]> git.saurik.com Git - bison.git/blob - NEWS
8e3280a3544c68e49664dc84bbb91a7fdee10312
[bison.git] / NEWS
1 Bison News
2 ----------
3
4 * Changes in version 2.5 (????-??-??):
5
6 ** Named References Support
7
8 Historically, Yacc and Bison have supported positional references
9 ($n, $$) to allow access to symbol values from inside of semantic
10 actions code.
11
12 Starting from this version, Bison can also accept named references.
13 When no ambiguity is possible, original symbol names may be used
14 as named references:
15
16 if_stmt : 'if' cond_expr 'then' then_stmt ';'
17 { $if_stmt = mk_if_stmt($cond_expr, $then_stmt); }
18
19 In the more common case, explicit names may be declared:
20
21 stmt[res] : 'if' expr[cond] 'then' stmt[then] 'else' stmt[else] ';'
22 { $res = mk_if_stmt($cond, $then, $else); }
23
24 Location information is also accessible using @name syntax. When
25 accessing symbol names containing dots or dashes, explicit bracketing
26 ($[sym.1]) must be used.
27
28 These features are experimental in this version. More user feedback
29 will help to stabilize them.
30
31 ** IELR(1) and Canonical LR(1) Support
32
33 IELR(1) is a minimal LR(1) parser table generation algorithm. That
34 is, given any context-free grammar, IELR(1) generates parser tables
35 with the full language recognition power of canonical LR(1) but with
36 nearly the same number of parser states as LALR(1). This reduction in
37 parser states is often an order of magnitude. More importantly,
38 because canonical LR(1)'s extra parser states may contain duplicate
39 conflicts in the case of non-LR(1) grammars, the number of conflicts
40 for IELR(1) is often an order of magnitude less as well. This can
41 significantly reduce the complexity of developing of a grammar.
42
43 Bison can now generate IELR(1) and canonical LR(1) parser tables in
44 place of its traditional LALR(1) parser tables, which remain the
45 default. You can specify the type of parser tables in the grammar
46 file with these directives:
47
48 %define lr.type lalr
49 %define lr.type ielr
50 %define lr.type canonical-lr
51
52 The default reduction optimization in the parser tables can also be
53 adjusted using `%define lr.default-reductions'. See the documentation
54 for `%define lr.type' and `%define lr.default-reductions' in the
55 section `Bison Declaration Summary' in the Bison manual for the
56 details.
57
58 These features are experimental. More user feedback will help to
59 stabilize them.
60
61 ** Unrecognized %code qualifiers are now an error not a warning.
62
63 ** %define improvements.
64
65 *** Unrecognized variables are now an error not a warning.
66
67 *** Multiple invocations for any variable is now an error not a warning.
68
69 *** Can now be invoked via the command line.
70
71 Each of these command-line options
72
73 -D NAME[=VALUE]
74 --define=NAME[=VALUE]
75
76 -F NAME[=VALUE]
77 --force-define=NAME[=VALUE]
78
79 is equivalent to this grammar file declaration
80
81 %define NAME ["VALUE"]
82
83 except that the manner in which Bison processes multiple definitions
84 for the same NAME differs. Most importantly, -F and --force-define
85 quietly override %define, but -D and --define do not. For further
86 details, see the section "Bison Options" in the Bison manual.
87
88 *** Variables renamed.
89
90 The following %define variables
91
92 api.push_pull
93 lr.keep_unreachable_states
94
95 have been renamed to
96
97 api.push-pull
98 lr.keep-unreachable-states
99
100 The old names are now deprecated but will be maintained indefinitely
101 for backward compatibility.
102
103 *** Values no longer need to be quoted in grammar file.
104
105 If a %define value is an identifier, it no longer needs to be placed
106 within quotations marks. For example,
107
108 %define api.push-pull "push"
109
110 can be rewritten as
111
112 %define api.push-pull push
113
114 ** Symbol names.
115
116 Consistently with directives (such as %error-verbose) and variables
117 (e.g. push-pull), symbol names may include dashes in any position,
118 similarly to periods and underscores. This is GNU extension over
119 POSIX Yacc whose use is reported by -Wyacc, and rejected in Yacc
120 mode (--yacc).
121
122 ** YYFAIL now produces warnings and Java parsers no longer implement it.
123
124 YYFAIL has existed for many years as an undocumented feature of
125 deterministic parsers in C generated by Bison. More recently, it was
126 a documented feature of Bison's experimental Java parsers. As
127 promised in Bison 2.4.2's NEWS entry, any appearance of YYFAIL in a
128 semantic action now produces a deprecation warning, and Java parsers
129 no longer implement YYFAIL at all. For further details, including a
130 discussion of how to suppress C preprocessor warnings about YYFAIL
131 being unused, see the Bison 2.4.2 NEWS entry.
132
133 ** Temporary hack for adding a semicolon to the user action.
134
135 Previously, Bison appended a semicolon to every user action for
136 reductions when the output language defaulted to C (specifically, when
137 neither %yacc, %language, %skeleton, or equivalent command-line
138 options were specified). This allowed actions such as
139
140 exp: exp "+" exp { $$ = $1 + $3 };
141
142 instead of
143
144 exp: exp "+" exp { $$ = $1 + $3; };
145
146 As a first step in removing this misfeature, Bison now issues a
147 warning when it appends a semicolon. Moreover, in cases where Bison
148 cannot easily determine whether a semicolon is needed (for example, an
149 action ending with a cpp directive or a braced compound initializer),
150 it no longer appends one. Thus, the C compiler might now complain
151 about a missing semicolon where it did not before. Future releases of
152 Bison will cease to append semicolons entirely.
153
154 ** Character literals not of length one.
155
156 Previously, Bison quietly converted all character literals to length
157 one. For example, without warning, Bison interpreted the operators in
158 the following grammar to be the same token:
159
160 exp: exp '++'
161 | exp '+' exp
162 ;
163
164 Bison now warns when a character literal is not of length one. In
165 some future release, Bison will report an error instead.
166
167 ** Verbose error messages fixed for nonassociative tokens.
168
169 When %error-verbose is specified, syntax error messages produced by
170 the generated parser include the unexpected token as well as a list of
171 expected tokens. Previously, this list erroneously included tokens
172 that would actually induce a syntax error because conflicts for them
173 were resolved with %nonassoc. Such tokens are now properly omitted
174 from the list.
