Support for C++20/23 modules

.gitignore

@@ -21,6 +21,7 @@ bld/
 [Bb]in/
 [Oo]bj/
 [Ll]og/
+out/
 
 # Visual Studio 2015 cache/options directory
 .vs/

CMakeLists.txt

@@ -4,6 +4,8 @@ if(POLICY CMP0135) # DOWNLOAD_EXTRACT_TIMESTAMP
   cmake_policy(SET CMP0135 NEW)
 endif()
 
+set(CMAKE_EXPERIMENTAL_CXX_IMPORT_STD "d0edc3af-4c50-42ea-a356-e2862fe7a444")
+
 # HUNTER_ENABLED is always set if this package is included in a project using hunter (HunterGate sets it) In this case
 # we will use hunter as well to stay consistent. If not the use can supply it on configure to force using hunter.
 if(HUNTER_ENABLED)
@@ -20,6 +22,8 @@ option(JWT_BUILD_TESTS "Configure CMake to build tests (or not)" OFF)
 option(JWT_BUILD_DOCS "Adds a target for building the doxygen documentation" OFF)
 option(JWT_ENABLE_COVERAGE "Enable code coverage testing" OFF)
 option(JWT_ENABLE_FUZZING "Enable fuzz testing" OFF)
+option(JWT_ENABLE_MODULES "Build C++ modules" OFF)
+option(JWT_USE_IMPORT_STD "Use import std" OFF)
 
 option(JWT_DISABLE_PICOJSON "Do not provide the picojson template specialiaze" OFF)
 option(JWT_DISABLE_BASE64 "Do not include the base64 implementation from this library" OFF)
@@ -89,50 +93,94 @@ endif()
 
 set(JWT_INCLUDE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/include)
 set(JWT_HEADER_FILES ${JWT_INCLUDE_PATH}/jwt-cpp/jwt.h)
+set(JWT_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/modules)
 foreach(traits ${JWT_JSON_TRAITS_OPTIONS})
   list(APPEND JWT_HEADER_FILES ${JWT_INCLUDE_PATH}/jwt-cpp/traits/${traits}/defaults.h
        ${JWT_INCLUDE_PATH}/jwt-cpp/traits/${traits}/traits.h)
 endforeach()
 
 if(NOT JWT_DISABLE_BASE64)
-  list(APPEND JWT_HEADER_FILES ${JWT_INCLUDE_PATH}/jwt-cpp/base.h)
+    list(APPEND JWT_HEADER_FILES ${JWT_INCLUDE_PATH}/jwt-cpp/base.h)
 endif()
 
-add_library(jwt-cpp INTERFACE)
+if (JWT_ENABLE_MODULES)
+  add_library(jwt-cpp STATIC)
+  set(JWT_LIBRARY_TYPE PUBLIC)
+else()
+  add_library(jwt-cpp INTERFACE)
+  set(JWT_LIBRARY_TYPE INTERFACE)
+endif()
 add_library(jwt-cpp::jwt-cpp ALIAS jwt-cpp) # To match export
-target_compile_features(jwt-cpp INTERFACE cxx_std_11)
+
+if (JWT_ENABLE_MODULES)
+  if(CMAKE_VERSION VERSION_LESS "4.0")
+    message(FATAL_ERROR "CMake >= 4.0 is required to build with modules")
+  endif()
+
+  set(CMAKE_CXX_SCAN_FOR_MODULES ON)
+
+  if(JWT_USE_IMPORT_STD)
+    target_compile_features(jwt-cpp ${JWT_LIBRARY_TYPE} cxx_std_23)
+    if (NOT CMAKE_GENERATOR MATCHES "Visual Studio")
+       set(CMAKE_CXX_MODULE_STD 1)
+    endif()
+  else()
+    target_compile_features(jwt-cpp ${JWT_LIBRARY_TYPE} cxx_std_20)
+  endif()
+
+  target_sources(jwt-cpp
+    PUBLIC
+      FILE_SET cxx_modules TYPE CXX_MODULES
+        BASE_DIRS ${JWT_MODULE_PATH}
+        FILES ${JWT_MODULE_PATH}/jwt.ixx
+  )
+else()
+  target_compile_features(jwt-cpp ${JWT_LIBRARY_TYPE} cxx_std_11)
+endif()
+
+if (JWT_USE_IMPORT_STD)
+  target_compile_definitions(jwt-cpp ${JWT_LIBRARY_TYPE} JWT_USE_IMPORT_STD)
+endif()
+
 if(JWT_DISABLE_BASE64)
-  target_compile_definitions(jwt-cpp INTERFACE JWT_DISABLE_BASE64)
+  target_compile_definitions(jwt-cpp ${JWT_LIBRARY_TYPE} JWT_DISABLE_BASE64)
 endif()
 if(JWT_DISABLE_PICOJSON)
-  target_compile_definitions(jwt-cpp INTERFACE JWT_DISABLE_PICOJSON)
+  target_compile_definitions(jwt-cpp ${JWT_LIBRARY_TYPE} JWT_DISABLE_PICOJSON)
 endif()
 
