Codebase list libdevel-declare-perl / 8dbaf4e
[svn-upgrade] new version libdevel-declare-perl (0.006003) Gregor Herrmann 13 years ago
10 changed file(s) with 64 addition(s) and 375 deletion(s). Raw diff Collapse all Expand all
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Changes less more
00 Changes for Devel-Declare
1
2 0.006003 - 12 Apr 2011
3 - Fix test-failures on old perl versions (Zefram).
4
5 0.006002 - 08 Apr 2011
6 - Re-add Support for very early growing of PL_linestr using filters (Zefram).
17
28 0.006001 - 26 Feb 2011
39 - Support perl >= 5.13.7 by re-allocating PL_linestr in block hooks (Zefram).
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Declare.xs less more
378378 return o;
379379 }
380380
381 #endif /* !DD_GROW_VIA_BLOCKHOOK */
382
381383 static I32 dd_filter_realloc(pTHX_ int idx, SV *sv, int maxlen)
382384 {
383385 const I32 count = FILTER_READ(idx+1, sv, maxlen);
385387 /* filter_del(dd_filter_realloc); */
386388 return count;
387389 }
388
389 #endif /* !DD_GROW_VIA_BLOCKHOOK */
390390
391391 static int dd_handle_const(pTHX_ char *name) {
392392 switch (PL_lex_inwhat) {
499499 hook_op_check(OP_CONST, dd_ck_const, NULL);
500500 #endif /* !DD_CONST_VIA_RV2CV */
501501 }
502 #if !DD_GROW_VIA_BLOCKHOOK
503502 filter_add(dd_filter_realloc, NULL);
504 #endif /* !DD_GROW_VIA_BLOCKHOOK */
505503
506504 char*
507505 get_linestr()
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MANIFEST less more
1010 Makefile.PL
1111 MANIFEST This list of files
1212 META.yml
13 README
1413 stolen_chunk_of_toke.c
1514 t/00load.t
1615 t/build_sub_installer.t
1918 t/ctx-simple.t
2019 t/debug.pl
2120 t/debug.t
21 t/early0.t
22 t/early1.t
23 t/early1_x.pm
2224 t/eval.t
2325 t/fail.t
2426 t/lines.t
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META.yml less more
2929 resources:
3030 license: http://dev.perl.org/licenses/
3131 repository: git://github.com/rafl/devel-declare.git
32 version: 0.006001
32 version: 0.006003
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README less more
0 NAME
1 Devel::Declare - Adding keywords to perl, in perl
2
3 SYNOPSIS
4 use Method::Signatures;
5 # or ...
6 use MooseX::Declare;
7 # etc.
8
9 # Use some new and exciting syntax like:
10 method hello (Str :$who, Int :$age where { $_ > 0 }) {
11 $self->say("Hello ${who}, I am ${age} years old!");
12 }
13
14 DESCRIPTION
15 Devel::Declare can install subroutines called declarators which locally
16 take over Perl's parser, allowing the creation of new syntax.
17
18 This document describes how to create a simple declarator.
19
20 USAGE
21 We'll demonstrate the usage of "Devel::Declare" with a motivating
22 example: a new "method" keyword, which acts like the builtin "sub", but
23 automatically unpacks $self and the other arguments.
24
25 package My::Methods;
26 use Devel::Declare;
27
28 Creating a declarator with "setup_for"
29 You will typically create
30
31 sub import {
32 my $class = shift;
33 my $caller = caller;
34
35 Devel::Declare->setup_for(
36 $caller,
37 { method => { const => \&parser } }
38 );
39 no strict 'refs';
40 *{$caller.'::method'} = sub (&) {};
41 }
42
43 Starting from the end of this import routine, you'll see that we're
44 creating a subroutine called "method" in the caller's namespace. Yes,
45 that's just a normal subroutine, and it does nothing at all (yet!) Note
46 the prototype "(&)" which means that the caller would call it like so:
47
48 method {
49 my ($self, $arg1, $arg2) = @_;
50 ...
51 }
52
53 However we want to be able to call it like this
54
55 method foo ($arg1, $arg2) {
56 ...
57 }
58
59 That's why we call "setup_for" above, to register the declarator
60 'method' with a custom parser, as per the next section. It acts on an
61 optype, usually 'const' as above. (Other valid values are 'check' and
62 'rv2cv').
