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ExtUtils/Constant/Base.pm: use constant folding to eliminated dead code
[perl5.git] / lib / ExtUtils / Constant / Base.pm
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1package ExtUtils::Constant::Base;
2
3use strict;
47520512 4use vars qw($VERSION);
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5use Carp;
6use Text::Wrap;
7use ExtUtils::Constant::Utils qw(C_stringify perl_stringify);
47520512 8$VERSION = '0.03_01';
af6ca1d0 9
47520512 10use constant is_perl56 => ($] < 5.007 && $] > 5.005_50);
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11
12
13=head1 NAME
14
15ExtUtils::Constant::Base - base class for ExtUtils::Constant objects
16
17=head1 SYNOPSIS
18
19 require ExtUtils::Constant::Base;
20 @ISA = 'ExtUtils::Constant::Base';
21
22=head1 DESCRIPTION
23
24ExtUtils::Constant::Base provides a base implementation of methods to
25generate C code to give fast constant value lookup by named string. Currently
26it's mostly used ExtUtils::Constant::XS, which generates the lookup code
27for the constant() subroutine found in many XS modules.
28
29=head1 USAGE
30
31ExtUtils::Constant::Base exports no subroutines. The following methods are
32available
33
34=over 4
35
36=cut
37
38sub valid_type {
39 # Default to assuming that you don't need different types of return data.
40 1;
41}
42sub default_type {
43 '';
44}
45
46=item header
47
48A method returning a scalar containing definitions needed, typically for a
49C header file.
50
51=cut
52
53sub header {
54 ''
55}
56
57# This might actually be a return statement. Note that you are responsible
58# for any space you might need before your value, as it lets to perform
59# "tricks" such as "return KEY_" and have strings appended.
60sub assignment_clause_for_type;
61# In which case this might be an empty string
62sub return_statement_for_type {undef};
63sub return_statement_for_notdef;
64sub return_statement_for_notfound;
65
66# "#if 1" is true to a C pre-processor
67sub macro_from_name {
68 1;
69}
70
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71sub macro_from_item {
72 1;
73}
74
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75sub macro_to_ifdef {
76 my ($self, $macro) = @_;
77 if (ref $macro) {
78 return $macro->[0];
79 }
80 if (defined $macro && $macro ne "" && $macro ne "1") {
71adef12 81 return $macro ? "#ifdef $macro\n" : "#if 0\n";
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82 }
83 return "";
84}
85
86sub macro_to_endif {
87 my ($self, $macro) = @_;
88
89 if (ref $macro) {
90 return $macro->[1];
91 }
92 if (defined $macro && $macro ne "" && $macro ne "1") {
93 return "#endif\n";
94 }
95 return "";
96}
97
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98sub name_param {
99 'name';
100}
101
102# This is possibly buggy, in that it's not mandatory (below, in the main
103# C_constant parameters, but is expected to exist here, if it's needed)
104# Buggy because if you're definitely pure 8 bit only, and will never be
105# presented with your constants in utf8, the default form of C_constant can't
106# be told not to do the utf8 version.
107
108sub is_utf8_param {
109 'utf8';
110}
111
112sub memEQ {
113 "!memcmp";
114}
115
116=item memEQ_clause args_hashref
117
118A method to return a suitable C C<if> statement to check whether I<name>
119is equal to the C variable C<name>. If I<checked_at> is defined, then it
120is used to avoid C<memEQ> for short names, or to generate a comment to
121highlight the position of the character in the C<switch> statement.
122
123If i<checked_at> is a reference to a scalar, then instead it gives
124the characters pre-checked at the beginning, (and the number of chars by
125which the C variable name has been advanced. These need to be chopped from
126the front of I<name>).
127
128=cut
129
130sub memEQ_clause {
131# if (memEQ(name, "thingy", 6)) {
132 # Which could actually be a character comparison or even ""
133 my ($self, $args) = @_;
134 my ($name, $checked_at, $indent) = @{$args}{qw(name checked_at indent)};
135 $indent = ' ' x ($indent || 4);
136 my $front_chop;
137 if (ref $checked_at) {
138 # regexp won't work on 5.6.1 without use utf8; in turn that won't work
139 # on 5.005_03.
