package Sub::Nary;
-use 5.008001;
+use 5.008_001;
use strict;
use warnings;
-use Carp qw/croak/;
-use List::Util qw/reduce sum/;
+use Carp qw<croak>;
-use B qw/class ppname svref_2object OPf_KIDS/;
+use B qw<class ppname svref_2object OPf_KIDS>;
=head1 NAME
=head1 VERSION
-Version 0.01
+Version 0.03
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.01';
+ $VERSION = '0.03';
}
=head1 SYNOPSIS
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<B> 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<B> 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<new>
-The usual constructor. Currently takes no argument.
+ my $sn = Sub::Nary->new;
-=head2 C<nary $coderf>
+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<nary>
+
+ 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<flush>
-Flushes the L<Sub::Nary> object cache. Returns the object itself.
+Flushes the L<Sub::Nary> object cache.
+Returns the object itself.
=head1 PROBABILITY OF RETURN
=over 4
-=item * All the returning points in the same subroutine (i.e. all the explicit C<return> and the last computed value) are considered equally possible.
+=item *
+
+When branching, each branch is considered equally possible.
For example, the subroutine
}
}
-it is considered to return 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), C<2> or C<3> arguments each with probability C<1/3>.
+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 *
-=item * The total probability law for a given returning point is the convolution product of the probabilities of its list elements.
+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
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 * The C<'list'> state is absorbant in regard of all the other ones.
+=item *
+
+If a core function may return different numbers of scalars, each kind is considered equally possible.
+
+For example, C<stat> 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<list> 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
}
is considered as always returning an unbounded list.
-The convolution law also does not behave the same when C<list> elements are involved : in the following example,
+
+Also, the convolution law does not behave the same when C<list> elements are involved : in the following example,
sub oneorlist {
if (rand < 0.1) {
my $sub = shift;
$self->{cv} = [ ];
- return $self->enter(svref_2object($sub));
+ return ($self->enter(svref_2object($sub)))[1];
}
sub name ($) {
+ local $SIG{__DIE__} = \&Carp::confess;
my $n = $_[0]->name;
$n eq 'null' ? substr(ppname($_[0]->targ), 3) : $n
}
-sub combine {
- reduce {{
- my %res;
- my $la = delete $a->{list};
- my $lb = delete $b->{list};
- if (defined $la || defined $lb) {
- $la ||= 0;
- $lb ||= 0;
- $res{list} = $la + $lb - $la * $lb;
- }
- while (my ($ka, $va) = each %$a) {
- $ka = int $ka;
- while (my ($kb, $vb) = each %$b) {
- my $key = $ka + int $kb;
- $res{$key} += $va * $vb;
- }
- }
- \%res
- }} map { (ref) ? $_ : { $_ => 1 } } grep defined, @_;
-}
-
-sub add {
- reduce {
- $a->{$_} += $b->{$_} for keys %$b;
- $a
- } map { (ref) ? $_ : { $_ => 1 } } grep defined, @_;
+sub power {
+ my ($p, $n, $c) = @_;
+ return unless defined $p;
+ return { 0 => $c } unless $n;
+ if ($n eq 'list') {
+ my $z = delete $p->{0};
+ return { 'list' => $c } unless $z;
+ return { 0 => $c } if $z == 1;
+ return { 0 => $c * $z, list => $c * (1 - $z) };
+ }
+ my $r = combine map { { %$p } } 1 .. $n;
+ $r->{$_} *= $c for keys %$r;
+ return $r;
}
my %ops;
+
$ops{$_} = 1 for scalops;
-$ops{$_} = 0 for qw/stub nextstate/;
-$ops{$_} = 1 for qw/padsv/;
-$ops{$_} = 'list' for qw/padav/;
-$ops{$_} = 'list' for qw/padhv rv2hv/;