175
176 ** Destructor calls fixed for lookaheads altered in semantic actions.
177
178 Previously for deterministic parsers in C, if a user semantic action
179 altered yychar, the parser in some cases used the old yychar value to
180 determine which destructor to call for the lookahead upon a syntax
181 error or upon parser return. This bug has been fixed.
182
183 * Changes in version 2.4.2 (????-??-??):
184
185 ** `%prec IDENTIFIER' requires IDENTIFIER to be defined separately.
186
187 POSIX specifies that an error be reported for any identifier that does
188 not appear on the LHS of a grammar rule and that is not defined by
189 %token, %left, %right, or %nonassoc. Bison 2.3b and later lost this
190 error report for the case when an identifier appears only after a
191 %prec directive. It is now restored. However, for backward
192 compatibility with recent Bison releases, it is only a warning for
193 now. In Bison 2.5 and later, it will return to being an error.
194
195 ** Detection of GNU M4 1.4.6 or newer during configure is improved.
196
197 ** Warnings from gcc's -Wundef option about undefined YYENABLE_NLS,
198 YYLTYPE_IS_TRIVIAL, and __STRICT_ANSI__ in C/C++ parsers are now
199 avoided.
200
201 ** %code is now a permanent feature.
202
203 A traditional Yacc prologue directive is written in the form:
204
205 %{CODE%}
206
207 To provide a more flexible alternative, Bison 2.3b introduced the
208 %code directive with the following forms for C/C++:
209
210 %code {CODE}
211 %code requires {CODE}
212 %code provides {CODE}
213 %code top {CODE}
214
215 These forms are now considered permanent features of Bison. See the
216 %code entries in the section "Bison Declaration Summary" in the Bison
217 manual for a summary of their functionality. See the section
218 "Prologue Alternatives" for a detailed discussion including the
219 advantages of %code over the traditional Yacc prologue directive.
220
221 Bison's Java feature as a whole including its current usage of %code
222 is still considered experimental.
223
224 ** YYFAIL is deprecated and will eventually be removed.
225
226 YYFAIL has existed for many years as an undocumented feature of
227 deterministic parsers in C generated by Bison. Previously, it was
228 documented for Bison's experimental Java parsers. YYFAIL is no longer
229 documented for Java parsers and is formally deprecated in both cases.
230 Users are strongly encouraged to migrate to YYERROR, which is
231 specified by POSIX.
232
233 Like YYERROR, you can invoke YYFAIL from a semantic action in order to
234 induce a syntax error. The most obvious difference from YYERROR is
235 that YYFAIL will automatically invoke yyerror to report the syntax
236 error so that you don't have to. However, there are several other
237 subtle differences between YYERROR and YYFAIL, and YYFAIL suffers from
238 inherent flaws when %error-verbose or `#define YYERROR_VERBOSE' is
239 used. For a more detailed discussion, see:
240
241 http://lists.gnu.org/archive/html/bison-patches/2009-12/msg00024.html
242
243 The upcoming Bison 2.5 will remove YYFAIL from Java parsers, but
244 deterministic parsers in C will continue to implement it. However,
245 because YYFAIL is already flawed, it seems futile to try to make new
246 Bison features compatible with it. Thus, during parser generation,
247 Bison 2.5 will produce a warning whenever it discovers YYFAIL in a
248 rule action. In a later release, YYFAIL will be disabled for
249 %error-verbose and `#define YYERROR_VERBOSE'. Eventually, YYFAIL will
250 be removed altogether.
251
252 There exists at least one case where Bison 2.5's YYFAIL warning will
253 be a false positive. Some projects add phony uses of YYFAIL and other
254 Bison-defined macros for the sole purpose of suppressing C
255 preprocessor warnings (from GCC cpp's -Wunused-macros, for example).
256 To avoid Bison's future warning, such YYFAIL uses can be moved to the
257 epilogue (that is, after the second `%%') in the Bison input file. In
258 this release (2.4.2), Bison already generates its own code to suppress
259 C preprocessor warnings for YYFAIL, so projects can remove their own
260 phony uses of YYFAIL if compatibility with Bison releases prior to
261 2.4.2 is not necessary.
262
263 ** Internationalization.
264
265 Fix a regression introduced in Bison 2.4: Under some circumstances,
266 message translations were not installed although supported by the
267 host system.
268
269 * Changes in version 2.4.1 (2008-12-11):
270
271 ** In the GLR defines file, unexpanded M4 macros in the yylval and yylloc
272 declarations have been fixed.
273
274 ** Temporary hack for adding a semicolon to the user action.
275
276 Bison used to prepend a trailing semicolon at the end of the user
277 action for reductions. This allowed actions such as
278
279 exp: exp "+" exp { $$ = $1 + $3 };
280
281 instead of
282
283 exp: exp "+" exp { $$ = $1 + $3; };
284
285 Some grammars still depend on this `feature'. Bison 2.4.1 restores
286 the previous behavior in the case of C output (specifically, when
287 neither %language or %skeleton or equivalent command-line options
288 are used) to leave more time for grammars depending on the old
289 behavior to be adjusted. Future releases of Bison will disable this
290 feature.
291
292 ** A few minor improvements to the Bison manual.
293
294 * Changes in version 2.4 (2008-11-02):
295
296 ** %language is an experimental feature.
297
298 We first introduced this feature in test release 2.3b as a cleaner
299 alternative to %skeleton. Since then, we have discussed the possibility of
300 modifying its effect on Bison's output file names. Thus, in this release,
301 we consider %language to be an experimental feature that will likely evolve
302 in future releases.
303
304 ** Forward compatibility with GNU M4 has been improved.
305
306 ** Several bugs in the C++ skeleton and the experimental Java skeleton have been
307 fixed.
308
309 * Changes in version 2.3b (2008-05-27):
310
311 ** The quotes around NAME that used to be required in the following directive
312 are now deprecated:
313
314 %define NAME "VALUE"
315
316 ** The directive `%pure-parser' is now deprecated in favor of:
317
318 %define api.pure
319
320 which has the same effect except that Bison is more careful to warn about
321 unreasonable usage in the latter case.
322
323 ** Push Parsing
324
325 Bison can now generate an LALR(1) parser in C with a push interface. That
326 is, instead of invoking `yyparse', which pulls tokens from `yylex', you can
327 push one token at a time to the parser using `yypush_parse', which will
328 return to the caller after processing each token. By default, the push
329 interface is disabled. Either of the following directives will enable it:
330
331 %define api.push_pull "push" // Just push; does not require yylex.
