* 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.
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).
Modern C++ (i.e., C++11 and later) introduced "move only" types: types such
as std::unique_ptr<T> that can never be duplicated. They must never be
copied (by assignments and constructors), they must be "moved". The
implementation of lalr1.cc used to copy symbols (including their semantic
values). This commit ensures that values are only moved in modern C++, yet
remain compatible with C++98/C++03.
Suggested by Frank Heckenbach, who provided a full implementation on
top of C++17's std::variant.
See http://lists.gnu.org/archive/html/bug-bison/2018-03/msg00002.html,
and https://lists.gnu.org/archive/html/bison-patches/2018-04/msg00002.html.
Symbols (terminal/non terminal) are handled by several functions that used
to take const-refs, which resulted eventually in a copy pushed on the stack.
With modern C++ (C++11 and later) the callers must use std::move, and the
callees must take their arguments as rvalue refs (foo&&). In order to avoid
duplicating these functions to support both legacy C++ and modern C++, let's
introduce macros (YY_MOVE, YY_RVREF, etc.) that rely on copy-semantics for
C++98/03, and move-semantics for modern C++.
That's easy for inner types, when the parser's functions pass arguments to
each other. Functions facing the user (make_NUMBER, make_STRING, etc.)
should support both rvalue-refs (for instance to support move-only types:
make_INT (std::make_unique<int> (1))), and lvalue-refs (so that we can pass
a variable: make_INT (my_int)). To avoid the multiplication of the
signatures (there is also the location), let's take the argument by value.
See:
https://lists.gnu.org/archive/html/bison-patches/2018-09/msg00024.html.
* data/c++.m4 (b4_cxx_portability): New.
(basic_symbol): In C++11, replace copy-ctors with move-ctors.
In C++11, replace copies with moves.
* data/lalr1.cc (stack_symbol_type, yypush_): Likewise.
Use YY_MOVE to avoid useless copies.
* data/variant.hh (variant): Support move-semantics.
(make_SYMBOL): In C++11, in order to support both read-only lvalues,
and rvalues, take the argument as a copy.
* data/stack.hh (yypush_): Use rvalue-refs in C++11.
* tests/c++.at: Use move semantics.
* tests/headers.at: Adjust to the new macros (YY_MOVE, etc.).
* configure.ac (CXX98_CXXFLAGS, CXX11_CXXFLAGS, CXX14_CXXFLAGS)
(CXX17_CXXFLAGS, ENABLE_CXX11): New.
* tests/atlocal.in: Receive them.
* examples/variant.yy: Don't define things in std.
* examples/variant-11.test, examples/variant-11.yy: New.
Check the support of move-only types.
* examples/README, examples/local.mk: Adjust.
* examples/mfcalc/local.mk, examples/rpcalc/local.mk: Define the
programs in a more natural order, source, preproc, then linker.
* examples/test: Be ready to work on programs that are not in
a subdir.
* examples/variant.test: New.
* examples/local.mk: Use it.
* examples/variant.yy: Don't use 0 for nullptr.
Use a more natural output for a list of string.
This file was meant to be shown as an example. Install it.
* README, data/README: Put Emacs metadata in the final section.
* examples/README: New.
* examples/variant.yy: Use %empty.
* examples/local.mk: Install both these files.
* data/lalr1.cc, doc/bison.texi, etc/bench.pl.in, examples/variant.yy,
* tests/actions.at, tests/atlocal.in, tests/c++.at, tests/headers.at,
* tests/local.at, tests/types.at:
Don't use std::endl, it flushes uselessly, and is considered bad
style.
* data/bison.m4 (b4_lex_symbol_if): Rename as...
(b4_token_ctor_if): this.
Depend upon api.token.constructor.
* data/c++.m4, data/lalr1.cc: Adjust.
* doc/bison.texi: Fix all the occurrences of lex_symbol.
* etc/bench.pl.in: Adjust.
* examples/variant.yy: Likewise.
* tests/local.at (AT_BISON_OPTION_PUSHDEFS, AT_BISON_OPTION_POPDEFS):
Handle AT_TOKEN_CTOR_IF.
* tests/c++.at: Adjust to using api.token.constructor and AT_TOKEN_CTOR_IF.
Simplify the test of both build call styles.
(AT_CHECK_VARIANTS): Rename as...
(AT_TEST): this.
And undef when done.
Yes, this obfuscates the point of this example, variants only. But glr.cc
cannot work (yet?) without locations. This change makes it easier to use
this example with glr.cc.
* examples/variant.yy (assert): %define it.
(locations): Request them.
(yylex): Bind the location to the stage.
There are two issues to handle: first scanning nested angle bracket pairs
to support types such as std::pair< std::string, std::list<std::string> > >.
Another issue is to address idiosyncracies of C++: do not glue two closing
angle brackets together (otherwise it's operator>>), and avoid sticking
blindly a TYPE to the opening <, as it can result in '<:' which is a
digraph for '['.
* src/scan-gram.l (brace_level): Rename as...
(nesting): this.
(SC_TAG): New.
Implement support for complex tags.
(tag): Accept \n, but not <.
* data/lalr1.cc (b4_symbol_value, b4_symbol_value_template)
(b4_symbol_variant): Leave space around types as parameters.
* examples/variant.yy: Use nested template types and leading ::.
* src/parse-gram.y (TYPE, TYPE_TAG_ANY, TYPE_TAG_NONE, type.opt):
Rename as...
(TAG, TAG_ANY, TAG_NONE, tag.opt): these.
* tests/c++.at: Test parametric types.
std::list cannot be copied via memcpy, they are more demanding than
std::string. Use one std::list to strengthen the test.
* examples/variant.yy: Use lalr1-fusion.cc, not lalr1.cc.
Adjust.
Create a list of strings, instead of a single large string.
This patch was inspired by work by Michiel De Wilde. But he used Boost
variants which (i) requires Boost on the user side, (ii) is slow, and
(iii) has useless overhead (the parser knows the type of the semantic value
there is no reason to duplicate this information as Boost.Variants do).
This implementation reserves a buffer large enough to store the largest
objects. yy::variant implements this buffer. It was implemented with
Quentin Hocquet.
* src/output.c (type_names_output): New.
(output_skeleton): Invoke it.
* data/c++.m4 (b4_variant_if): New.
(b4_symbol_value): If needed, provide a definition for variants.
* data/lalr1.cc (b4_symbol_value, b4_symbol_action_)
(b4_symbol_variant, _b4_char_sizeof_counter, _b4_char_sizeof_dummy)
(b4_char_sizeof, yy::variant): New.
(parser::parse): If variants are requested, define
parser::union_type, parser::variant, change the definition of
semantic_type, construct $$ before running the user action instead
of performing a default $$ = $1.
* examples/variant.yy: New.
Based on an example by Michiel De Wilde.
