feat(cpp11): add 16-generalized-unions sample code (#39)

Author: MaoApoot

dslings/cpp11/16-generalized-unions-0.cpp

@@ -0,0 +1,48 @@
+// d2mcpp: https://github.com/mcpp-community/d2mcpp
+// license: Apache-2.0
+// file: dslings/cpp11/16-generalized-unions-0.cpp
+//
+// Exercise/练习: cpp11 | 16 - generalized unions | 广义非平凡联合体
+//
+// Tips/提示:
+// - 允许初始化一个成员变量
+//
+// Docs/文档:
+//   - https://cppreference.com/w/cpp/language/union.html
+//   - https://github.com/mcpp-community/d2mcpp/blob/main/book/src/cpp11/16-generalized-unions.md
+//
+// 练习交流讨论: http://forum.d2learn.org/category/20
+//
+// Auto-Checker/自动检测命令:
+//
+//   d2x checker generalized-unions
+//
+
+#include <d2x/cpp/common.hpp>
+
+
+union M
+{
+    int a1 = D2X_YOUR_ANSWER;
+    int a2 = 21;    // 移除多余的初始化
+    D2X_YOUR_ANSWER a3;
+    char c;
+};
+
+
+int main() {
+
+    M u1;
+    //初始化成员
+    d2x_assert(u1.a1 == 42);
+    u1.a2 = 21;
+
+    double val = 3.14;
+    u1.a3 = val;
+
+    u1.c = 'x';
+
+    D2X_WAIT
+
+    return 0;
+}

dslings/cpp11/16-generalized-unions-1.cpp

@@ -0,0 +1,54 @@
+// d2mcpp: https://github.com/mcpp-community/d2mcpp
+// license: Apache-2.0
+// file: dslings/cpp11/16-generalized-unions-1.cpp
+//
+// Exercise/练习: cpp11 | 16 - generalized unions | 广义非平凡联合体
+//
+// Tips/提示:
+// - 允许联合体包含非平凡类型(非 POD)
+//
+// Docs/文档:
+//   - https://cppreference.com/w/cpp/language/union.html
+//   - https://github.com/mcpp-community/d2mcpp/blob/main/book/src/cpp11/16-generalized-unions.md
+//
+// 练习交流讨论: http://forum.d2learn.org/category/20
+//
+// Auto-Checker/自动检测命令:
+//
+//   d2x checker generalized-unions
+//
+
+#include <d2x/cpp/common.hpp>
+#include <vector>
+
+union M
+{
+    int a1;
+    D2X_YOUR_ANSWER a2;
+    M() {}
+    M(const std::vector<int>& vec) : a2(vec) {
+    }
+    ~M() {}
+};
+
+
+int main() {
+
+    M u1;
+    u1.a1 = 21;
+
+    // 1. 使用placement new构造
+    new (&u1.a2) std::vector<int>();
+
+    u1.a2 = {1, D2X_YOUR_ANSWER, 3};
+
+    // 2. 验证：正常访问
+    d2x_assert_eq(u1.a2[1], 42);
+
+    // 3. 手动析构
+    u1.a2.~vector();
+
+    D2X_WAIT
+
+    return 0;
+}

dslings/cpp11/xmake.lua

@@ -169,6 +169,14 @@ target("cpp11-15-variadic-templates-0")
 target("cpp11-15-variadic-templates-1")
     add_files("15-variadic-templates-1.cpp")
 
+-- target: cpp11-16-generalized-unions
+
+target("cpp11-16-generalized-unions-0")
+    add_files("16-generalized-unions-0.cpp")
+
+target("cpp11-16-generalized-unions-1")
+    add_files("16-generalized-unions-1.cpp")
+
 -- target: cpp11-17-pod-type
 
 target("cpp11-17-pod-type-0")

dslings/en/cpp11/16-generalized-unions-0.cpp

@@ -0,0 +1,48 @@
+// d2mcpp: https://github.com/mcpp-community/d2mcpp
+// license: Apache-2.0
+// file: dslings/en/cpp11/16-generalized-unions-0.cpp
+//
+// Exercise: cpp11 | 16 - generalized unions | generalized (non-trivial) unions
+//
+// Tips:
+// - Allowing the initialization of a member variable
+//
+// Docs:
+//   - https://cppreference.com/w/cpp/language/union.html
+//   - https://github.com/mcpp-community/d2mcpp/blob/main/book/en/src/cpp11/16-generalized-unions.md
+//
+// Discussion Forum: http://forum.d2learn.org/category/20
+//
+// Auto-Checker:
+//
+//   d2x checker generalized-unions
+//
+
+#include <d2x/cpp/common.hpp>
+
+
+union M
+{
+    int a1 = D2X_YOUR_ANSWER;
+    int a2 = 21;    // Remove redundant initializations
+    D2X_YOUR_ANSWER a3;
+    char c;
+};
+
+
+int main() {
+
+    M u1;
+    //Initialize union members
+    d2x_assert(u1.a1 == 42);
+    u1.a2 = 21;
+
+    double val = 3.14;
+    u1.a3 = val;
+
+    u1.c = 'x';
+
+    D2X_WAIT
+
+    return 0;
+}

dslings/en/cpp11/16-generalized-unions-1.cpp

@@ -0,0 +1,54 @@
+// d2mcpp: https://github.com/mcpp-community/d2mcpp
+// license: Apache-2.0
+// file: dslings/en/cpp11/16-generalized-unions-1.cpp
+//
+// Exercise: cpp11 | 16 - generalized unions | generalized (non-trivial) unions
+//
+// Tips:
+// - Allow unions to contain non-trivial types(non-POD)
+//
+// Docs:
+//   - https://cppreference.com/w/cpp/language/union.html
+//   - https://github.com/mcpp-community/d2mcpp/blob/main/book/en/src/cpp11/16-generalized-unions.md
+//
+// Discussion Forum: http://forum.d2learn.org/category/20
+//
+// Auto-Checker:
+//
+//   d2x checker generalized-unions
+//
+
+#include <d2x/cpp/common.hpp>
+#include <vector>
+
+union M
+{
+    int a1;
+    D2X_YOUR_ANSWER a2;
+    M() {}
+    M(const std::vector<int>& vec) : a2(vec) {
+    }
+    ~M() {}
+};
+
+
+int main() {
+
+    M u1;
+    u1.a1 = 21;
+
+    // 1. Construct with placement new
+    new (&u1.a2) std::vector<int>();
+
+    u1.a2 = {1, D2X_YOUR_ANSWER, 3};
+
+    // 2. use assert to verify the contents
+    d2x_assert_eq(u1.a2[1], 42);
+
+    // 3. Manually call the destructor
+    u1.a2.~vector();
+
+    D2X_WAIT
+
+    return 0;
+}

dslings/en/cpp11/xmake.lua

@@ -160,6 +160,14 @@ target("cpp11-14-type-alias-2")
 target("cpp11-14-type-alias-3")
     add_files("14-type-alias-3.cpp")
 
+-- target: cpp11-16-generalized-unions
+
+target("cpp11-16-generalized-unions-0")
+    add_files("16-generalized-unions-0.cpp")
+
+target("cpp11-16-generalized-unions-1")
+    add_files("16-generalized-unions-1.cpp")
+
 -- target: cpp11-17-pod-type
 
 target("cpp11-17-pod-type-0")