332 %define api.push_pull "both" // Push and pull; requires yylex.
333
334 See the new section `A Push Parser' in the Bison manual for details.
335
336 The current push parsing interface is experimental and may evolve. More user
337 feedback will help to stabilize it.
338
339 ** The -g and --graph options now output graphs in Graphviz DOT format,
340 not VCG format. Like --graph, -g now also takes an optional FILE argument
341 and thus cannot be bundled with other short options.
342
343 ** Java
344
345 Bison can now generate an LALR(1) parser in Java. The skeleton is
346 `data/lalr1.java'. Consider using the new %language directive instead of
347 %skeleton to select it.
348
349 See the new section `Java Parsers' in the Bison manual for details.
350
351 The current Java interface is experimental and may evolve. More user
352 feedback will help to stabilize it.
353
354 ** %language
355
356 This new directive specifies the programming language of the generated
357 parser, which can be C (the default), C++, or Java. Besides the skeleton
358 that Bison uses, the directive affects the names of the generated files if
359 the grammar file's name ends in ".y".
360
361 ** XML Automaton Report
362
363 Bison can now generate an XML report of the LALR(1) automaton using the new
364 `--xml' option. The current XML schema is experimental and may evolve. More
365 user feedback will help to stabilize it.
366
367 ** The grammar file may now specify the name of the parser header file using
368 %defines. For example:
369
370 %defines "parser.h"
371
372 ** When reporting useless rules, useless nonterminals, and unused terminals,
373 Bison now employs the terms "useless in grammar" instead of "useless",
374 "useless in parser" instead of "never reduced", and "unused in grammar"
375 instead of "unused".
376
377 ** Unreachable State Removal
378
379 Previously, Bison sometimes generated parser tables containing unreachable
380 states. A state can become unreachable during conflict resolution if Bison
381 disables a shift action leading to it from a predecessor state. Bison now:
382
383 1. Removes unreachable states.
384
385 2. Does not report any conflicts that appeared in unreachable states.
386 WARNING: As a result, you may need to update %expect and %expect-rr
387 directives in existing grammar files.
388
389 3. For any rule used only in such states, Bison now reports the rule as
390 "useless in parser due to conflicts".
391
392 This feature can be disabled with the following directive:
393
394 %define lr.keep_unreachable_states
395
396 See the %define entry in the `Bison Declaration Summary' in the Bison manual
397 for further discussion.
398
399 ** Lookahead Set Correction in the `.output' Report
400
401 When instructed to generate a `.output' file including lookahead sets
402 (using `--report=lookahead', for example), Bison now prints each reduction's
403 lookahead set only next to the associated state's one item that (1) is
404 associated with the same rule as the reduction and (2) has its dot at the end
405 of its RHS. Previously, Bison also erroneously printed the lookahead set
406 next to all of the state's other items associated with the same rule. This
407 bug affected only the `.output' file and not the generated parser source
408 code.
409
410 ** --report-file=FILE is a new option to override the default `.output' file
411 name.
412
413 ** The `=' that used to be required in the following directives is now
414 deprecated:
415
416 %file-prefix "parser"
417 %name-prefix "c_"
418 %output "parser.c"
419
420 ** An Alternative to `%{...%}' -- `%code QUALIFIER {CODE}'
421
422 Bison 2.3a provided a new set of directives as a more flexible alternative to
423 the traditional Yacc prologue blocks. Those have now been consolidated into
424 a single %code directive with an optional qualifier field, which identifies
425 the purpose of the code and thus the location(s) where Bison should generate
426 it:
427
428 1. `%code {CODE}' replaces `%after-header {CODE}'
429 2. `%code requires {CODE}' replaces `%start-header {CODE}'
430 3. `%code provides {CODE}' replaces `%end-header {CODE}'
431 4. `%code top {CODE}' replaces `%before-header {CODE}'
432
433 See the %code entries in section `Bison Declaration Summary' in the Bison
434 manual for a summary of the new functionality. See the new section `Prologue
435 Alternatives' for a detailed discussion including the advantages of %code
436 over the traditional Yacc prologues.
437
438 The prologue alternatives are experimental. More user feedback will help to
439 determine whether they should become permanent features.
440
441 ** Revised warning: unset or unused mid-rule values
442
443 Since Bison 2.2, Bison has warned about mid-rule values that are set but not
444 used within any of the actions of the parent rule. For example, Bison warns
445 about unused $2 in:
446
447 exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; };
448
449 Now, Bison also warns about mid-rule values that are used but not set. For
450 example, Bison warns about unset $$ in the mid-rule action in:
451
452 exp: '1' { $1 = 1; } '+' exp { $$ = $2 + $4; };
453
454 However, Bison now disables both of these warnings by default since they
455 sometimes prove to be false alarms in existing grammars employing the Yacc
456 constructs $0 or $-N (where N is some positive integer).
457
458 To enable these warnings, specify the option `--warnings=midrule-values' or
459 `-W', which is a synonym for `--warnings=all'.
460
461 ** Default %destructor or %printer with `<*>' or `<>'
462
463 Bison now recognizes two separate kinds of default %destructor's and
464 %printer's:
465
466 1. Place `<*>' in a %destructor/%printer symbol list to define a default
467 %destructor/%printer for all grammar symbols for which you have formally
468 declared semantic type tags.
469
470 2. Place `<>' in a %destructor/%printer symbol list to define a default
471 %destructor/%printer for all grammar symbols without declared semantic
472 type tags.
473
474 Bison no longer supports the `%symbol-default' notation from Bison 2.3a.
475 `<*>' and `<>' combined achieve the same effect with one exception: Bison no
476 longer applies any %destructor to a mid-rule value if that mid-rule value is
477 not actually ever referenced using either $$ or $n in a semantic action.
478
479 The default %destructor's and %printer's are experimental. More user
480 feedback will help to determine whether they should become permanent
481 features.
482
483 See the section `Freeing Discarded Symbols' in the Bison manual for further
484 details.
485
486 ** %left, %right, and %nonassoc can now declare token numbers. This is required
487 by POSIX. However, see the end of section `Operator Precedence' in the Bison
488 manual for a caveat concerning the treatment of literal strings.
