sygac-components.hpp

#pragma once
/*
Copyright 2023 Travis J. West, https://traviswest.ca, Input Devices and Music Interaction Laboratory
(IDMIL), Centre for Interdisciplinary Research in Music Media and Technology
(CIRMMT), McGill University, Montréal, Canada, and Univ. Lille, Inria, CNRS,
Centrale Lille, UMR 9189 CRIStAL, F-59000 Lille, France
 
SPDX-License-Identifier: MIT
*/
 
#include <utility>
#include <boost/pfr.hpp>
#include <boost/mp11.hpp>
#include "sygac-tuple.hpp"
#include "sygac-metadata.hpp"
#include "sygac-functions.hpp"
#include "sygac-endpoints.hpp"
 
namespace sygaldry {
 
using boost::mp11::mp_transform;
 
 
 
template<typename T>
concept SimpleAggregate
    =  not std::is_union_v<T>
    && (  std::is_aggregate_v<T>
       || std::is_scalar_v<T>
       )
    ;
 
template <typename T> struct main_subroutine_reflection {using exists = std::false_type;};
 
template <typename T>
    requires (std::same_as<void, typename function_reflection<&T::operator()>::return_type>
          && !std::same_as<void, typename function_reflection<&T::main>::return_type>)
struct main_subroutine_reflection<T> : function_reflection<&T::operator()> {};
 
template <typename T>
    requires std::same_as<void, typename function_reflection<&T::main>::return_type>
struct main_subroutine_reflection<T> : function_reflection<&T::main> {};
template <typename T> struct init_subroutine_reflection {using exists = std::false_type;};
 
template <typename T>
    requires std::same_as<void, typename function_reflection<&T::init>::return_type>
struct init_subroutine_reflection<T> : function_reflection<&T::init> {};
 
template <typename T> struct external_sources_subroutine_reflection {using exists = std::false_type;};
 
template <typename T>
    requires std::same_as<void, typename function_reflection<&T::external_sources>::return_type>
struct external_sources_subroutine_reflection<T> : function_reflection<&T::external_sources> {};
 
template <typename T> struct external_destinations_subroutine_reflection {using exists = std::false_type;};
 
template <typename T>
    requires std::same_as<void, typename function_reflection<&T::external_destinations>::return_type>
struct external_destinations_subroutine_reflection<T> : function_reflection<&T::external_destinations> {};
template<typename T>
concept has_main_subroutine // = main_subroutine_reflection<T>::exists::value;
    =  std::same_as<void, typename function_reflection<&T::operator()>::return_type>
    || std::same_as<void, typename function_reflection<&T::main>::return_type>
    ;
template<typename T>
concept has_init_subroutine
    = std::same_as<void, typename function_reflection<&T::init>::return_type>;
template<typename T>
concept has_external_sources_subroutine
    = std::same_as<void, typename function_reflection<&T::external_sources>::return_type>;
template<typename T>
concept has_external_destinations_subroutine
    = std::same_as<void, typename function_reflection<&T::external_destinations>::return_type>;
 
#define has_type_or_value(NAME)\
template<typename T> concept has_##NAME = requires (T t)\
{\
    t.NAME;\
    requires SimpleAggregate<decltype(t.NAME)>;\
};\
\
template<has_##NAME T> struct type_of_##NAME\
{\
    using type = decltype(std::declval<T>().NAME);\
};\
\
template<typename T> using NAME##_t = typename type_of_##NAME<T>::type;\
\
template<typename T> requires has_##NAME<T> constexpr auto& NAME##_of(T& t) { return t.NAME; }\
template<typename T> requires has_##NAME<T> constexpr const auto& NAME##_of(const T& t) { return t.NAME; }\
 
has_type_or_value(inputs);
has_type_or_value(outputs);
 
#undef has_type_or_value
 
 
template<typename T>
concept Component
    =  has_name<T>
    &&  (  has_init_subroutine<T>
        || has_external_sources_subroutine<T>
        || has_main_subroutine<T>
        || has_external_destinations_subroutine<T>
        || has_inputs<T>
        || has_outputs<T>
        )
    ;
 
namespace detail {
 
template<typename T>
struct assembly_predicate : std::false_type {};
template<typename T>
    requires Component<T>
struct assembly_predicate<T> : std::true_type {};
 
template<typename T>
    requires Tuple<T>
struct assembly_predicate<T> : std::false_type {};
 
