Re: compare of 2 existing methods to implement grammar recursion

On 07/30/2016 01:47 PM, Larry Evans wrote:
> On 07/29/2016 10:31 AM, Larry Evans wrote:
>> The repository:
>>    https://github.com/boostorg/spirit/tree/develop
>> has toy.cpp here:
>>    */workbench/x3/toy/toy.cpp
>> which connects the rule with it's rule_definition using
>> the context; however, it's not clear from the code how
>> to connect multiple rule's withe their rule_definition's.
>>
>> In contrast:
>>
>>    */include/boost/spirit/home/x3/nonterminal/rule.hpp
>>
>> uses the BOOST_SPIRIT_DEFINE macro to do this, as illustrated by:
>>
>>    */example/x3/calc/calc1.cpp
>>
>> The gist:
>>
>>    https://gist.github.com/cppljevans/3634cc4e8ad4da81531608e6aa847de5
>>
>> shows both methods except, in contrast to toy.cpp, it uses
>> make_defns to link multiple rule's with their definitions.

OOPS, apparently the idea of make_defns (which makes a mapping
from the rule to it's definition) had already been tried here:

https://gist.github.com/jamboree/11133291

where it's called rule_map.

However, the file given in that gist:

boost/spirit/home/x3/nonterminal/grammar.hpp

is not present here:

https://github.com/djowel/spirit_x3/tree/master/include/boost/spirit/home/x3/nonterminal

The history for this directory:

https://github.com/djowel/spirit_x3/commits/master/include/boost/spirit/home/x3/nonterminal

mentions nothing about grammar.hpp.

Would someone explain why this idea was not used?

-regards,
Larry



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