489
490 ** The nonfunctional --no-parser, -n, and %no-parser options have been
491 completely removed from Bison.
492
493 * Changes in version 2.3a, 2006-09-13:
494
495 ** Instead of %union, you can define and use your own union type
496 YYSTYPE if your grammar contains at least one <type> tag.
497 Your YYSTYPE need not be a macro; it can be a typedef.
498 This change is for compatibility with other Yacc implementations,
499 and is required by POSIX.
500
501 ** Locations columns and lines start at 1.
502 In accordance with the GNU Coding Standards and Emacs.
503
504 ** You may now declare per-type and default %destructor's and %printer's:
505
506 For example:
507
508 %union { char *string; }
509 %token <string> STRING1
510 %token <string> STRING2
511 %type <string> string1
512 %type <string> string2
513 %union { char character; }
514 %token <character> CHR
515 %type <character> chr
516 %destructor { free ($$); } %symbol-default
517 %destructor { free ($$); printf ("%d", @$.first_line); } STRING1 string1
518 %destructor { } <character>
519
520 guarantees that, when the parser discards any user-defined symbol that has a
521 semantic type tag other than `<character>', it passes its semantic value to
522 `free'. However, when the parser discards a `STRING1' or a `string1', it
523 also prints its line number to `stdout'. It performs only the second
524 `%destructor' in this case, so it invokes `free' only once.
525
526 [Although we failed to mention this here in the 2.3a release, the default
527 %destructor's and %printer's were experimental, and they were rewritten in
528 future versions.]
529
530 ** Except for LALR(1) parsers in C with POSIX Yacc emulation enabled (with `-y',
531 `--yacc', or `%yacc'), Bison no longer generates #define statements for
532 associating token numbers with token names. Removing the #define statements
533 helps to sanitize the global namespace during preprocessing, but POSIX Yacc
534 requires them. Bison still generates an enum for token names in all cases.
535
536 ** Handling of traditional Yacc prologue blocks is now more consistent but
537 potentially incompatible with previous releases of Bison.
538
539 As before, you declare prologue blocks in your grammar file with the
540 `%{ ... %}' syntax. To generate the pre-prologue, Bison concatenates all
541 prologue blocks that you've declared before the first %union. To generate
542 the post-prologue, Bison concatenates all prologue blocks that you've
543 declared after the first %union.
544
545 Previous releases of Bison inserted the pre-prologue into both the header
546 file and the code file in all cases except for LALR(1) parsers in C. In the
547 latter case, Bison inserted it only into the code file. For parsers in C++,
548 the point of insertion was before any token definitions (which associate
549 token numbers with names). For parsers in C, the point of insertion was
550 after the token definitions.
551
552 Now, Bison never inserts the pre-prologue into the header file. In the code
553 file, it always inserts it before the token definitions.
554
555 ** Bison now provides a more flexible alternative to the traditional Yacc
556 prologue blocks: %before-header, %start-header, %end-header, and
557 %after-header.
558
559 For example, the following declaration order in the grammar file reflects the
560 order in which Bison will output these code blocks. However, you are free to
561 declare these code blocks in your grammar file in whatever order is most
562 convenient for you:
563
564 %before-header {
565 /* Bison treats this block like a pre-prologue block: it inserts it into
566 * the code file before the contents of the header file. It does *not*
567 * insert it into the header file. This is a good place to put
568 * #include's that you want at the top of your code file. A common
569 * example is `#include "system.h"'. */
570 }
571 %start-header {
572 /* Bison inserts this block into both the header file and the code file.
573 * In both files, the point of insertion is before any Bison-generated
574 * token, semantic type, location type, and class definitions. This is a
575 * good place to define %union dependencies, for example. */
576 }
577 %union {
578 /* Unlike the traditional Yacc prologue blocks, the output order for the
579 * new %*-header blocks is not affected by their declaration position
580 * relative to any %union in the grammar file. */
581 }
582 %end-header {
583 /* Bison inserts this block into both the header file and the code file.
584 * In both files, the point of insertion is after the Bison-generated
585 * definitions. This is a good place to declare or define public
586 * functions or data structures that depend on the Bison-generated
587 * definitions. */
588 }
589 %after-header {
590 /* Bison treats this block like a post-prologue block: it inserts it into
591 * the code file after the contents of the header file. It does *not*
592 * insert it into the header file. This is a good place to declare or
593 * define internal functions or data structures that depend on the
594 * Bison-generated definitions. */
595 }
596
597 If you have multiple occurrences of any one of the above declarations, Bison
598 will concatenate the contents in declaration order.
599
600 [Although we failed to mention this here in the 2.3a release, the prologue
601 alternatives were experimental, and they were rewritten in future versions.]
602
603 ** The option `--report=look-ahead' has been changed to `--report=lookahead'.
604 The old spelling still works, but is not documented and may be removed
605 in a future release.
606
607 * Changes in version 2.3, 2006-06-05:
608
609 ** GLR grammars should now use `YYRECOVERING ()' instead of `YYRECOVERING',
610 for compatibility with LALR(1) grammars.
611
612 ** It is now documented that any definition of YYSTYPE or YYLTYPE should
613 be to a type name that does not contain parentheses or brackets.
614
615 * Changes in version 2.2, 2006-05-19:
616
617 ** The distribution terms for all Bison-generated parsers now permit
618 using the parsers in nonfree programs. Previously, this permission
619 was granted only for Bison-generated LALR(1) parsers in C.
620
621 ** %name-prefix changes the namespace name in C++ outputs.
622
623 ** The C++ parsers export their token_type.
624
625 ** Bison now allows multiple %union declarations, and concatenates
626 their contents together.
627
628 ** New warning: unused values
629 Right-hand side symbols whose values are not used are reported,
630 if the symbols have destructors. For instance:
631
632 exp: exp "?" exp ":" exp { $1 ? $1 : $3; }
633 | exp "+" exp
634 ;
635
636 will trigger a warning about $$ and $5 in the first rule, and $3 in
637 the second ($1 is copied to $$ by the default rule). This example
638 most likely contains three errors, and could be rewritten as:
639
640 exp: exp "?" exp ":" exp
641 { $$ = $1 ? $3 : $5; free ($1 ? $5 : $3); free ($1); }
642 | exp "+" exp
643 { $$ = $1 ? $1 : $3; if ($1) free ($3); }
644 ;
645
646 However, if the original actions were really intended, memory leaks
647 and all, the warnings can be suppressed by letting Bison believe the
648 values are used, e.g.:
649
650 exp: exp "?" exp ":" exp { $1 ? $1 : $3; (void) ($$, $5); }
651 | exp "+" exp { $$ = $1; (void) $3; }
652 ;
653
654 If there are mid-rule actions, the warning is issued if no action
655 uses it. The following triggers no warning: $1 and $3 are used.