63
64 For a simpler way to install new methods, see also
65 Devel::Declare::MethodInstaller::Simple
66
67 Writing a parser subroutine
68 This subroutine is called at *compilation* time, and allows you to read
69 the custom syntaxes that we want (in a syntax that may or may not be
70 valid core Perl 5) and munge it so that the result will be parsed by the
71 "perl" compiler.
72
73 For this example, we're defining some globals for convenience:
74
75 our ($Declarator, $Offset);
76
77 Then we define a parser subroutine to handle our declarator. We'll look
78 at this in a few chunks.
79
80 sub parser {
81 local ($Declarator, $Offset) = @_;
82
83 "Devel::Declare" provides some very low level utility methods to parse
84 character strings. We'll define some useful higher level routines below
85 for convenience, and we can use these to parse the various elements in
86 our new syntax.
87
88 Notice how our parser subroutine is invoked at compile time, when the
89 "perl" parser is pointed just *before* the declarator name.
90
91 skip_declarator; # step past 'method'
92 my $name = strip_name; # strip out the name 'foo', if present
93 my $proto = strip_proto; # strip out the prototype '($arg1, $arg2)', if present
94
95 Now we can prepare some code to 'inject' into the new subroutine. For
96 example we might want the method as above to have "my ($self, $arg1,
97 $arg2) = @_" injected at the beginning of it. We also do some clever
98 stuff with scopes that we'll look at shortly.
99
100 my $inject = make_proto_unwrap($proto);
101 if (defined $name) {
102 $inject = scope_injector_call().$inject;
103 }
104 inject_if_block($inject);
105
106 We've now managed to change "method ($arg1, $arg2) { ... }" into "method
107 { injected_code; ... }". This will compile... but we've lost the name of
108 the method!
109
110 In a cute (or horrifying, depending on your perspective) trick, we
111 temporarily change the definition of the subroutine "method" itself, to
112 specialise it with the $name we stripped, so that it assigns the code
113 block to that name.
114
115 Even though the *next* time "method" is compiled, it will be redefined
116 again, "perl" caches these definitions in its parse tree, so we'll
117 always get the right one!
118
119 Note that we also handle the case where there was no name, allowing an
120 anonymous method analogous to an anonymous subroutine.
121
122 if (defined $name) {
123 $name = join('::', Devel::Declare::get_curstash_name(), $name)
124 unless ($name =~ /::/);
125 shadow(sub (&) { no strict 'refs'; *{$name} = shift; });
126 } else {
127 shadow(sub (&) { shift });
128 }
129 }
130
131 Parser utilities in detail
132 For simplicity, we're using global variables like $Offset in these
133 examples. You may prefer to look at Devel::Declare::Context::Simple,
134 which encapsulates the context much more cleanly.
135
136 "skip_declarator"
137 This simple parser just moves across a 'token'. The common case is to
138 skip the declarator, i.e. to move to the end of the string 'method' and
139 before the prototype and code block.
140
141 sub skip_declarator {
142 $Offset += Devel::Declare::toke_move_past_token($Offset);
143 }
144
145 "toke_move_past_token"
146 This builtin parser simply moves past a 'token' (matching
147 "/[a-zA-Z_]\w*/") It takes an offset into the source document, and skips
148 past the token. It returns the number of characters skipped.
149
150 "strip_name"
151 This parser skips any whitespace, then scans the next word (again
152 matching a 'token'). We can then analyse the current line, and
153 manipulate it (using pure Perl). In this case we take the name of the
154 method out, and return it.
155
156 sub strip_name {
157 skipspace;
158 if (my $len = Devel::Declare::toke_scan_word($Offset, 1)) {
159 my $linestr = Devel::Declare::get_linestr();
160 my $name = substr($linestr, $Offset, $len);
161 substr($linestr, $Offset, $len) = '';
162 Devel::Declare::set_linestr($linestr);
163 return $name;
164 }
165 return;
166 }
167
168 "toke_scan_word"
169 This builtin parser, given an offset into the source document, matches a
170 'token' as above but does not skip. It returns the length of the token
171 matched, if any.
172
173 "get_linestr"
174 This builtin returns the full text of the current line of the source
175 document.
176
177 "set_linestr"
178 This builtin sets the full text of the current line of the source
179 document.
