Let's use GNU readline and its TAB autocompletion to demonstrate the
use of yyexpected_tokens.
This shows a number of weaknesses in our current approach:
- some macros (yyssp, etc.) from push parsers "leak" in user code, we
need to undefine them
- the context needed by yyexpected_tokens does not need the token,
yypstate actually suffices
- yypstate is not properly setup when first allocated, which results
in a crash of yyexpected_tokens if fired before a first token was
read. We should move initialization from yypush_parse into
yypstate_new.
* examples/c/bistromathic/parse.y (yylex): Take input as a string, not
a file.
(EXIT): New token.
(input): Adjust to work only on a line.
(line): Remove.
(symbol_count, process_line, expected_tokens, completion)
(init_readline): New.
* examples/c/bistromathic/bistromathic.test: Adjust expectations.
This example will soon use GNU readline, so its scanner should be easy
to use (concurrently) on strings, not streams. This is not a place
where Flex shines, and anyway, these are examples of Bison, not Flex.
There's already lexcalc and reccalc that demonstrate the use of Flex.
* examples/c/bistromathic/scan.l: Remove.
* examples/c/bistromathic/parse.y (yylex): New.
Adjust dependencies.
The bistromathic example should not use Flex, it makes it too complex.
But it was the only example to show location tracking with Flex.
* examples/c/lexcalc/lexcalc.test, examples/c/lexcalc/parse.y,
* examples/c/lexcalc/scan.l: Demonstrate location tracking as is done
in bistromathic.
The current implementation of parser::context keeps a copy of the
lookahead. This is troublesome since we support move-only types.
Besides, while GCC is happy with the current implementation, Clang
complains that the ctor it needs to build the copy of the lookahead is
not yet available.
461. calc.at:1120: testing Calculator C++ %defines %locations parse.error=verbose %name-prefix "calc" %verbose ...
calc.at:1120: COLUMNS=1000; export COLUMNS; bison --color=no -fno-caret -Wno-deprecated -o calc.cc calc.y
calc.at:1120: $CXX $CXXFLAGS $CPPFLAGS $LDFLAGS -o calc calc.cc calc-lex.cc calc-main.cc $LIBS
stderr:
In file included from calc-lex.cc:7:
calc.hh:351:12: error: instantiation of function 'calc::parser::basic_symbol<calc::parser::by_type>::basic_symbol' required here, but no definition is available [-Werror,-Wundefined-func-template]
struct symbol_type : basic_symbol<by_type>
^
calc.hh:273:7: note: forward declaration of template entity is here
basic_symbol (const basic_symbol& that);
^
calc.hh:351:12: note: add an explicit instantiation declaration to suppress this warning if 'calc::parser::basic_symbol<calc::parser::by_type>::basic_symbol' is explicitly instantiated in another translation unit
struct symbol_type : basic_symbol<by_type>
^
1 error generated.
In file included from calc-main.cc:7:
calc.hh:351:12: error: instantiation of function 'calc::parser::basic_symbol<calc::parser::by_type>::basic_symbol' required here, but no definition is available [-Werror,-Wundefined-func-template]
struct symbol_type : basic_symbol<by_type>
^
calc.hh:273:7: note: forward declaration of template entity is here
basic_symbol (const basic_symbol& that);
^
calc.hh:351:12: note: add an explicit instantiation declaration to suppress this warning if 'calc::parser::basic_symbol<calc::parser::by_type>::basic_symbol' is explicitly instantiated in another translation unit
struct symbol_type : basic_symbol<by_type>
^
1 error generated.
stdout:
calc.at:1120: exit code was 1, expected 0
461. calc.at:1120: 461. Calculator C++ %defines %locations parse.error=verbose %name-prefix "calc" %verbose (calc.at:1120): FAILED (calc.at:1120)
* data/skeletons/lalr1.cc (context::yyla_): Make it a const-ref.
Move the implementation out of the declaration.
Address compiler warnings such as
warning: declaration of 'yyla' shadows a member of 'yy::parser::context' [-Wshadow]
* data/skeletons/lalr1.cc (context): Don't use the same names for
variables and members.