656
657 exp: exp { push ($1); } '+' exp { push ($3); sum (); };
658
659 The warning is intended to help catching lost values and memory leaks.
660 If a value is ignored, its associated memory typically is not reclaimed.
661
662 ** %destructor vs. YYABORT, YYACCEPT, and YYERROR.
663 Destructors are now called when user code invokes YYABORT, YYACCEPT,
664 and YYERROR, for all objects on the stack, other than objects
665 corresponding to the right-hand side of the current rule.
666
667 ** %expect, %expect-rr
668 Incorrect numbers of expected conflicts are now actual errors,
669 instead of warnings.
670
671 ** GLR, YACC parsers.
672 The %parse-params are available in the destructors (and the
673 experimental printers) as per the documentation.
674
675 ** Bison now warns if it finds a stray `$' or `@' in an action.
676
677 ** %require "VERSION"
678 This specifies that the grammar file depends on features implemented
679 in Bison version VERSION or higher.
680
681 ** lalr1.cc: The token and value types are now class members.
682 The tokens were defined as free form enums and cpp macros. YYSTYPE
683 was defined as a free form union. They are now class members:
684 tokens are enumerations of the `yy::parser::token' struct, and the
685 semantic values have the `yy::parser::semantic_type' type.
686
687 If you do not want or can update to this scheme, the directive
688 `%define "global_tokens_and_yystype" "1"' triggers the global
689 definition of tokens and YYSTYPE. This change is suitable both
690 for previous releases of Bison, and this one.
691
692 If you wish to update, then make sure older version of Bison will
693 fail using `%require "2.2"'.
694
695 ** DJGPP support added.
696 \f
697 * Changes in version 2.1, 2005-09-16:
698
699 ** The C++ lalr1.cc skeleton supports %lex-param.
700
701 ** Bison-generated parsers now support the translation of diagnostics like
702 "syntax error" into languages other than English. The default
703 language is still English. For details, please see the new
704 Internationalization section of the Bison manual. Software
705 distributors should also see the new PACKAGING file. Thanks to
706 Bruno Haible for this new feature.
707
708 ** Wording in the Bison-generated parsers has been changed slightly to
709 simplify translation. In particular, the message "memory exhausted"
710 has replaced "parser stack overflow", as the old message was not
711 always accurate for modern Bison-generated parsers.
712
713 ** Destructors are now called when the parser aborts, for all symbols left
714 behind on the stack. Also, the start symbol is now destroyed after a
715 successful parse. In both cases, the behavior was formerly inconsistent.
716
717 ** When generating verbose diagnostics, Bison-generated parsers no longer
718 quote the literal strings associated with tokens. For example, for
719 a syntax error associated with '%token NUM "number"' they might
720 print 'syntax error, unexpected number' instead of 'syntax error,
721 unexpected "number"'.
722 \f
723 * Changes in version 2.0, 2004-12-25:
724
725 ** Possibly-incompatible changes
726
727 - Bison-generated parsers no longer default to using the alloca function
728 (when available) to extend the parser stack, due to widespread
729 problems in unchecked stack-overflow detection. You can "#define
730 YYSTACK_USE_ALLOCA 1" to require the use of alloca, but please read
731 the manual to determine safe values for YYMAXDEPTH in that case.
732
733 - Error token location.
734 During error recovery, the location of the syntax error is updated
735 to cover the whole sequence covered by the error token: it includes
736 the shifted symbols thrown away during the first part of the error
737 recovery, and the lookahead rejected during the second part.
738
739 - Semicolon changes:
740 . Stray semicolons are no longer allowed at the start of a grammar.
741 . Semicolons are now required after in-grammar declarations.
742
743 - Unescaped newlines are no longer allowed in character constants or
744 string literals. They were never portable, and GCC 3.4.0 has
745 dropped support for them. Better diagnostics are now generated if
746 forget a closing quote.
747
748 - NUL bytes are no longer allowed in Bison string literals, unfortunately.
749
750 ** New features
751
752 - GLR grammars now support locations.
753
754 - New directive: %initial-action.
755 This directive allows the user to run arbitrary code (including
756 initializing @$) from yyparse before parsing starts.
757
758 - A new directive "%expect-rr N" specifies the expected number of
759 reduce/reduce conflicts in GLR parsers.
760
761 - %token numbers can now be hexadecimal integers, e.g., `%token FOO 0x12d'.
762 This is a GNU extension.
763
764 - The option `--report=lookahead' was changed to `--report=look-ahead'.
765 [However, this was changed back after 2.3.]
766
767 - Experimental %destructor support has been added to lalr1.cc.
768
769 - New configure option --disable-yacc, to disable installation of the
770 yacc command and -ly library introduced in 1.875 for POSIX conformance.
771
772 ** Bug fixes
773
774 - For now, %expect-count violations are now just warnings, not errors.
775 This is for compatibility with Bison 1.75 and earlier (when there are
776 reduce/reduce conflicts) and with Bison 1.30 and earlier (when there
777 are too many or too few shift/reduce conflicts). However, in future
778 versions of Bison we plan to improve the %expect machinery so that
779 these violations will become errors again.
780
781 - Within Bison itself, numbers (e.g., goto numbers) are no longer
782 arbitrarily limited to 16-bit counts.
783
784 - Semicolons are now allowed before "|" in grammar rules, as POSIX requires.
785 \f
786 * Changes in version 1.875, 2003-01-01:
787
788 ** The documentation license has been upgraded to version 1.2
789 of the GNU Free Documentation License.
790
791 ** syntax error processing
792
793 - In Yacc-style parsers YYLLOC_DEFAULT is now used to compute error
794 locations too. This fixes bugs in error-location computation.
795
796 - %destructor
797 It is now possible to reclaim the memory associated to symbols
798 discarded during error recovery. This feature is still experimental.
799
800 - %error-verbose
801 This new directive is preferred over YYERROR_VERBOSE.
802
803 - #defining yyerror to steal internal variables is discouraged.