140 substr ($name, 0, length $$checked_at,) = '';
141 $front_chop = C_stringify ($$checked_at);
142 undef $checked_at;
143 }
144 my $len = length $name;
145
146 if ($len < 2) {
147 return $indent . "{\n"
148 if (defined $checked_at and $checked_at == 0) or $len == 0;
149 # We didn't switch, drop through to the code for the 2 character string
150 $checked_at = 1;
151 }
152
153 my $name_param = $self->name_param;
154
155 if ($len < 3 and defined $checked_at) {
156 my $check;
157 if ($checked_at == 1) {
158 $check = 0;
159 } elsif ($checked_at == 0) {
160 $check = 1;
161 }
162 if (defined $check) {
163 my $char = C_stringify (substr $name, $check, 1);
164 # Placate 5.005 with a break in the string. I can't see a good way of
165 # getting it to not take [ as introducing an array lookup, even with
166 # ${name_param}[$check]
167 return $indent . "if ($name_param" . "[$check] == '$char') {\n";
168 }
169 }
170 if (($len == 2 and !defined $checked_at)
171 or ($len == 3 and defined ($checked_at) and $checked_at == 2)) {
172 my $char1 = C_stringify (substr $name, 0, 1);
173 my $char2 = C_stringify (substr $name, 1, 1);
174 return $indent .
175 "if ($name_param" . "[0] == '$char1' && $name_param" . "[1] == '$char2') {\n";
176 }
177 if (($len == 3 and defined ($checked_at) and $checked_at == 1)) {
178 my $char1 = C_stringify (substr $name, 0, 1);
179 my $char2 = C_stringify (substr $name, 2, 1);
180 return $indent .
181 "if ($name_param" . "[0] == '$char1' && $name_param" . "[2] == '$char2') {\n";
182 }
183
184 my $pointer = '^';
185 my $have_checked_last = defined ($checked_at) && $len == $checked_at + 1;
186 if ($have_checked_last) {
187 # Checked at the last character, so no need to memEQ it.
188 $pointer = C_stringify (chop $name);
189 $len--;
190 }
191
192 $name = C_stringify ($name);
193 my $memEQ = $self->memEQ();
194 my $body = $indent . "if ($memEQ($name_param, \"$name\", $len)) {\n";
195 # Put a little ^ under the letter we checked at
196 # Screws up for non printable and non-7 bit stuff, but that's too hard to
197 # get right.
198 if (defined $checked_at) {
199 $body .= $indent . "/* " . (' ' x length $memEQ)
200 . (' ' x length $name_param)
201 . (' ' x $checked_at) . $pointer
202 . (' ' x ($len - $checked_at + length $len)) . " */\n";
203 } elsif (defined $front_chop) {
204 $body .= $indent . "/* $front_chop"
205 . (' ' x ($len + 1 + length $len)) . " */\n";
206 }
207 return $body;
208}
209
210=item dump_names arg_hashref, ITEM...
211
212An internal function to generate the embedded perl code that will regenerate
213the constant subroutines. I<default_type>, I<types> and I<ITEM>s are the
214same as for C_constant. I<indent> is treated as number of spaces to indent
215by. If C<declare_types> is true a C<$types> is always declared in the perl
216code generated, if defined and false never declared, and if undefined C<$types>
217is only declared if the values in I<types> as passed in cannot be inferred from
218I<default_types> and the I<ITEM>s.
219
220=cut
221
222sub dump_names {
223 my ($self, $args, @items) = @_;
224 my ($default_type, $what, $indent, $declare_types)
225 = @{$args}{qw(default_type what indent declare_types)};
226 $indent = ' ' x ($indent || 0);
227
228 my $result;
229 my (@simple, @complex, %used_types);
230 foreach (@items) {
231 my $type;
232 if (ref $_) {
233 $type = $_->{type} || $default_type;
234 if ($_->{utf8}) {
235 # For simplicity always skip the bytes case, and reconstitute this entry
236 # from its utf8 twin.
237 next if $_->{utf8} eq 'no';
238 # Copy the hashref, as we don't want to mess with the caller's hashref.
239 $_ = {%$_};
47520512 240 unless (is_perl56) {
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241 utf8::decode ($_->{name});
242 } else {
243 $_->{name} = pack 'U*', unpack 'U0U*', $_->{name};
244 }
245 delete $_->{utf8};
246 }
247 } else {
248 $_ = {name=>$_};
249 $type = $default_type;
250 }
251 $used_types{$type}++;
252 if ($type eq $default_type
253 # grr 5.6.1
254 and length $_->{name}
255 and length $_->{name} == ($_->{name} =~ tr/A-Za-z0-9_//)
256 and !defined ($_->{macro}) and !defined ($_->{value})
257 and !defined ($_->{default}) and !defined ($_->{pre})
258 and !defined ($_->{post}) and !defined ($_->{def_pre})
b760f360 259 and !defined ($_->{def_post}) and !defined ($_->{weight})) {
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260 # It's the default type, and the name consists only of A-Za-z0-9_
261 push @simple, $_->{name};
262 } else {
263 push @complex, $_;
264 }
265 }
266
267 if (!defined $declare_types) {
268 # Do they pass in any types we weren't already using?
269 foreach (keys %$what) {
270 next if $used_types{$_};
271 $declare_types++; # Found one in $what that wasn't used.