+
+source_group( 
+  TREE "${JWT_INCLUDE_PATH}"
+  PREFIX "Implementation files"
+  FILES ${JWT_HEADER_FILES}
+)
+
 include(GNUInstallDirs)
 include(CMakePackageConfigHelpers)
-target_include_directories(jwt-cpp INTERFACE $<BUILD_INTERFACE:${JWT_INCLUDE_PATH}>
+target_include_directories(jwt-cpp ${JWT_LIBRARY_TYPE} $<BUILD_INTERFACE:${JWT_INCLUDE_PATH}>
                                              $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
 
 if(${JWT_SSL_LIBRARY} MATCHES "OpenSSL")
-  target_link_libraries(jwt-cpp INTERFACE OpenSSL::SSL OpenSSL::Crypto)
+  target_link_libraries(jwt-cpp ${JWT_LIBRARY_TYPE} OpenSSL::SSL OpenSSL::Crypto)
 endif()
 
 if(${JWT_SSL_LIBRARY} MATCHES "LibreSSL")
-  target_link_libraries(jwt-cpp INTERFACE LibreSSL::TLS)
+  target_link_libraries(jwt-cpp ${JWT_LIBRARY_TYPE} LibreSSL::TLS)
 endif()
 
 if(${JWT_SSL_LIBRARY} MATCHES "wolfSSL")
-  target_link_libraries(jwt-cpp INTERFACE PkgConfig::wolfssl)
+  target_link_libraries(jwt-cpp ${JWT_LIBRARY_TYPE} PkgConfig::wolfssl)
   # This is required to access OpenSSL compatibility API
-  target_include_directories(jwt-cpp INTERFACE ${wolfssl_INCLUDE_DIRS})
+  target_include_directories(jwt-cpp ${JWT_LIBRARY_TYPE} ${wolfssl_INCLUDE_DIRS})
   # This flag is required to have the mandatory header included automatically 
   # https://github.com/Thalhammer/jwt-cpp/pull/352#discussion_r1627971786
   # https://github.com/wolfSSL/wolfssl/blob/3b74a6402998a8b8839e25e31ba8ac74749aa9b0/wolfssl/wolfcrypt/settings.h#L58
-  target_compile_definitions(jwt-cpp INTERFACE EXTERNAL_OPTS_OPENVPN)
+  target_compile_definitions(jwt-cpp ${JWT_LIBRARY_TYPE} EXTERNAL_OPTS_OPENVPN)
 endif()
 
 if(NOT JWT_DISABLE_PICOJSON AND JWT_EXTERNAL_PICOJSON)
-  target_link_libraries(jwt-cpp INTERFACE picojson::picojson)
+  target_link_libraries(jwt-cpp ${JWT_LIBRARY_TYPE} picojson::picojson)
 endif()
 
