Re: Design/structure X3 parser more like Qi parser

On 12/20/2016 03:02 AM, Sandro Pirkwieser wrote:
 > Hi Larry,
 >
 >> This doesn't use BOOST_SPIRIT_DEFINE, and I don't think it can because
 >> that would generate one or more parse_rule's template functions within
 >> the make_csv_parser function.  Is that right?
 >> If so, then wouldn't that make this method slower to compile than if
 >> BOOST_SPIRIT_DEFINE could be used?
 >
 > yes, to my knowledge using BOOST_SPIRIT_DEFINE inside a function, 
e.g. make_csv_parser, is not possible.
 > But I don't know whether this influences compile time.

According to:

https://github.com/cppljevans/spirit/blob/get_rhs/workbench/x3/rule_defns/bench.tmp

there's a significant compile-time penalty without using 
BOOST_SPIRIT_DEFINE.

The benchmark code:

https://github.com/cppljevans/spirit/blob/get_rhs/workbench/x3/rule_defns/rule_defns_bench.cpp

was run with various methods and results were tabulated in
the bench.tmp file.  The method descriptions are found in
comments to:

https://github.com/cppljevans/spirit/blob/get_rhs/workbench/x3/rule_defns/RULE2RHS_METHODS.hpp

The method:

   RULE2RHS_CTX_LIST

is the one which runs without using BOOST_SPIRIT_DEFINE.
As shown in bench.tmp, this performs worse than any other
method, by every measure, when number of rules=12.  In
particular, the elapsed time is significantly worse:

 
https://github.com/cppljevans/spirit/blob/get_rhs/workbench/x3/rule_defns/bench.tmp#L17 


Note, the code was not run with spirit, but with an
"emulation" of spirit found in the rule_defns_benchmark.cpp.
That emulation just doesn't handle attributes, but, AFAICT,
faithfully mimics what spirit does.   If someone sees where
that's not so; please let me know.

HTH.

-regards,
Larry








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