Add C++20 module

.gitignore

@@ -1,3 +1,5 @@
+build/
+.xmake
 tests/test_main
 tests/*.o
 *.*~

.stylua.toml

@@ -0,0 +1 @@
+indent_type = "Spaces"

examples/enum_to_string.cpp

@@ -1,5 +1,3 @@
-#include <cstdio> // for std::puts
-
 /* ELF Relocations */
 
 #define ELF_RELOC(name, value) name = value,
@@ -57,12 +55,21 @@ ELF_RELOC(R_386_NUM,            43)
 
 #ifndef SWITCH_VERSION
 
-#ifdef FROZEN_VERSION
-#include "frozen/map.h"
+#ifdef FROZEN_STD_MODULE
+import std;
 #else
+#include <cstdio>
 #include <map>
 #endif
 
+#ifdef FROZEN_VERSION
+#ifdef FROZEN_MODULE
+import frozen;
+#else
+#include "frozen/map.h"
+#endif
+#endif
+
 #ifdef FROZEN_VERSION
 constexpr
 frozen::map<RELOC_i386, const char*, 41>

examples/enum_to_string_hash.cpp

@@ -1,5 +1,3 @@
-#include <cstdio> // for std::puts
-
 /* ELF Relocations */
 
 #define ELF_RELOC(name, value) name = value,
@@ -55,14 +53,26 @@ ELF_RELOC(R_386_IRELATIVE,      42)
 ELF_RELOC(R_386_NUM,            43)
 };
 
+#ifdef FROZEN_STD_MODULE
+import std;
+#else
+#include <cstdio>
+#include <unordered_map>
+#endif
+
 #ifdef FROZEN_VERSION
-#include "frozen/unordered_map.h"
+#include <frozen/bits/elsa.h> // this is not exported by the module
+
+#ifdef FROZEN_MODULE
+import frozen;
+#else 
+#include <frozen/unordered_map.h>
+#endif
+
 namespace frozen {
     template <> struct elsa<RELOC_i386> : elsa<int> {
     };
 }
-#else
-#include <unordered_map>
 #endif
 
 #ifdef FROZEN_VERSION

examples/html_entities_map.cpp

@@ -1,12 +1,21 @@
+#ifdef FROZEN_STD_MODULE
+import std;
+#else
+#include <cstdint>
+#include <utility>
+#endif
 
-#include <cinttypes>
+#ifdef FROZEN_MODULE
+import frozen;
+#else 
 #include <frozen/unordered_map.h>
 #include <frozen/string.h>
+#endif
 
 struct codes_t
 {
-	uint32_t iCodepoint1;
-	uint32_t iCodepoint2{0};
+  std::uint32_t iCodepoint1;
+  std::uint32_t iCodepoint2{0};
 };
 
 static constexpr std::pair<frozen::string, codes_t> s_Entities[]

examples/pixel_art.cpp

@@ -3,9 +3,18 @@ g++ $0 -std=c++14 -Iinclude && ./a.out && rm -f a.out && qiv panda.ppm 1up.ppm
 exit
 #else
 
+#ifdef FROZEN_STD_MODULE
+import std;
+#else
 #include <array>
-#include <frozen/map.h>
 #include <fstream>
+#endif
+
+#ifdef FROZEN_MODULE
+import frozen;
+#else 
+#include <frozen/map.h>
+#endif
 
 constexpr frozen::map<char, std::array<char, 3>, 5> Tans{
     {'R', {(char)0xFF, (char)0x00, (char)0x00}},

examples/static_assert.cpp

@@ -1,4 +1,8 @@
+#ifdef FROZEN_MODULE
+import frozen;
+#else 
 #include <frozen/set.h>
+#endif
 
 static constexpr frozen::set<unsigned, 3> supported_sizes = {
   1, 2, 4

examples/value_modification.cpp

@@ -1,7 +1,16 @@
+#ifdef FROZEN_STD_MODULE
+import std;
+#else
+#include <iostream>
+#endif
+
+#ifdef FROZEN_MODULE
+import frozen;
+#else 
 #include <frozen/set.h>
 #include <frozen/string.h>
 #include <frozen/unordered_map.h>
-#include <iostream>
+#endif
 
 /// MAYBE_CONSTINIT expands to `constinit` if available.
 #if __cpp_constinit
@@ -34,4 +43,4 @@ int main() {
   auto range = fruits.equal_range("n_apples");
   range.first->second = 1337;
   std::cout << "n_apples: " << fruits.at("n_apples") << std::endl;
-}
+}

include/frozen/algorithm.h

@@ -167,7 +167,7 @@ template <std::size_t size> class boyer_moore_searcher {
     if (size == 0)
       return { first, first };
 
-    if (size > size_t(last - first))
+    if (size > std::size_t(last - first))
       return { last, last };
 
     RandomAccessIterator iter = first + size - 1;

include/frozen/bits/algorithms.h

@@ -25,8 +25,10 @@
 
 #include "frozen/bits/basic_types.h"
 
+#ifndef FROZEN_STD_MODULE
 #include <limits>
 #include <tuple>
+#endif
 
 namespace frozen {
 

include/frozen/bits/basic_types.h

@@ -26,10 +26,12 @@
 #include "frozen/bits/exceptions.h"
 #include "frozen/bits/constexpr_assert.h"
 