Use foo_ for private members, as in parser.
Also, use the + trick in array accesses to please ICC and provide it
with an int.
* etc/bench.pl.in: Adjust to the current use of %define's values.
Don't use %error-verbose.
Prefer Bison to CPP (e.g., api.value.type).
Avoid returning characters directly, so that %define api.token.raw works.
* doc/bison.texi (Parser Internationalization): Move most of its
content into...
(Enabling I18n): this new node.
(Token I18n): New.
(Token Decl): Refer to token internationalization.
(Error Reporting Function): Promote parse.error detailed.
bison 3.5.2
* tag 'v3.5.2':
version 3.5.2
news: 3.5.2
gnulib: update
doc: update Doxygen template
java: avoid trailing white spaces
m4: fix b4_token_format
doc: clearly state that %yacc only makes sense with yacc.c
doc: spell check
examples: be more robust to spaces in paths
larlr1.cc: Reject unsupported values for parse.lac
We used to emit:
/** Token number,to be returned by the scanner. */
static final int NUM = 258;
/** Token number,to be returned by the scanner. */
static final int NEG = 259;
with no space after the comma. Fix that.
* data/skeletons/bison.m4 (b4_token_format): Quote where appropriate.
This revealed a number of things I had not realized:
- the Java location tracking was aliasing the same pair of positions
for all the symbols (see previous commit).
- in impure parsers, it's quite easy to use incorrect locations for
diagnostics, since yyerror uses yylloc, which is the location of the
lookahead, not that of the current lhs. So we need something like
{
YYLTYPE old_yylloc = yylloc;
yylloc = @$;
yyerror (]AT_PARAM_IF([result, count, nerrs, ])[buf);
yylloc = old_yylloc;
}
Maybe we should do that little yylloc dance in the skeleton instead
of leaving it to the user? It might be costly... But that's only
for users of the impure parsers, which are asking for trouble
anyway.
- in glr.cc invoking yyerror is somewhat cumbersome: the C++ interface
is not available as we are in yyparse (which in C), and yyerror is
used by glr.cc itself to bind it to the user's parser::error. If we
call yyerror, we need:
yyerror (]AT_LOCATION_IF([[&@$, ]])[yyparser, ]AT_PARAM_IF([result, count, nerrs, ])[msg);
However calling yy::parser::error is easier, once we know that the
current parser object is available as 'yyparser'. Which also saves
us from having to pass the parse-params ourselves:
yyparser.error (]AT_LOCATION_IF([[@$, ]])[msg);
* tests/calc.at: Invoke yyerror by hand, instead of using fprintf etc.
Adjust expectations.
* data/skeletons/lalr1.java (Context): Make data members private.
(Context.getLocation): New.
* examples/java/calc/Calc.y, tests/java.at, tests/local.at: Adjust.
* doc/bison.texi (Tokens from Literals): Move to code using
%token-table to...
(Decl Summary: %token-table): here.
* data/skeletons/bison.m4: Implement mutual exclusion.
* tests/input.at: Check it.
* doc/local.mk: Be robust to the removal of doc/.
With texinfo.tex 2019-09-24.13, node names with + are not properly
handled.
https://lists.gnu.org/r/bug-texinfo/2020-02/msg00004.html
* doc/bison.texi: Always use the three-argument form for references to
node with a + in the name.
This reverts commit ebab1ffca8.
