use warnings;
use Carp qw/croak/;
-use List::Util qw/reduce/;
use B qw/class ppname svref_2object OPf_KIDS/;
-use Test::More; use Data::Dumper;
-
=head1 NAME
Sub::Nary - Try to count how many elements a subroutine can return in list context.
=head1 VERSION
-Version 0.02
+Version 0.03
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.02';
+ $VERSION = '0.03';
}
-our $DEBUG = 0;
-
=head1 SYNOPSIS
use Sub::Nary;
=head2 C<nary $coderef>
-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
+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. A few special keys are also used :
+
+=over 4
+
+=item *
+
+C<'list'> is used to denote a possibly infinite number of returned arguments ;
+
+=item *
+
+C<'exit'> gives the probability for C<exit> to be called somewhere in the code.
+
+=back
+
+The return value hence would look at
- { 1 => 0.2, 2 => 0.4, 4 => 0.3, list => 0.1 }
+ { 1 => 0.2, 2 => 0.4, 4 => 0.25, list => 0.1, exit => 0.05 }
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.
=over 4
-=item * When branching, each branch is considered equally possible.
+=item *
+
+When branching, each branch is considered equally possible.
For example, the subroutine
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,
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 *
+
+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.
+=item *
+
+The C<list> and C<exit> states are absorbing in regard of all the other ones.
-This is just a pedantic way to say that "list + fixed length = list".
+This is just a pedantic way to say that C<list + fixed length = list>, C<exit + fixed length = exit>, but note also that C<exit + list = exit>.
That's why
sub listy {
is considered as always returning an unbounded list.
-Also, the convolution law 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> or C<exit> elements are involved : in the following example,
sub oneorlist {
if (rand < 0.1) {
$n eq 'null' ? substr(ppname($_[0]->targ), 3) : $n
}
-sub normalize ($) {
- my $r = $_[0];
- return unless defined $r;
- return { 0 => 1 } unless keys %$r;
- my $total = count $r;
- return { map { $_ => $r->{$_} / $total } keys %$r };
-}
-
-sub scale {
- my ($c, $r) = @_;
- return unless defined $r;
- return (ref $r) ? { map { $_ => $r->{$_} * $c } keys %$r } : { $r => $c };
-}
-
-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) ? $_ : { $_ => 1 } } grep defined, @_;
-}
-
sub power {
my ($p, $n, $c) = @_;
return unless defined $p;
return $r;
}
-sub add {
- reduce {
- $a->{$_} += $b->{$_} for keys %$b;
- $a
- } map { (ref) ? $_ : { $_ => 1 } } grep defined, @_;
-}
-
my %ops;
$ops{$_} = 1 for scalops;
-$ops{$_} = 0 for qw/stub nextstate pushmark iter unstack/;
+$ops{$_} = 0 for qw/stub nextstate iter unstack/;
$ops{$_} = 1 for qw/padsv/;
$ops{$_} = 'list' for qw/padav/;
$ops{$_} = 'list' for qw/padhv rv2hv/;
$ops{$_} = { 0 => 0.5, 3 => 0.5 } for qw/gpbyname gpbynumber gprotoent/;
$ops{$_} = { 0 => 0.5, 4 => 0.5 } for qw/gsbyname gsbyport gservent/;
+# Stolen from B::Deparse
+
+sub padval { $_[0]->{cv}->[0]->PADLIST->ARRAYelt(1)->ARRAYelt($_[1]) }
+
+sub gv_or_padgv {
+ my ($self, $op) = @_;
+ if (class($op) eq 'PADOP') {
+ return $self->padval($op->padix)
+ } else { # class($op) eq "SVOP"
+ return $op->gv;
+ }
+}
+
+sub const_sv {
+ my ($self, $op) = @_;
+ my $sv = $op->sv;
+ # the constant could be in the pad (under useithreads)
+ $sv = $self->padval($op->targ) unless $$sv;
+ return $sv;
+}
+
sub enter {
my ($self, $cv) = @_;
return undef, 'list' if class($cv) ne 'CV';
my $op = $cv->ROOT;
+ return undef, 'list' if null $op;
my $tag = tag($op);
return undef, { %{$self->{cache}->{$tag}} } if exists $self->{cache}->{$tag};
my $r = add $self->inspect($op->first);
shift @{$self->{cv}};
- $r = { $r => 1 } unless ref $r;
$self->{cache}->{$tag} = { %$r };
return undef, $r;
}
+use Test::More;
+use Data::Dumper;
+
sub inspect {
my ($self, $op) = @_;
my $n = name($op);
