This change allows one to document (and check) which rules participate
in shift/reduce and reduce/reduce conflicts. This is particularly
important GLR parsers, where conflicts are a normal occurrence. For
example,
%glr-parser
%expect 1
%%
...
argument_list:
arguments %expect 1
| arguments ','
| %empty
;
arguments:
expression
| argument_list ',' expression
;
...
Looking at the output from -v, one can see that the shift-reduce
conflict here is due to the fact that the parser does not know whether
to reduce arguments to argument_list until it sees the token AFTER the
following ','. By marking the rule with %expect 1 (because there is a
conflict in one state), we document the source of the 1 overall shift-
reduce conflict.
In GLR parsers, we can use %expect-rr in a rule for reduce/reduce
conflicts. In this case, we mark each of the conflicting rules. For
example,
%glr-parser
%expect-rr 1
%%
stmt:
target_list '=' expr ';'
| expr_list ';'
;
target_list:
target
| target ',' target_list
;
target:
ID %expect-rr 1
;
expr_list:
expr
| expr ',' expr_list
;
expr:
ID %expect-rr 1
| ...
;
In a statement such as
x, y = 3, 4;
the parser must reduce x to a target or an expr, but does not know
which until it sees the '='. So we notate the two possible reductions
to indicate that each conflicts in one rule.
See https://lists.gnu.org/archive/html/bison-patches/2013-02/msg00105.html.
* doc/bison.texi (Suppressing Conflict Warnings): Document %expect,
%expect-rr in grammar rules.
* src/conflicts.c (count_state_rr_conflicts): Adjust comment.
(rule_has_state_sr_conflicts): New static function.
(count_rule_sr_conflicts): New static function.
(rule_nast_state_rr_conflicts): New static function.
(count_rule_rr_conflicts): New static function.
(rule_conflicts_print): New static function.
(conflicts_print): Also use rule_conflicts_print to report on individual
rules.
* src/gram.h (struct rule): Add new fields expected_sr_conflicts,
expected_rr_conflicts.
* src/reader.c (grammar_midrule_action): Transfer expected_sr_conflicts,
expected_rr_conflicts to new rule, and turn off in current_rule.
(grammar_current_rule_expect_sr): New function.
(grammar_current_rule_expect_rr): New function.
(packgram): Transfer expected_sr_conflicts, expected_rr_conflicts
to new rule.
* src/reader.h (grammar_current_rule_expect_sr): New function.
(grammar_current_rule_expect_rr): New function.
* src/symlist.c (symbol_list_sym_new): Initialize expected_sr_conflicts,
expected_rr_conflicts.
* src/symlist.h (struct symbol_list): Add new fields expected_sr_conflicts,
expected_rr_conflicts.
* tests/conflicts.at: Add tests "%expect in grammar rule not enough",
"%expect in grammar rule right.", "%expect in grammar rule too much."
The "Report translation bugs to..." part of --help is issued only on
glibc systems. So if the tarball is not wrapped on such a system, and
used on such a system (or the converse), then bison.help will differ
on the user's system, and help2man will be called to update bison.1.
But help2man should not be a requirement.
Reported by Alexandre Duret-Lutz.
* doc/local.mk (doc/bison.help): Remove the possible doc about
translation bugs.
Pass LC_ALL=C, as reported in src/getargs.c's usage().
(doc/cross-options.texi): Use bison.help instead of calling bison
--help.
* doc/bison.texi (Calc++ Scanner): Show how exception can be thrown
from auxiliary functions.
Clarify the meaning of the various flex %options we use.
Get rid of a warning.
(Calc++ Parsing Driver): Use the parser as a functor.
* doc/bison.texi: Simplify wording.
Fix Texinfo error.
(Complete Symbols): Handle the token EOF.
(Calc++ Parser): In the modern C++ world, prefer assignment to swap.
(Strings are Destroyed): Prefer an explicit 'continue' to a comment.
Suggested by Victor Khomenko.
http://lists.gnu.org/archive/html/bug-bison/2018-08/msg00037.html
* doc/bison.texi (A Simple C++ Example): New.
* examples/c++/local.mk, examples/c++/simple.test: New.
Extract, check, and install this new example.
* examples/local.mk: Adjust.
* examples/test: Adjust to the case where the dirname differs
from the test name.
* data/lalr1.cc: Fix oldish comment.
* data/stack.hh: Prefer typename for type names.
Use size() instead of duplicating it.
* examples/variant-11.yy, examples/variant.yy (yylex): Use int,
as this is the type of the semantic value.
When we introduced variants in Bison, C++ did not have the 'emplace'
functions, and we chose 'build'. Let's align with modern C++ and
promote 'emplace' rather than 'build'.