272 last; # And one is enough to terminate this loop
273 }
274 }
275 if ($declare_types) {
276 $result = $indent . 'my $types = {map {($_, 1)} qw('
277 . join (" ", sort keys %$what) . ")};\n";
278 }
279 local $Text::Wrap::huge = 'overflow';
280 local $Text::Wrap::columns = 80;
281 $result .= wrap ($indent . "my \@names = (qw(",
282 $indent . " ", join (" ", sort @simple) . ")");
283 if (@complex) {
284 foreach my $item (sort {$a->{name} cmp $b->{name}} @complex) {
285 my $name = perl_stringify $item->{name};
286 my $line = ",\n$indent {name=>\"$name\"";
287 $line .= ", type=>\"$item->{type}\"" if defined $item->{type};
288 foreach my $thing (qw (macro value default pre post def_pre def_post)) {
289 my $value = $item->{$thing};
290 if (defined $value) {
291 if (ref $value) {
292 $line .= ", $thing=>[\""
293 . join ('", "', map {perl_stringify $_} @$value) . '"]';
294 } else {
295 $line .= ", $thing=>\"" . perl_stringify($value) . "\"";
296 }
297 }
298 }
299 $line .= "}";
300 # Ensure that the enclosing C comment doesn't end
301 # by turning */ into *" . "/
302 $line =~ s!\*\/!\*" . "/!gs;
303 # gcc -Wall doesn't like finding /* inside a comment
304 $line =~ s!\/\*!/" . "\*!gs;
305 $result .= $line;
306 }
307 }
308 $result .= ");\n";
309
310 $result;
311}
312
313=item assign arg_hashref, VALUE...
314
315A method to return a suitable assignment clause. If I<type> is aggregate
316(eg I<PVN> expects both pointer and length) then there should be multiple
317I<VALUE>s for the components. I<pre> and I<post> if defined give snippets
318of C code to proceed and follow the assignment. I<pre> will be at the start
319of a block, so variables may be defined in it.
320
321=cut
322# Hmm. value undef to to NOTDEF? value () to do NOTFOUND?
323
324sub assign {
325 my $self = shift;
326 my $args = shift;
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327 my ($indent, $type, $pre, $post, $item)
328 = @{$args}{qw(indent type pre post item)};
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329 $post ||= '';
330 my $clause;
331 my $close;
332 if ($pre) {
333 chomp $pre;
334 $close = "$indent}\n";
335 $clause = $indent . "{\n";
336 $indent .= " ";
337 $clause .= "$indent$pre";
338 $clause .= ";" unless $pre =~ /;$/;
339 $clause .= "\n";
340 }
341 confess "undef \$type" unless defined $type;
342 confess "Can't generate code for type $type"
343 unless $self->valid_type($type);
344
345 $clause .= join '', map {"$indent$_\n"}
b760f360 346 $self->assignment_clause_for_type({type=>$type,item=>$item}, @_);
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347 chomp $post;
348 if (length $post) {
349 $clause .= "$post";
350 $clause .= ";" unless $post =~ /;$/;
351 $clause .= "\n";
352 }
353 my $return = $self->return_statement_for_type($type);
354 $clause .= "$indent$return\n" if defined $return;
355 $clause .= $close if $close;
356 return $clause;
357}
358
359=item return_clause arg_hashref, ITEM
360
361A method to return a suitable C<#ifdef> clause. I<ITEM> is a hashref
362(as passed to C<C_constant> and C<match_clause>. I<indent> is the number
363of spaces to indent, defaulting to 6.
364
365=cut
366
367sub return_clause {
368
369##ifdef thingy
370# *iv_return = thingy;
371# return PERL_constant_ISIV;
372##else
373# return PERL_constant_NOTDEF;
374##endif
375 my ($self, $args, $item) = @_;
376 my $indent = $args->{indent};
377
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378 my ($name, $value, $default, $pre, $post, $def_pre, $def_post, $type)
379 = @$item{qw (name value default pre post def_pre def_post type)};
af6ca1d0 380 $value = $name unless defined $value;
c48e04e6 381 my $macro = $self->macro_from_item($item);
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382 $indent = ' ' x ($indent || 6);
383 unless (defined $type) {
384 # use Data::Dumper; print STDERR Dumper ($item);
385 confess "undef \$type";
386 }
387
af6ca1d0 388 ##ifdef thingy
329b93cd 389 my $clause = $self->macro_to_ifdef($macro);
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390
391 # *iv_return = thingy;
392 # return PERL_constant_ISIV;
393 $clause
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394 .= $self->assign ({indent=>$indent, type=>$type, pre=>$pre, post=>$post,
395 item=>$item}, ref $value ? @$value : $value);
af6ca1d0 396
329b93cd 397 if (defined $macro && $macro ne "" && $macro ne "1") {
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398 ##else
399 $clause .= "#else\n";
400
401 # return PERL_constant_NOTDEF;
402 if (!defined $default) {
403 my $notdef = $self->return_statement_for_notdef();
404 $clause .= "$indent$notdef\n" if defined $notdef;
405 } else {
406 my @default = ref $default ? @$default : $default;
407 $type = shift @default;
408 $clause .= $self->assign ({indent=>$indent, type=>$type, pre=>$pre,
b760f360 409 post=>$post, item=>$item}, @default);
af6ca1d0 410 }
af6ca1d0 411 }
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412 ##endif
413 $clause .= $self->macro_to_endif($macro);
414
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415 return $clause;
416}
417
418sub match_clause {
419 # $offset defined if we have checked an offset.