- diag "@ $n" if $DEBUG;
- return add($self->inspect_kids($op)), undef if $n eq 'return';
-
my $meth = $self->can('pp_' . $n);
return $self->$meth($op) if $meth;
+ my $l;
if (exists $ops{$n}) {
- my $l = $ops{$n};
+ $l = $ops{$n};
$l = { %$l } if ref $l;
- return undef, $l;
}
- if (class($op) eq 'LOGOP' and not null $op->first) {
- my @res;
+ my $c = class($op);
+ $meth = $self->can('OPc_' . $c);
+ if ($meth) {
+ my ($r, $lc) = $self->$meth($op);
+ $lc = $l if defined $l;
+ return $r, $lc;
+ }
- diag "? logop\n" if $DEBUG;
+ return undef, (defined $l) ? $l : 0;
+}
- my $op = $op->first;
- my ($r1, $l1) = $self->inspect($op);
- return $r1, $l1 if $r1 and zero $l1;
- my $c = count $l1;
+# UNOPs
- $op = $op->sibling;
- my ($r2, $l2) = $self->inspect($op);
+sub OPc_UNOP { $_[0]->inspect($_[1]->first); }
- $op = $op->sibling;
- my ($r3, $l3);
- if (null $op) {
- # If the logop has no else branch, it can also return the *scalar* result of
- # the conditional
- $l3 = { 1 => $c };
- } else {
- ($r3, $l3) = $self->inspect($op);
- }
+# BINOPs
- my $r = add $r1, scale $c / 2, add $r2, $r3;
- my $l = scale $c / 2, add $l2, $l3;
- return $r, $l
- }
+sub OPc_BINOP {
+ my ($self, $op) = @_;
+
+ my ($r, $l1) = $self->inspect($op->first);
+ return $r, $l1 unless defined $l1;
- return $self->inspect_kids($op);
+ my ($r2, $l2) = $self->inspect($op->last);
+ my $c = 1 - count $r;
+ $r = add $r, scale $c, $r2 if defined $r2;
+
+ my $l = scale +(1 - count $r), normalize combine $l1, $l2;
+
+ return $r, $l;
}
-sub inspect_kids {
+# LOGOPs
+
+sub OPc_LOGOP {
my ($self, $op) = @_;
+ my @res;
+
+ $op = $op->first;
+ return undef, 0 if null $op;
+
+ my ($r1, $l1) = $self->inspect($op);
+ return $r1, $l1 if defined $r1 and zero $l1;
+ my $c = count $l1;
- return undef, 0 unless $op->flags & OPf_KIDS;
+ $op = $op->sibling;
+ my ($r2, $l2) = $self->inspect($op);
+
+ $op = $op->sibling;
+ my ($r3, $l3);
+ if (null $op) {
+ # If the logop has no else branch, it can also return the *scalar* result of
+ # the conditional
+ $l3 = { 1 => 1 };
+ } else {
+ ($r3, $l3) = $self->inspect($op);
+ }
+
+ my $r = add $r1, scale $c / 2, add $r2, $r3;
+ my $l = scale $c / 2, add $l2, $l3;
+ return $r, $l;
+
+ return $self->OPc_LISTOP($op);
+}
+
+# LISTOPs
+
+sub OPc_LISTOP {
+ my ($self, $op) = @_;
$op = $op->first;
return undef, 0 if null $op;
$op = $op->first;
redo;
}
- diag "> $n ($c)" if $DEBUG;
my ($rc, $lc) = $self->inspect($op);
+ $c = 1 - count $r;
$r = add $r, scale $c, $rc if defined $rc;
- if ($rc and not defined $lc) {
+ if (not defined $lc) {
@l = ();
last;
}
push @l, scale $c, $lc;
- $c *= count $lc if defined $lc;
}
- my $l = combine @l;
+ my $l = scale +(1 - count $r), normalize combine @l;
return $r, $l;
}
-# Stolen from B::Deparse
-
-sub padval { $_[0]->{cv}->[0]->PADLIST->ARRAYelt(1)->ARRAYelt($_[1]) }
-
-sub gv_or_padgv {
- my ($self, $op) = @_;
- if (class($op) eq 'PADOP') {
- return $self->padval($op->padix)
- } else { # class($op) eq "SVOP"
- return $op->gv;
- }
-}
-
-sub const_sv {
- my ($self, $op) = @_;
- my $sv = $op->sv;
- # the constant could be in the pad (under useithreads)
- $sv = $self->padval($op->targ) unless $$sv;
- return $sv;
-}
+sub pp_return { add($_[0]->OPc_LISTOP($_[1])), undef }
sub pp_entersub {
my ($self, $op) = @_;
$op = $op->first while $op->flags & OPf_KIDS;
- return undef, 0 if null $op;
- if (name($op) eq 'pushmark') {
- $op = $op->sibling;
- return undef, 0 if null $op;
- }
+ # 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 $n = name($op);
- next if $n eq 'nextstate';
- diag "* $n" if $DEBUG;
my ($rc, $lc) = $self->inspect($op);
- $r = add $r, scale $c, $rc if defined $rc;
- if (zero $lc) {
- $c = 1 - count $r;
- return $r, $c ? { 0 => $c } : undef
- }
+ return $rc, $lc if defined $rc and not defined $lc;
+ $r = add $r, scale $c, $rc;
$c *= count $lc;
}
$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 $op->flags & OPf_KIDS and ($n eq 'null' or $n eq 'leave');