* data/lalr1.cc, data/variant.hh (emplace): New.
(build): Deprecate in favor of emplace.
* doc/bison.texi: Adjust.
As a matter of fact, I think it is wrong to gitignore generated files
that belong to the build tree. There should be the strict minimum,
and it's up to people that build in place to adjust their own
~/.gitignore.
* doc/.gitignore: here.
Remove files we no longer produce (thanks to texi2dvi).
The files stack.hh and position.hh are deprecated. Rather than
devoting specify %define variables to discard them (api.position.file
and api.stack.file), and rather than having to use special rules when
api.location.file is used, let's simply decide that from %require
"3.2" onwards, these files will not be generated.
The only noticeable thing here is that, in order to be able to check
the behavior of %require "3.2", to have this version (which is still
3.1-*) to accept %require "3.2".
* src/gram.h, src/gram.c (required_version): New.
* src/parse-gram.y (version_check): Set it.
* src/output.c (prepare): Pass it m4.
* data/bison.m4 (b4_required_version_if): Receive it and use it.
* data/location.cc, data/stack.hh: Replace the api.*.file with only
required version comparison.
* tests/input.at: No longer check api.stack.file and api.position.file.
* NEWS, doc/bison.texi: Don't mention them.
Document the %require 3.2 behavior.
* tests/output.at: Use %require 3.2 instead.
Currently, in C, the default semantic action is implemented by being
always run before running the actual user semantic action. As a
consequence, when the user action is run, $$ is already set as $1.
In C++ with variants, we don't do that, since we cannot manipulate the
semantic value without knowing its exact type. When variants are
enabled, the only guarantee is that $$ is default contructed and ready
to the used.
Some users still would like the default action to be run with
variants. Frank Heckenbach's parser in
C++17 (http://lists.gnu.org/archive/html/bug-bison/2018-04/msg00011.html)
provides this feature, but relying on std::variant's dynamic typing,
which we forbid in lalr1.cc.
The simplest seems to be actually generating the default semantic
action (in all languages/skeletons). This makes the pre-action (that
sets $$ to $1) useless. But... maybe some users depend on this, in
spite of the comments that clearly warn againt this. So let's not
turn this off just yet.
* src/reader.c (grammar_rule_check_and_complete): Rename as...
(grammar_rule_check_and_complete): this.
Install the default semantic action when applicable.
* examples/variant-11.yy, examples/variant.yy, tests/calc.at:
Exercise the default semantic action, even with variants.
Now that distcheck no longer fails (see previous commit), let's
address the shortcomings.
* Makefile.am (CLEANDIRS, clean-local): New.
* doc/local.mk, examples/calc++/local.mk, examples/local.mk,
* examples/mfcalc/local.mk, examples/rpcalc/local.mk,
* src/local.mk
(CLEANDIRS): Get rid of Apple's *.dSYM directories.
(CLEANFILES): Get rid of *.output files.
* examples/variant-11.yy, examples/variant.yy: Don't generate
any of the auxiliary files (location.hh and the like).
* doc/bison.texi: Minor fixes in typography.
It is no longer require to pass --defines for C++ (it was addressed
long ago).
No longer refer to the `variant` define variable, it was replaced by
`api.value.type variant`.
Prefer nullptr to 0 for the null pointer.
Use deftypeop for constructors.
(Complete Symbols): Give the expected signature of yylex.
Don't document the symbol_type constructors, as we want users to focus
on make_TOKEN.
Also show the case without locations.
The code was already using midrule only, never mid_rule. This is
simpler to remember, and matches a similar change we made from
look-ahead to lookahead.
* NEWS, doc/bison.texi, src/reader.c, src/scan-code.h, src/scan-code.l
* tests/actions.at, tests/c++.at, tests/existing.at: here.
See ea0db44fed. We also need to disable
the warning in the examples (but don't want to clutter the
documentation with such details).
* doc/bison.texi (scanner.ll): Disable Clang's -Wdocumentation.
While at it, hide the other kludges.
That's the version on Ubuntu Precise.
See also 1dac131ec4.
* src/flex-scanner.h: Disable -Wdocumentation.
* doc/bison.texi: Turn off a warning triggered by Flex 2.6.4.
* doc/bison.texi (A Complete C++ Example): Prefer throw exceptions
from the scanner.
Show the invalid characters.
Since the scanner sends exceptions, it no longer needs to report
errors, so we can get rid of the driver's routine to report error,
do it in yyerror.
Use @group/@end group to improve rendering.
This example uses the calcxx_ prefix for each class. That's uselessly
heavy.
* doc/bison.texi (A Complete C++ Example): Simplify the class names.
Since now 'driver' denotes the class, use 'drv' for the values.
Formatting changes.