420 my ($self, $args, $item) = @_;
421 my ($offset, $indent) = @{$args}{qw(checked_at indent)};
422 $indent = ' ' x ($indent || 4);
423 my $body = '';
424 my ($no, $yes, $either, $name, $inner_indent);
425 if (ref $item eq 'ARRAY') {
426 ($yes, $no) = @$item;
427 $either = $yes || $no;
428 confess "$item is $either expecting hashref in [0] || [1]"
429 unless ref $either eq 'HASH';
430 $name = $either->{name};
431 } else {
432 confess "$item->{name} has utf8 flag '$item->{utf8}', should be false"
433 if $item->{utf8};
434 $name = $item->{name};
435 $inner_indent = $indent;
436 }
437
438 $body .= $self->memEQ_clause ({name => $name, checked_at => $offset,
439 indent => length $indent});
440 # If we've been presented with an arrayref for $item, then the user string
441 # contains in the range 128-255, and we need to check whether it was utf8
442 # (or not).
443 # In the worst case we have two named constants, where one's name happens
444 # encoded in UTF8 happens to be the same byte sequence as the second's
445 # encoded in (say) ISO-8859-1.
446 # In this case, $yes and $no both have item hashrefs.
447 if ($yes) {
448 $body .= $indent . " if (" . $self->is_utf8_param . ") {\n";
449 } elsif ($no) {
450 $body .= $indent . " if (!" . $self->is_utf8_param . ") {\n";
451 }
452 if ($either) {
453 $body .= $self->return_clause ({indent=>4 + length $indent}, $either);
454 if ($yes and $no) {
455 $body .= $indent . " } else {\n";
456 $body .= $self->return_clause ({indent=>4 + length $indent}, $no);
457 }
458 $body .= $indent . " }\n";
459 } else {
460 $body .= $self->return_clause ({indent=>2 + length $indent}, $item);
461 }
462 $body .= $indent . "}\n";
463}
464
465
466=item switch_clause arg_hashref, NAMELEN, ITEMHASH, ITEM...
467
468An internal method to generate a suitable C<switch> clause, called by
469C<C_constant> I<ITEM>s are in the hash ref format as given in the description
470of C<C_constant>, and must all have the names of the same length, given by
471I<NAMELEN>. I<ITEMHASH> is a reference to a hash, keyed by name, values being
472the hashrefs in the I<ITEM> list. (No parameters are modified, and there can
473be keys in the I<ITEMHASH> that are not in the list of I<ITEM>s without
474causing problems - the hash is passed in to save generating it afresh for
475each call).
476
477=cut
478
479sub switch_clause {
480 my ($self, $args, $namelen, $items, @items) = @_;
481 my ($indent, $comment) = @{$args}{qw(indent comment)};
482 $indent = ' ' x ($indent || 2);
483
484 local $Text::Wrap::huge = 'overflow';
485 local $Text::Wrap::columns = 80;
486
487 my @names = sort map {$_->{name}} @items;
488 my $leader = $indent . '/* ';
489 my $follower = ' ' x length $leader;
490 my $body = $indent . "/* Names all of length $namelen. */\n";
491 if (defined $comment) {
492 $body = wrap ($leader, $follower, $comment) . "\n";
493 $leader = $follower;
494 }
495 my @safe_names = @names;
496 foreach (@safe_names) {
497 confess sprintf "Name '$_' is length %d, not $namelen", length
498 unless length == $namelen;
499 # Argh. 5.6.1
500 # next unless tr/A-Za-z0-9_//c;
501 next if tr/A-Za-z0-9_// == length;
502 $_ = '"' . perl_stringify ($_) . '"';
503 # Ensure that the enclosing C comment doesn't end
504 # by turning */ into *" . "/
505 s!\*\/!\*"."/!gs;
506 # gcc -Wall doesn't like finding /* inside a comment
507 s!\/\*!/"."\*!gs;
508 }
509 $body .= wrap ($leader, $follower, join (" ", @safe_names) . " */") . "\n";
510 # Figure out what to switch on.