This commit removed "useless" initializers, going from
/* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
STATE-NUM. */
private static final byte yypact_[] = yypact_init ();
private static final byte[] yypact_init ()
{
return new byte[]
{
25, -7, -8, 37, -8, 40, -8, 20, -8, 61,
-8, -8, 3, 9, 51, -8, -8, -2, -2, -2,
-2, -2, -2, -8, -8, -8, 1, 66, 66, 3,
3, 3
};
}
to
/* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
STATE-NUM. */
private static final byte[] yypact_ =
{
25, -7, -8, 37, -8, 40, -8, 20, -8, 61,
-8, -8, 3, 9, 51, -8, -8, -2, -2, -2,
-2, -2, -2, -8, -8, -8, 1, 66, 66, 3,
3, 3
};
But it turns out that this was on purpose, to work around the 64KB
limitation in JVM methods. It was introduced on the 2008-11-10 by
Di-an Jan in 09ccae9b18: "Work around
Java's ``code too large'' problem for parser tables". See
https://lists.gnu.org/r/help-bison/2008-11/msg00004.html. A real
test, where we would hit the JVM limitation, would be nice.
To avoid further regressions, add comments.
parse.error has more than two possible values.
* data/skeletons/bison.m4 (b4_error_verbose_if, b4_error_verbose_flag):
Remove.
(b4_parse_error_case, b4_parse_error_bmatch): New.
Adjust dependencies.
* data/skeletons/lalr1.java (yyexpectedTokens)
(yysyntaxErrorArguments): Make them methods of Context.
(Context.yysymbolName): New.
* tests/local.at: Adjust.
The error format should be translated, but contrary to the case of
C/C++, we cannot just depend on macros to adapt on the
presence/absence of '_'. Let's consider that the message format is to
be translated iff there are some internationalized tokens.
* src/output.c (prepare_symbol_names): Define b4_has_translations.
* data/skeletons/java.m4 (b4_trans): New.
* data/skeletons/lalr1.java: Use it to emit translatable or not the
format string.
And allow syntax error messages for 'detailed' and 'verbose' to be
translated.
* data/skeletons/lalr1.java (Context, yyexpectedTokens)
(yysyntaxErrorArguments): New.
(yysyntax_error): Use it.
In Java there is no need for N_ and yytranslate_. So instead of
hard-coding the use of N_ in the table of the symbol names, rely on
b4_symbol_translate.
* src/output.c (prepare_symbol_names): Use b4_symbol_translate instead
of N_.
* data/skeletons/c.m4 (b4_symbol_translate): New.
* data/skeletons/lalr1.java (yysymbolName): New.
Use it.
* examples/java/calc/Calc.y: Use parse.error=detailed.
* tests/calc.at: Check parse.error=detailed.
We used to emit:
/** Token number,to be returned by the scanner. */
static final int NUM = 258;
/** Token number,to be returned by the scanner. */
static final int NEG = 259;
with no space after the comma. Fix that.
* data/skeletons/bison.m4 (b4_token_format): Quote where appropriate.
Unfortunately in the Java skeleton the user cannot override the way
locations are displayed, and locations don't know the structure of the
positions. So they cannot implement the tricks used in the C/C++
skeletons to display "1.1" instead of "1.1-1.2".
* tests/local.at (Java): Add support for column tracking in the
locations, as we did in examples/java/calc.
* tests/calc.at: Use AT_CALC_YYLEX.
Soon calculator tests for Java will move from java.at to calc.at.
Which implies improving the Java testing infrastructure in
local.at (for instance really tracking columns in positions, not just
token number). Detach java.at from local.at.
* tests/java.at (AT_JAVA_POSITION_DEFINE_OLD): New.
Use it.
* examples/java/calc/Calc.y: The StreamTokenizer cannot "peek" for the
next character, it reads it, and keeps it for the next call. So the
current location is one passed the end of the current token. To avoid
this, keep the previous position, and use it to end the current token.
* examples/java/calc/Calc.test: Adjust.
The C, C++ and D skeletons used to show the stack right after popping
the stack during the reduction. Now that the stack is printed after
reaching a new state, that has become useless:
Entering state 1
Stack now 0 1
Reducing stack by rule 5 (line 83):
$1 = token "number" (1)
-> $$ = nterm exp (1)
Stack now 0
Entering state 8
Stack now 0 8
Remove the "Stack now 0" line.
* data/skeletons/lalr1.cc, data/skeletons/lalr1.d,
* data/skeletons/lalr1.java, data/skeletons/yacc.c:
Here.
