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', 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<wrap $name, %opts>
97 Generates a wrapper that calls the function C<$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>.
100 my $push = wrap 'CORE::push', compile => 1;
101 $push->($a, 3, 4); # returns 3 + 2 = 5 and $a now contains 0 .. 4
103 You can force the use of a specific prototype. In this case, C<$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.
105 my $push = wrap { 'CORE::push' => '\@$' }, compile => 1; # only pushes 1 arg
107 Others arguments are seen as key / value pairs that are meant to tune the code generated by L</wrap>. Valid keys are :
111 =item C<< ref => $func >>
113 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>.
115 =item C<< wrong_ref => $code >>
117 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.
119 =item C<< sub => $bool >>
121 Encloses the code into a C<sub { }> block. Default is true.
123 =item C<< compile => $bool >>
125 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.
129 For example, this allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
131 my $grep = wrap { 'CORE::grep' => '\&@' }, compile => 1;
132 sub mygrep (&@) { $grep->(@_) } # the prototypes are intentionally different
137 my ($name, $proto, $i, $args, $cr, $opts) = @_;
138 if ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])(.*)/g) {
139 my ($ref, $p) = ($1, $2);
141 $p = $1 if $p =~ /^\[([^\]]+)\]/;
142 my $cur = '$_[' . $i . ']';
145 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
148 "if (\$r eq '" . $reftypes{$_} ."') { "
149 . _wrap($name, $proto, ($i + 1),
150 $args . $_ . '{' . $cur . '}, ',
154 'e { ' . $opts->{wrong_ref} . ' }'
156 $args .= $p . '{' . $cur . '}, ';
158 } elsif ($p =~ /[\@\%]/) {
159 $args .= '@_[' . $i . '..$#_]';
160 } elsif ($p =~ /\&/) {
161 my %h = do { my $c; map { $_ => $c++ } @$cr };
163 if (not exists $h{$i}) {
169 $args .= 'sub{&{$c[' . $j . ']}}, ';
170 } elsif ($p eq '_') {
171 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
173 $args .= $cur . ', ';
175 return _wrap($name, $proto, ($i + 1), $args, $cr, $opts);
178 return $name . '(' . $args . ')';
184 croak 'No subroutine specified' unless $name;
188 $proto = prototype $name;
189 } elsif ($r eq 'HASH') {
190 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
191 ($name, $proto) = %$name;
193 croak 'Unhandled ' . $r . ' reference as first argument';
196 $name =~ s/[\s\$\@\%\*\&;].*//;
197 return $name, $proto;
201 my ($name, $proto) = _check_name shift;
202 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
204 $opts{ref} ||= 'ref';
205 $opts{sub} = 1 if not exists $opts{sub} or $opts{compile};
206 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
209 if (defined $proto) {
210 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
212 $call = _wrap $name, '', 0, '@_';
216 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
219 $call = '{ ' . $call . ' }';
220 $call = 'sub ' . $call if $opts{sub};
221 if ($opts{compile}) {
228 =head2 C<recall $name, @args>
230 Calls the function C<$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 => $proto } >> as the first argument.
233 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # $a just contains 1
235 It's implemented in terms of L</wrap>, and hence calls C<eval> at each run.
236 If you plan to recall several times, consider using L</wrap> instead.
241 my $wrap = eval { wrap shift, compile => 1 };
248 The functions L</flatten>, L</wrap> and L</recall> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
252 use base qw/Exporter/;
254 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
258 'funcs' => [ qw/flatten wrap recall/ ]
260 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
261 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
265 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
269 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
271 You can contact me by mail or on C<irc.perl.org> (vincent).
275 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.
279 You can find documentation for this module with the perldoc command.
281 perldoc Sub::Prototype::Util
283 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
285 =head1 COPYRIGHT & LICENSE
287 Copyright 2008 Vincent Pit, all rights reserved.
289 This program is free software; you can redistribute it and/or modify it
290 under the same terms as Perl itself.
294 1; # End of Sub::Prototype::Util