For easily-capturable objects, just use the original type

This is ever-so-slightly more efficient, and also makes looking at symbols a
whole lot easier.

include/mettle/detail/any_capture.hpp

@@ -7,27 +7,22 @@
 
 namespace mettle::detail {
 
-  template<typename T, typename Enable = void>
-  class any_capture {
-  public:
-    using type = T;
+  struct any_capture_tag {};
 
-    constexpr any_capture(const T &t) : value(t) {}
-    constexpr any_capture(T &&t) : value(std::move(t)) {}
-
-    T value;
-  };
+  template<typename T, typename Enable = void>
+  class capture_array;
 
   template<typename T, std::size_t N>
-  class any_capture<T[N], std::enable_if_t<std::is_trivial_v<T>>> {
+  class capture_array<T[N], std::enable_if_t<std::is_trivial_v<T>>>
+    : public any_capture_tag {
   public:
     using type = T[N];
 
-    constexpr any_capture(const T (&t)[N]) {
+    constexpr capture_array(const T (&t)[N]) {
       for(std::size_t i = 0; i != N; i++)
         value[i] = t[i];
     }
-    constexpr any_capture(T (&&t)[N]) {
+    constexpr capture_array(T (&&t)[N]) {
       for(std::size_t i = 0; i != N; i++)
         value[i] = std::move(t[i]);
     }
@@ -42,41 +37,62 @@ namespace mettle::detail {
 #endif
 
   template<typename T, std::size_t N>
-  class any_capture<T[N], std::enable_if_t<!std::is_trivial_v<T>>> {
+  class capture_array<T[N], std::enable_if_t<!std::is_trivial_v<T>>>
+    : public any_capture_tag {
   public:
     using type = T[N];
 
-    constexpr any_capture(const T (&t)[N])
-      : any_capture(t, std::make_index_sequence<N>()) {}
-    constexpr any_capture(T (&&t)[N])
-      : any_capture(std::move(t), std::make_index_sequence<N>()) {}
+    constexpr capture_array(const T (&t)[N])
+      : capture_array(t, std::make_index_sequence<N>()) {}
+    constexpr capture_array(T (&&t)[N])
+      : capture_array(std::move(t), std::make_index_sequence<N>()) {}
 
     T value[N];
   private:
     template<std::size_t ...I>
-    constexpr any_capture(const T (&t)[N], std::index_sequence<I...>)
+    constexpr capture_array(const T (&t)[N], std::index_sequence<I...>)
       : value{t[I]...} {}
 
     template<std::size_t ...I>
-    constexpr any_capture(T (&&t)[N], std::index_sequence<I...>)
+    constexpr capture_array(T (&&t)[N], std::index_sequence<I...>)
       : value{std::move(t[I])...} {}
   };
 
 #if defined(_MSC_VER) && !defined(__clang__)
 #  pragma warning(pop)
 #endif
 
-  template<typename Ret, typename ...Args>
-  class any_capture<Ret(Args...)> : public any_capture<Ret(*)(Args...)> {
-    using any_capture<Ret(*)(Args...)>::any_capture;
-  };
-
   template<typename T>
-  class any_capture<T[]> {
+  class capture_array<T[]> : public any_capture_tag {
     static_assert(std::is_same<T, void>::value,
                   "any_capture can't be used by incomplete array types");
   };
 
+  template<typename T, typename = void>
+  struct any_capture_type {
+    using type = T;
+  };
+  template<typename T>
+  struct any_capture_type<T, std::void_t<typename capture_array<T>::type>> {
+    using type = capture_array<T>;
+  };
+  template<typename Ret, typename ...Args>
+  struct any_capture_type<Ret(Args...)> {
+    using type = Ret(*)(Args...);
+  };
+
+  template<typename T>
+  using any_capture = typename any_capture_type<T>::type;
+
+  template<typename T>
+  decltype(auto) unwrap_capture(T &&t) {
+    using V = std::remove_reference_t<std::remove_cv_t<T>>;
+    if constexpr(std::is_base_of_v<any_capture_tag, V>)
+      return (t.value);
+    else
+      return std::forward<T>(t);
+  }
+
 } // namespace mettle::detail
 