511 # (RMS, Spread of jump table, Position, Hashref)
512 my @best = (1e38, ~0);
513 # Prefer the last character over the others. (As it lets us shorten the
514 # memEQ clause at no cost).
515 foreach my $i ($namelen - 1, 0 .. ($namelen - 2)) {
516 my ($min, $max) = (~0, 0);
517 my %spread;
47520512 518 if (is_perl56) {
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519 # Need proper Unicode preserving hash keys for bytes in range 128-255
520 # here too, for some reason. grr 5.6.1 yet again.
521 tie %spread, 'ExtUtils::Constant::Aaargh56Hash';
522 }
523 foreach (@names) {
524 my $char = substr $_, $i, 1;
525 my $ord = ord $char;
526 confess "char $ord is out of range" if $ord > 255;
527 $max = $ord if $ord > $max;
528 $min = $ord if $ord < $min;
529 push @{$spread{$char}}, $_;
530 # warn "$_ $char";
531 }
532 # I'm going to pick the character to split on that minimises the root
533 # mean square of the number of names in each case. Normally this should
534 # be the one with the most keys, but it may pick a 7 where the 8 has
535 # one long linear search. I'm not sure if RMS or just sum of squares is
536 # actually better.
537 # $max and $min are for the tie-breaker if the root mean squares match.
538 # Assuming that the compiler may be building a jump table for the
539 # switch() then try to minimise the size of that jump table.
540 # Finally use < not <= so that if it still ties the earliest part of
541 # the string wins. Because if that passes but the memEQ fails, it may
542 # only need the start of the string to bin the choice.
543 # I think. But I'm micro-optimising. :-)
544 # OK. Trump that. Now favour the last character of the string, before the
545 # rest.
546 my $ss;
547 $ss += @$_ * @$_ foreach values %spread;
548 my $rms = sqrt ($ss / keys %spread);
549 if ($rms < $best[0] || ($rms == $best[0] && ($max - $min) < $best[1])) {
550 @best = ($rms, $max - $min, $i, \%spread);
551 }
552 }
553 confess "Internal error. Failed to pick a switch point for @names"
554 unless defined $best[2];
555 # use Data::Dumper; print Dumper (@best);
556 my ($offset, $best) = @best[2,3];
557 $body .= $indent . "/* Offset $offset gives the best switch position. */\n";
558
559 my $do_front_chop = $offset == 0 && $namelen > 2;
560 if ($do_front_chop) {
561 $body .= $indent . "switch (*" . $self->name_param() . "++) {\n";
562 } else {
563 $body .= $indent . "switch (" . $self->name_param() . "[$offset]) {\n";
564 }
565 foreach my $char (sort keys %$best) {
566 confess sprintf "'$char' is %d bytes long, not 1", length $char
567 if length ($char) != 1;
568 confess sprintf "char %#X is out of range", ord $char if ord ($char) > 255;
569 $body .= $indent . "case '" . C_stringify ($char) . "':\n";
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570 foreach my $thisone (sort {
571 # Deal with the case of an item actually being an array ref to 1 or 2
4e1a4e48 572 # hashrefs. Don't assign to $a or $b, as they're aliases to the orignal
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573 my $l = ref $a eq 'ARRAY' ? ($a->[0] || $->[1]) : $a;
574 my $r = ref $b eq 'ARRAY' ? ($b->[0] || $->[1]) : $b;
4e1a4e48 575 # Sort by weight first
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576 ($r->{weight} || 0) <=> ($l->{weight} || 0)
577 # Sort equal weights by name
4e1a4e48
NC
578 or $l->{name} cmp $r->{name}}
579 # If this looks evil, maybe it is. $items is a
580 # hashref, and we're doing a hash slice on it
581 @{$items}{@{$best->{$char}}}) {
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582 # warn "You are here";
583 if ($do_front_chop) {
584 $body .= $self->match_clause ({indent => 2 + length $indent,
585 checked_at => \$char}, $thisone);
586 } else {
587 $body .= $self->match_clause ({indent => 2 + length $indent,
588 checked_at => $offset}, $thisone);
589 }
590 }
591 $body .= $indent . " break;\n";
592 }
593 $body .= $indent . "}\n";
594 return $body;
595}
596
597sub C_constant_return_type {
598 "static int";
599}
600
601sub C_constant_prefix_param {
602 '';
603}
604
605sub C_constant_prefix_param_defintion {
606 '';
607}
608
f8901870 609sub name_param_definition {
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610 "const char *" . $_[0]->name_param;
611}
612
f8901870 613sub namelen_param {
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614 'len';
615}
616
f8901870
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617sub namelen_param_definition {
618 'size_t ' . $_[0]->namelen_param;
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619}
620
f8901870 621sub C_constant_other_params {
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622 '';
623}
624
f8901870 625sub C_constant_other_params_defintion {
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626 '';
627}
628
629=item params WHAT
630
631An "internal" method, subject to change, currently called to allow an
632overriding class to cache information that will then be passed into all
633the C<*param*> calls. (Yes, having to read the source to make sense of this is
634considered a known bug). I<WHAT> is be a hashref of types the constant
635function will return. In ExtUtils::Constant::XS this method is used to
636returns a hashref keyed IV NV PV SV to show which combination of pointers will
f8901870
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637be needed in the C argument list generated by
638C_constant_other_params_definition and C_constant_other_params
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639
640=cut
641
642sub params {
643 '';
644}
645
646
647=item dogfood arg_hashref, ITEM...