804 It is not guaranteed to work forever.
805
806 ** POSIX conformance
807
808 - Semicolons are once again optional at the end of grammar rules.
809 This reverts to the behavior of Bison 1.33 and earlier, and improves
810 compatibility with Yacc.
811
812 - `parse error' -> `syntax error'
813 Bison now uniformly uses the term `syntax error'; formerly, the code
814 and manual sometimes used the term `parse error' instead. POSIX
815 requires `syntax error' in diagnostics, and it was thought better to
816 be consistent.
817
818 - The documentation now emphasizes that yylex and yyerror must be
819 declared before use. C99 requires this.
820
821 - Bison now parses C99 lexical constructs like UCNs and
822 backslash-newline within C escape sequences, as POSIX 1003.1-2001 requires.
823
824 - File names are properly escaped in C output. E.g., foo\bar.y is
825 output as "foo\\bar.y".
826
827 - Yacc command and library now available
828 The Bison distribution now installs a `yacc' command, as POSIX requires.
829 Also, Bison now installs a small library liby.a containing
830 implementations of Yacc-compatible yyerror and main functions.
831 This library is normally not useful, but POSIX requires it.
832
833 - Type clashes now generate warnings, not errors.
834
835 - If the user does not define YYSTYPE as a macro, Bison now declares it
836 using typedef instead of defining it as a macro.
837 For consistency, YYLTYPE is also declared instead of defined.
838
839 ** Other compatibility issues
840
841 - %union directives can now have a tag before the `{', e.g., the
842 directive `%union foo {...}' now generates the C code
843 `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility.
844 The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc.
845 For consistency, YYLTYPE's struct tag is now `YYLTYPE' not `yyltype'.
846 This is for compatibility with both Yacc and Bison 1.35.
847
848 - `;' is output before the terminating `}' of an action, for
849 compatibility with Bison 1.35.
850
851 - Bison now uses a Yacc-style format for conflict reports, e.g.,
852 `conflicts: 2 shift/reduce, 1 reduce/reduce'.
853
854 - `yystype' and `yyltype' are now obsolescent macros instead of being
855 typedefs or tags; they are no longer documented and are planned to be
856 withdrawn in a future release.
857
858 ** GLR parser notes
859
860 - GLR and inline
861 Users of Bison have to decide how they handle the portability of the
862 C keyword `inline'.
863
864 - `parsing stack overflow...' -> `parser stack overflow'
865 GLR parsers now report `parser stack overflow' as per the Bison manual.
866
867 ** Bison now warns if it detects conflicting outputs to the same file,
868 e.g., it generates a warning for `bison -d -o foo.h foo.y' since
869 that command outputs both code and header to foo.h.
870
871 ** #line in output files
872 - --no-line works properly.
873
874 ** Bison can no longer be built by a K&R C compiler; it requires C89 or
875 later to be built. This change originally took place a few versions
876 ago, but nobody noticed until we recently asked someone to try
877 building Bison with a K&R C compiler.
878 \f
879 * Changes in version 1.75, 2002-10-14:
880
881 ** Bison should now work on 64-bit hosts.
882
883 ** Indonesian translation thanks to Tedi Heriyanto.
884
885 ** GLR parsers
886 Fix spurious parse errors.
887
888 ** Pure parsers
889 Some people redefine yyerror to steal yyparse' private variables.
890 Reenable this trick until an official feature replaces it.
891
892 ** Type Clashes
893 In agreement with POSIX and with other Yaccs, leaving a default
894 action is valid when $$ is untyped, and $1 typed:
895
896 untyped: ... typed;
897
898 but the converse remains an error:
899
900 typed: ... untyped;
901
902 ** Values of mid-rule actions
903 The following code:
904
905 foo: { ... } { $$ = $1; } ...
906
907 was incorrectly rejected: $1 is defined in the second mid-rule
908 action, and is equal to the $$ of the first mid-rule action.
909 \f
910 * Changes in version 1.50, 2002-10-04:
911
912 ** GLR parsing
913 The declaration
914 %glr-parser
915 causes Bison to produce a Generalized LR (GLR) parser, capable of handling
916 almost any context-free grammar, ambiguous or not. The new declarations
917 %dprec and %merge on grammar rules allow parse-time resolution of
918 ambiguities. Contributed by Paul Hilfinger.
919
920 Unfortunately Bison 1.50 does not work properly on 64-bit hosts
921 like the Alpha, so please stick to 32-bit hosts for now.
922
923 ** Output Directory
924 When not in Yacc compatibility mode, when the output file was not
925 specified, running `bison foo/bar.y' created `foo/bar.c'. It
926 now creates `bar.c'.
927
928 ** Undefined token
929 The undefined token was systematically mapped to 2 which prevented
930 the use of 2 by the user. This is no longer the case.
931
932 ** Unknown token numbers
933 If yylex returned an out of range value, yyparse could die. This is
934 no longer the case.
935
936 ** Error token
937 According to POSIX, the error token must be 256.
938 Bison extends this requirement by making it a preference: *if* the
939 user specified that one of her tokens is numbered 256, then error
940 will be mapped onto another number.
941
942 ** Verbose error messages
943 They no longer report `..., expecting error or...' for states where
944 error recovery is possible.
945
946 ** End token
947 Defaults to `$end' instead of `$'.
948
949 ** Error recovery now conforms to documentation and to POSIX
950 When a Bison-generated parser encounters a syntax error, it now pops
951 the stack until it finds a state that allows shifting the error
952 token. Formerly, it popped the stack until it found a state that
953 allowed some non-error action other than a default reduction on the
954 error token. The new behavior has long been the documented behavior,
955 and has long been required by POSIX. For more details, please see
956 Paul Eggert, "Reductions during Bison error handling" (2002-05-20)
957 <http://lists.gnu.org/archive/html/bug-bison/2002-05/msg00038.html>.
958
959 ** Traces
960 Popped tokens and nonterminals are now reported.
961
962 ** Larger grammars
963 Larger grammars are now supported (larger token numbers, larger grammar
964 size (= sum of the LHS and RHS lengths), larger LALR tables).
965 Formerly, many of these numbers ran afoul of 16-bit limits;
966 now these limits are 32 bits on most hosts.
967
968 ** Explicit initial rule
969 Bison used to play hacks with the initial rule, which the user does
970 not write. It is now explicit, and visible in the reports and
971 graphs as rule 0.