-$ops{$_} = 'list' for qw/padany flip match entereval/;
+$ops{$_} = 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>;
+
+$ops{each} = { 0 => 0.5, 2 => 0.5 };
+$ops{stat} = { 0 => 0.5, 13 => 0.5 };
+
+$ops{caller} = sub { my @a = caller 0; scalar @a }->();
+$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{$_} = { 0 => 0.5, 4 => 0.5 } for qw<gsbyname gsbyport gservent>;
sub enter {
my ($self, $cv) = @_;
- return 'list' if class($cv) ne 'CV';
+ return undef, 'list' if class($cv) ne 'CV';
my $op = $cv->ROOT;
my $tag = tag($op);
- return { %{$self->{cache}->{$tag}} } if exists $self->{cache}->{$tag};
+ return undef, { %{$self->{cache}->{$tag}} } if exists $self->{cache}->{$tag};
# Anything can happen with recursion
for (@{$self->{cv}}) {
- return 'list' if $tag == tag($_->ROOT);
+ return undef, 'list' if $tag == tag($_->ROOT);
}
unshift @{$self->{cv}}, $cv;
- (my $r, undef) = $self->expect_any($op->first);
+ my $r = add $self->inspect($op->first);
shift @{$self->{cv}};
- $r = { $r => 1} unless ref $r;
- my $total = sum values %$r;
- $r = { map { $_ => $r->{$_} / $total } keys %$r };
$self->{cache}->{$tag} = { %$r };
- return $r;
-}
-
-sub expect_return {
- my ($self, $op) = @_;
-
- return ($self->expect_list($op))[0] => 1 if name($op) eq 'return';
-
- if ($op->flags & OPf_KIDS) {
- for ($op = $op->first; not null $op; $op = $op->sibling) {
- my ($p, $r) = $self->expect_return($op);
- return $p => 1 if $r;
- }
- }
-
- return;
+ return undef, $r;
}
-sub expect_list {
+sub inspect {
my ($self, $op) = @_;
my $n = name($op);
+ return add($self->inspect_kids($op)), undef if $n eq 'return';
+
my $meth = $self->can('pp_' . $n);
return $self->$meth($op) if $meth;
- return $ops{$n} => 0 if exists $ops{$n};
-
- if ($op->flags & OPf_KIDS) {
- my @res = (0);
- my ($p, $r);
- for ($op = $op->first; not null $op; $op = $op->sibling) {
- my $n = name($op);
- next if $n eq 'pushmark';
- if ($n eq 'nextstate'
- and not null(($op = $op->sibling)->sibling)) {
- ($p, $r) = $self->expect_return($op);
- return $p => 1 if $r;
- } else {
- ($p, $r) = $self->expect_any($op);
- return $p => 1 if $r;
- push @res, $p;
- }
- }
- return (combine @res) => 0;
- }
-
- return;
-}
-sub expect_any {
- my ($self, $op) = @_;
-
- return ($self->expect_list($op))[0] => 1 if name($op) eq 'return';
+ if (exists $ops{$n}) {
+ my $l = $ops{$n};
+ $l = { %$l } if ref $l;
+ return undef, $l;
+ }
if (class($op) eq 'LOGOP' and not null $op->first) {
my @res;
- my ($p, $r);
- my $op = $op->first;
- ($p, $r) = $self->expect_return($op);
- return $p => 1 if $r;
+ my $op = $op->first;
+ my ($r1, $l1) = $self->inspect($op);
+ return $r1, $l1 if defined $r1 and zero $l1;
+ my $c = count $l1;
$op = $op->sibling;
- push @res, ($self->expect_any($op))[0];
+ my ($r2, $l2) = $self->inspect($op);
- # If the logop has no else branch, it can also return the *scalar* result of
- # the conditional
$op = $op->sibling;
+ my ($r3, $l3);
if (null $op) {
- push @res, 1;
+ # If the logop has no else branch, it can also return the *scalar* result of
+ # the conditional
+ $l3 = { 1 => 1 };
} else {
- push @res, ($self->expect_any($op))[0];
+ ($r3, $l3) = $self->inspect($op);
}
- return (add @res) => 0;
+ my $r = add $r1, scale $c / 2, add $r2, $r3;
+ my $l = scale $c / 2, add $l2, $l3;
+ return $r, $l
}
- return $self->expect_list($op);
+ return $self->inspect_kids($op);
+}
+
+sub inspect_kids {
+ my ($self, $op) = @_;
+
+ return undef, 0 unless $op->flags & OPf_KIDS;
+
+ $op = $op->first;
+ return undef, 0 if null $op;
+ if (name($op) eq 'pushmark') {
+ $op = $op->sibling;
+ return undef, 0 if null $op;
+ }
+
+ my ($r, @l);
+ my $c = 1;
+ for (; not null $op; $op = $op->sibling) {
