From f4675ed641157632cecbed8cd3ee82ed72594ffb Mon Sep 17 00:00:00 2001
From: Neargye <neargye@gmail.com>
Date: Tue, 7 Aug 2018 21:13:40 +0500
Subject: [PATCH] improve cstring

---
 example/example.cpp |  2 +-
 include/nameof.hpp  | 26 ++++++++++++--------------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/example/example.cpp b/example/example.cpp
index 79639b1..144b46d 100644
--- a/example/example.cpp
+++ b/example/example.cpp
@@ -86,7 +86,7 @@ int main() {
 #if (__cplusplus >= 201402L || (defined(_MSVC_LANG) && _MSC_VER >= 1910 && _MSVC_LANG >= 201402L))
   // Compile-time supported by C++14.
   constexpr auto constexpr_work_fine = NAMEOF(somevar);
-  static_assert(constexpr_work_fine == "somevar", "");
+  static_assert("somevar" == constexpr_work_fine, "");
 #endif
 
   // Enum name.
diff --git a/include/nameof.hpp b/include/nameof.hpp
index 1015390..dd80fbf 100644
--- a/include/nameof.hpp
+++ b/include/nameof.hpp
@@ -60,18 +60,26 @@ template <typename T>
 using Decay = std::remove_reference<typename std::remove_cv<typename remove_all_pointers<T>::type>::type>;
 
 inline constexpr bool StrEquals(const char* lhs, const char* rhs, std::size_t size) {
-  return size == 0 ? (lhs[0] == rhs[0]) : ((lhs[size - 1] == rhs[size - 1]) && StrEquals(lhs, rhs, size - 1));
+  return (size == 0) ? (lhs[0] == rhs[0]) : ((lhs[size - 1] == rhs[size - 1]) && StrEquals(lhs, rhs, size - 1));
 }
 
-// STD like compile-time string.
+inline constexpr std::size_t StrLen(const char* str, std::size_t size = 0) {
+  return (str == nullptr) ? 0 : ((str[size] == '\0') ? size : StrLen(str, size + 1));
+}
+
+// STD like compile-time const char* string.
 class cstring final {
   const char* str_;
   std::size_t size_;
 
  public:
-  constexpr cstring(const char* str, std::size_t size) noexcept : str_(str), size_(size) {}
+  constexpr cstring(const char* str, std::size_t length, std::size_t prefix = 0, std::size_t suffix = 0) noexcept
+      : str_{str + prefix},
+        size_(length - prefix - suffix) {}
 
-  cstring() noexcept : str_(nullptr), size_(0) {}
+  constexpr cstring() noexcept : cstring{nullptr, 0, 0, 0} {}
+
+  constexpr cstring(const char* str) noexcept : cstring{str, StrLen(str), 0, 0} {}
 
   cstring(const cstring&) = default;
 
@@ -125,16 +133,6 @@ class cstring final {
     return !(lhs == rhs);
   }
 
-  template <std::size_t N>
-  inline friend constexpr bool operator==(const cstring& lhs, const char(&str)[N]) noexcept {
-    return (lhs.size_ == N - 1) && StrEquals(lhs.begin(), str, lhs.size());
-  }
-
-  template <std::size_t N>
-  inline friend constexpr bool operator!=(const cstring& lhs, const char(&str)[N]) noexcept {
-    return !(lhs == str);
-  }
-
   inline friend std::ostream& operator<<(std::ostream& os, const cstring& str) {
     os.write(str.begin(), str.size());
     return os;