972
973 ** Useless rules
974 Before, Bison reported the useless rules, but, although not used,
975 included them in the parsers. They are now actually removed.
976
977 ** Useless rules, useless nonterminals
978 They are now reported, as a warning, with their locations.
979
980 ** Rules never reduced
981 Rules that can never be reduced because of conflicts are now
982 reported.
983
984 ** Incorrect `Token not used'
985 On a grammar such as
986
987 %token useless useful
988 %%
989 exp: '0' %prec useful;
990
991 where a token was used to set the precedence of the last rule,
992 bison reported both `useful' and `useless' as useless tokens.
993
994 ** Revert the C++ namespace changes introduced in 1.31
995 as they caused too many portability hassles.
996
997 ** Default locations
998 By an accident of design, the default computation of @$ was
999 performed after another default computation was performed: @$ = @1.
1000 The latter is now removed: YYLLOC_DEFAULT is fully responsible of
1001 the computation of @$.
1002
1003 ** Token end-of-file
1004 The token end of file may be specified by the user, in which case,
1005 the user symbol is used in the reports, the graphs, and the verbose
1006 error messages instead of `$end', which remains being the default.
1007 For instance
1008 %token MYEOF 0
1009 or
1010 %token MYEOF 0 "end of file"
1011
1012 ** Semantic parser
1013 This old option, which has been broken for ages, is removed.
1014
1015 ** New translations
1016 Brazilian Portuguese, thanks to Alexandre Folle de Menezes.
1017 Croatian, thanks to Denis Lackovic.
1018
1019 ** Incorrect token definitions
1020 When given `%token 'a' "A"', Bison used to output `#define 'a' 65'.
1021
1022 ** Token definitions as enums
1023 Tokens are output both as the traditional #define's, and, provided
1024 the compiler supports ANSI C or is a C++ compiler, as enums.
1025 This lets debuggers display names instead of integers.
1026
1027 ** Reports
1028 In addition to --verbose, bison supports --report=THINGS, which
1029 produces additional information:
1030 - itemset
1031 complete the core item sets with their closure
1032 - lookahead [changed to `look-ahead' in 1.875e through 2.3, but changed back]
1033 explicitly associate lookahead tokens to items
1034 - solved
1035 describe shift/reduce conflicts solving.
1036 Bison used to systematically output this information on top of
1037 the report. Solved conflicts are now attached to their states.
1038
1039 ** Type clashes
1040 Previous versions don't complain when there is a type clash on
1041 the default action if the rule has a mid-rule action, such as in:
1042
1043 %type <foo> bar
1044 %%
1045 bar: '0' {} '0';
1046
1047 This is fixed.
1048
1049 ** GNU M4 is now required when using Bison.
1050 \f
1051 * Changes in version 1.35, 2002-03-25:
1052
1053 ** C Skeleton
1054 Some projects use Bison's C parser with C++ compilers, and define
1055 YYSTYPE as a class. The recent adjustment of C parsers for data
1056 alignment and 64 bit architectures made this impossible.
1057
1058 Because for the time being no real solution for C++ parser
1059 generation exists, kludges were implemented in the parser to
1060 maintain this use. In the future, when Bison has C++ parsers, this
1061 kludge will be disabled.
1062
1063 This kludge also addresses some C++ problems when the stack was
1064 extended.
1065 \f
1066 * Changes in version 1.34, 2002-03-12:
1067
1068 ** File name clashes are detected
1069 $ bison foo.y -d -o foo.x
1070 fatal error: header and parser would both be named `foo.x'
1071
1072 ** A missing `;' at the end of a rule triggers a warning
1073 In accordance with POSIX, and in agreement with other
1074 Yacc implementations, Bison will mandate this semicolon in the near
1075 future. This eases the implementation of a Bison parser of Bison
1076 grammars by making this grammar LALR(1) instead of LR(2). To
1077 facilitate the transition, this release introduces a warning.
1078
1079 ** Revert the C++ namespace changes introduced in 1.31, as they caused too
1080 many portability hassles.
1081
1082 ** DJGPP support added.
1083
1084 ** Fix test suite portability problems.
1085 \f
1086 * Changes in version 1.33, 2002-02-07:
1087
1088 ** Fix C++ issues
1089 Groff could not be compiled for the definition of size_t was lacking
1090 under some conditions.
1091
1092 ** Catch invalid @n
1093 As is done with $n.
1094 \f
1095 * Changes in version 1.32, 2002-01-23:
1096
1097 ** Fix Yacc output file names
1098
1099 ** Portability fixes
1100
1101 ** Italian, Dutch translations
1102 \f
1103 * Changes in version 1.31, 2002-01-14:
1104
1105 ** Many Bug Fixes
1106
1107 ** GNU Gettext and %expect
1108 GNU Gettext asserts 10 s/r conflicts, but there are 7. Now that
1109 Bison dies on incorrect %expectations, we fear there will be
1110 too many bug reports for Gettext, so _for the time being_, %expect
1111 does not trigger an error when the input file is named `plural.y'.
1112
1113 ** Use of alloca in parsers
1114 If YYSTACK_USE_ALLOCA is defined to 0, then the parsers will use
1115 malloc exclusively. Since 1.29, but was not NEWS'ed.
1116
1117 alloca is used only when compiled with GCC, to avoid portability
1118 problems as on AIX.
1119
1120 ** yyparse now returns 2 if memory is exhausted; formerly it dumped core.
1121
1122 ** When the generated parser lacks debugging code, YYDEBUG is now 0
1123 (as POSIX requires) instead of being undefined.
1124
1125 ** User Actions
1126 Bison has always permitted actions such as { $$ = $1 }: it adds the
1127 ending semicolon. Now if in Yacc compatibility mode, the semicolon
1128 is no longer output: one has to write { $$ = $1; }.
1129
1130 ** Better C++ compliance
1131 The output parsers try to respect C++ namespaces.
1132 [This turned out to be a failed experiment, and it was reverted later.]
1133
1134 ** Reduced Grammars
1135 Fixed bugs when reporting useless nonterminals.
1136
1137 ** 64 bit hosts
1138 The parsers work properly on 64 bit hosts.
1139
1140 ** Error messages
1141 Some calls to strerror resulted in scrambled or missing error messages.
1142
1143 ** %expect
1144 When the number of shift/reduce conflicts is correct, don't issue
1145 any warning.