template<typename T>
    requires SimpleAggregate<T> && (not Component<T>) && (not std::is_scalar_v<T>) && (not Tuple<T>)
struct assembly_predicate<T>
{
    using tup = decltype(boost::pfr::structure_to_tuple(std::declval<T&>()));
    using valid_components = boost::mp11::mp_transform<assembly_predicate, tup>;
    using all_valid = boost::mp11::mp_apply<boost::mp11::mp_all, valid_components>;
    static constexpr bool value = all_valid::value;
};
}
 
template<typename T>
concept Assembly = detail::assembly_predicate<T>::value && not Component<T> && not Tuple<T>;
 
namespace node
{
    struct assembly {};
    struct component {};
    struct inputs_container {};
    struct outputs_container {};
    struct endpoints_container {};
    struct input_endpoint {};
    struct output_endpoint {};
    struct endpoint {};
    template<typename> struct is_assembly : std::false_type {};
    template<>         struct is_assembly<assembly> : std::true_type {};
    template<typename> struct is_component : std::false_type {};
    template<>         struct is_component<component> : std::true_type {};
    template<typename> struct is_inputs_container : std::false_type {};
    template<>         struct is_inputs_container<inputs_container> : std::true_type {};
    template<typename> struct is_outputs_container : std::false_type {};
    template<>         struct is_outputs_container<outputs_container> : std::true_type {};
    template<typename> struct is_input_endpoint : std::false_type {};
    template<>         struct is_input_endpoint<input_endpoint> : std::true_type {};
    template<typename> struct is_output_endpoint : std::false_type {};
    template<>         struct is_output_endpoint<output_endpoint> : std::true_type {};
    template<typename> struct is_endpoints_container : std::false_type {};
    template<>         struct is_endpoints_container<inputs_container> : std::true_type {};
    template<>         struct is_endpoints_container<outputs_container> : std::true_type {};
    template<>         struct is_endpoints_container<endpoints_container> : std::true_type {};
    template<typename> struct is_endpoint : std::false_type {};
    template<>         struct is_endpoint<input_endpoint> : std::true_type {};
    template<>         struct is_endpoint<output_endpoint> : std::true_type {};
    template<>         struct is_endpoint<endpoint> : std::true_type {};
}
 
template<typename Tag, typename Val>
struct tagged
{
    using tag = Tag;
    using type = Val;
    Val& ref;
};
struct tagged {…};
template<typename Tag, typename T>
constexpr auto endpoint_subtree(T& component)
{
    using ContainerTag = boost::mp11::mp_if_c< std::same_as<Tag, node::input_endpoint>
                                             , node::inputs_container
                                             , node::outputs_container
                                             >;
 
    constexpr auto f = []<typename Container>(Container& container)
    {
        auto endpoints = sygaldry::pfr::structure_tie(container);
        auto head = tpl::make_tuple(tagged<ContainerTag, Container>{container});
        auto tail = endpoints.map([]<typename Ep>(Ep& endpoint)
        {
            return tpl::make_tuple(tagged<Tag, Ep>{endpoint});
        });
        return tpl::make_tuple(tpl::tuple_cat(head, tail));
    };
 
    constexpr bool inputs = std::same_as<Tag, node::input_endpoint> && has_inputs<T>;
    constexpr bool outputs = std::same_as<Tag, node::output_endpoint> && has_outputs<T>;
         if constexpr (inputs) return f(inputs_of(component));
    else if constexpr (outputs) return f(outputs_of(component));
    else return tpl::tuple<>{};
}
 
template<typename T>
constexpr auto component_to_tree(T& component)
{
    if constexpr (Component<T>)
    {
        return tpl::tuple_cat( tpl::make_tuple(tagged<node::component, T>{component})
                             , endpoint_subtree<node::input_endpoint>(component)
                             , endpoint_subtree<node::output_endpoint>(component)
                             );
    }
    else
    {
        auto subcomponents = sygaldry::pfr::structure_tie(component);
        auto head = tpl::make_tuple(tagged<node::assembly, T>{component});
        auto tail = subcomponents.map([](auto& subcomponent)
        {
            return component_to_tree(subcomponent);
        });
        return tpl::tuple_cat( head, tail);
    }
}
template<Tuple T>
constexpr auto component_tree_to_node_list(T tree)
{
    if constexpr (std::tuple_size_v<T> == 0) return tree;
    auto head = tuple_head(tree);
    auto tail = tuple_tail(tree);
    if constexpr (Tuple<decltype(head)>) return tpl::tuple_cat(component_tree_to_node_list(head), component_tree_to_node_list(tail));
    else return tpl::tuple_cat(tpl::make_tuple(head), component_tree_to_node_list(tail));
}
template<typename T>
constexpr auto component_to_node_list(T& component)
{
    return component_tree_to_node_list(component_to_tree(component));
}
template<template<typename>typename F>
constexpr auto node_list_filter(Tuple auto tup)
{
    return tpl::apply([](auto...args)
    {
        auto ret = tpl::tuple_cat(args...);
        if constexpr (std::tuple_size_v<decltype(ret)> == 0)
            return;
        else if constexpr (std::tuple_size_v<decltype(ret)> == 1)
            return tpl::get<0>(ret);
        else return ret;
    }
    , tup.map([]<typename E>(E element)
    {
        if constexpr (F<E>::value) return tpl::make_tuple(element);
        else return tpl::tuple<>{};
    }));
}
template<template<typename>typename F, typename T>
constexpr auto component_filter(T& component)
{
    return node_list_filter<F>(component_to_node_list(component));
}
template<typename T>
struct tagged_is_same
{
    template<typename Y>
    struct fn : std::is_same<T, typename Y::type> {};
};
struct tagged_is_same {…};
 
