use warnings;
use Carp qw/croak/;
-use List::Util qw/reduce sum/;
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 0.01
+Version 0.02
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.01';
+ $VERSION = '0.02';
}
+our $DEBUG = 0;
+
=head1 SYNOPSIS
use Sub::Nary;
The usual constructor. Currently takes no argument.
-=head2 C<nary $coderf>
+=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
=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 * The total probability law for a given returning point is the convolution product of the probabilities of its list elements.
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/;
+$ops{$_} = 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 flip match/;
+$ops{$_} = '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, $cv) = @_;
+ return undef, 'list' if class($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 };
+ $r = { $r => 1 } unless ref $r;
$self->{cache}->{$tag} = { %$r };
- return $r;
+ return undef, $r;
}
-sub expect_return {
+sub inspect {
my ($self, $op) = @_;
- return ($self->expect_list($op))[0] => 1 if name($op) eq 'return';
+ 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 $meth;
- if ($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;
- }
+ if (exists $ops{$n}) {
+ my $l = $ops{$n};
+ $l = { %$l } if ref $l;
+ return undef, $l;
}
- return;
-}
+ if (class($op) eq 'LOGOP' and not null $op->first) {
+ my @res;
-sub expect_list {
- my ($self, $op) = @_;
+ diag "? logop\n" if $DEBUG;
- my $n = name($op);
- 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;
- }
+ my $op = $op->first;
+ my ($r1, $l1) = $self->inspect($op);
+ return $r1, $l1 if $r1 and zero $l1;
+ my $c = count $l1;
+
+ $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);
}
- return (combine @res) => 0;
+
+ my $r = add $r1, scale $c / 2, add $r2, $r3;
+ my $l = scale $c / 2, add $l2, $l3;
+ return $r, $l
}
- return;
+ return $self->inspect_kids($op);
}
-sub expect_any {
+sub inspect_kids {
my ($self, $op) = @_;
- return ($self->expect_list($op))[0] => 1 if name($op) eq 'return';
-
- if (class($op) eq 'LOGOP') {
- my @res;
- my ($p, $r);
-
- my $op = $op->first;
- ($p, $r) = $self->expect_return($op);
- return $p => 1 if $r;
+ return undef, 0 unless $op->flags & OPf_KIDS;
+ $op = $op->first;
+ return undef, 0 if null $op;
+ if (name($op) eq 'pushmark') {
$op = $op->sibling;
- push @res, ($self->expect_any($op))[0];
+ return undef, 0 if null $op;
+ }
- # If the logop has no else branch, it can also return the *scalar* result of
- # the conditional
- $op = $op->sibling;
- if (null $op) {
- push @res, 1;
- } else {
- push @res, ($self->expect_any($op))[0];
+ my ($r, @l);
+ my $c = 1;
+ for (; not null $op; $op = $op->sibling) {
+ my $n = name($op);
+ if ($n eq 'nextstate') {
+ @l = ();
+ next;
}
-
- return (add @res) => 0;
+ if ($n eq 'lineseq') {
+ @l = ();
+ $op = $op->first;
+ redo;
+ }
+ diag "> $n" if $DEBUG;
+ my ($rc, $lc) = $self->inspect($op);
+ $c = 1 - count $r;
+ diag Dumper [ $c, $r, \@l, $rc, $lc ] if $DEBUG;
+ $r = add $r, scale $c, $rc if defined $rc;
+ if (not defined $lc) {
+ @l = ();
+ last;
+ }
+ push @l, scale $c, $lc;
}
- return $self->expect_list($op);
+# diag Dumper \@l if $DEBUG;
+ my $l = scale +(1 - count $r), normalize combine @l;
+
+ return $r, $l;
}
-# Stolen from Sub::Deparse
+# Stolen from B::Deparse
sub padval { $_[0]->{cv}->[0]->PADLIST->ARRAYelt(1)->ARRAYelt($_[1]) }
}
sub pp_entersub {
- my ($self, $op, $exp) = @_;
+ my ($self, $op) = @_;
- my $next = $op;
- while ($next->flags & OPf_KIDS) {
- $next = $next->first;
+ $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;
}
- while (not null $next) {
- $op = $next;
- my ($p, $r) = $self->expect_return($op, $exp);
- return $p => 1 if $r;
- $next = $op->sibling;
+
+ 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
+ }
+ $c *= count $lc;
}
if (name($op) eq 'rv2cv') {
}
$n = name($op)
} while ($op->flags & OPf_KIDS and { map { $_ => 1 } qw/null leave/ }->{$n});
- return 'list' unless { map { $_ => 1 } qw/gv refgen/ }->{$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';
+ my ($r, $l) = $self->inspect($op);
+ if (name($op) ne 'const') {
+ my $c = 1 - count $r;
+ $l = $c ? { list => $c } : 0;
+ }
+ return $r, $l;
+}
+
+sub pp_aassign {
+ my ($self, $op) = @_;
+
+ $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) = @_;
+
+ diag "* leaveloop" if $DEBUG;
+
+ $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;
+ diag "& leaveloop $c" if $DEBUG;
+ 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_aassign { $_[0]->expect_any($_[1]->first) }
+sub pp_grepwhile {
+ my ($self, $op) = @_;
-sub pp_leaveloop { $_[0]->expect_return($_[1]->first->sibling) }
+ $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 $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 $r1 and zero $l1 and not zero $l2;
+ diag Dumper [ [ $r1, $l1 ], [ $r2, $l2 ] ] if $DEBUG;
+ 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 $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 $r1 and zero $l1 and not zero $l2;
+ diag Dumper [ [ $r1, $l1 ], [ $r2, $l2 ] ] if $DEBUG;
+ 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).
+L<Carp> (standard since perl 5), L<B> (since perl 5.005) and L<XSLoader> (since perl 5.006).
=head1 AUTHOR
projects / perl / modules / Sub-Nary.git / blobdiff