Re: [PATCH 3/5] c++: improvements on symbol kinds

[Akim Demaille]

> Le 15 avr. 2020 à 18:42, Hans Åberg <address@hidden> a écrit :
> 
>> 
>> On 15 Apr 2020, at 18:25, Akim Demaille <address@hidden> wrote:
>> 
>>> Le 15 avr. 2020 à 18:15, Hans Åberg <address@hidden> a écrit :
>>>>>> In retrospect, it would have been better to have it named "token_type", 
>>>>>> and "stack_symbol_type" would have been "symbol_type".
>>>>> 
>>>>> Maybe so. I only need the symbol value for the return to the parser from 
>>>>> the lexer, and mostly, they are symbol constants (tokens), but I am not 
>>>>> sure they always have to be.
>>>> 
>>>> So that's the kind.
>>> 
>>> I think it is unkind! :-) The word “kind” does not seem to be in line with 
>>> any C++ lingo at least.
>> 
>> The parser is fed with tokens by yylex.  A lexeme such as "123" in an 
>> arithmetical expression, has:
>> 
>> - a kind, NUMBER.  That coincides with what people refer to as a "token" 
>> when they talk about the grammar.
>> 
>> - a value, the int 100 + 20 + 3.
>> 
>> - a location, from Line 1 Col 1 to Line 1 Col 4 (excluded)
>> 
>> The type of the kind is token_kind_type, the type of the value is 
>> value_type, and the type of the location is location_type.  The type of the 
>> kind is not kind_type, because we actually deal with two kinds, so we must 
>> be clearer.  But there's only one concept of value_type and one of 
>> location_type.
>> 
>> And token_type denotes the type which is a triple: token_kind_type, 
>> value_type, location_type.
>> 
>> yylex returns the kind, and takes pointers to yylval (value) and yylloc 
>> (location).
> 
> Currently, I return the token value,

That's called "token kind" here.

> and the semantic and location values are passed through the argument. It is 
> more logical to have them in the return, but bundling them together do not 
> make them tokens,

Yes it does.  That's the whole point of using names: providing meaning to 
words, and that's the meaning "token" has here.

Besides, you're describing api.token.constructor.