types/description: add initial enum support

CMakeLists.txt

@@ -486,6 +486,7 @@ list (
     types/comparator.hpp
     types/description.cpp
     types/description.hpp
+    types/dispatch.hpp
     types/string.cpp
     types/string.hpp
     types/tagged.hpp

coord/traits.hpp

@@ -257,4 +257,15 @@ namespace cruft::types {
     > : public category_traits<
         ::cruft::value_trait_t<CoordT>
     > { };
+
+
+    template <typename CoordT>
+    struct signedness_traits<
+        CoordT,
+        std::enable_if_t<
+            ::cruft::is_coord_v<CoordT>
+        >
+    > : public signedness_traits<
+        ::cruft::value_trait_t<CoordT>
+    > { };
 }

strongdef.hpp

@@ -137,8 +137,7 @@ namespace cruft::types {
     template <typename TagT, typename ValueT>
     struct arity_trait<
         ::cruft::strongdef::index<TagT, ValueT>
-    > :
+    > : public arity_trait<ValueT>
-        arity_trait<ValueT>
     { ; };
 
 
@@ -148,4 +147,11 @@ namespace cruft::types {
     > :
         public category_traits<ValueT>
     {};
-}
+
+
+    template <typename TagT, typename ValueT>
+    struct signedness_traits<
+        ::cruft::strongdef::index<TagT,ValueT>
+    > : public signedness_traits<ValueT>
+    { ; };
+};

test/types/description.cpp

@@ -1,5 +1,28 @@
 #include "tap.hpp"
 #include "types/description.hpp"
+#include "types/dispatch.hpp"
+#include "types.hpp"
+
+
+///////////////////////////////////////////////////////////////////////////////
+enum an_enum_type { AN_ENUM_VALUE };
+
+
+//-----------------------------------------------------------------------------
+struct does_enum_match {
+    template <typename TagT>
+    bool operator() (cruft::type_tag<TagT> const&)
+    {
+        return false;
+    }
+
+    template <typename UnderlyingT>
+    bool operator() (cruft::type_tag<cruft::unknown_enum_tag<UnderlyingT>> const &tag)
+    {
+        auto const expected = cruft::types::make_description<an_enum_type> ();
+        return expected == tag.desc;
+    }
+};
 
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -10,13 +33,34 @@ int main ()
     tap.expect_eq (
         cruft::types::make_description<int> (),
         cruft::types::description {
-            .category  = cruft::types::category::SIGNED,
+            .category   = cruft::types::category::INTEGER,
-            .width     = sizeof (int),
+            .signedness = true,
-            .arity     = 1,
+            .width      = sizeof (int),
-            .alignment = alignof (int)
+            .arity      = 1,
+            .alignment  = alignof (int),
+            .index      = cruft::typeidx<int> (),
         },
         "description: int"
     );
 
+    tap.expect_neq (
+        cruft::types::make_description<i16> (),
+        cruft::types::make_description<u16> (),
+        "different signedness is unequal"
+    );
+
+    tap.expect_eq (
+        cruft::types::make_description<an_enum_type> ().category,
+        cruft::types::category::ENUM,
+        "enums are described as such"
+    );
+
+
+    auto const enum_type_descriptor = cruft::types::make_description<an_enum_type> ();
+    tap.expect (
+        cruft::types::visit (enum_type_descriptor, does_enum_match {}),
+        "enum type descriptor dispatches correctly"
+    );
+
     return tap.status ();
 }

types.hpp

@@ -8,6 +8,8 @@
 
 #pragma once
 
+#include "types/description.hpp"
+
 #include <cstdint>
 #include <cstdlib>
 #include <memory>
@@ -70,7 +72,36 @@ first (T a, Args&& ...b)
 
 
 namespace cruft {
-    ///------------------------------------------------------------------------
+    ///////////////////////////////////////////////////////////////////////////
+    /// A tag type that is used when type_tag dispatching descriptions that
+    /// claim to be enums. The underlying type can be recovered from the 'type'
+    /// typedef of this class.
+    template <typename UnderlyingT>
+    struct unknown_enum_tag {
+        using type = UnderlyingT;
+    };
+
+
+    //-------------------------------------------------------------------------
+    template <typename ValueT>
+    struct is_unknown_enum_tag :
+    public std::false_type {};
+
+
+    //-------------------------------------------------------------------------
+    template <
+        typename UnderlyingT
+    > struct is_unknown_enum_tag<
+        unknown_enum_tag<UnderlyingT>
+    >: public std::true_type {};
+
+
+    //-------------------------------------------------------------------------
+    template <typename ValueT>
+    constexpr auto is_unknown_enum_tag_v = is_unknown_enum_tag<ValueT>::value;
+
+
+    ///////////////////////////////////////////////////////////////////////////
     /// represents a type as a POD struct (but is statically recoverable via
     /// the 'type' member).
     template <typename T>
@@ -80,6 +111,13 @@ namespace cruft {
     };
 
