1 package Sub::Prototype::Util;
7 use Scalar::Util qw/reftype/;
11 Sub::Prototype::Util - Prototype-related utility routines.
19 use vars qw/$VERSION/;
25 use Sub::Prototype::Util qw/flatten recall wrap/;
28 my @args = ( \@a, 1, { d => 2 }, undef, 3 );
30 my @flat = flatten '\@$;$', @args; # ('a', 'b', 'c', 1, { d => 2 })
31 recall 'CORE::push', @args; # @a contains 'a', 'b', 'c', 1, { d => 2 }, undef, 3
32 my $splice = wrap 'CORE::splice', compile => 1;
33 my @b = $splice->(\@a, 4, 2); # @a is now ('a', 'b', 'c', 1, 3) and @b is ({ d => 2 }, undef)
37 Prototypes are evil, but sometimes you just have to bear with them, especially when messing with core functions. This module provides several utilities aimed at facilitating "overloading" of prototyped functions.
39 They all handle C<5.10>'s C<_> prototype.
45 my %sigils = qw/SCALAR $ ARRAY @ HASH % GLOB * CODE &/;
46 my %reftypes = reverse %sigils;
51 if (!defined $a || !defined($r = reftype $a)) { # not defined or plain scalar
52 croak 'Got ' . ((defined $a) ? 'a plain scalar' : 'undef')
53 . ' where a reference was expected';
55 croak 'Unexpected ' . $r . ' reference' unless exists $sigils{$r}
56 and $p =~ /\Q$sigils{$r}\E/;
60 =head2 C<flatten $proto, @args>
62 Flattens the array C<@args> according to the prototype C<$proto>. When C<@args> is what C<@_> is after calling a subroutine with prototype C<$proto>, C<flatten> returns the list of what C<@_> would have been if there were no prototype.
68 return @_ unless defined $proto;
70 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
74 my $r = _check_ref $a, $p;
76 SCALAR => sub { push @args, $$a },
77 ARRAY => sub { push @args, @$a },
78 HASH => sub { push @args, %$a },
79 GLOB => sub { push @args, *$a },
80 CODE => sub { push @args, &$a }
83 } elsif ($p =~ /[\@\%]/) {
86 } elsif ($p eq '_' && @_ == 0) {
95 =head2 C<recall $name, @args>
97 Calls the function C<$name> with the prototyped argument list C<@args>. That is, C<@args> should be what C<@_> is when you define a subroutine with the same prototype as C<$name>. For example,
100 recall 'CORE::push', $a, 1, 2, 3;
102 will call C<push @$a, 1, 2, 3> and so fill the arrayref C<$a> with C<1, 2, 3>. This is especially needed for core functions because you can't C<goto> into them.
104 You can also force the use of a specific prototype. In this case, C<$name> must be a hash reference that holds exactly one key/value pair, the key being the function name and the value the prototpye that should be used to call it.
106 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # will only push 1
108 This allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
110 sub mygrep (&@) { recall { 'CORE::grep' => '\&@' }, @_ } # the prototypes are intentionally different
116 croak 'No subroutine specified' unless $name;
120 $proto = prototype $name;
121 } elsif ($r eq 'HASH') {
122 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
123 ($name, $proto) = %$name;
125 croak 'Unhandled ' . $r . ' reference as first argument';
128 $name =~ s/[\s\$\@\%\*\&;].*//;
129 return $name, $proto;
133 my ($name, $proto) = _check_name shift;
134 my $call = $name . '(';
136 if (defined $proto) {
138 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
141 my $r = _check_ref $_[$i], $p;
142 $call .= $sigils{$r} . '{$_[' . $i . ']},';
143 } elsif ($p =~ /[\@\%]/) {
144 $call .= '@_[' . $i . '..' . (@_ - 1) . ']';
146 } elsif ($p =~ /\&/) {
148 $call .= 'sub{&{$cr[' . $#cr . ']}},';
149 } elsif ($p eq '_' && $i >= @_) {
152 $call .= '$_[' . $i . '],';
158 $call .= join ',', map '$_[' . $_ . ']', 0 .. @_ - 1;
161 my @ret = eval $call;
166 =head2 C<wrap $name, %opts>
168 Generates a wrapper that does the same thing as L</recall>, but specialized for a given function. This wrapper can be compiled once for all to avoid calling C<eval> at each run (like L</recall> does). You can still force the prototype by passing C<< { $name => $proto } >> as the first argument. Others arguments are seen as key / value pairs and tune the code generated by L</wrap>. Valid keys are :
172 =item C<< ref => $func >>
174 Specifies the function used in the generated code to test the reference type of scalars. Defaults to C<'ref'>. You may also want to use C<Scalar::Util::reftype>.