+ my $n = name($op);
+ if ($n eq 'nextstate') {
+ @l = ();
+ next;
+ }
+ if ($n eq 'lineseq') {
+ @l = ();
+ $op = $op->first;
+ redo;
+ }
+ my ($rc, $lc) = $self->inspect($op);
+ $c = 1 - count $r;
+ $r = add $r, scale $c, $rc if defined $rc;
+ if (not defined $lc) {
+ @l = ();
+ last;
+ }
+ push @l, scale $c, $lc;
+ }
+
+ my $l = scale +(1 - count $r), normalize combine @l;
+
+ return $r, $l;
}
# Stolen from B::Deparse
}
sub pp_entersub {
- my ($self, $op, $exp) = @_;
+ my ($self, $op) = @_;
- my $next = $op;
- while ($next->flags & OPf_KIDS) {
- $next = $next->first;
- }
- while (not null $next) {
- $op = $next;
- my ($p, $r) = $self->expect_return($op, $exp);
- return $p => 1 if $r;
- $next = $op->sibling;
+ $op = $op->first while $op->flags & OPf_KIDS;
+ # First must be a pushmark
+ $op = $op->sibling;
+ # Next must be non null - at worse it's the rv2cv
+
+ my $r;
+ my $c = 1;
+ for (; not null $op->sibling; $op = $op->sibling) {
+ my ($rc, $lc) = $self->inspect($op);
+ return $rc, $lc if defined $rc and not defined $lc;
+ $r = add $r, scale $c, $rc;
+ $c *= count $lc;
}
if (name($op) eq 'rv2cv') {
$next = $next->sibling;
}
$n = name($op)
- } while ($op->flags & OPf_KIDS and { map { $_ => 1 } qw/null leave/ }->{$n});
- return 'list' unless { map { $_ => 1 } qw/gv refgen/ }->{$n};
+ } while ($op->flags & OPf_KIDS and { map { $_ => 1 } qw<null leave> }->{$n});
+ return 'list', undef unless { map { $_ => 1 } qw<gv refgen> }->{$n};
local $self->{sub} = 1;
- return $self->expect_any($op, $exp);
+ my ($rc, $lc) = $self->inspect($op);
+ return $r, scale $c, $lc;
} else {
# Method call ?
- return 'list';
+ return $r, { 'list' => $c };
}
}
sub pp_gv {
my ($self, $op) = @_;
- return $self->{sub} ? $self->enter($self->gv_or_padgv($op)->CV) : 1
+ return $self->{sub} ? $self->enter($self->gv_or_padgv($op)->CV) : (undef, 1)
}
sub pp_anoncode {
my ($self, $op) = @_;
- return $self->{sub} ? $self->enter($self->const_sv($op)) : 1
+ return $self->{sub} ? $self->enter($self->const_sv($op)) : (undef, 1)
}
sub pp_goto {
$n = $nn;
}
- return 'list';
+ return undef, 'list';
}
sub pp_const {
my ($self, $op) = @_;
- if (class($op) eq 'SVOP' and (my $sv = $self->const_sv($op))) {
- my $c = class($sv);
- if ($c eq 'AV') {
- return $sv->FILL + 1;
- } elsif ($c eq 'HV') {
- return 2 * $sv->FILL;
- }
+ return undef, 0 unless $op->isa('B::SVOP');
+
+ my $sv = $self->const_sv($op);
+ my $n = 1;
+ my $c = class($sv);
+ if ($c eq 'AV') {
+ $n = $sv->FILL + 1
+ } elsif ($c eq 'HV') {
+ $n = 2 * $sv->KEYS
}
- return 1;
+ return undef, $n
}
-sub pp_aslice { $_[0]->expect_any($_[1]->first->sibling) }
+sub pp_aslice { $_[0]->inspect($_[1]->first->sibling) }
sub pp_hslice;
*pp_hslice = *pp_aslice{CODE};
-sub pp_lslice { $_[0]->expect_any($_[1]->first) }
+sub pp_lslice { $_[0]->inspect($_[1]->first) }
sub pp_rv2av {
my ($self, $op) = @_;
$op = $op->first;
- return (name($op) eq 'const') ? $self->expect_any($op) : 'list';
+ if (name($op) eq 'gv') {
+ return undef, { list => 1 };
+ }
+
+ $self->inspect($op);
}
-sub pp_aassign { $_[0]->expect_any($_[1]->first) }
+sub pp_sassign {
+ my ($self, $op) = @_;
+
+ my $r = ($self->inspect($op->first))[0];
+
+ my $c = 1 - count $r;
+ return $r, $c ? { 1 => $c } : undef
+}
+
+sub pp_aassign {
+ my ($self, $op) = @_;
-sub pp_leaveloop { $_[0]->expect_return($_[1]->first->sibling) }
+ $op = $op->first;
+
+ # Can't assign to return
+ my $l = ($self->inspect($op->sibling))[1];
+ return undef, $l if not exists $l->{list};
+
+ $self->inspect($op);
+}
+
+sub pp_leaveloop {
+ my ($self, $op) = @_;
+
+ $op = $op->first;
+ my ($r1, $l1);
+ my $for;
+ if (name($op) eq 'enteriter') { # for loop ?