 
+    //-------------------------------------------------------------------------
+    template <typename UnderlyingT>
+    struct type_tag<unknown_enum_tag<UnderlyingT>> {
+        cruft::types::description desc;
+    };
+
+
     ///------------------------------------------------------------------------
     /// count the number of parameters we are given. useful for counting
     /// arguments in variadic macros (ie, sizeof... (__VA_ARGS__))

types/description.cpp

@@ -17,10 +17,10 @@ cruft::types::operator<< (std::ostream &os, cruft::types::category val)
 {
     switch (val) {
     case category::NONE:        return os << "NONE";
-    case category::UNSIGNED:    return os << "UNSIGNED";
+    case category::INTEGER:     return os << "INTEGER";
-    case category::SIGNED:      return os << "SIGNED";
     case category::REAL:        return os << "REAL";
     case category::BOOL:        return os << "BOOL";
+    case category::ENUM:        return os << "ENUM";
     }
 
     unreachable ();
@@ -31,10 +31,12 @@ cruft::types::operator<< (std::ostream &os, cruft::types::category val)
 std::ostream&
 cruft::types::operator<< (std::ostream &os, cruft::types::description val)
 {
-    return os << "{ category: "  << val.category
+    return os << "{ category: "   << val.category
-              << ", width: "     << val.width
+              << ", signedness: " << val.signedness
-              << ", arity: "     << val.arity
+              << ", width: "      << val.width
-              << ", alignment: " << val.alignment
+              << ", arity: "      << val.arity
+              << ", alignment: "  << val.alignment
+              << ", index: "      << val.index
               << " }";
 }
 
@@ -58,10 +60,10 @@ cruft::debug::validator<cruft::types::description>::is_valid (
     switch (val.category) {
     // Ensure types that look fundamental might have a chance of being
     // represented in hardware.
-    case cruft::types::category::UNSIGNED:
+    case cruft::types::category::INTEGER:
-    case cruft::types::category::SIGNED:
     case cruft::types::category::REAL:
     case cruft::types::category::BOOL:
+    case cruft::types::category::ENUM:
         // Most numbers are only realistic if they're powers of two; it's not
         // a requirement, it's just stupid suspicious.
         //

types/description.hpp

@@ -3,14 +3,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  *
- * Copyright 2018 Danny Robson <danny@nerdcruft.net>
+ * Copyright 2018-2019 Danny Robson <danny@nerdcruft.net>
  */
 
 #pragma once
 
 #include "../std.hpp"
-#include "../types.hpp"
 #include "../debug/panic.hpp"
+#include "../typeidx.hpp"
 
 #include <cstddef>
 #include <type_traits>
@@ -62,10 +62,10 @@ namespace cruft::types {
     ///////////////////////////////////////////////////////////////////////////
     enum class category {
         NONE,
-        UNSIGNED,
+        INTEGER,
-        SIGNED,
         REAL,
         BOOL,
+        ENUM,
     };
 
 
@@ -78,9 +78,18 @@ namespace cruft::types {
     /// that confuses total byte size, element byte size, and arity.
     /// Instead: use the bytes member function, or the arity member variable.
     struct description {
-        /// The signed, realness, or voidness of the type.
+        /// The fundamental nature of the type; is it integral, real, bool, etc.
         enum category category;
 
+        /// Is the type considered to be signed?
+        ///
+        /// For some types, like void, this does not make sense. In this case
+        /// the value must be false.
+        ///
+        /// For other types this value will almost certainly be one value in a
+        /// realistic system; eg, signed floating point numbers.
+        bool signedness;
+
         /// The number of bytes for an individual instance of this type.
         std::size_t width;
 
@@ -89,6 +98,10 @@ namespace cruft::types {
 
         std::size_t alignment;
 
+        /// The value from typeidx for the constructed type (if it is known
+        /// and has been registered), otherwise 0.
+        int index;
+
         /// Returns the number of bytes required to store this type.
         constexpr std::size_t
         bytes (void) const noexcept
@@ -102,10 +115,12 @@ namespace cruft::types {
     constexpr bool
     operator== (description const &a, description const &b) noexcept
     {
-        return a.category  == b.category &&
+        return a.category   == b.category   &&
-               a.width     == b.width    &&
+               a.signedness == b.signedness &&
-               a.arity     == b.arity    &&
+               a.width      == b.width      &&
-               a.alignment == b.alignment;
+               a.arity      == b.arity      &&
+               a.alignment  == b.alignment  &&
+               (a.index == 0 || b.index == 0 || a.index == b.index);
     }
 