template<typename T>
constexpr auto& find(Tuple auto tup)
{
    return node_list_filter<tagged_is_same<T>::template fn>(tup).ref;
}
 
template<typename T>
constexpr auto& find(auto& component)
{
    return node_list_filter<tagged_is_same<T>::template fn>(component_to_node_list(component)).ref;
}
template<typename ... RequestedNodes>
struct _search_by_tags
{
    template<typename Tag> using fn = boost::mp11::mp_contains<tpl::tuple<RequestedNodes...>, typename Tag::tag>;
};
struct _search_by_tags {…};
 
template<typename ... RequestedNodes>
constexpr auto node_list_filter_by_tag(Tuple auto tup)
{
    return node_list_filter<_search_by_tags<RequestedNodes...>::template fn>(tup);
}
 
template<typename ... RequestedNodes>
constexpr auto component_filter_by_tag(auto& component)
{
    return node_list_filter<_search_by_tags<RequestedNodes...>::template fn>(component_to_node_list(component));
}
 
template<typename ... RequestedNodes>
constexpr auto for_each_node_in_list(const Tuple auto node_list, auto callback)
{
    auto f = [&](auto tagged_node)
    {
        callback(tagged_node.ref, typename decltype(tagged_node)::tag{});
    };
    if constexpr (sizeof...(RequestedNodes) > 0)
    {
        constexpr auto filtered = node_list_filter_by_tag<RequestedNodes...>(node_list);
        tuple_for_each(filtered, f);
    }
    else tuple_for_each(node_list, f);
}
template<typename T, Tuple Tup>
constexpr auto path_of(const Tup tree)
{
    if constexpr (std::tuple_size_v<Tup> == 0) // tail of a leaf node
        return tpl::tuple<>{};
 
    // split the tuple into its head and its tail
    auto head = tuple_head(tree);
    auto tail_path = path_of<T>(tuple_tail(tree));
 
    if constexpr (Tuple<decltype(head)>) // search subtrees
        return tpl::tuple_cat(path_of<T>(head), tail_path);
    else if constexpr (std::same_as<typename decltype(head)::type, T>) // the node that we are looking for
        return tpl::make_tuple(head);
    else if constexpr (std::tuple_size_v<decltype(tail_path)> > 0) // head is a parent
    {
        if constexpr (has_name<typename decltype(head)::type>) // prepend named parent
            return tpl::tuple_cat(tpl::make_tuple(head), tail_path);
        else return tail_path; // return sub-path
    }
    else return tpl::tuple<>{}; // node is in another subtree
}
 
template<typename T, typename C>
    requires Component<C> || Assembly<C>
constexpr auto path_of(C& component)
{
    return path_of<T>(component_to_tree(component));
}
template<typename Tag> using untagged = typename Tag::type;
 
// TODO: shouldn't this return references?
template<Tuple T>
constexpr auto remove_node_tags(T tup)
{
    return tup.map([](auto&& tagged) -> auto& {return tagged.ref;});
}
template<typename T> using output_endpoints_t =
    decltype(remove_node_tags(component_filter_by_tag<node::output_endpoint>(std::declval<T&>())));
template<typename T> using input_endpoints_t =
    decltype(remove_node_tags(component_filter_by_tag<node::input_endpoint>(std::declval<T&>())));
template<typename T> using endpoints_t =
    decltype(remove_node_tags(component_filter_by_tag<node::input_endpoint, node::output_endpoint>(std::declval<T&>())));
template<typename T, typename C> using path_t =
    decltype(remove_node_tags(path_of<T>(std::declval<C&>())));
 
