I'm working on a hobby project that use flex/bison to generate C++
scanner/parser. Because there are gazillion number of the parsing objects.
The parsing itself is embarrassingly parallel problem. I want to pool a
couple of ready-to-run scanner/parser object and let them run in parallel.
I read through Flex and Bison official document and skim through their
generated codes.
I can confirm that from Flex document and its code the generating C++
scanner is re-entrant.
However, I have hard time to confirm this from Bison document. It does have
document stating how to build an re-entrant C parser in Bison. But it
doesn't explicitly imply if you build a C++ parser, it is re-entrant. I
found a couple of static class member in Bison generated parser header
file, which make me concern on this matter:
// Tables.
// YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
// STATE-NUM.
static const short int yypact_[];
// YYDEFACT[STATE-NUM] -- Default reduction number in state STATE-NUM.
// Performed when YYTABLE does not specify something else to do. Zero
// means the default is an error.
static const unsigned char yydefact_[];
// YYPGOTO[NTERM-NUM].
static const signed char yypgoto_[];
// YYDEFGOTO[NTERM-NUM].
static const signed char yydefgoto_[];
// YYTABLE[YYPACT[STATE-NUM]] -- What to do in state STATE-NUM. If
// positive, shift that token. If negative, reduce the rule whose
// number is the opposite. If YYTABLE_NINF, syntax error.
static const short int yytable_[];
static const short int yycheck_[];
// YYSTOS[STATE-NUM] -- The (internal number of the) accessing
// symbol of state STATE-NUM.
static const unsigned char yystos_[];
// YYR1[YYN] -- Symbol number of symbol that rule YYN derives.
static const unsigned char yyr1_[];
// YYR2[YYN] -- Number of symbols on the right hand side of rule YYN.
static const unsigned char yyr2_[];
Is generate C++ Bison parser re-entrant?
Cheers,
Ricky
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