Currently, if we have long rules and series of shift, we stack states
without showing stack. Let's be more incremental, and do how the Java
skeleton does.
* data/skeletons/lalr1.cc, data/skeletons/lalr1.d,
* data/skeletons/yacc.c:
Here.
Adjust test cases.
* tests/torture.at (AT_DATA_STACK_TORTURE): Disable stack traces: this
test produces a very large stack, and showing the stack each time we
shift a token goes quadatric.
The Java skeleton displays
Reading a token:
Next token is token "number" (1)
while the other display
Reading a token: Next token is token "number" (1)
When generating logs in the scanner, the first part is separated from
the second, and the end of the scanner logs have the second part
pasted in. So let's propagate the Java way, but with the colon.
* data/skeletons/glr.c, data/skeletons/lalr1.cc, data/skeletons/lalr1.d,
* data/skeletons/lalr1.java, data/skeletons/yacc.c: Do it.
Adjust test cases and doc.
* tests/local.at (AT_LANG_MATCH): New.
(AT_YYERROR_DECLARE(java), AT_YYERROR_DECLARE_EXTERN(java)): New.
* tests/calc.at: The grammar file for Java is quite different for the
others, and continuing to assemble it from pieces makes the grammar
file hard to understand. Let's also dispatch on the language to
assemble it, and isolate Java from the others.
Most of this comes from java.at.
This example, so far, was tracking the current token number, not the
current column number. This is not nice for an example...
* examples/java/Calc.y (PositionReader): New.
Use it.
* examples/java/Calc.test: Check the output.
AFAICT, autoboxing/unboxing was added in Java 5 (September 30, 2004).
I think we can afford to use it. It should help us merge some Java
tests with the main ones.
However, beware that != does not unbox: it compares the object
addresses.
* examples/java/Calc.y, tests/java.at: Simplify.
* examples/java/Calc.test, tests/java.at: Improve tests.
When building the test cases, emitting code in the epilogue is very
constraining. Let's make it simpler thanks to %code epilogue.
However, I don't want to document this: it is bad style to use it (we
should avoid having too many ways to write the same thing,
TI!MTOWTDI), just put your code in the true epilogue section.
* data/skeletons/glr.c, data/skeletons/lalr1.d, data/skeletons/lalr1.java,
* data/skeletons/yacc.c: Implement support for %code epilogue.
Remove useless comments.
* tests/calc.at, tests/java.at: Simplify.
Modeled after what was done in yacc.c, yet somewhat different since
yyGLRStack play the role of the full yyparse_context_t. It will
probably be defined as a alias, to make interfaces compatible.
LAC is not supported here. And is somewhat tricky.
* data/skeletons/glr.c (yyexpected_tokens, yysyntax_error_arguments): New.
* data/skeletons/glr.c: Move the handling of error messages after the
definition of types. Especially after yyGLRStack, which we will need
in forthcoming patches.
Simplify: yyGLRStack is defined at this point.
The PDF output is more consistent: some nodes were not pointed to with
their title. The HTML output becomes "see section Foo" instead of
"see Foo", but this should be addressed in the next Texinfo release.
Info output is simplified, as it uses only the node name and not its
title. But it's considered easier to read this way.
See https://lists.gnu.org/r/help-texinfo/2020-01/msg00031.html.
* doc/bison.texi: Set @xrefautomaticsectiontitle on.
Simplify all uses of ref.
Add an example to demonstrate the use of push parser. I'm pleasantly
surprised: parse.error=detailed works like a charm with push parsers.
* examples/c/local.mk, examples/c/pushcalc/Makefile
* examples/c/pushcalc/README.md, examples/c/pushcalc/calc.test,
* examples/c/pushcalc/calc.y, examples/c/pushcalc/local.mk:
New.
* examples/c/calc/calc.y: Restore to its original state, with
parse.error=detailed instead of parse.error=custom (this example
should be simple).
* examples/c/calc/calc.test: Check syntax errors.
* examples/c/lexcalc/parse.y: Add comments.
Akim Demaille