C++17ification.

C++17ification!

- Filesystem interaction now uses std::filesystem::path.
- Usage of const char*, std::string have been changed to
  std::string_view where appropriate.
- Usage of printf-style functions changed to use fmt.

src/xenia/base/string_key.h

@@ -0,0 +1,103 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2020 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_BASE_STRING_KEY_H_
+#define XENIA_BASE_STRING_KEY_H_
+
+#include <string>
+#include <variant>
+
+#include "utf8.h"
+
+namespace xe {
+
+namespace internal {
+
+struct string_key_base {
+ private:
+  std::variant<std::string, std::string_view> value_;
+
+ public:
+  explicit string_key_base(const std::string_view value) : value_(value) {}
+  explicit string_key_base(std::string value) : value_(std::move(value)) {}
+
+  std::string_view view() const {
+    return std::holds_alternative<std::string>(value_)
+               ? std::get<std::string>(value_)
+               : std::get<std::string_view>(value_);
+  }
+};
+
+}  // namespace internal
+
+struct string_key : internal::string_key_base {
+ public:
+  explicit string_key(const std::string_view value) : string_key_base(value) {}
+  explicit string_key(std::string value) : string_key_base(value) {}
+
+  static string_key create(const std::string_view value) {
+    return string_key(std::string(value));
+  }
+
+  static string_key create(std::string value) { return string_key(value); }
+
+  bool operator==(const string_key& other) const {
+    return other.view() == view();
+  }
+
+  size_t hash() const { return utf8::hash_fnv1a(view()); }
+
+  struct Hash {
+    size_t operator()(const string_key& t) const { return t.hash(); }
+  };
+};
+
+struct string_key_case : internal::string_key_base {
+ public:
+  explicit string_key_case(const std::string_view value)
+      : string_key_base(value) {}
+  explicit string_key_case(std::string value) : string_key_base(value) {}
+
+  static string_key_case create(const std::string_view value) {
+    return string_key_case(std::string(value));
+  }
+
+  static string_key_case create(std::string value) {
+    return string_key_case(value);
+  }
+
+  bool operator==(const string_key_case& other) const {
+    return utf8::equal_case(other.view(), view());
+  }
+
+  size_t hash() const { return utf8::hash_fnv1a_case(view()); }
+
+  struct Hash {
+    size_t operator()(const string_key_case& t) const { return t.hash(); }
+  };
+};
+
+}  // namespace xe
+
+namespace std {
+template <>
+struct std::hash<xe::string_key> {
+  std::size_t operator()(const xe::string_key& t) const { return t.hash(); }
+};
+
+template <>
+struct std::hash<xe::string_key_case> {
+  std::size_t operator()(const xe::string_key_case& t) const {
+    return t.hash();
+  }
+};
+
+};  // namespace std
+
+#endif  // XENIA_BASE_STRING_KEY_H_