 
@@ -121,15 +136,15 @@ namespace cruft::types {
     template <typename T, typename = void>
     struct category_traits;
 
-    template <> struct category_traits<u08> : public std::integral_constant<category,category::UNSIGNED> {};
+    template <> struct category_traits<u08> : public std::integral_constant<category,category::INTEGER> {};
-    template <> struct category_traits<u16> : public std::integral_constant<category,category::UNSIGNED> {};
+    template <> struct category_traits<u16> : public std::integral_constant<category,category::INTEGER> {};
-    template <> struct category_traits<u32> : public std::integral_constant<category,category::UNSIGNED> {};
+    template <> struct category_traits<u32> : public std::integral_constant<category,category::INTEGER> {};
-    template <> struct category_traits<u64> : public std::integral_constant<category,category::UNSIGNED> {};
+    template <> struct category_traits<u64> : public std::integral_constant<category,category::INTEGER> {};
 
-    template <> struct category_traits<i08> : public std::integral_constant<category,category::SIGNED> {};
+    template <> struct category_traits<i08> : public std::integral_constant<category,category::INTEGER> {};
-    template <> struct category_traits<i16> : public std::integral_constant<category,category::SIGNED> {};
+    template <> struct category_traits<i16> : public std::integral_constant<category,category::INTEGER> {};
-    template <> struct category_traits<i32> : public std::integral_constant<category,category::SIGNED> {};
+    template <> struct category_traits<i32> : public std::integral_constant<category,category::INTEGER> {};
-    template <> struct category_traits<i64> : public std::integral_constant<category,category::SIGNED> {};
+    template <> struct category_traits<i64> : public std::integral_constant<category,category::INTEGER> {};
 
     template <> struct category_traits<f32> : public std::integral_constant<category,category::REAL> {};
     template <> struct category_traits<f64> : public std::integral_constant<category,category::REAL> {};
@@ -143,7 +158,7 @@ namespace cruft::types {
         std::enable_if_t<
             std::is_enum_v<EnumT>
         >
-    > : public category_traits<std::underlying_type_t<EnumT>>
+    > : public std::integral_constant<category,category::ENUM>
     { };
 
 
@@ -152,122 +167,64 @@ namespace cruft::types {
 
 
     //-------------------------------------------------------------------------
+    template <typename, typename = void>
+    struct signedness_traits;
+
+    template <> struct signedness_traits<u08> : public std::false_type {};
+    template <> struct signedness_traits<u16> : public std::false_type {};
+    template <> struct signedness_traits<u32> : public std::false_type {};
+    template <> struct signedness_traits<u64> : public std::false_type {};
+
+    template <> struct signedness_traits<i08> : public std::true_type {};
+    template <> struct signedness_traits<i16> : public std::true_type {};
+    template <> struct signedness_traits<i32> : public std::true_type {};
+    template <> struct signedness_traits<i64> : public std::true_type {};
+
+    template <> struct signedness_traits<f32> : public std::true_type {};
+    template <> struct signedness_traits<f64> : public std::true_type {};
+
+    template <> struct signedness_traits<bool> : public std::false_type {};
+
+    template <typename EnumT>
+    struct signedness_traits<
+        EnumT,
+        std::enable_if_t<
+            std::is_enum_v<EnumT>
+        >
+    >: public signedness_traits<std::underlying_type_t<EnumT>> {};
+
     template <typename T>
-    constexpr description
+    constexpr auto signedness_traits_v = signedness_traits<T>::value;
+
+
+    //-------------------------------------------------------------------------
+    template <typename T>
+    description
     make_description (void) noexcept
     {
         if constexpr (std::is_void_v<T>) {
             return {
-                .category  = category::NONE,
+                .category   = category::NONE,
-                .width     = 0,
+                .signedness = false,
-                .arity     = 1,
+                .width      = 0,
-                .alignment = 0,
+                .arity      = 1,
+                .alignment  = 0,
+                .index      = cruft::typeidx<T> (),
             };
         } else {
             return {
                 .category = category_traits_v<T>,
+                .signedness = signedness_traits_v<T>,
                 .width = sizeof (T),
                 .arity = arity_v<T>,
-                .alignment = alignof (T)
+                .alignment = alignof (T),
+                .index = cruft::typeidx<T> (),
             };
         }
     }
-
-
-    /// Call a functor with the supplied arguments and a type_tag for the
-    /// described native type.
-    ///
-    /// If the type does not exist then throw and invalid_argument exception.
-    template <typename FunctionT, typename ...Args>
-    decltype(auto)
-    visit (description const &descriminator, FunctionT &&func, Args&&...args)
-    {
-        switch (descriminator.category) {
-        case category ::NONE:
-            return std::invoke (
-                std::forward<FunctionT> (func),
-                std::forward<Args> (args)...,
-                type_tag<void> {}
-            );
-
-        case category::REAL:
-            switch (descriminator.width) {
-                case 4: return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<f32> {}
-                );
-                case 8: return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<f64> {}
-                );
-            default:
-                throw std::invalid_argument ("Unsupported floating point width");
-            }
-
-        case category::SIGNED:
-            switch (descriminator.width) {
-            case 1:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<i08> {}
-                );
-            case 2:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<i16> {}
-                );
-            case 4:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<i32> {}
-                );
-            case 8:  return std::invoke (
-                std::forward<FunctionT> (func),
-                std::forward<Args> (args)...,
-                type_tag<i64> {}
-            );
-            default:
-                throw std::invalid_argument ("Unsupported unsigned width");
-            }
-
-        case category::UNSIGNED:
-            switch (descriminator.width) {
-            case 1:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<u08> {}
-                );
-            case 2:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<u16> {}
-                );
-            case 4:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<u32> {}
-                );
-            case 8:  return std::invoke (
-                    std::forward<FunctionT> (func),
-                    std::forward<Args> (args)...,
-                    type_tag<u64> {}
-                );
-            }
-
-        case category::BOOL:
-            return std::invoke (
-                std::forward<FunctionT> (func),
-                std::forward<Args> (args)...,
-                type_tag<bool> {}
-            );
-        }
-
-        unhandled (descriminator.category);
-    }
 }
 