 # Hunter needs relative paths so the files are placed correctly
@@ -143,18 +191,21 @@ endif()
 configure_package_config_file(
   ${CMAKE_CURRENT_LIST_DIR}/cmake/jwt-cpp-config.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/jwt-cpp-config.cmake
   INSTALL_DESTINATION ${JWT_CMAKE_FILES_INSTALL_DIR})
-write_basic_package_version_file(${CMAKE_CURRENT_BINARY_DIR}/jwt-cpp-config-version.cmake VERSION 0.7.1
-                                 COMPATIBILITY ExactVersion)
-
-install(TARGETS jwt-cpp EXPORT jwt-cpp-targets PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+write_basic_package_version_file(${CMAKE_CURRENT_BINARY_DIR}/jwt-cpp-config-version.cmake VERSION 0.7.1 COMPATIBILITY ExactVersion)
+if (JWT_ENABLE_MODULES)
+  install(TARGETS jwt-cpp EXPORT jwt-cpp-targets
+          PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+          FILE_SET cxx_modules DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/modules)
+else()
+  install(TARGETS jwt-cpp EXPORT jwt-cpp-targets
+          PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+endif()
 install(EXPORT jwt-cpp-targets NAMESPACE jwt-cpp:: FILE jwt-cpp-targets.cmake
         DESTINATION ${JWT_CMAKE_FILES_INSTALL_DIR})
 install(DIRECTORY ${JWT_INCLUDE_PATH}/jwt-cpp DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 if(NOT JWT_EXTERNAL_PICOJSON AND NOT JWT_DISABLE_PICOJSON)
   install(FILES ${JWT_INCLUDE_PATH}/picojson/picojson.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/picojson)
 endif()
-install(FILES ${CMAKE_CURRENT_BINARY_DIR}/jwt-cpp-config.cmake ${CMAKE_CURRENT_BINARY_DIR}/jwt-cpp-config-version.cmake
-        DESTINATION ${JWT_CMAKE_FILES_INSTALL_DIR})
 
 if(JWT_BUILD_EXAMPLES)
   add_subdirectory(example)
@@ -171,4 +222,4 @@ endif()
 
 if(JWT_BUILD_DOCS)
   add_subdirectory(docs)
-endif()
+endif()

example/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.15)
 project(jwt-cpp-examples)
 
 if(NOT TARGET jwt-cpp)
@@ -14,25 +14,43 @@ endif()
 add_executable(print-claims print-claims.cpp)
 target_link_libraries(print-claims jwt-cpp::jwt-cpp)
 add_custom_target(print-claims-run COMMAND print-claims)
+if (JWT_ENABLE_MODULES) 
+  target_compile_definitions(print-claims PRIVATE JWT_ENABLE_MODULES)
+endif()
 
 add_executable(private-claims private-claims.cpp)
 target_link_libraries(private-claims jwt-cpp::jwt-cpp)
 add_custom_target(private-claims-run COMMAND private-claims)
+if (JWT_ENABLE_MODULES) 
+  target_compile_definitions(private-claims PRIVATE JWT_ENABLE_MODULES)
+endif()
 
 add_executable(rsa-create rsa-create.cpp)
 target_link_libraries(rsa-create jwt-cpp::jwt-cpp)
 add_custom_target(rsa-create-run COMMAND rsa-create)
+if (JWT_ENABLE_MODULES) 
+  target_compile_definitions(rsa-create PRIVATE JWT_ENABLE_MODULES)
+endif()
 
 add_executable(rsa-verify rsa-verify.cpp)
 target_link_libraries(rsa-verify jwt-cpp::jwt-cpp)
 add_custom_target(rsa-verify-run COMMAND rsa-verify)
+if (JWT_ENABLE_MODULES) 
+  target_compile_definitions(rsa-verify PRIVATE JWT_ENABLE_MODULES)
+endif()
 
 add_executable(jwks-verify jwks-verify.cpp)
 target_link_libraries(jwks-verify jwt-cpp::jwt-cpp)
 add_custom_target(jwks-verify-run COMMAND jwks-verify)
+if (JWT_ENABLE_MODULES) 
+  target_compile_definitions(jwks-verify PRIVATE JWT_ENABLE_MODULES)
+endif()
 