1146
1147 ** The verbose report includes the rule line numbers.
1148
1149 ** Rule line numbers are fixed in traces.
1150
1151 ** Swedish translation
1152
1153 ** Parse errors
1154 Verbose parse error messages from the parsers are better looking.
1155 Before: parse error: unexpected `'/'', expecting `"number"' or `'-'' or `'(''
1156 Now: parse error: unexpected '/', expecting "number" or '-' or '('
1157
1158 ** Fixed parser memory leaks.
1159 When the generated parser was using malloc to extend its stacks, the
1160 previous allocations were not freed.
1161
1162 ** Fixed verbose output file.
1163 Some newlines were missing.
1164 Some conflicts in state descriptions were missing.
1165
1166 ** Fixed conflict report.
1167 Option -v was needed to get the result.
1168
1169 ** %expect
1170 Was not used.
1171 Mismatches are errors, not warnings.
1172
1173 ** Fixed incorrect processing of some invalid input.
1174
1175 ** Fixed CPP guards: 9foo.h uses BISON_9FOO_H instead of 9FOO_H.
1176
1177 ** Fixed some typos in the documentation.
1178
1179 ** %token MY_EOF 0 is supported.
1180 Before, MY_EOF was silently renumbered as 257.
1181
1182 ** doc/refcard.tex is updated.
1183
1184 ** %output, %file-prefix, %name-prefix.
1185 New.
1186
1187 ** --output
1188 New, aliasing `--output-file'.
1189 \f
1190 * Changes in version 1.30, 2001-10-26:
1191
1192 ** `--defines' and `--graph' have now an optional argument which is the
1193 output file name. `-d' and `-g' do not change; they do not take any
1194 argument.
1195
1196 ** `%source_extension' and `%header_extension' are removed, failed
1197 experiment.
1198
1199 ** Portability fixes.
1200 \f
1201 * Changes in version 1.29, 2001-09-07:
1202
1203 ** The output file does not define const, as this caused problems when used
1204 with common autoconfiguration schemes. If you still use ancient compilers
1205 that lack const, compile with the equivalent of the C compiler option
1206 `-Dconst='. autoconf's AC_C_CONST macro provides one way to do this.
1207
1208 ** Added `-g' and `--graph'.
1209
1210 ** The Bison manual is now distributed under the terms of the GNU FDL.
1211
1212 ** The input and the output files has automatically a similar extension.
1213
1214 ** Russian translation added.
1215
1216 ** NLS support updated; should hopefully be less troublesome.
1217
1218 ** Added the old Bison reference card.
1219
1220 ** Added `--locations' and `%locations'.
1221
1222 ** Added `-S' and `--skeleton'.
1223
1224 ** `%raw', `-r', `--raw' is disabled.
1225
1226 ** Special characters are escaped when output. This solves the problems
1227 of the #line lines with path names including backslashes.
1228
1229 ** New directives.
1230 `%yacc', `%fixed_output_files', `%defines', `%no_parser', `%verbose',
1231 `%debug', `%source_extension' and `%header_extension'.
1232
1233 ** @$
1234 Automatic location tracking.
1235 \f
1236 * Changes in version 1.28, 1999-07-06:
1237
1238 ** Should compile better now with K&R compilers.
1239
1240 ** Added NLS.
1241
1242 ** Fixed a problem with escaping the double quote character.
1243
1244 ** There is now a FAQ.
1245 \f
1246 * Changes in version 1.27:
1247
1248 ** The make rule which prevented bison.simple from being created on
1249 some systems has been fixed.
1250 \f
1251 * Changes in version 1.26:
1252
1253 ** Bison now uses automake.
1254
1255 ** New mailing lists: <bug-bison@gnu.org> and <help-bison@gnu.org>.
1256
1257 ** Token numbers now start at 257 as previously documented, not 258.
1258
1259 ** Bison honors the TMPDIR environment variable.
1260
1261 ** A couple of buffer overruns have been fixed.
1262
1263 ** Problems when closing files should now be reported.
1264
1265 ** Generated parsers should now work even on operating systems which do
1266 not provide alloca().
1267 \f
1268 * Changes in version 1.25, 1995-10-16:
1269
1270 ** Errors in the input grammar are not fatal; Bison keeps reading
1271 the grammar file, and reports all the errors found in it.
1272
1273 ** Tokens can now be specified as multiple-character strings: for
1274 example, you could use "<=" for a token which looks like <=, instead
1275 of chosing a name like LESSEQ.
1276
1277 ** The %token_table declaration says to write a table of tokens (names
1278 and numbers) into the parser file. The yylex function can use this
1279 table to recognize multiple-character string tokens, or for other
1280 purposes.
1281
1282 ** The %no_lines declaration says not to generate any #line preprocessor
1283 directives in the parser file.
1284
1285 ** The %raw declaration says to use internal Bison token numbers, not
1286 Yacc-compatible token numbers, when token names are defined as macros.
1287
1288 ** The --no-parser option produces the parser tables without including
1289 the parser engine; a project can now use its own parser engine.
1290 The actions go into a separate file called NAME.act, in the form of
1291 a switch statement body.
1292 \f
1293 * Changes in version 1.23:
1294
1295 The user can define YYPARSE_PARAM as the name of an argument to be
1296 passed into yyparse. The argument should have type void *. It should
1297 actually point to an object. Grammar actions can access the variable
1298 by casting it to the proper pointer type.
1299
1300 Line numbers in output file corrected.
1301 \f
1302 * Changes in version 1.22:
1303
1304 --help option added.
1305 \f
1306 * Changes in version 1.20:
1307
1308 Output file does not redefine const for C++.
1309
1310 Local Variables:
1311 mode: outline
1312 End:
1313
1314 -----
1315
1316 Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
1317 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
1318
1319 This file is part of Bison, the GNU Parser Generator.
1320
1321 This program is free software: you can redistribute it and/or modify
1322 it under the terms of the GNU General Public License as published by
1323 the Free Software Foundation, either version 3 of the License, or
1324 (at your option) any later version.
1325
1326 This program is distributed in the hope that it will be useful,
1327 but WITHOUT ANY WARRANTY; without even the implied warranty of
1328 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
1329 GNU General Public License for more details.
1330
1331 You should have received a copy of the GNU General Public License
1332 along with this program. If not, see <http://www.gnu.org/licenses/>.