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todo: update
This commit is contained in:
Akim Demaille
123
TODO
123
TODO
@@ -1,5 +1,9 @@
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* Bison 3.6
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** Questions
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*** C++
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We still have occurrences of `type` that should read `kind`, in
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basic_symbol.
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*** Java
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- Should i18n be part of the Lexer? Currently it's a static method of
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Lexer.
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@@ -7,6 +11,10 @@
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- is there a migration path that would allow to use TokenKinds in
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yylex?
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- define the tokens as an enum too.
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- promote YYEOF rather than EOF.
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*** D
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- is there a way to attach yysymbol_name to the enum itself? As we did
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in Java.
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@@ -22,113 +30,28 @@
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Beware that returning 0 is unclear: does it mean there are no possible
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lookahead, or that there are too many?
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** bistromathic
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Beware of portability of __attribute__.
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** YYERRCODE
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How about using "return YYERRCODE" to tell the parser to enter
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error-recovery, but not emit an error message? I have frequently felt the
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need for the scanner to be able to do that. In C++ we can, thanks to throw
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syntax_error.
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Give it another name, it's ugly and conflicts with the way some people have
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used it so far.
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Some people seem to be aware that return YYERRCODE is possible...
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https://github.com/search?q=%22return+YYERRCODE%22&type=Code
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Possible names:
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*** unixODBC
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There are tons of copies on GitHub, I don't know where the original is.
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- YYERROR_TOKEN, but it's too different from the other tokens, included the
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special ones (YYEOF, YYUNDEF).
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https://github.com/faiz-akhtar/Calico/blob/01b49089a3eb535380877bbdc6c641b8b4e7ca6f/Drivers/nn/yylex.c
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- YYerror. It looks weird, but at least it is correct: that's the name
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under which the error token appears in the grammar: "error". Without the
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'YY' prefix though, granted.
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But they define YYERRCODE themselves! They are stepping on "our" namespace.
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yacc.c should `#define YYERRCODE` to that new name in the *.c for sake of the
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projects that used it. In particular
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```
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# define YYERRCODE 256
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```
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https://git.savannah.gnu.org/gitweb/?p=gettext.git;a=blob;f=gettext-runtime/intl/plural.y;h=a712255af4f2f739c93336d4ff6556d932a426a5;hb=HEAD
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Besides, what they do is super-weird: they use YYERRCODE is several places
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for their own error tracking.
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```
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int nnsql_yylex(YYSTYPE* pyylval, yyenv_t* penv)
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{
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[...]
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len = getname(penv->texts_bufptr, -1, penv);
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if( len == YYERRCODE )
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return len;
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```
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*** avrdude-6.3
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Latest version: http://svn.savannah.gnu.org/viewvc/avrdude/trunk/avrdude/lexer.l?view=markup
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We can certainly talk to them about their use of YYERRCODE.
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Replicas on GitHub:
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https://github.com/tam1035/Phys605-March27/blob/0f856baf20877b6f333f91ed17860bd752c7d68e/AVR/avrdude-6.3/lexer.l
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They emit error messages from the scanner and force error recovery. But
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then, they get two error messages.
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```
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c: { yyerror("possible old-style config file entry\n"
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" Update your config file (see " CONFIG_DIR
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"/avrdude.conf.sample for a sample)");
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return YYERRCODE; }
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```
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Unfortunately they also expect the error message at some places. Here,
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return YYUNDEFTOK (or just return yytext[0]) would have been better.
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```
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. { return YYERRCODE; }
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```
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*** Casacore A suite of C++ libraries for radio astronomy data processing.
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https://github.com/casacore/casacore/blob/110bf435c3fe292ee0c3e4bdd039853d257c9536/ms/MSSel/MSAntennaGram.ll
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```
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/* Any other character is invalid */
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. { return YYERRCODE; }
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```
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A pattern they used several times.
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https://github.com/casacore/casacore/search?q=YYERRCODE&unscoped_q=YYERRCODE
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I don't understand how this works: AFAICT, we only define YYERRCODE in
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y.tab.c, not y.tab.h. That's the case in Apple's Bison 2.3 for instance.
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Flex does not generate it either.
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*** Some shell
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Seems to be old versions of busybox.
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https://github.com/luotao717/arsdk/blob/9f9004157afcd26b915125576a815f6b3e0cd715/apps/busybox-1.01/shell/msh.c
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```
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#define YYERRCODE 300
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```
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Used only in one function (collect)
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But today the parser is written by hand.
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https://github.com/mirror/busybox/blob/master/shell/ash.c#L11527
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*** glibc's intl
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https://sourceware.org/git/?p=glibc.git;a=blob;f=intl/plural.y;h=f69fba7c602e9f890f8e5c3b2cd7fe1c487714ea;hb=HEAD
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Their yylex returns YYERRCODE, but they don't want any error message.
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```
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379 static void
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380 yyerror (struct parse_args *arg, const char *str)
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381 {
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382 /* Do nothing. We don't print error messages here. */
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383 }
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```
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This code was not updated in years.
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should be updated.
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** Java
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*** Examples
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