pfr_view

CMakeLists.txt

@@ -23,4 +23,6 @@ target_link_libraries(boost_fusion
         Boost::type_traits
         Boost::typeof
         Boost::utility
+        Boost::pfr
+        Boost::mp11
 )

appveyor.yml

@@ -82,6 +82,8 @@ install:
   - git submodule init libs/type_traits
   - git submodule init libs/typeof
   - git submodule init libs/utility
+  - git submodule init libs/pfr
+  - git submodule init libs/mp11
 
   - git submodule init libs/headers tools/boost_install tools/build
   - git submodule update

doc/algorithm.qbk

@@ -2,6 +2,7 @@
     Copyright (C) 2001-2011 Joel de Guzman
     Copyright (C) 2006 Dan Marsden
     Copyright (C) 2010 Christopher Schmidt
+    Copyright (c) 2022 Denis Mikhailov
 
     Use, modification and distribution is subject to the Boost Software
     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -139,6 +140,96 @@ Linear, exactly `__result_of_size__<Sequence>::value`.
 
 [endsect]
 
+[section pfr]
+
+[caution This function requires at least C++14! Pre C++14 compilers (C++11, C++03...) are not supported.]
+[important Also, please read __boost_pfr_lims__ before using this function. Pay special attention to the SimpleAggregate concept.]
+
+[heading Description]
+
+`pfr` is a generic version of __pfr_fields__. For a `val` conforming Fusion __sequence__, `pfr` returns it sequence unchanged. 
+Otherwise, for a `val` like SimpleAggregate, `pfr` returns a new sequence with elements extracted by using __boost_pfr__.
+
+[heading Synopsis]
+    template<
+        typename SequenceOrSimpleAggregate
+        >
+    typename __result_of_pfr__<SequenceOrSimpleAggregate>::type pfr(
+        SequenceOrSimpleAggregate& val);
+
+    template<
+        typename SequenceOrSimpleAggregate
+        >
+    typename __result_of_pfr__<SequenceOrSimpleAggregate const>::type pfr(
+        SequenceOrSimpleAggregate const& val);
+
+[table Parameters
+    [[Parameter][Requirement][Description]]
+    [[`val`][A model of Sequence, or a model of SimpleAggregate][Operation's argument]]
+]
+
+[heading Expression Semantics]
+    __pfr__(val);
+
+[*Return type]:
+
+* A model of __forward_sequence__ if `val` is a __forward_sequence__
+else, __bidirectional_sequence__ if `val` is a __bidirectional_sequence__
+else, __random_access_sequence__ if `val` is a __random_access_sequence__ or SimpleAggregate.
+* A model of __associative_sequence__ if `val` implements the __associative_sequence__ model.
+
+[*Semantics]: Returns a sequence with all elements of `SequenceOrSimpleAggregate`.
+
+[heading Complexity]
+Constant.
+
+[heading Header]
+
+    #include <boost/fusion/algorithm/auxiliary/pfr.hpp>
+    #include <boost/fusion/include/pfr.hpp>
+
+[note This algorithm won't defined by inclusion of 'boost/fusion/algorithm/auxiliary.hpp' or 'boost/fusion/algorithm.hpp'. ]
+
+[heading Example]
+
+    struct some_person {       // SimpleAggregate
+        std::string name;
+        unsigned birth_year;
+    };
+
+    some_person val{"Edgar Allan Poe", 1809};
+    std::cout << __pfr__(val) << std::endl; // (Edgar Allan Poe 1809)
+
+[heading Example]
+
+    struct empty {             // SimpleAggregate
+    };
+
+    struct aggregate : empty { // not a SimpleAggregate, not a Sequence
+        std::string name;
+        int age;
+        boost::uuids::uuid uuid;
+    };
+
+    aggregate val{"Edgar Allan Poe", 1809, {}};
+    __pfr__(val); // non-portable behavior
+
+[heading Example]
+
+    using some_person = __vector__< // not a SimpleAggregate, but Sequence
+        std::string
+      , unsigned
+    >;
+
+    some_person val("Edgar Allan Poe", 1809);
+    std::cout << __pfr__(val) << std::endl; // (Edgar Allan Poe 1809)
+
+[heading See also]
+
+__boost_pfr__
+
+[endsect]
+
 [endsect]
 
 [section Metafunctions]
@@ -215,6 +306,54 @@ Constant.
 