 #endif

include/mettle/matchers/collection.hpp

@@ -290,13 +290,13 @@ namespace mettle {
         using std::begin, std::end;
         return std::is_permutation(
           begin(actual), end(actual),
-          begin(container_.value), end(container_.value)
+          begin(unwrap_capture(container_)), end(unwrap_capture(container_))
         );
       }
 
       std::string desc() const {
         std::ostringstream ss;
-        ss << "permutation of " << to_printable(container_.value);
+        ss << "permutation of " << to_printable(unwrap_capture(container_));
         return ss.str();
       }
     private:
@@ -314,15 +314,15 @@ namespace mettle {
         using std::begin, std::end;
         return std::is_permutation(
           begin(actual), end(actual),
-          begin(container_.value), end(container_.value),
+          begin(unwrap_capture(container_)), end(unwrap_capture(container_)),
           predicate_
         );
       }
 
       std::string desc() const {
         std::ostringstream ss;
-        ss << "permutation of " << to_printable(container_.value) << " for "
-           << to_printable(predicate_);
+        ss << "permutation of " << to_printable(unwrap_capture(container_))
+           << " for " << to_printable(predicate_);
         return ss.str();
       }
     private:

include/mettle/matchers/core.hpp

@@ -43,12 +43,13 @@ namespace mettle {
 
     template<typename U>
     decltype(auto) operator ()(U &&actual) const {
-      return f_(std::forward<U>(actual), thing_.value);
+      return f_(std::forward<U>(actual), detail::unwrap_capture(thing_));
     }
 
     std::string desc() const {
       std::ostringstream ss;
-      ss << prefix_ << detail::matcher_desc(thing_.value) << suffix_;
+      ss << prefix_ << detail::matcher_desc(detail::unwrap_capture(thing_))
+         << suffix_;
       return ss.str();
     }
   private:
@@ -95,7 +96,7 @@ namespace mettle {
   }
 
   template<typename T>
-  inline auto ensure_matcher(T &&t) {
+  inline decltype(auto) ensure_matcher(T &&t) {
     if constexpr(is_matcher_v<T>) {
       return std::forward<T>(t);
     } else {

include/mettle/matchers/relational.hpp

@@ -50,25 +50,28 @@ namespace mettle {
 
     template<typename U>
     bool operator ()(U &&actual) const {
+      using detail::unwrap_capture;
       if (left_open()) {
-        if (actual <= low_.value) return false;
+        if (actual <= unwrap_capture(low_)) return false;
       } else {
-        if (actual < low_.value) return false;
+        if (actual < unwrap_capture(low_)) return false;
       }
 
       if (right_open()) {
-        if (actual >= high_.value) return false;
+        if (actual >= unwrap_capture(high_)) return false;
       } else {
-        if (actual > high_.value) return false;
+        if (actual > unwrap_capture(high_)) return false;
       }
 
       return true;
     }
 
     std::string desc() const {
+      using detail::unwrap_capture;
       std::ostringstream ss;
-      ss << "in " << (left_open() ? "(" : "[") << to_printable(low_.value)
-         << " .. " << to_printable(high_.value) << (right_open() ? ")" : "]");
+      ss << "in " << (left_open() ? "(" : "[")
+         << to_printable(unwrap_capture(low_)) << " .. "
+         << to_printable(unwrap_capture(high_)) << (right_open() ? ")" : "]");
       return ss.str();
     }
   private:

include/mettle/suite/factory.hpp

@@ -45,7 +45,7 @@ namespace mettle {
     private:
       template<typename T, std::size_t ...I>
       T make_impl(std::index_sequence<I...>) const {
-        return T(std::get<I>(args_).value...);
+        return T(detail::unwrap_capture(std::get<I>(args_))...);
       }
 