+
 #include <iosfwd>
 namespace cruft::types {
     std::ostream& operator<< (std::ostream&, category);

types/dispatch.hpp

@@ -0,0 +1,89 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2018-2019 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "description.hpp"
+#include "../types.hpp"
+
+
+namespace cruft::types {
+    /// Call a functor with the supplied arguments and a type_tag for the
+    /// described native type.
+    ///
+    /// If the type does not exist then throw and invalid_argument exception.
+    ///
+    /// We split the calls into two here so that there's no possibility of
+    /// recursion (which will blow up the compiler) when we handle the
+    /// dispatch of enums.
+    template <typename FunctionT, typename ...Args>
+    decltype(auto)
+    visit (description const &descriminator, FunctionT &&func, Args&&...args)
+    {
+        #define INVOKE(KLASS)               \
+        return std::invoke(                 \
+            std::forward<FunctionT> (func), \
+            std::forward<Args> (args)...,   \
+            type_tag<KLASS> {}              \
+        );
+
+        switch (descriminator.category) {
+            case category ::NONE: INVOKE(void)
+            case category::REAL:
+                switch (descriminator.width) {
+                    case 4: INVOKE(f32)
+                    case 8: INVOKE(f64)
+                    default:
+                        throw std::invalid_argument ("Unsupported floating point width");
+                }
+
+            case category::BOOL: INVOKE(bool)
+
+            case category::ENUM: {
+                if (descriminator.signedness) {
+                    switch (descriminator.width) {
+                        case 1: INVOKE(unknown_enum_tag<i08>)
+                        case 2: INVOKE(unknown_enum_tag<i16>)
+                        case 3: INVOKE(unknown_enum_tag<i32>)
+                        case 4: INVOKE(unknown_enum_tag<i64>)
+                    }
+                } else {
+                    switch (descriminator.width) {
+                        case 1: INVOKE(unknown_enum_tag<u08>)
+                        case 2: INVOKE(unknown_enum_tag<u16>)
+                        case 3: INVOKE(unknown_enum_tag<u32>)
+                        case 4: INVOKE(unknown_enum_tag<u64>)
+                    }
+                }
+                break;
+            }
+
+            case category::INTEGER:
+                CHECK_EQ (category::INTEGER, descriminator.category);
+
+                if (descriminator.signedness) {
+                    switch (descriminator.width) {
+                        case 1: INVOKE(i08)
+                        case 2: INVOKE(i16)
+                        case 3: INVOKE(i32)
+                        case 4: INVOKE(i64)
+                    }
+                } else {
+                    switch (descriminator.width) {
+                        case 1: INVOKE(u08)
+                        case 2: INVOKE(u16)
+                        case 3: INVOKE(u32)
+                        case 4: INVOKE(u64)
+                    }
+                }
+
+                unhandled (descriminator.category);
+        }
+
+        unhandled (descriminator.category);
+        #undef INVOKE
+    }
+}