 [endsect]
 
+[section pfr]
+
+[caution This metafunction requires at least C++14! Pre C++14 compilers (C++11, C++03...) are not supported.]
+[important Also, please read __boost_pfr_lims__ before using this metafunction. Pay special attention to the SimpleAggregate concept.]
+
+[heading Description]
+A metafunction returning the result type of applying __pfr__.
+
+[heading Synopsis]
+    template <typename SequenceOrSimpleAggregate>
+    struct pfr
+    {
+        typedef __unspecified__ type;
+    };
+
+[table Parameters
+    [[Parameter] [Requirement] [Description]]
+    [[`SequenceOrSimpleAggregate`] [Model of Fusion __sequence__ or model of SimpleAggregate from __boost_pfr__] [Operation's argument]]
+]
+
+[heading Expression Semantics]
+    result_of::pfr<SequenceOrSimpleAggregate>::type
+
+[*Return type]:
+
+* A model of __forward_sequence__ if `val` is a __forward_sequence__
+else, __bidirectional_sequence__ if `val` is a __bidirectional_sequence__
+else, __random_access_sequence__ if `val` is a __random_access_sequence__ or SimpleAggregate.
+* A model of __associative_sequence__ if `val` implements the __associative_sequence__ model.
+
+[*Semantics]: Returns a sequence with all elements of `SequenceOrSimpleAggregate`.
+
+[heading Complexity]
+Constant.
+
+[heading Header]
+
+    #include <boost/fusion/algorithm/auxiliary/pfr.hpp>
+    #include <boost/fusion/include/pfr.hpp>
+
+[note This algorithm won't defined by inclusion of 'boost/fusion/algorithm/auxiliary.hpp' or 'boost/fusion/algorithm.hpp'. ]
+
+[heading See also]
+
+__boost_pfr__
+
+[endsect]
+
 [endsect]
 
 [endsect]

doc/fusion.qbk

@@ -48,6 +48,9 @@
 [def __boost_func_forward__     [@http://www.boost.org/libs/functional/forward Boost.Functional/Forward Library]]
 [def __boost_func_factory__     [@http://www.boost.org/libs/functional/factory Boost.Functional/Factory Library]]
 [def __boost_func_hash__        [@http://www.boost.org/doc/html/hash.html Boost.ContainerHash Library]]
+[def __boost_pfr__              [@http://www.boost.org/doc/html/boost_pfr.html Boost.PFR Library]]
+[def __boost_pfr_lims__         [@http://www.boost.org/doc/html/boost_pfr/limitations_and_configuration.html Boost.PFR Limitations and Configuration]]
+[def __boost_pfr_simple_aggregate__ [@http://www.boost.org/doc/html/boost_pfr/limitations_and_configuration.html SimpleAggregate]]
 [def __std_pair_doc__           [@http://en.cppreference.com/w/cpp/utility/pair `std::pair`]]
 [def __std_tuple_doc__          [@http://en.cppreference.com/w/cpp/utility/tuple `std::tuple`]]
 [def __std_plus_doc__           [@http://en.cppreference.com/w/cpp/utility/functional/plus `std::plus`]]
@@ -131,6 +134,7 @@
 [def __zip_view__               [link fusion.view.zip_view `zip_view`]]
 [def __flatten_view__           [link fusion.view.flatten_view `flatten_view`]]
 [def __identity_view__          [link fusion.view.identity_view `identity_view`]]
+[def __pfr_view__               [link fusion.view.pfr_view `pfr_view`]]
 