+ return 'list', undef unless $n eq 'gv' or $n eq 'refgen';
local $self->{sub} = 1;
my ($rc, $lc) = $self->inspect($op);
return $r, scale $c, $lc;
return $self->{sub} ? $self->enter($self->const_sv($op)) : (undef, 1)
}
+sub pp_exit {
+ my ($self, $op) = @_;
+
+ my $r;
+ if ($op->flags & OPf_KIDS) {
+ ($r, my $l) = $self->inspect($op->first);
+ return $r, $l if defined $r and zero $l;
+ $r->{exit} = 1 - count $r;
+ } else {
+ $r = { 'exit' => 1 };
+ }
+
+ return $r, undef;
+}
+
+sub pp_die {
+ my ($self, $op) = @_;
+
+ my ($r, undef) = $self->OPc_LISTOP($op);
+ if (defined $r) {
+ my $c = 1 - count $r;
+ $r->{die} = $c if $c;
+ } else {
+ $r = { die => 1 };
+ }
+
+ return $r, undef;
+}
+
sub pp_goto {
my ($self, $op) = @_;
if ($c eq 'AV') {
$n = $sv->FILL + 1
} elsif ($c eq 'HV') {
- $n = 2 * $sv->FILL
+ $n = 2 * $sv->KEYS
}
return undef, $n
my ($self, $op) = @_;
$op = $op->first;
- my ($r, $l) = $self->inspect($op);
- if (name($op) ne 'const') {
- my $c = 1 - count $r;
- $l = $c ? { list => $c } : 0;
+ if (name($op) eq 'gv') {
+ return undef, { list => 1 };
}
- return $r, $l;
+
+ $self->inspect($op);
+}
+
+sub pp_sassign {
+ my ($self, $op) = @_;
+
+ my $r = ($self->inspect($op->first))[0];
+
+ my $c = 1 - count $r;
+ return $r, $c ? { 1 => $c } : undef
}
+=cut
+
sub pp_aassign {
my ($self, $op) = @_;
$self->inspect($op);
}
-sub pp_leaveloop {
+=cut
+
+sub pp_leavetry {
my ($self, $op) = @_;
- diag "* leaveloop" if $DEBUG;
+ my ($r, $l) = $self->OPc_LISTOP($op);
+ if (defined $r) {
+ my $d = delete $r->{die};
+ return $r, $l if not defined $d;
+ if (defined $l) {
+ my $z = delete $l->{0};
+ $l = { %$l, 0 => $z };
+ $l->{0} += $d;
+ } else {
+ $l = { 0 => $d };
+ }
+ }
+
+ return $r, $l;
+}
+
+sub pp_leaveloop {
+ my ($self, $op) = @_;
$op = $op->first;
my ($r1, $l1);
- if (name($op) eq 'enteriter') {
+ my $for;
+ if (name($op) eq 'enteriter') { # for loop ?
+ $for = 1;
($r1, $l1) = $self->inspect($op);
- return $r1, $l1 if $r1 and zero $l1;
+ return $r1, $l1 if defined $r1 and zero $l1;
}
$op = $op->sibling;
- my $r = (name($op->first) eq 'and') ? ($self->inspect($op->first->first->sibling))[0]
- : ($self->inspect($op))[0];
+ 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;
- diag "& leaveloop" if $DEBUG;
return $r, $c ? { 0 => $c } : undef;
}
}
my $c = 1 - count $r;
- return $r, ($l && $c) ? { 'list' => $c } : undef
+ return $r, $c ? { 'list' => $c } : undef
}
sub pp_grepwhile {
$op = $op->first->sibling;
my ($r2, $l2) = $self->inspect($op->sibling);
- return $r2, $l2 if $r2 and zero $l2;
- diag Dumper [ $r2, $l2 ] if $DEBUG;
- my $c = count $l2; # First one to happen
+ return $r2, $l2 if defined $r2 and zero $l2;
+ my $c2 = count $l2; # First one to happen
my ($r1, $l1) = $self->inspect($op);
- diag Dumper [ $r1, $l1 ] if $DEBUG;
- return (add $r2, scale $c, $r1), undef if $r1 and zero $l1 and not zero $l2;
- return { 'list' => 1 }, undef if list $l2;
+ 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 $c,
- normalize
- add map { power $r1, $_, $l2->{$_} } keys %$l2;
- $c = 1 - count $r;
+ 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;
}
$op = $op->first->sibling;
my ($r2, $l2) = $self->inspect($op->sibling);
- return $r2, $l2 if $r2 and zero $l2;
- my $c = count $l2; # First one to happen
+ 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 $c, $r1), undef if $r1 and zero $l1 and not zero $l2;
- diag Dumper [ [ $r1, $l1 ], [ $r2, $l2 ] ] if $DEBUG;
+ 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 $c,
- normalize
- add map { power $r1, $_, $l2->{$_} } keys %$l2;
- $c = 1 - count $r;
+ 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;
}
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).
+L<Carp> (standard since perl 5), L<B> (since perl 5.005) and L<XSLoader> (since perl 5.006).
=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