 add_executable(es256k es256k.cpp)
 target_link_libraries(es256k jwt-cpp::jwt-cpp)
+if (JWT_ENABLE_MODULES) 
+  target_compile_definitions(es256k PRIVATE JWT_ENABLE_MODULES)
+endif()
 
 add_executable(partial-claim-verifier partial-claim-verifier.cpp)
 target_link_libraries(partial-claim-verifier jwt-cpp::jwt-cpp nlohmann_json::nlohmann_json)

example/es256k.cpp

@@ -1,6 +1,12 @@
 /// @file es256k.cpp
 #include <iostream>
+#include <chrono>
+
+#ifndef JWT_ENABLE_MODULES
 #include <jwt-cpp/jwt.h>
+#else
+import jwt_cpp;
+#endif
 
 int main() {
 	// openssl ecparam -name secp256k1 -genkey -noout -out ec-secp256k1-priv-key.pem

example/jwks-verify.cpp

@@ -5,7 +5,13 @@
  * and using the corresponding x5c from the JWK to verify the token
  */
 #include <iostream>
+#include <chrono>
+
+#ifndef JWT_ENABLE_MODULES
 #include <jwt-cpp/jwt.h>
+#else
+import jwt_cpp;
+#endif
 #include <openssl/rand.h>
 
 int main() {

example/print-claims.cpp

@@ -1,6 +1,11 @@
 /// @file print-claims.cpp
 #include <iostream>
+
+#ifndef JWT_ENABLE_MODULES
 #include <jwt-cpp/jwt.h>
+#else
+import jwt_cpp;
+#endif
 
 int main() {
 	const std::string token =

example/private-claims.cpp

@@ -1,8 +1,13 @@
 /// @file private-claims.cpp
-#include <jwt-cpp/jwt.h>
-
 #include <iostream>
 #include <sstream>
+#include <chrono>
+
+#ifndef JWT_ENABLE_MODULES
+#include <jwt-cpp/jwt.h>
+#else
+import jwt_cpp;
+#endif
 
 using sec = std::chrono::seconds;
 using min = std::chrono::minutes;

example/rsa-create.cpp

@@ -1,6 +1,12 @@
 /// @file rsa-create.cpp
 #include <iostream>
+#include <chrono>
+
+#ifndef JWT_ENABLE_MODULES
 #include <jwt-cpp/jwt.h>
+#else
+import jwt_cpp;
+#endif
 
 int main() {
 	std::string const rsa_priv_key = R"(-----BEGIN PRIVATE KEY-----

example/rsa-verify.cpp

@@ -1,6 +1,12 @@
 /// \file rsa-verify.cpp
 #include <iostream>
+#include <chrono>
+
+#ifndef JWT_ENABLE_MODULES
 #include <jwt-cpp/jwt.h>
+#else
+import jwt_cpp;
+#endif
 
 int main() {
 	const std::string rsa_pub_key = R"(-----BEGIN PUBLIC KEY-----

include/jwt-cpp/base.h

@@ -1,12 +1,16 @@
 #ifndef JWT_CPP_BASE_H
 #define JWT_CPP_BASE_H
 
+#ifdef JWT_USE_IMPORT_STD
+import std;
+#else
 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <stdexcept>
 #include <string>
 #include <vector>
+#endif
 
 #ifdef __has_cpp_attribute
 #if __has_cpp_attribute(fallthrough)

include/jwt-cpp/jwt.h

@@ -21,6 +21,9 @@
 #include <openssl/rsa.h>
 #include <openssl/ssl.h>
 
+#ifdef JWT_USE_IMPORT_STD
+import std;
+#else
 #include <algorithm>
 #include <chrono>
 #include <climits>
@@ -45,6 +48,8 @@
 #endif
 #endif
 
+#endif
+
 #if OPENSSL_VERSION_NUMBER >= 0x30000000L // 3.0.0
 #define JWT_OPENSSL_3_0
 #include <openssl/param_build.h>