Add enum class and nested enumeration example

sample/Enum-Class.cpp

@@ -0,0 +1,54 @@
+#include "matchit.h"
+#include <iostream>
+
+enum class OS_Type
+{
+  Linux,
+  BSD
+};
+
+enum class Arch_Type
+{
+  ARM64,
+  X8664
+};
+
+int
+get_sample_write_syscode_code(OS_Type os_type, Arch_Type arch_type)
+{
+  namespace m = matchit;
+
+  // Dependent enum case example:
+  return m::match(os_type)(
+    m::pattern | OS_Type::BSD =
+      [&] {
+        return m::match(arch_type)(m::pattern | Arch_Type::ARM64 = 1,
+                                   m::pattern | Arch_Type::X8664 = 4,
+                                   m::pattern | m::_ = 1);
+      },
+    m::pattern | OS_Type::Linux =
+      [&] {
+        return m::match(arch_type)(m::pattern | Arch_Type::ARM64 = 2,
+                                   m::pattern | Arch_Type::X8664 = 5,
+                                   m::pattern | m::_ = 1);
+      },
+    m::pattern | m::_ = 1);
+}
+
+int32_t
+main()
+{
+  // Independent enum case example:
+  auto independent_sample = m::match(os_type, arch_type)(
+    m::pattern | m::ds(OS_Type::Linux, Arch_Type::ARM64) = 2,
+    m::pattern | m::ds(OS_Type::Linux, Arch_Type::X8664) = 5,
+    m::pattern | m::ds(OS_Type::BSD, Arch_Type::X8664) = 4,
+    m::pattern | m::_ = 1);
+
+  std::cout << "independent write(3) enum case example: " << independent_sample
+            << std::endl;
+
+  std::cout << "dependent write(3) enum case example: "
+            << get_sample_write_syscode_code(OS_Type::Linux, Arch_Type::ARM64)
+            << std::endl;
+}