X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;f=lib%2FSub%2FNary.pm;h=de42e73576a67eba931eca0956f58f4a9ccc08d5;hb=790ba71f0305951a6d7bb04ca02a1dad7563f439;hp=0b505f3dc8a99415ac077b044092e598fcdae80d;hpb=6faf4b78a5c4fdcf2f3d42e3decceb4968ba0347;p=perl%2Fmodules%2FSub-Nary.git diff --git a/lib/Sub/Nary.pm b/lib/Sub/Nary.pm index 0b505f3..de42e73 100644 --- a/lib/Sub/Nary.pm +++ b/lib/Sub/Nary.pm @@ -1,14 +1,13 @@ 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; -use B qw/class ppname svref_2object OPf_KIDS/; +use B qw; =head1 NAME @@ -16,43 +15,54 @@ Sub::Nary - Try to count how many elements a subroutine can return in list conte =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 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 @@ -60,7 +70,9 @@ The probability is computed as such : =over 4 -=item * All the returning points in the same subroutine (i.e. all the explicit C and the last computed value) are considered equally possible. +=item * + +When branching, each branch is considered equally possible. For example, the subroutine @@ -84,11 +96,13 @@ As for } } -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 @@ -102,7 +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 * 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 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 @@ -112,7 +135,8 @@ That's why } is considered as always returning an unbounded list. -The convolution law also does not behave the same when C elements are involved : in the following example, + +Also, the convolution law does not behave the same when C elements are involved : in the following example, sub oneorlist { if (rand < 0.1) { @@ -160,149 +184,158 @@ sub nary { 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 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 }; + +$ops{caller} = sub { my @a = caller 0; scalar @a }->(); +$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; +$ops{$_} = { 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, $cv) = @_; - return 'list' if class($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, $l; } # Stolen from B::Deparse @@ -327,17 +360,20 @@ sub const_sv { } sub pp_entersub { - my ($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') { @@ -350,26 +386,27 @@ sub pp_entersub { $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 { $_ => 1 } qw }->{$n}); + return 'list', undef unless { map { $_ => 1 } qw }->{$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 { @@ -390,41 +427,176 @@ 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 @@ -440,17 +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), L (since perl 5.006) and L (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 (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