1 package Sub::Prototype::Util;
7 use Scalar::Util qw/reftype/;
11 Sub::Prototype::Util - Prototype-related utility routines.
19 use vars qw/$VERSION/;
25 use Sub::Prototype::Util qw/flatten wrap recall/;
28 my @args = ( \@a, 1, { d => 2 }, undef, 3 );
30 my @flat = flatten '\@$;$', @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';
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;
75 push @args, $r eq 'SCALAR'
83 : &$a # _check_ref ensures this must be a code ref
87 } elsif ($p =~ /[\@\%]/) {
91 shift; # without prototype, this argument wouldn't have been passed
99 =head2 C<wrap $name, %opts>
101 Generates a wrapper that calls the function C<$name> with a prototyped argument list. That is, the wrapper's arguments should be what C<@_> is when you define a subroutine with the same prototype as C<$name>.
104 my $push = wrap 'CORE::push';
105 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
107 You can force the use of a specific prototype. In this case, C<$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.
109 my $push = wrap { 'CORE::push' => '\@$' }; # only pushes 1 arg
111 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>. Valid keys are :
115 =item C<< ref => $func >>
117 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>.
119 =item C<< wrong_ref => $code >>
121 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.
123 =item C<< sub => $bool >>
125 Encloses the code into a C<sub { }> block. Default is true.
127 =item C<< compile => $bool >>
129 Makes L</wrap> compile the code generated and return the resulting code reference. Be careful that in this case C<ref> must be a fully qualified function name. Defaults to true, but turned off when C<sub> is false.
133 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
135 my $grep = wrap { 'CORE::grep' => '\&@' };
136 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
141 my ($name, $proto, $i, $args, $cr, $opts) = @_;
142 while ($proto =~ s/(\\?)(\[[^\]]+\]|[^\];])//) {
143 my ($ref, $p) = ($1, $2);
144 $p = $1 if $p =~ /^\[([^\]]+)\]/;
145 my $cur = '$_[' . $i . ']';
148 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
151 "if (\$r eq '" . $reftypes{$_} ."') { "
152 . _wrap($name, $proto, ($i + 1),
153 $args . $_ . '{' . $cur . '}, ',
157 'e { ' . $opts->{wrong_ref} . ' }'
159 $args .= $p . '{' . $cur . '}, ';
161 } elsif ($p =~ /[\@\%]/) {
162 $args .= '@_[' . $i . '..$#_]';
163 } elsif ($p =~ /\&/) {
164 my %h = do { my $c; map { $_ => $c++ } @$cr };
166 if (not exists $h{$i}) {
172 $args .= 'sub{&{$c[' . $j . ']}}, ';
173 } elsif ($p eq '_') {
174 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
176 $args .= $cur . ', ';
181 return $name . '(' . $args . ')';
186 croak 'No subroutine specified' unless $name;
190 $proto = prototype $name;
191 } elsif ($r eq 'HASH') {
192 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
193 ($name, $proto) = %$name;
195 croak 'Unhandled ' . $r . ' reference as first argument';
198 $name =~ s/[\s\$\@\%\*\&;].*//;
199 return $name, $proto;
203 my ($name, $proto) = _check_name shift;
204 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
206 $opts{ref} ||= 'ref';
207 $opts{sub} = 1 if not defined $opts{sub};
208 $opts{compile} = 1 if not defined $opts{compile} and $opts{sub};
209 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
212 if (defined $proto) {
213 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
215 $call = _wrap $name, '', 0, '@_';
219 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
222 $call = '{ ' . $call . ' }';
223 $call = 'sub ' . $call if $opts{sub};
224 if ($opts{compile}) {
231 =head2 C<recall $name, @args>
233 Calls the function C<$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>. You can still force the prototype by passing C<< { $name => $proto } >> as the first argument.
236 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
238 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
239 If you plan to recall several times, consider using L</wrap> instead.
244 my $wrap = eval { wrap shift };
251 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
255 use base qw/Exporter/;
257 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
261 'funcs' => [ qw/flatten wrap recall/ ]
263 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
264 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
268 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
272 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
274 You can contact me by mail or on C<irc.perl.org> (vincent).
278 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.
282 You can find documentation for this module with the perldoc command.
284 perldoc Sub::Prototype::Util
286 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
288 =head1 COPYRIGHT & LICENSE
290 Copyright 2008 Vincent Pit, all rights reserved.
292 This program is free software; you can redistribute it and/or modify it
293 under the same terms as Perl itself.
297 1; # End of Sub::Prototype::Util