template<typename T, typename ... RequestedNodes>
constexpr auto for_each_node(T& component, auto callback)
{
    using boost::mp11::mp_list;
    using boost::mp11::mp_contains;
    using boost::mp11::mp_empty;
 
    using nodes = mp_list<RequestedNodes...>;
 
    if constexpr (Assembly<T>)
    {
        if constexpr (  mp_empty<nodes>::value
                     || mp_contains<nodes, node::assembly>::value
                     )  callback(component, node::assembly{});
        boost::pfr::for_each_field(component, [&]<typename S>(S& subcomponent)
        {
            for_each_node<S, RequestedNodes...>(subcomponent, callback);
        });
    }
    else if constexpr (Component<T>)
    {
        if constexpr (  mp_empty<nodes>::value
                     || mp_contains<nodes, node::component>::value
                     )  callback(component, node::component{});
        if constexpr (has_inputs<T>)
        {
            auto& inputs = inputs_of(component);
 
            if constexpr (  mp_empty<nodes>::value
                         || mp_contains<nodes, node::inputs_container>::value
                         || mp_contains<nodes, node::endpoints_container>::value
                         )  callback(inputs, node::inputs_container{});
 
            // iterate only if we are visiting input endpoints
            if constexpr (  mp_empty<nodes>::value
                         || mp_contains<nodes, node::input_endpoint>::value
                         || mp_contains<nodes, node::endpoint>::value
                         )  boost::pfr::for_each_field(inputs, [&](auto& in)
            {
                callback(in, node::input_endpoint{});
            });
        }
        if constexpr (has_outputs<T>)
        {
            auto& outputs = outputs_of(component);
 
            if constexpr (  mp_empty<nodes>::value
                         || mp_contains<nodes, node::outputs_container>::value
                         || mp_contains<nodes, node::endpoints_container>::value
                         )  callback(outputs, node::outputs_container{});
 
            // iterate only if we are visiting output endpoints
            if constexpr (  mp_empty<nodes>::value
                         || mp_contains<nodes, node::output_endpoint>::value
                         || mp_contains<nodes, node::endpoint>::value
                         )  boost::pfr::for_each_field(outputs, [&](auto& out)
            {
                callback(out, node::output_endpoint{});
            });
        }
    }
}
template <typename T> constexpr void for_each_component(T& component, auto callback)
{
    for_each_node<T, node::component>(component, [&](auto& c, auto) { callback(c); });
}
 
template<typename T> constexpr void for_each_endpoint(T& component, auto callback)
{
    for_each_node<T, node::endpoint>(component, [&](auto& c, auto) { callback(c); });
}
 
template<typename T> constexpr void for_each_input(T& component, auto callback)
{
    for_each_node<T, node::input_endpoint>(component, [&](auto& c, auto) { callback(c); });
}
 
template<typename T> constexpr void for_each_output(T& component, auto callback)
{
    for_each_node<T, node::output_endpoint>(component, [&](auto& c, auto) { callback(c); });
}
 
template<typename Y>
void clear_flag(Y& endpoint)
{
    if constexpr (ClearableFlag<Y>) clear_flag(endpoint);
}
 
void clear_flags(auto& component)
{
    for_each_endpoint(component, [](auto& endpoint) { clear_flag(endpoint); });
}
 
void clear_output_flags(auto& component)
{
    for_each_output(component, [](auto& endpoint) { clear_flag(endpoint); });
}
 
void clear_input_flags(auto& component)
{
    for_each_input(component, [](auto& endpoint) { clear_flag(endpoint); });
}
 
template<Component T>
void init(T& component)
{
    if constexpr (requires {component.init();}) component.init();
}
 
template<Assembly T>
void init(T& container)
{
    for_each_component(container, [](auto& component) {init(component);});
};
 
template<Component T>
void activate_inner(T& component)
{
    if constexpr (requires {component.main(component.inputs, component.outputs);})
        component.main(component.inputs, component.outputs);
    else if constexpr (requires {component(component.inputs, component.outputs);})
        component(component.inputs, component.outputs);
    else if constexpr (requires {component();})
        component();
 
}
 
template<Component T>
void activate(T& component)
{
    clear_output_flags(component);
    activate_inner(component);
    clear_input_flags(component);
}
 
template<Assembly T>
void activate(T& container)
{
    clear_output_flags(container);
    for_each_component(container, activate_inner);
    clear_input_flags(container);
};
 
 
}