 [def __array__                  [link fusion.adapted.array array]]
 [def __std_pair__               [link fusion.adapted.std__pair `std::pair`]]
@@ -229,6 +233,8 @@
 [def __result_of_copy__         [link fusion.algorithm.auxiliary.metafunctions.copy `result_of::copy`]]
 [def __move__                   [link fusion.algorithm.auxiliary.functions.move `move`]]
 [def __result_of_move__         [link fusion.algorithm.auxiliary.metafunctions.move `result_of::move`]]
+[def __pfr__                    [link fusion.algorithm.auxiliary.functions.pfr `pfr`]]
+[def __result_of_pfr__          [link fusion.algorithm.auxiliary.metafunctions.pfr `result_of::pfr`]]
 [def __fold__                   [link fusion.algorithm.iteration.functions.fold `fold`]]
 [def __result_of_fold__         [link fusion.algorithm.iteration.metafunctions.fold `result_of::fold`]]
 [def __reverse_fold__           [link fusion.algorithm.iteration.functions.reverse_fold `reverse_fold`]]

doc/html/index.html

@@ -164,6 +164,7 @@
 <dt><span class="section"><a href="fusion/view/transform_view.html">transform_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/reverse_view.html">reverse_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/identity_view.html">identity_view</a></span></dt>
+<dt><span class="section"><a href="fusion/view/pfr_view.html">pfr_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/nview.html">nview</a></span></dt>
 <dt><span class="section"><a href="fusion/view/repetitive_view.html">repetitive_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/flatten_view.html">flatten_view</a></span></dt>

doc/organization.qbk

@@ -61,6 +61,7 @@ link against.
     * transform_view
     * zip_view
     * identity_view
+    * pfr_view
 * container
     * deque
     * list

doc/sequence.qbk

@@ -134,6 +134,7 @@ For any Forward Sequence s the following invariants always hold:
 * __reverse_view__
 * __zip_view__
 * __identity_view__
+* __pfr_view__
 
 [endsect]
 
@@ -203,6 +204,7 @@ are not defined in __forward_sequence__.
 * __transform_view__ (where adapted sequence is a Bidirectional Sequence)
 * __zip_view__       (where adapted sequences are models of Bidirectional Sequence)
 * __identity_view__  (where adapted sequence is a Bidirectional Sequence)
+* __pfr_view__       (where adapted type is a Bidirectional Sequence or a __boost_pfr_simple_aggregate__)
 
 [endsect]
 
@@ -292,6 +294,7 @@ are not defined in __bidirectional_sequence__.
 * __transform_view__ (where adapted sequence is a Random Access Sequence)
 * __zip_view__       (where adapted sequences are models of Random Access Sequence)
 * __identity_view__  (where adapted sequence is a Random Access Sequence)
+* __pfr_view__       (where adapted type is a Random Access Sequence or a __boost_pfr_simple_aggregate__)
 
 [endsect]
 
@@ -365,6 +368,7 @@ you can use `__result_of_value_at_key__<S, K>`.]
 * __reverse_view__   (where adapted sequence is an __associative_sequence__ and a __bidirectional_sequence__)
 * __transform_view__ (where adapted sequence is an __associative_sequence__ and a __forward_sequence__)
 * __identity_view__  (where adapted sequence is an __associative_sequence__ and a __forward_sequence__)
+* __pfr_view__       (where adapted type is an __associative_sequence__ and a __forward_sequence__)
 
 [endsect]
 

doc/view.qbk

@@ -721,4 +721,103 @@ defined in the implemented models.
 