180
181 "skipspace"
182 This parser skips whitsepace.
183
184 sub skipspace {
185 $Offset += Devel::Declare::toke_skipspace($Offset);
186 }
187
188 "toke_skipspace"
189 This builtin parser, given an offset into the source document, skips
190 over any whitespace, and returns the number of characters skipped.
191
192 "strip_proto"
193 This is a more complex parser that checks if it's found something that
194 starts with '(' and returns everything till the matching ')'.
195
196 sub strip_proto {
197 skipspace;
198
199 my $linestr = Devel::Declare::get_linestr();
200 if (substr($linestr, $Offset, 1) eq '(') {
201 my $length = Devel::Declare::toke_scan_str($Offset);
202 my $proto = Devel::Declare::get_lex_stuff();
203 Devel::Declare::clear_lex_stuff();
204 $linestr = Devel::Declare::get_linestr();
205 substr($linestr, $Offset, $length) = '';
206 Devel::Declare::set_linestr($linestr);
207 return $proto;
208 }
209 return;
210 }
211
212 "toke_scan_str"
213 This builtin parser uses Perl's own parsing routines to match a
214 "stringlike" expression. Handily, this includes bracketed expressions
215 (just think about things like "q(this is a quote)").
216
217 Also it Does The Right Thing with nested delimiters (like "q(this (is
218 (a) quote))").
219
220 It returns the length of the expression matched. Use "get_lex_stuff" to
221 get the actual matched text.
222
223 "get_lex_stuff"
224 This builtin returns what was matched by "toke_scan_str". To avoid
225 segfaults, you should call "clear_lex_stuff" immediately afterwards.
226
227 Munging the subroutine
228 Let's look at what we need to do in detail.
229
230 "make_proto_unwrap"
231 We may have defined our method in different ways, which will result in a
232 different value for our prototype, as parsed above. For example:
233
234 method foo { # undefined
235 method foo () { # ''
236 method foo ($arg1) { # '$arg1'
237
238 We deal with them as follows, and return the appropriate "my ($self,
239 ...) = @_;" string.
240
241 sub make_proto_unwrap {
242 my ($proto) = @_;
243 my $inject = 'my ($self';
244 if (defined $proto) {
245 $inject .= ", $proto" if length($proto);
246 $inject .= ') = @_; ';
247 } else {
248 $inject .= ') = shift;';
249 }
250 return $inject;
251 }
252
253 "inject_if_block"
254 Now we need to inject it after the opening '{' of the method body. We
255 can do this with the building blocks we defined above like "skipspace"
256 and "get_linestr".
257
258 sub inject_if_block {
259 my $inject = shift;
260 skipspace;
261 my $linestr = Devel::Declare::get_linestr;
262 if (substr($linestr, $Offset, 1) eq '{') {
263 substr($linestr, $Offset+1, 0) = $inject;
264 Devel::Declare::set_linestr($linestr);
265 }
266 }
267
268 "scope_injector_call"
269 We want to be able to handle both named and anonymous methods. i.e.
270
271 method foo () { ... }
272 my $meth = method () { ... };
273
274 These will then get rewritten as
275
276 method { ... }
277 my $meth = method { ... };
278
279 where 'method' is a subroutine that takes a code block. Spot the
280 problem? The first one doesn't have a semicolon at the end of it! Unlike
281 'sub' which is a builtin, this is just a normal statement, so we need to
282 terminate it. Luckily, using "B::Hooks::EndOfScope", we can do this!
283
284 use B::Hooks::EndOfScope;
285
286 We'll add this to what gets 'injected' at the beginning of the method
287 source.
288
289 sub scope_injector_call {
290 return ' BEGIN { MethodHandlers::inject_scope }; ';
291 }
292
293 So at the beginning of every method, we are passing a callback that will
294 get invoked at the *end* of the method's compilation... i.e. exactly
295 then the closing '}' is compiled.