648
649An internal function to generate the embedded perl code that will regenerate
650the constant subroutines. Parameters are the same as for C_constant.
651
652Currently the base class does nothing and returns an empty string.
653
654=cut
655
656sub dogfood {
657 ''
658}
659
329b93cd 660=item normalise_items args, default_type, seen_types, seen_items, ITEM...
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661
662Convert the items to a normalised form. For 8 bit and Unicode values converts
663the item to an array of 1 or 2 items, both 8 bit and UTF-8 encoded.
664
665=cut
666
667sub normalise_items
668{
669 my $self = shift;
329b93cd 670 my $args = shift;
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671 my $default_type = shift;
672 my $what = shift;
673 my $items = shift;
674 my @new_items;
675 foreach my $orig (@_) {
676 my ($name, $item);
677 if (ref $orig) {
678 # Make a copy which is a normalised version of the ref passed in.
679 $name = $orig->{name};
680 my ($type, $macro, $value) = @$orig{qw (type macro value)};
681 $type ||= $default_type;
682 $what->{$type} = 1;
683 $item = {name=>$name, type=>$type};
684
685 undef $macro if defined $macro and $macro eq $name;
686 $item->{macro} = $macro if defined $macro;
687 undef $value if defined $value and $value eq $name;
688 $item->{value} = $value if defined $value;
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689 foreach my $key (qw(default pre post def_pre def_post weight
690 not_constant)) {
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691 my $value = $orig->{$key};
692 $item->{$key} = $value if defined $value;
693 # warn "$key $value";
694 }
695 } else {
696 $name = $orig;
697 $item = {name=>$name, type=>$default_type};
698 $what->{$default_type} = 1;
699 }
700 warn +(ref ($self) || $self)
701 . "doesn't know how to handle values of type $_ used in macro $name"
702 unless $self->valid_type ($item->{type});
703 # tr///c is broken on 5.6.1 for utf8, so my original tr/\0-\177//c
704 # doesn't work. Upgrade to 5.8
705 # if ($name !~ tr/\0-\177//c || $] < 5.005_50) {
329b93cd
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706 if ($name =~ tr/\0-\177// == length $name || $] < 5.005_50
707 || $args->{disable_utf8_duplication}) {
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708 # No characters outside 7 bit ASCII.
709 if (exists $items->{$name}) {
710 die "Multiple definitions for macro $name";
711 }
712 $items->{$name} = $item;
713 } else {
714 # No characters outside 8 bit. This is hardest.
715 if (exists $items->{$name} and ref $items->{$name} ne 'ARRAY') {
716 confess "Unexpected ASCII definition for macro $name";
717 }
718 # Again, 5.6.1 tr broken, so s/5\.6.*/5\.8\.0/;
719 # if ($name !~ tr/\0-\377//c) {
720 if ($name =~ tr/\0-\377// == length $name) {
721# if ($] < 5.007) {
722# $name = pack "C*", unpack "U*", $name;
723# }
724 $item->{utf8} = 'no';
725 $items->{$name}[1] = $item;
726 push @new_items, $item;
727 # Copy item, to create the utf8 variant.
728 $item = {%$item};
729 }
730 # Encode the name as utf8 bytes.
47520512 731 unless (is_perl56) {
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732 utf8::encode($name);
733 } else {
734# warn "Was >$name< " . length ${name};
735 $name = pack 'C*', unpack 'C*', $name . pack 'U*';
736# warn "Now '${name}' " . length ${name};
737 }
738 if ($items->{$name}[0]) {
739 die "Multiple definitions for macro $name";
740 }
741 $item->{utf8} = 'yes';
742 $item->{name} = $name;
743 $items->{$name}[0] = $item;
744 # We have need for the utf8 flag.
745 $what->{''} = 1;
746 }
747 push @new_items, $item;
748 }
749 @new_items;
750}
751
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752=item C_constant arg_hashref, ITEM...