176 =item C<< wrong_ref => $code >>
178 The code executed when a reference of incorrect type is encountered. The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>. It's a good place to C<croak> or C<die> too.
180 =item C<< sub => $bool >>
182 Encloses the code into a C<sub { }> block. Default is true.
184 =item C<< compile => $bool >>
186 Makes L</wrap> compile the code generated and return the resulting code reference. Implies C<< sub => 1 >>. Be careful that in this case C<ref> must be a fully qualified function name. Defaults to false.
190 This is how you make your own C<push> that pushes into array references :
193 my $push = wrap 'CORE::push', compile => 1;
194 $push->(\@a, 3 .. 7); # returns 3 + 5 = 8, and @a now contains 0 .. 7
199 my ($name, $proto, $i, $args, $cr, $opts) = @_;
200 if ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])(.*)/g) {
201 my ($ref, $p) = ($1, $2);
203 $p = $1 if $p =~ /^\[([^\]]+)\]/;
204 my $cur = '$_[' . $i . ']';
207 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
210 "if (\$r eq '" . $reftypes{$_} ."') { "
211 . _wrap($name, $proto, ($i + 1),
212 $args . $_ . '{' . $cur . '}, ',
216 'e { ' . $opts->{wrong_ref} . ' }'
218 $args .= $p . '{' . $cur . '}, ';
220 } elsif ($p =~ /[\@\%]/) {
221 $args .= '@_[' . $i . '..$#_]';
222 } elsif ($p =~ /\&/) {
223 my %h = do { my $c; map { $_ => $c++ } @$cr };
225 if (not exists $h{$i}) {
231 $args .= 'sub{&{$c[' . $j . ']}}, ';
232 } elsif ($p eq '_') {
233 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
235 $args .= $cur . ', ';
237 return _wrap($name, $proto, ($i + 1), $args, $cr, $opts);
240 return $name . '(' . $args . ')';
245 my ($name, $proto) = _check_name shift;
246 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
248 $opts{ref} ||= 'ref';
249 $opts{sub} = 1 if not exists $opts{sub} or $opts{compile};
250 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
253 if (defined $proto) {
254 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
256 $call = _wrap $name, '', 0, '@_';
260 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
263 $call = '{ ' . $call . ' }';
264 $call = 'sub ' . $call if $opts{sub};
265 if ($opts{compile}) {
274 The functions L</flatten>, L</recall> and L</wrap> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
278 use base qw/Exporter/;
280 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
284 'funcs' => [ qw/flatten recall wrap/ ]
286 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
287 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
291 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
295 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
297 You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).
301 Please report any bugs or feature requests to C<bug-sub-prototype-util at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Sub-Prototype-Util>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
305 You can find documentation for this module with the perldoc command.
307 perldoc Sub::Prototype::Util
309 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
311 =head1 COPYRIGHT & LICENSE
313 Copyright 2008 Vincent Pit, all rights reserved.
315 This program is free software; you can redistribute it and/or modify it
316 under the same terms as Perl itself.
320 1; # End of Sub::Prototype::Util