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 $name;
120 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
121 ($name, $proto) = %$name;
122 } elsif (length $r) {
123 croak 'Unhandled ' . $r . ' reference as first argument';
126 $name =~ s/[\s\$\@\%\*\&;].*//;
127 $proto = prototype $name unless $proto;
128 return $name, $proto;
132 my ($name, $proto) = _check_name shift;
133 my $call = $name . '(';
135 if (defined $proto) {
137 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
140 my $r = _check_ref $_[$i], $p;
141 $call .= $sigils{$r} . '{$_[' . $i . ']},';
142 } elsif ($p =~ /[\@\%]/) {
143 $call .= '@_[' . $i . '..' . (@_ - 1) . ']';
145 } elsif ($p =~ /\&/) {
147 $call .= 'sub{&{$cr[' . $#cr . ']}},';
148 } elsif ($p eq '_' && $i >= @_) {
151 $call .= '$_[' . $i . '],';
157 $call .= join ',', map '$_[' . $_ . ']', 0 .. @_ - 1;
160 my @ret = eval $call;
165 =head2 C<wrap $name, %opts>
167 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 :
171 =item C<< ref => $func >>
173 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>.
175 =item C<< wrong_ref => $code >>
177 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.
179 =item C<< sub => $bool >>
181 Encloses the code into a C<sub { }> block. Default is true.
183 =item C<< compile => $bool >>
185 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.
189 This is how you make your own C<push> that pushes into array references :
192 my $push = wrap 'CORE::push', compile => 1;
193 $push->(\@a, 3 .. 7); # returns 3 + 5 = 8, and @a now contains 0 .. 7
198 my ($name, $proto, $i, $args, $cr, $opts) = @_;
199 if ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])(.*)/g) {
200 my ($ref, $p) = ($1, $2);
202 $p = $1 if $p =~ /^\[([^\]]+)\]/;
203 my $cur = '$_[' . $i . ']';
206 return 'my $r = ' . $opts->{ref} . '(' . $cur . '); '
209 "if (\$r eq '" . $reftypes{$_} ."') { "
210 . _wrap($name, $proto, ($i + 1),
211 $args . $_ . '{' . $cur . '}, ',
215 'e { ' . $opts->{wrong_ref} . ' }'
217 $args .= $p . '{' . $cur . '}, ';
219 } elsif ($p =~ /[\@\%]/) {
220 $args .= '@_[' . $i . '..$#_]';
221 } elsif ($p =~ /\&/) {
222 my %h = do { my $c; map { $_ => $c++ } @$cr };
224 if (not exists $h{$i}) {
230 $args .= 'sub{&{$c[' . $j . ']}}, ';
231 } elsif ($p eq '_') {
232 $args .= '((@_ > ' . $i . ') ? ' . $cur . ' : $_), ';
234 $args .= $cur . ', ';
236 return _wrap($name, $proto, ($i + 1), $args, $cr, $opts);
239 return $name . '(' . $args . ')';
244 my ($name, $proto) = _check_name shift;
245 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
247 $opts{ref} ||= 'ref';
248 $opts{sub} = 1 if not exists $opts{sub} or $opts{compile};
249 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
252 if (defined $proto) {
253 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
255 $call = _wrap $name, '', 0, '@_';
259 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
262 $call = '{ ' . $call . ' }';
263 $call = 'sub ' . $call if $opts{sub};
264 if ($opts{compile}) {
273 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.
277 use base qw/Exporter/;
279 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
283 'funcs' => [ qw/flatten recall wrap/ ]
285 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
286 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
290 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
294 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
296 You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).
300 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.
304 You can find documentation for this module with the perldoc command.
306 perldoc Sub::Prototype::Util
308 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
310 =head1 COPYRIGHT & LICENSE
312 Copyright 2008 Vincent Pit, all rights reserved.
314 This program is free software; you can redistribute it and/or modify it
315 under the same terms as Perl itself.
319 1; # End of Sub::Prototype::Util