296
297 sub inject_scope {
298 on_scope_end {
299 my $linestr = Devel::Declare::get_linestr;
300 my $offset = Devel::Declare::get_linestr_offset;
301 substr($linestr, $offset, 0) = ';';
302 Devel::Declare::set_linestr($linestr);
303 };
304 }
305
306 Shadowing each method.
307 "shadow"
308 We override the current definition of 'method' using "shadow".
309
310 sub shadow {
311 my $pack = Devel::Declare::get_curstash_name;
312 Devel::Declare::shadow_sub("${pack}::${Declarator}", $_[0]);
313 }
314
315 For a named method we invoked like this:
316
317 shadow(sub (&) { no strict 'refs'; *{$name} = shift; });
318
319 So in the case of a "method foo { ... }", this call would redefine
320 "method" to be a subroutine that exports 'sub foo' as the (munged)
321 contents of "{...}".
322
323 The case of an anonymous method is also cute:
324
325 shadow(sub (&) { shift });
326
327 This means that
328
329 my $meth = method () { ... };
330
331 is rewritten with "method" taking the codeblock, and returning it as is
332 to become the value of $meth.
333
334 "get_curstash_name"
335 This returns the package name *currently being compiled*.
336
337 "shadow_sub"
338 Handles the details of redefining the subroutine.
339
340 SEE ALSO
341 One of the best ways to learn "Devel::Declare" is still to look at
342 modules that use it:
343
344 <http://cpants.perl.org/dist/used_by/Devel-Declare>.
345
346 AUTHORS
347 Matt S Trout - <mst@shadowcat.co.uk> - original author
348
349 Company: http://www.shadowcat.co.uk/ Blog: http://chainsawblues.vox.com/
350
351 Florian Ragwitz <rafl@debian.org> - maintainer
352
353 osfameron <osfameron@cpan.org> - first draft of documentation
354
355 COPYRIGHT AND LICENSE
356 This library is free software under the same terms as perl itself
357
358 Copyright (c) 2007, 2008, 2009 Matt S Trout
359
360 Copyright (c) 2008, 2009 Florian Ragwitz
361
362 stolen_chunk_of_toke.c based on toke.c from the perl core, which is
363
364 Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
365 2000, 2001, 2002, 2003, 2004, 2005, 2006, by Larry Wall and others
366
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lib/Devel/Declare/MethodInstaller/Simple.pm less more
66 use strict;
77 use warnings;
88
9 our $VERSION = '0.006001';
9 our $VERSION = '0.006003';
1010
1111 sub install_methodhandler {
1212 my $class = shift;
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lib/Devel/Declare.pm less more
33 use warnings;
44 use 5.008001;
55
6 our $VERSION = '0.006001';
6 our $VERSION = '0.006003';
77
88 use constant DECLARE_NAME => 1;
99 use constant DECLARE_PROTO => 2;
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t/early0.t less more
0 use strict;
1 use warnings;
2 use Test::More tests => 1;
3 BEGIN {
4 require Devel::Declare;
5 *class = sub (&) { $_[0]->() };
6 Devel::Declare->setup_for(__PACKAGE__, {
7 class => {
8 const => sub {
9 my ($kw, $off) = @_;
10 $off += Devel::Declare::toke_move_past_token($off);
11 $off += Devel::Declare::toke_skipspace($off);
12 die unless substr(Devel::Declare::get_linestr(), $off, 1) eq '{';
13 my $l = Devel::Declare::get_linestr();
14 substr $l, $off + 1, 0, 'pass q[injected];' . (';' x 1000);
15 Devel::Declare::set_linestr($l);
16 },
17 },
18 });
19 }
20 class {};
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t/early1.t less more
0 use strict;
1 use warnings;
2 use Test::More tests => 1;
3 use t::early1_x;
4 class {};
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t/early1_x.pm less more
0 package t::early1_x;
1 use strict;
2 use warnings;
3 sub import {
4 require Devel::Declare;
5 my $caller = caller();
6 no strict 'refs';
7 *{ "${caller}::class" } = sub (&) { $_[0]->() };
8 Devel::Declare->setup_for($caller, {
9 class => {
10 const => sub {
11 my ($kw, $off) = @_;
12 $off += Devel::Declare::toke_move_past_token($off);
13 $off += Devel::Declare::toke_skipspace($off);
14 die unless substr(Devel::Declare::get_linestr(), $off, 1) eq '{';
15 my $l = Devel::Declare::get_linestr();
16 substr $l, $off + 1, 0, 'pass q[injected];' . (';' x 1000);
17 Devel::Declare::set_linestr($l);
18 },
19 },
20 });
21 }
22
23 1;