 [endsect]
 
+[section pfr_view]
+
+[caution This view requires at least C++14! Pre C++14 compilers (C++11, C++03...) are not supported.]
+[important Also, please read __boost_pfr_lims__ before using this view. Pay special attention to the SimpleAggregate concept.]
+
+[heading Description]
+
+`pfr_view` is a generic version of __pfr_fields_view__. If underlying type is a conforming Fusion __sequence__, then it type will be 
+presented unchanged. Otherwise, the underlying type must satisfy SimpleAggregate concept, because it type will be presented as a random 
+access sequence by using __boost_pfr__.
+
+[heading Header]
+
+    #include <boost/fusion/view/pfr_view.hpp>
+    #include <boost/fusion/include/pfr_view.hpp>
+
+[note This view won't defined by inclusion of 'boost/fusion/view.hpp'. ]
+
+[heading Synopsis]
+
+    template <typename SequenceOrSimpleAggregate>
+    struct pfr_view;
+
+[heading Template parameters]
+
+[table
+    [[Parameter]                   [Description]                                                                             [Default]]
+    [[`SequenceOrSimpleAggregate`] [A fusion __sequence__ or an user defined structure, satisfied 'SimpleAggregate' concept] []]
+]
+
+[heading Model of]
+
+* A model of __forward_sequence__ if underlying type is a __forward_sequence__
+else, __bidirectional_sequence__ if underlying type is a __bidirectional_sequence__
+else, __random_access_sequence__ if underlying type is a __random_access_sequence__ or SimpleAggregate.
+* __associative_sequence__ if underlying type implements the __associative_sequence__ model.
+
+[variablelist Notation
+    [[`P`]              [A `pfr_view` type]]
+    [[`p`, `p2`]        [Instances of `pfr_view`]]
+    [[`a`]              [An instance of `SimpleAggregate`]]
+    [[`s`]              [An instance of `Sequence`]]
+]
+
+[heading Expression Semantics]
+
+Semantics of an expression is defined only where it differs from, or is not
+defined in __random_access_sequence__.
+
+[table
+    [[Expression]           [Semantics]]
+    [[`P(a)`]               [Creates a `pfr_view` from simple aggregate `a`.]]
+    [[`P(s)`]               [Creates a `pfr_view` from sequence `s`.]]
+    [[`P(p)`]               [Copy constructs a `pfr_view` from another `pfr_view`, `p`.]]
+    [[`p = p2`]             [Assigns to a `pfr_view`, `p`, from another `pfr_view`, `p2`.]]
+]
+
+[heading Example]
+
+    struct some_person {       // SimpleAggregate
+        std::string name;
+        unsigned birth_year;
+    };
+
+    some_person val{"Edgar Allan Poe", 1809};
+    __pfr_view__<some_person> view(val);
+    std::cout << view << std::endl; // (Edgar Allan Poe 1809)
+
+[heading Example]
+
+    struct empty {             // SimpleAggregate
+    };
+
+    struct aggregate : empty { // not a SimpleAggregate
+        std::string name;
+        int age;
+        boost::uuids::uuid uuid;
+    };
+
+    aggregate val{"Edgar Allan Poe", 1809, {}};
+    __pfr_view__<aggregate> view(val); // non-portable behavior
+
+[heading Example]
+
+    using some_person = __vector__< // not a SimpleAggregate, but Sequence
+        std::string
+      , unsigned
+    >;
+
+    some_person val("Edgar Allan Poe", 1809);
+    __pfr_view__<some_person> view(val);
+    std::cout << view << std::endl; // (Edgar Allan Poe 1809)
+
+[heading See also]
+
+__boost_pfr__
+
+[endsect]
+
 [endsect]

include/boost/fusion/algorithm/auxiliary.hpp

@@ -13,4 +13,12 @@
 #include <boost/fusion/algorithm/auxiliary/move.hpp>
 #endif
 
+// Unfortunately, there is no way to determine the compatibility of the pfr library with the current compiler.
+// The "boost/fusion/algorithm/auxiliary/pfr.hpp" include has been commented out to ensure backward compatibility
+// Please include it manually in your project
+
+// #if !defined(BOOST_FUSION_NO_PFR)
+// #include <boost/fusion/algorithm/auxiliary/pfr.hpp>
+// #endif
+
 #endif