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Suggested by Eric S. Raymond. https://lists.gnu.org/archive/html/bison-patches/2019-02/msg00066.html * examples/c/reentrant-calc/Makefile, examples/c/reentrant-calc/README.md, * examples/c/reentrant-calc/parse.y, examples/c/reentrant-calc/scan.l * examples/c/reentrant-calc/lexcalc.test, * examples/c/reentrant-calc/local.mk: New.
reccalc - recursive calculator with Flex and Bison
In this example the generated parser is pure and reentrant: it can be used concurrently in different threads, or recursively. As a proof of this reentrancy, expressions in parenthesis are tokenized as strings, and then recursively parsed from the parser:
exp: STR
{
result r = parse_string ($1);
free ($1);
if (r.nerrs)
{
res->nerrs += r.nerrs;
YYERROR;
}
else
$$ = r.value;
}