+ $for = 1;
+ ($r1, $l1) = $self->inspect($op);
+ return $r1, $l1 if defined $r1 and zero $l1;
+ }
+
+ $op = $op->sibling;
+ my ($r2, $l2);
+ if (name($op->first) eq 'and') {
+ ($r2, $l2) = $self->inspect($op->first->first);
+ return $r2, $l2 if defined $r2 and zero $l2;
+ my $c = count $l2;
+ return { list => 1 }, undef if !$for and defined $r2;
+ my ($r3, $l3) = $self->inspect($op->first->first->sibling);
+ return { list => 1 }, undef if defined $r3 and defined $l3;
+ $r2 = add $r2, scale $c, $r3;
+ } else {
+ ($r2, $l2) = $self->inspect($op);
+ return { list => 1 }, undef if defined $r2 and defined $l2;
+ }
+
+ my $r = (defined $r1) ? add $r1, scale +(1 - count $r1), $r2
+ : $r2;
+ my $c = 1 - count $r;
+ return $r, $c ? { 0 => $c } : undef;
+}
+
+sub pp_flip {
+ my ($self, $op) = @_;
+
+ $op = $op->first;
+ return $self->inspect($op) if name($op) ne 'range';
+
+ my ($r, $l);
+ my $begin = $op->first;
+ if (name($begin) eq 'const') {
+ my $end = $begin->sibling;
+ if (name($end) eq 'const') {
+ $begin = $self->const_sv($begin);
+ $end = $self->const_sv($end);
+ {
+ no warnings 'numeric';
+ $begin = int ${$begin->object_2svref};
+ $end = int ${$end->object_2svref};
+ }
+ return undef, $end - $begin + 1;
+ } else {
+ ($r, $l) = $self->inspect($end);
+ }
+ } else {
+ ($r, $l) = $self->inspect($begin);
+ }
+
+ my $c = 1 - count $r;
+ return $r, $c ? { 'list' => $c } : undef
+}
+
+sub pp_grepwhile {
+ my ($self, $op) = @_;
+
+ $op = $op->first;
+ return $self->inspect($op) if name($op) ne 'grepstart';
+ $op = $op->first->sibling;
+
+ my ($r2, $l2) = $self->inspect($op->sibling);
+ return $r2, $l2 if defined $r2 and zero $l2;
+ my $c2 = count $l2; # First one to happen
+
+ my ($r1, $l1) = $self->inspect($op);
+ return (add $r2, scale $c2, $r1), undef if defined $r1 and zero $l1
+ and not zero $l2;
+ my $c1 = count $l1;
+
+ $l2 = { $l2 => 1 } unless ref $l2;
+ my $r = add $r2,
+ scale $c2,
+ add map { scale $l2->{$_}, cumulate $r1, $_, $c1 } keys %$l2;
+ my $c = 1 - count $r;
+ return $r, $c ? { ((zero $l2) ? 0 : 'list') => $c } : undef;
+}
+
+sub pp_mapwhile {
+ my ($self, $op) = @_;
+
+ $op = $op->first;
+ return $self->inspect($op) if name($op) ne 'mapstart';
+ $op = $op->first->sibling;
+
+ my ($r2, $l2) = $self->inspect($op->sibling);
+ return $r2, $l2 if defined $r2 and zero $l2;
+ my $c2 = count $l2; # First one to happen
+
+ my ($r1, $l1) = $self->inspect($op);
+ return (add $r2, scale $c2, $r1), undef if defined $r1 and zero $l1
+ and not zero $l2;
+ my $c1 = count $l1;
+
+ $l2 = { $l2 => 1 } unless ref $l2;
+ my $r = add $r2,
+ scale $c2,
+ add map { scale $l2->{$_}, cumulate $r1, $_, $c1 } keys %$l2;
+ my $c = 1 - count $r;
+ my $l = scale $c, normalize add map { power $l1, $_, $l2->{$_} } keys %$l2;
+ return $r, $l;
+}
=head1 EXPORT
L<perl> 5.8.1.
-L<Carp> (standard since perl 5), L<B> (since perl 5.005), L<XSLoader> (since perl 5.006) and L<List::Util> (since perl 5.007003).
+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<Carp> (standard since perl 5), L<B> (since perl 5.005) and L<XSLoader> (since perl 5.6.0).
=head1 AUTHOR
Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
-You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).
+You can contact me by mail or on C<irc.perl.org> (vincent).
=head1 BUGS
-Please report any bugs or feature requests to C<bug-b-nary at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Nary>. 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<bug-sub-nary at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Nary>.
+I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
=head1 SUPPORT
projects / perl / modules / Sub-Nary.git / blobdiff