       tuple_type args_;

test/test_any_capture.cpp

@@ -6,57 +6,60 @@ using namespace mettle;
 void func() {}
 
 suite<> test_capture("any_capture", [](auto &_) {
+  using detail::any_capture;
+  using detail::unwrap_capture;
+
   _.test("capture int", []() {
-    detail::any_capture<int> capture1(1);
-    expect(capture1.value, equal_to(1));
+    any_capture<int> capture1(1);
+    expect(unwrap_capture(capture1), equal_to(1));
 
     int i = 2;
-    detail::any_capture<int> capture2(i);
-    expect(capture2.value, equal_to(i));
+    any_capture<int> capture2(i);
+    expect(unwrap_capture(capture2), equal_to(i));
   });
 
   _.test("capture std::string", []() {
-    detail::any_capture<std::string> capture1("foo");
-    expect(capture1.value, equal_to("foo"));
+    any_capture<std::string> capture1("foo");
+    expect(unwrap_capture(capture1), equal_to("foo"));
 
     std::string s = "bar";
-    detail::any_capture<std::string> capture2(s);
-    expect(capture2.value, equal_to(s));
+    any_capture<std::string> capture2(s);
+    expect(unwrap_capture(capture2), equal_to(s));
   });
 
   _.test("capture char[]", []() {
     char s[] = "foo";
-    detail::any_capture<char[4]> capture(s);
-    expect(capture.value, equal_to(std::string("foo")));
+    any_capture<char[4]> capture(s);
+    expect(unwrap_capture(capture), equal_to(std::string("foo")));
   });
 
   _.test("capture function", []() {
-    detail::any_capture<void()> capture(func);
+    any_capture<void()> capture(func);
 
-    expect(capture.value, equal_to(func));
-    expect(capture.value, equal_to(&func));
+    expect(unwrap_capture(capture), equal_to(func));
+    expect(unwrap_capture(capture), equal_to(&func));
   });
 
   _.test("capture by copy", []() {
     copyable_type t;
-    detail::any_capture<copyable_type> capture(t);
+    any_capture<copyable_type> capture(t);
 
-    expect("number of copies", capture.value.copies, equal_to(1));
+    expect("number of copies", unwrap_capture(capture).copies, equal_to(1));
   });
 
   _.test("capture by move", []() {
     moveable_type t;
-    detail::any_capture<moveable_type> capture(std::move(t));
+    any_capture<moveable_type> capture(std::move(t));
 
-    expect("number of copies", capture.value.copies, equal_to(0));
-    expect("number of moves", capture.value.moves, equal_to(1));
+    expect("number of copies", unwrap_capture(capture).copies, equal_to(0));
+    expect("number of moves", unwrap_capture(capture).moves, equal_to(1));
   });
 
   _.test("capture array by copy", []() {
     copyable_type t[2];
-    detail::any_capture<copyable_type[2]> capture(t);
+    any_capture<copyable_type[2]> capture(t);
 
-    expect("number of copies", capture.value, each(
+    expect("number of copies", unwrap_capture(capture), each(
       filter([](auto &&x) { return x.copies; }, equal_to(1))
     ));
   });
@@ -68,12 +71,12 @@ suite<> test_capture("any_capture", [](auto &_) {
 
   _.test("capture array by move", move_arr_attrs, []() {
     moveable_type t[2];
-    detail::any_capture<moveable_type[2]> capture(std::move(t));
+    any_capture<moveable_type[2]> capture(std::move(t));
 
-    expect("number of copies", capture.value, each(
+    expect("number of copies", unwrap_capture(capture), each(
       filter([](auto &&x) { return x.copies; }, equal_to(0))
     ));
-    expect("number of moves", capture.value, each(
+    expect("number of moves", unwrap_capture(capture), each(
       filter([](auto &&x) { return x.moves; }, equal_to(1))
     ));
   });