Mixing
Position annotation for sequences in Spirit X3
What is considered good form for adding position annotations for rules that return sequences?
Assuming I have a rule in my grammar of the form:
const auto array_def = '[' >> *int_ >> ']';
that synthesizes an attribute of type std::vector< int >, I thought about adding position annotation via an encapsulation of the vector sequence into a made-up type:
struct array_t { std::vector< int > value; };
and add position annotation as per the X3 tutorials:
struct array_t : x3::position_tagged { std::vector< int > value; };
, etc. Unfortunately, this does not work as explained in Boost.Spirit X3 parser "no type named type in(...)" where I see that collapsing single element sequences has been rejected in Spirit.
What's left is perhaps to go the route of:
struct array_t : x3::position_tagged, std::vector< int > { };
which would work (actually, works) but it contradicts decades of good practice that says don't inherit std types. What is good X3 form here?
boost-spirit-x3
asked Jan 2 at 21:14
EngineeristEngineerist
1138
add a comment |
What is considered good form for adding position annotations for rules that return sequences?
Assuming I have a rule in my grammar of the form:
const auto array_def = '[' >> *int_ >> ']';
that synthesizes an attribute of type std::vector< int >, I thought about adding position annotation via an encapsulation of the vector sequence into a made-up type:
struct array_t { std::vector< int > value; };
and add position annotation as per the X3 tutorials:
struct array_t : x3::position_tagged { std::vector< int > value; };
, etc. Unfortunately, this does not work as explained in Boost.Spirit X3 parser "no type named type in(...)" where I see that collapsing single element sequences has been rejected in Spirit.
What's left is perhaps to go the route of:
struct array_t : x3::position_tagged, std::vector< int > { };
which would work (actually, works) but it contradicts decades of good practice that says don't inherit std types. What is good X3 form here?
boost-spirit-x3
asked Jan 2 at 21:14
EngineeristEngineerist
1138
1) If you want your type to be treated as a container - implement container API for it. 2) UsingBOOST_FUSION_ADAPT_STRUCTon a type makes the type a Fusion sequence (check withis_sequencetrait) and has an implication for Spirit. 3) There is nothing wrong with inheritingstd::vectorand your case is a perfect example of a situation when it is justified.
– Nikita Kniazev
Jan 4 at 16:21
Awesome, thanks! If you create an answer I will mark it answered.
– Engineerist
Jan 4 at 18:59
add a comment |
What is considered good form for adding position annotations for rules that return sequences?
Assuming I have a rule in my grammar of the form:
const auto array_def = '[' >> *int_ >> ']';
that synthesizes an attribute of type std::vector< int >, I thought about adding position annotation via an encapsulation of the vector sequence into a made-up type:
struct array_t { std::vector< int > value; };
and add position annotation as per the X3 tutorials:
struct array_t : x3::position_tagged { std::vector< int > value; };
, etc. Unfortunately, this does not work as explained in Boost.Spirit X3 parser "no type named type in(...)" where I see that collapsing single element sequences has been rejected in Spirit.
What's left is perhaps to go the route of:
struct array_t : x3::position_tagged, std::vector< int > { };
which would work (actually, works) but it contradicts decades of good practice that says don't inherit std types. What is good X3 form here?
boost-spirit-x3
asked Jan 2 at 21:14
EngineeristEngineerist
1138
What is considered good form for adding position annotations for rules that return sequences?
Assuming I have a rule in my grammar of the form:
const auto array_def = '[' >> *int_ >> ']';
that synthesizes an attribute of type std::vector< int >, I thought about adding position annotation via an encapsulation of the vector sequence into a made-up type:
struct array_t { std::vector< int > value; };
and add position annotation as per the X3 tutorials:
struct array_t : x3::position_tagged { std::vector< int > value; };
, etc. Unfortunately, this does not work as explained in Boost.Spirit X3 parser "no type named type in(...)" where I see that collapsing single element sequences has been rejected in Spirit.
What's left is perhaps to go the route of:
struct array_t : x3::position_tagged, std::vector< int > { };
which would work (actually, works) but it contradicts decades of good practice that says don't inherit std types. What is good X3 form here?
boost-spirit-x3
boost-spirit-x3
asked Jan 2 at 21:14
EngineeristEngineerist
1138
asked Jan 2 at 21:14
EngineeristEngineerist
1138
edited Jan 3 at 20:20
Engineerist
asked Jan 2 at 21:14
EngineeristEngineerist
1138
asked Jan 2 at 21:14
EngineeristEngineerist
1138
asked Jan 2 at 21:14
EngineeristEngineerist
1138
1138
1) If you want your type to be treated as a container - implement container API for it. 2) UsingBOOST_FUSION_ADAPT_STRUCTon a type makes the type a Fusion sequence (check withis_sequencetrait) and has an implication for Spirit. 3) There is nothing wrong with inheritingstd::vectorand your case is a perfect example of a situation when it is justified.
– Nikita Kniazev
Jan 4 at 16:21
Awesome, thanks! If you create an answer I will mark it answered.
– Engineerist
Jan 4 at 18:59
add a comment |
1) If you want your type to be treated as a container - implement container API for it. 2) UsingBOOST_FUSION_ADAPT_STRUCTon a type makes the type a Fusion sequence (check withis_sequencetrait) and has an implication for Spirit. 3) There is nothing wrong with inheritingstd::vectorand your case is a perfect example of a situation when it is justified.
– Nikita Kniazev
Jan 4 at 16:21
Awesome, thanks! If you create an answer I will mark it answered.
– Engineerist
Jan 4 at 18:59
1) If you want your type to be treated as a container - implement container API for it. 2) Using
BOOST_FUSION_ADAPT_STRUCT on a type makes the type a Fusion sequence (check with is_sequence trait) and has an implication for Spirit. 3) There is nothing wrong with inheriting std::vector and your case is a perfect example of a situation when it is justified.– Nikita Kniazev
Jan 4 at 16:21
1) If you want your type to be treated as a container - implement container API for it. 2) Using
BOOST_FUSION_ADAPT_STRUCT on a type makes the type a Fusion sequence (check with is_sequence trait) and has an implication for Spirit. 3) There is nothing wrong with inheriting std::vector and your case is a perfect example of a situation when it is justified.– Nikita Kniazev
Jan 4 at 16:21
Awesome, thanks! If you create an answer I will mark it answered.
– Engineerist
Jan 4 at 18:59
Awesome, thanks! If you create an answer I will mark it answered.
– Engineerist
Jan 4 at 18:59
add a comment |
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1) If you want your type to be treated as a container - implement container API for it. 2) Using
BOOST_FUSION_ADAPT_STRUCTon a type makes the type a Fusion sequence (check withis_sequencetrait) and has an implication for Spirit. 3) There is nothing wrong with inheritingstd::vectorand your case is a perfect example of a situation when it is justified.– Nikita Kniazev
Jan 4 at 16:21
Awesome, thanks! If you create an answer I will mark it answered.
– Engineerist
Jan 4 at 18:59