified, and then you'll automatically be notified of progress on your bug as I make changes. =head1 SUPPORT