tests and changes for final_act

include/gsl.h

@@ -40,25 +40,97 @@ using std::shared_ptr;
 //
 
 // Final_act allows you to ensure something gets run at the end of a scope
-template <class F>
+template <typename F_t>
-class Final_act
+class Final_act_noexcept
 {
+  F_t f;
+  bool run;
+
 public:
-    explicit Final_act(F f) : f_(f) {}
+  explicit Final_act_noexcept(F_t f_) : f(f_), run(true) { }
 
-    Final_act(const Final_act&& other) : f_(other.f_) {}
+  ~Final_act_noexcept()
-    Final_act(const Final_act&) = delete;
+  {
-    Final_act& operator=(const Final_act&) = delete;
+    if (!run) return;
+    f();
+  }
 
-    ~Final_act() { f_(); }
+  Final_act_noexcept(const Final_act_noexcept& s) = delete;
+  Final_act_noexcept(Final_act_noexcept&& s)
+      : f(std::move(s.f)), run(s.run)
+  { s.run = false; }
 
-private:
+  Final_act_noexcept& operator=(const Final_act_noexcept& s) = delete;
-    F f_;
+
+  Final_act_noexcept& operator=(Final_act_noexcept&& s)
+  {
+    f = std::move(s.f);
+    run = s.run;
+    s.run = false;
+    return *this;
+  }
+
+  void release() { run = false; }
 };
 
+// Final_act allows you to ensure something gets run at the end of a scope
+template <typename F_t>
+class Final_act
+{
+  F_t f;
+  bool run;
+
+public:
+  explicit Final_act(F_t f_) : f(f_), run(true) { }
+
+  ~Final_act()
+  {
+    if (!run)
+      return;
+
+    try { f(); }
+    catch (...) { }
+  }
+
+  Final_act(const Final_act& s) = delete;
+
+  Final_act(Final_act&& s) : f(std::move(s.f)), run(s.run)
+  {
+    s.run = false;
+  }
+
+  Final_act& operator=(const Final_act& s) = delete;
+
+  Final_act& operator=(Final_act&& s)
+  {
+    f = std::move(s.f);
+    run = s.run;
+    s.run = false;
+    return *this;
+  }
+
+  void release() { run = false; }
+};
+
+template <bool b, typename T, typename U>
+struct if_type_else_type { };
+
+template <typename T, typename U>
+struct if_type_else_type<true, T, U> { typedef T type; };
+
+template <typename T, typename U>
+struct if_type_else_type<false, T, U> { typedef U type; };
+
+template <bool b, typename T, typename U>
+using if_type_else_type_t = typename if_type_else_type<b, T, U>::type;
+
 // finally() - convenience function to generate a Final_act
-template <class F>
+template <typename F_t, typename Final_act_t = if_type_else_type_t<
-Final_act<F> finally(F f) { return Final_act<F>(f); }
+                            noexcept(std::declval<F_t&>()()),
+                            Final_act_noexcept<F_t>, Final_act<F_t>>>
+auto finally(F_t f) {
+  return Final_act_t(std::move(f));
+}
 
 // narrow_cast(): a searchable way to do narrowing casts of values
 template<class T, class U>

tests/CMakeLists.txt

@@ -87,6 +87,20 @@ add_test(
     COMMAND bounds_tests
 )
 
+add_executable(final_act_tests
+    final_act_tests.cpp    
+)
+target_link_libraries(final_act_tests
+    UnitTest++
+)
+install(TARGETS final_act_tests
+    RUNTIME DESTINATION bin
+)
+add_test(
+    NAME final_act_tests
+    COMMAND final_act_tests
+)
+
 add_executable(maybenull_tests
     maybenull_tests.cpp
 )

tests/final_act_tests.cpp

@@ -0,0 +1,70 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <UnitTest++/UnitTest++.h>
+#include <gsl.h>
+#include <exception>
+
+using namespace std;
+using namespace Guide;
+
+struct Increment {
+  int* i_;
+
+  Increment(int& i) : i_(&i) {}
+
+  void operator()() const noexcept { ++*i_; }
+};
+
+struct ThrowOnInvocation {
+  class Exception : public exception {};
+  void operator()() const { throw Exception(); }
+};
+
+SUITE(finallyTests) {
+  TEST(SingleInvocationOnConvenienceConstruction) {
+    int i = 0;
+    { auto f = finally(Increment(i)); }
+    CHECK(i == 1);
+  }
+
+  TEST(SingleInvocationOnMoveConstruction) {
+    int i = 0;
+    {
+      auto f = Final_act<Increment>(Increment(i));
+      auto ff(move(f));
+    }
+    CHECK(i == 1);
+  }
+
+  TEST(NoexceptFinalActIsCreated) {
+    int i = 0;
+    auto f = finally(Increment(i));
+    CHECK((is_same<decltype(f), Final_act_noexcept<Increment>>::value));
+  }
+
+  TEST(FinalActDoesNotThrow) {
+    bool exceptionCaught = false;
+    try {
+      finally(ThrowOnInvocation());
+    } catch (...) {
+      exceptionCaught = true;
+    }
+    CHECK(!exceptionCaught);
+  }
+}
+
+int main(int, const char* []) { return UnitTest::RunAllTests(); }