753
754A function that returns a B<list> of C subroutine definitions that return
755the value and type of constants when passed the name by the XS wrapper.
756I<ITEM...> gives a list of constant names. Each can either be a string,
757which is taken as a C macro name, or a reference to a hash with the following
758keys
759
760=over 8
761
762=item name
763
764The name of the constant, as seen by the perl code.
765
766=item type
767
768The type of the constant (I<IV>, I<NV> etc)
769
770=item value
771
772A C expression for the value of the constant, or a list of C expressions if
773the type is aggregate. This defaults to the I<name> if not given.
774
775=item macro
776
777The C pre-processor macro to use in the C<#ifdef>. This defaults to the
778I<name>, and is mainly used if I<value> is an C<enum>. If a reference an
779array is passed then the first element is used in place of the C<#ifdef>
780line, and the second element in place of the C<#endif>. This allows
781pre-processor constructions such as
782
783 #if defined (foo)
784 #if !defined (bar)
785 ...
786 #endif
787 #endif
788
789to be used to determine if a constant is to be defined.
790
791A "macro" 1 signals that the constant is always defined, so the C<#if>/C<#endif>
792test is omitted.
793
794=item default
795
796Default value to use (instead of C<croak>ing with "your vendor has not
797defined...") to return if the macro isn't defined. Specify a reference to
798an array with type followed by value(s).
799
800=item pre
801
802C code to use before the assignment of the value of the constant. This allows
803you to use temporary variables to extract a value from part of a C<struct>
804and return this as I<value>. This C code is places at the start of a block,
805so you can declare variables in it.
806
807=item post
808
809C code to place between the assignment of value (to a temporary) and the
810return from the function. This allows you to clear up anything in I<pre>.
811Rarely needed.
812
813=item def_pre
814
815=item def_post
816
817Equivalents of I<pre> and I<post> for the default value.
818
819=item utf8
820
821Generated internally. Is zero or undefined if name is 7 bit ASCII,
822"no" if the name is 8 bit (and so should only match if SvUTF8() is false),
823"yes" if the name is utf8 encoded.
824
825The internals automatically clone any name with characters 128-255 but none
826256+ (ie one that could be either in bytes or utf8) into a second entry
827which is utf8 encoded.
828
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829=item weight
830
831Optional sorting weight for names, to determine the order of
832linear testing when multiple names fall in the same case of a switch clause.
833Higher comes earlier, undefined defaults to zero.
834
af6ca1d0
NC
835=back
836
837In the argument hashref, I<package> is the name of the package, and is only
838used in comments inside the generated C code. I<subname> defaults to
839C<constant> if undefined.
840
841I<default_type> is the type returned by C<ITEM>s that don't specify their
842type. It defaults to the value of C<default_type()>. I<types> should be given
843either as a comma separated list of types that the C subroutine I<subname>
844will generate or as a reference to a hash. I<default_type> will be added to
845the list if not present, as will any types given in the list of I<ITEM>s. The
846resultant list should be the same list of types that C<XS_constant> is
847given. [Otherwise C<XS_constant> and C<C_constant> may differ in the number of
848parameters to the constant function. I<indent> is currently unused and
849ignored. In future it may be used to pass in information used to change the C
850indentation style used.] The best way to maintain consistency is to pass in a
851hash reference and let this function update it.
852
853I<breakout> governs when child functions of I<subname> are generated. If there
854are I<breakout> or more I<ITEM>s with the same length of name, then the code
855to switch between them is placed into a function named I<subname>_I<len>, for
856example C<constant_5> for names 5 characters long. The default I<breakout> is
8573. A single C<ITEM> is always inlined.
858
859=cut
860
861# The parameter now BREAKOUT was previously documented as:
862#
863# I<NAMELEN> if defined signals that all the I<name>s of the I<ITEM>s are of
864# this length, and that the constant name passed in by perl is checked and
865# also of this length. It is used during recursion, and should be C<undef>
866# unless the caller has checked all the lengths during code generation, and
867# the generated subroutine is only to be called with a name of this length.
868#
869# As you can see it now performs this function during recursion by being a
870# scalar reference.
871
872sub C_constant {
873 my ($self, $args, @items) = @_;
874 my ($package, $subname, $default_type, $what, $indent, $breakout) =
875 @{$args}{qw(package subname default_type types indent breakout)};
876 $package ||= 'Foo';
877 $subname ||= 'constant';
878 # I'm not using this. But a hashref could be used for full formatting without
879 # breaking this API
880 # $indent ||= 0;
881
882 my ($namelen, $items);
883 if (ref $breakout) {
884 # We are called recursively. We trust @items to be normalised, $what to
885 # be a hashref, and pinch %$items from our parent to save recalculation.
