1 package Sub::Prototype::Util;
7 use Scalar::Util qw/reftype/;
11 Sub::Prototype::Util - Prototype-related utility routines.
19 use vars qw/$VERSION/;
25 use Sub::Prototype::Util qw/flatten recall/;
28 my @args = ( \@a, 1, { d => 2 }, undef, 3 );
30 my @flat = flatten '\@$;$', @args; # ('a', 'b', 'c', 1, { d => 2 })
31 recall 'CORE::push', @args; # @a contains 'a', 'b', 'c', 1, { d => 2 }, undef, 3
35 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.
37 They all handle C<5.10>'s C<_> prototype.
43 my %sigils = qw/SCALAR $ ARRAY @ HASH % GLOB * CODE &/;
44 my %reftypes = reverse %sigils;
49 if (!defined $a || !defined($r = reftype $a)) { # not defined or plain scalar
50 croak 'Got ' . ((defined $a) ? 'a plain scalar' : 'undef')
51 . ' where a reference was expected';
53 croak 'Unexpected ' . $r . ' reference' unless exists $sigils{$r}
54 and $p =~ /\Q$sigils{$r}\E/;
58 =head2 C<flatten $proto, @args>
60 Flattens the array C<@args> according to the prototype C<$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.
66 return @_ unless defined $proto;
68 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
72 my $r = _check_ref $a, $p;
74 SCALAR => sub { push @args, $$a },
75 ARRAY => sub { push @args, @$a },
76 HASH => sub { push @args, %$a },
77 GLOB => sub { push @args, *$a },
78 CODE => sub { push @args, &$a }
81 } elsif ($p =~ /[\@\%]/) {
84 } elsif ($p eq '_' && @_ == 0) {
93 =head2 C<recall $name, @args>
95 Calls the function C<$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,
98 recall 'CORE::push', $a, 1, 2, 3;
100 will call C<push @$a, 1, 2, 3> and so fill the arrayref C<$a> with C<1, 2, 3>. This is especially needed for core functions because you can't C<goto> into them.
102 You can also force the use of a specific prototype. In this case, C<$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.
104 recall { 'CORE::push' => '\@$' }, $a, 1, 2, 3; # will only push 1
106 This allows you to recall into C<CORE::grep> and C<CORE::map> by using the C<\&@> prototype :
108 sub mygrep (&@) { recall { 'CORE::grep' => '\&@' }, @_ } # the prototypes are intentionally different
114 croak 'No subroutine specified' unless $name;
118 croak 'Forced prototype hash reference must contain exactly one key/value pair' unless keys %$name == 1;
119 ($name, $proto) = %$name;
120 } elsif (length $r) {
121 croak 'Unhandled ' . $r . ' reference as first argument';
124 $name =~ s/[\s\$\@\%\*\&;].*//;
125 $proto = prototype $name unless $proto;
126 return $name, $proto;
130 my ($name, $proto) = _check_name shift;
131 my $call = $name . '(';
133 if (defined $proto) {
135 while ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])/g) {
138 my $r = _check_ref $_[$i], $p;
139 $call .= $sigils{$r} . '{$_[' . $i . ']},';
140 } elsif ($p =~ /[\@\%]/) {
141 $call .= '@_[' . $i . '..' . (@_ - 1) . ']';
143 } elsif ($p =~ /\&/) {
145 $call .= 'sub{&{$cr[' . $#cr . ']}},';
146 } elsif ($p eq '_' && $i >= @_) {
149 $call .= '$_[' . $i . '],';
155 $call .= join ',', map '$_[' . $_ . ']', 0 .. @_ - 1;
158 my @ret = eval $call;
163 =head2 C<wrap $name, %opts>
165 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 :
169 =item C<< ref => $func >>
171 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>.
173 =item C<< wrong_ref => $code >>
175 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.
177 =item C<< sub => $bool >>
179 Encloses the code into a C<sub { }> block. Default is true.
181 =item C<< compile => $bool >>
183 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.
187 This is how you make your own C<push> that pushes into array references :
190 my $push = wrap 'CORE::push', compile => 1;
191 $push->(\@a, 3 .. 7); # returns 3 + 5 = 8, and @a now contains 0 .. 7
196 my ($name, $proto, $i, $args, $cr, $opts) = @_;
197 if ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])(.*)/g) {
198 my ($ref, $p) = ($1, $2);
200 $p = $1 if $p =~ /^\[([^\]]+)\]/;
203 return 'my $r = ' . $opts->{ref} . '($_[' . $i . ']); '
206 "if (\$r eq '" . $reftypes{$_} ."') { "
207 . _wrap($name, $proto, ($i + 1),
208 $args . $_ . '{$_[' . $i . ']}, ',
212 'e { ' . $opts->{wrong_ref} . ' }'
214 $args .= $p . '{$_[' . $i . ']}, ';
216 } elsif ($p =~ /[\@\%]/) {
217 $args .= '@_[' . $i . '..$#_]';
218 } elsif ($p =~ /\&/) {
219 my %h = do { my $c; map { $_ => $c++ } @$cr };
221 if (not exists $h{$i}) {
227 $args .= 'sub{&{$c[' . $j . ']}}, ';
228 } elsif ($p eq '_') {
229 $args .= '((@_ > ' . $i . ') ? $_[' . $i . '] : $_), ';
231 $args .= '$_[' . $i . '], ';
233 return _wrap($name, $proto, ($i + 1), $args, $cr, $opts);
236 return $name . '(' . $args . ')';
241 my ($name, $proto) = _check_name shift;
242 croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
244 $opts{ref} ||= 'ref';
245 $opts{sub} = 1 if not exists $opts{sub} or $opts{compile};
246 $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
249 if (defined $proto) {
250 $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
252 $call = _wrap $name, '', 0, '@_';
256 . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
259 $call = '{ ' . $call . ' }';
260 $call = 'sub ' . $call if $opts{sub};
261 $call = eval $call if $opts{compile};
267 The functions L</flatten>, L</recall> and L</wrap> are only exported on request, either by providing their name or by the C<':funcs'> and C<':all'> tags.
271 use base qw/Exporter/;
273 use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;
277 'funcs' => [ qw/flatten recall wrap/ ]
279 @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
280 $EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
284 L<Carp>, L<Exporter> (core modules since perl 5), L<Scalar::Util> (since 5.7.3).
288 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
290 You can contact me by mail or on #perl @ FreeNode (vincent or Prof_Vince).
294 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.
298 You can find documentation for this module with the perldoc command.
300 perldoc Sub::Prototype::Util
302 Tests code coverage report is available at L<http://www.profvince.com/perl/cover/Sub-Prototype-Util>.
304 =head1 COPYRIGHT & LICENSE
306 Copyright 2008 Vincent Pit, all rights reserved.
308 This program is free software; you can redistribute it and/or modify it
309 under the same terms as Perl itself.
313 1; # End of Sub::Prototype::Util