From 1ff5900a6d197eed89edcceeff9396954ac34ef0 Mon Sep 17 00:00:00 2001
From: mutouyun <orz@orzz.org>
Date: Tue, 1 Mar 2022 10:59:30 +0800
Subject: [PATCH] =?UTF-8?q?=E8=B0=83=E6=95=B4ut=EF=BC=9B=E6=B7=BB=E5=8A=A0?=
 =?UTF-8?q?=E6=96=B0utility=E5=B0=8F=E5=B7=A5=E5=85=B7?=
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---
 src/libipc/utility/construct.h |  4 ++--
 src/libipc/utility/countof.h   | 34 ++++++++++++++++++++++++++++++++++
 src/libipc/utility/enum_cast.h | 20 ++++++++++++++++++++
 test/test_utility.cpp          | 17 ++++++++++-------
 4 files changed, 66 insertions(+), 9 deletions(-)
 create mode 100644 src/libipc/utility/countof.h
 create mode 100644 src/libipc/utility/enum_cast.h

diff --git a/src/libipc/utility/construct.h b/src/libipc/utility/construct.h
index 888cdbd..ad21ffd 100644
--- a/src/libipc/utility/construct.h
+++ b/src/libipc/utility/construct.h
@@ -45,7 +45,7 @@ auto construct(void *p, A &&... args)
 
 template <typename T>
 void *destroy(T *p) noexcept {
-#if defined(LIBIPC_CPP_17) && !defined(LIBIPC_CC_GNUC)
+#if defined(LIBIPC_CPP_17)
   std::destroy_at(p);
 #else
   p->~T();
@@ -57,7 +57,7 @@ template <typename T, std::size_t N>
 void *destroy(T (*p)[N]) noexcept {
 #if defined(LIBIPC_CPP_20)
   std::destroy_at(p);
-#elif defined(LIBIPC_CPP_17) && !defined(LIBIPC_CC_GNUC)
+#elif defined(LIBIPC_CPP_17)
   std::destroy(std::begin(*p), std::end(*p));
 #else
   for (auto &elem : *p) destroy(std::addressof(elem));
diff --git a/src/libipc/utility/countof.h b/src/libipc/utility/countof.h
new file mode 100644
index 0000000..0fa2dd8
--- /dev/null
+++ b/src/libipc/utility/countof.h
@@ -0,0 +1,34 @@
+/**
+ * @file src/countof.h
+ * @author mutouyun (orz@orzz.org)
+ * @brief Returns the size of the given range
+ * @date 2022-03-01
+ */
+#pragma once
+
+#include <cstddef>  // std::size_t
+
+#include "libipc/def.h"
+
+LIBIPC_NAMESPACE_BEG_
+
+/**
+ * @see https://en.cppreference.com/w/cpp/iterator/size
+*/
+
+template <typename T, std::size_t N>
+constexpr std::size_t countof(T const (&)[N]) noexcept {
+  return N;
+}
+
+template <typename C>
+constexpr auto countof(C const &c) -> decltype(c.size()) {
+  return c.size();
+}
+
+template <typename C>
+constexpr auto countof(C const &c) -> decltype(c.Size()) {
+  return c.Size();
+}
+
+LIBIPC_NAMESPACE_END_
diff --git a/src/libipc/utility/enum_cast.h b/src/libipc/utility/enum_cast.h
new file mode 100644
index 0000000..23fd65e
--- /dev/null
+++ b/src/libipc/utility/enum_cast.h
@@ -0,0 +1,20 @@
+/**
+ * @file src/enum_cast.h
+ * @author mutouyun (orz@orzz.org)
+ * @brief Returns the underlying type of the given enum
+ * @date 2022-03-01
+ */
+#pragma once
+
+#include <type_traits>  // std::underlying_type_t
+
+#include "libipc/def.h"
+
+LIBIPC_NAMESPACE_BEG_
+
+template <typename E>
+constexpr auto enum_cast(E e) noexcept {
+  return static_cast<std::underlying_type_t<E>>(e);
+}
+
+LIBIPC_NAMESPACE_END_
diff --git a/test/test_utility.cpp b/test/test_utility.cpp
index 8d3751e..d2c3dae 100644
--- a/test/test_utility.cpp
+++ b/test/test_utility.cpp
@@ -6,6 +6,7 @@
 
 #include "libipc/utility/construct.h"
 #include "libipc/utility/pimpl.h"
+#include "libipc/utility/countof.h"
 
 TEST(utility, construct) {
   struct Foo {
@@ -20,18 +21,22 @@ TEST(utility, construct) {
   EXPECT_EQ(pfoo->c_, '1');
   ipc::destroy(pfoo);
 
+  static int bar_test_flag = 0;
   struct Bar : Foo {
     Bar(int a, short b, char c)
-        : Foo{a, b, c} {}
-    ~Bar() { a_ = 0; }
+        : Foo{a, b, c} {
+      ++bar_test_flag;
+    }
+    ~Bar() { --bar_test_flag; }
   };
   std::aligned_storage_t<sizeof(Bar)> bar;
   Bar *pbar = ipc::construct<Bar>(&bar, 123, short(321), '1');
   EXPECT_EQ(pbar->a_, 123);
   EXPECT_EQ(pbar->b_, 321);
   EXPECT_EQ(pbar->c_, '1');
+  EXPECT_EQ(bar_test_flag, 1);
   ipc::destroy(pbar);
-  EXPECT_EQ(pbar->a_, 0);
+  EXPECT_EQ(bar_test_flag, 0);
 
   std::aligned_storage_t<sizeof(Bar)> bars[3];
   for (auto &b : bars) {
@@ -40,11 +45,9 @@ TEST(utility, construct) {
     EXPECT_EQ(pb->b_, 123);
     EXPECT_EQ(pb->c_, '3');
   }
+  EXPECT_EQ(bar_test_flag, ipc::countof(bars));
   ipc::destroy(reinterpret_cast<Bar(*)[3]>(&bars));
-  for (auto &b : bars) {
-    auto pb = reinterpret_cast<Bar *>(&b);
-    EXPECT_EQ(pb->a_, 0);
-  }
+  EXPECT_EQ(bar_test_flag, 0);
 }
 
 namespace {