+#ifndef FROZEN_STD_MODULE
 #include <array>
 #include <utility>
 #include <string>
 #include <type_traits>
+#endif
 
 namespace frozen {
 

include/frozen/bits/constexpr_assert.h

@@ -23,8 +23,10 @@
 #ifndef FROZEN_LETITGO_CONSTEXPR_ASSERT_H
 #define FROZEN_LETITGO_CONSTEXPR_ASSERT_H
 
+#ifndef FROZEN_STD_MODULE
 #include <cassert>
 #include <utility>
+#endif
 
 inline void constexpr_assert_failed() {}
 

include/frozen/bits/defines.h

@@ -29,13 +29,23 @@
 
 // Code taken from https://stackoverflow.com/questions/43639122/which-values-can-msvc-lang-have
 #if defined(FROZEN_LETITGO_IS_MSVC)
-  #if _MSVC_LANG > 201402
+  #if _MSVC_LANG > 201703L
+    #define FROZEN_LETITGO_HAS_CXX20  1
+  #else
+    #define FROZEN_LETITGO_HAS_CXX20  0
+  #endif
+  #if _MSVC_LANG > 201402L
     #define FROZEN_LETITGO_HAS_CXX17  1
   #else /* _MSVC_LANG > 201402 */
     #define FROZEN_LETITGO_HAS_CXX17  0
   #endif /* _MSVC_LANG > 201402 */
 #else /* _MSVC_LANG etc. */
-  #if __cplusplus > 201402
+  #if __cplusplus > 201703L
+    #define FROZEN_LETITGO_HAS_CXX20  1
+  #else /* __cplusplus > 201402 */
+    #define FROZEN_LETITGO_HAS_CXX20  0
+  #endif /* __cplusplus > 201402 */
+  #if __cplusplus > 201402L
     #define FROZEN_LETITGO_HAS_CXX17  1
   #else /* __cplusplus > 201402 */
     #define FROZEN_LETITGO_HAS_CXX17  0
@@ -51,6 +61,12 @@
   #endif
 #endif
 
+#if FROZEN_LETITGO_HAS_CXX20 && __has_include(<compare>)
+  #if defined(_cpp_lib_three_way_comparison) && __cpp_lib_three_way_comparison >= 201907
+    #define FROZEN_LETITGO_HAS_THREE_WAY_COMPARISON
+  #endif
+#endif
+
 #ifdef __cpp_char8_t
   #define FROZEN_LETITGO_HAS_CHAR8T
 #endif

include/frozen/bits/elsa.h

@@ -23,7 +23,9 @@
 #ifndef FROZEN_LETITGO_ELSA_H
 #define FROZEN_LETITGO_ELSA_H
 
+#ifndef FROZEN_STD_MODULE
 #include <type_traits>
+#endif
 
 namespace frozen {
 

include/frozen/bits/elsa_std.h

@@ -5,10 +5,12 @@
 #include "elsa.h"
 #include "hash_string.h"
 
+#ifndef FROZEN_STD_MODULE
 #ifdef FROZEN_LETITGO_HAS_STRING_VIEW
 #include <string_view>
 #endif
 #include <string>
+#endif 
 
 namespace frozen {
 

include/frozen/bits/exceptions.h

@@ -25,12 +25,16 @@
 
 #if defined(FROZEN_NO_EXCEPTIONS) || (defined(_MSC_VER) && !defined(_CPPUNWIND)) || (!defined(_MSC_VER) && !defined(__cpp_exceptions))
 
+#ifndef FROZEN_STD_MODULE
 #include <cstdlib>
+#endif
 #define FROZEN_THROW_OR_ABORT(_) std::abort()
 
 #else
 
+#ifndef FROZEN_STD_MODULE
 #include <stdexcept>
+#endif
 #define FROZEN_THROW_OR_ABORT(err) throw err
 
 

include/frozen/bits/hash_string.h

@@ -1,7 +1,9 @@
 #ifndef FROZEN_LETITGO_BITS_HASH_STRING_H
 #define FROZEN_LETITGO_BITS_HASH_STRING_H
 
+#ifndef FROZEN_STD_MODULE
 #include <cstddef>
+#endif
 
 namespace frozen {
 
@@ -25,4 +27,4 @@ constexpr std::size_t hash_string(const String& value, std::size_t seed) {
 
 } // namespace frozen
 
-#endif // FROZEN_LETITGO_BITS_HASH_STRING_H
+#endif // FROZEN_LETITGO_BITS_HASH_STRING_H

include/frozen/bits/mpl.h

@@ -23,7 +23,9 @@
 #ifndef FROZEN_LETITGO_BITS_MPL_H
 #define FROZEN_LETITGO_BITS_MPL_H
 
+#ifndef FROZEN_STD_MODULE
 #include <utility>
+#endif
 
 namespace frozen {
 

include/frozen/bits/pmh.h

@@ -27,10 +27,12 @@
 #include "frozen/bits/algorithms.h"
 #include "frozen/bits/basic_types.h"
 
+#ifndef FROZEN_STD_MODULE
 #include <array>
 #include <cstddef>
 #include <cstdint>
 #include <limits>
+#endif
 
 namespace frozen {
 

include/frozen/map.h

@@ -29,8 +29,10 @@
 #include "frozen/bits/mpl.h"
 #include "frozen/bits/version.h"
 
+#ifndef FROZEN_STD_MODULE
 #include <iterator>
 #include <utility>
+#endif
 
 namespace frozen {
 

include/frozen/random.h

@@ -26,8 +26,10 @@
 #include "frozen/bits/algorithms.h"
 #include "frozen/bits/version.h"
 
+#ifndef FROZEN_STD_MODULE
 #include <cstdint>
 #include <type_traits>
+#endif
 
 namespace frozen {
 template <class UIntType, UIntType a, UIntType c, UIntType m>

include/frozen/set.h

@@ -28,8 +28,10 @@
 #include "frozen/bits/version.h"
 #include "frozen/bits/defines.h"
 
+#ifndef FROZEN_STD_MODULE
 #include <iterator>
 #include <utility>
+#endif
 
 namespace frozen {