886 ($namelen, $items) = @$breakout;
887 } else {
efa32bb4 888 $items = {};
47520512 889 if (is_perl56) {
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890 # Need proper Unicode preserving hash keys.
891 require ExtUtils::Constant::Aaargh56Hash;
af6ca1d0
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892 tie %$items, 'ExtUtils::Constant::Aaargh56Hash';
893 }
894 $breakout ||= 3;
895 $default_type ||= $self->default_type();
896 if (!ref $what) {
897 # Convert line of the form IV,UV,NV to hash
898 $what = {map {$_ => 1} split /,\s*/, ($what || '')};
899 # Figure out what types we're dealing with, and assign all unknowns to the
900 # default type
901 }
329b93cd 902 @items = $self->normalise_items ({}, $default_type, $what, $items, @items);
af6ca1d0
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903 # use Data::Dumper; print Dumper @items;
904 }
905 my $params = $self->params ($what);
906
907 # Probably "static int"
908 my ($body, @subs);
909 $body = $self->C_constant_return_type($params) . "\n$subname ("
910 # Eg "pTHX_ "
911 . $self->C_constant_prefix_param_defintion($params)
912 # Probably "const char *name"
f8901870 913 . $self->name_param_definition($params);
af6ca1d0 914 # Something like ", STRLEN len"
f8901870 915 $body .= ", " . $self->namelen_param_definition($params)
af6ca1d0 916 unless defined $namelen;
f8901870 917 $body .= $self->C_constant_other_params_defintion($params);
af6ca1d0
NC
918 $body .= ") {\n";
919
920 if (defined $namelen) {
921 # We are a child subroutine. Print the simple description
922 my $comment = 'When generated this function returned values for the list'
923 . ' of names given here. However, subsequent manual editing may have'
924 . ' added or removed some.';
925 $body .= $self->switch_clause ({indent=>2, comment=>$comment},
926 $namelen, $items, @items);
927 } else {
928 # We are the top level.
929 $body .= " /* Initially switch on the length of the name. */\n";
930 $body .= $self->dogfood ({package => $package, subname => $subname,
931 default_type => $default_type, what => $what,
932 indent => $indent, breakout => $breakout},
933 @items);
f8901870 934 $body .= ' switch ('.$self->namelen_param().") {\n";
af6ca1d0
NC
935 # Need to group names of the same length
936 my @by_length;
937 foreach (@items) {
938 push @{$by_length[length $_->{name}]}, $_;
939 }
940 foreach my $i (0 .. $#by_length) {
941 next unless $by_length[$i]; # None of this length
942 $body .= " case $i:\n";
943 if (@{$by_length[$i]} == 1) {
944 my $only_thing = $by_length[$i]->[0];
945 if ($only_thing->{utf8}) {
946 if ($only_thing->{utf8} eq 'yes') {
947 # With utf8 on flag item is passed in element 0
948 $body .= $self->match_clause (undef, [$only_thing]);
949 } else {
950 # With utf8 off flag item is passed in element 1
951 $body .= $self->match_clause (undef, [undef, $only_thing]);
952 }
953 } else {
954 $body .= $self->match_clause (undef, $only_thing);
955 }
956 } elsif (@{$by_length[$i]} < $breakout) {
957 $body .= $self->switch_clause ({indent=>4},
958 $i, $items, @{$by_length[$i]});
959 } else {
960 # Only use the minimal set of parameters actually needed by the types
961 # of the names of this length.
962 my $what = {};
963 foreach (@{$by_length[$i]}) {
964 $what->{$_->{type}} = 1;
965 $what->{''} = 1 if $_->{utf8};
966 }
967 $params = $self->params ($what);
968 push @subs, $self->C_constant ({package=>$package,
969 subname=>"${subname}_$i",
970 default_type => $default_type,
971 types => $what, indent => $indent,
972 breakout => [$i, $items]},
973 @{$by_length[$i]});
974 $body .= " return ${subname}_$i ("
975 # Eg "aTHX_ "
976 . $self->C_constant_prefix_param($params)
977 # Probably "name"
978 . $self->name_param($params);
f8901870 979 $body .= $self->C_constant_other_params($params);
af6ca1d0
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980 $body .= ");\n";
981 }
982 $body .= " break;\n";
983 }
984 $body .= " }\n";
985 }
986 my $notfound = $self->return_statement_for_notfound();
987 $body .= " $notfound\n" if $notfound;
988 $body .= "}\n";
989 return (@subs, $body);
990}
991
9921;
993__END__
994
995=back
996
997=head1 BUGS
998
999Not everything is documented yet.
1000
1001Probably others.
1002
1003=head1 AUTHOR
1004
1005Nicholas Clark <nick@ccl4.org> based on the code in C<h2xs> by Larry Wall and
1006others