Add C++ module support

Author: mikomikotaishi

CMakeLists.txt

@@ -67,6 +67,7 @@ cpr_option(CPR_FORCE_DARWINSSL_BACKEND "Force to use the DarwinSSL backend. If C
 cpr_option(CPR_FORCE_MBEDTLS_BACKEND "Force to use the Mbed TLS backend. If CPR_FORCE_OPENSSL_BACKEND, CPR_FORCE_DARWINSSL_BACKEND, CPR_FORCE_MBEDTLS_BACKEND, and CPR_FORCE_WINSSL_BACKEND are set to to OFF, cpr will try to automatically detect the best available SSL backend (WinSSL - Windows, OpenSSL - Linux, DarwinSSL - Mac ...)." OFF)
 cpr_option(CPR_ENABLE_LINTING "Set to ON to enable clang linting." OFF)
 cpr_option(CPR_ENABLE_CPPCHECK "Set to ON to enable Cppcheck static analysis. Requires CPR_BUILD_TESTS and CPR_BUILD_TESTS_SSL to be OFF to prevent checking google tests source code." OFF)
+cpr_option(CPR_BUILD_MODULES "Set to ON to build cpr as a C++ module." OFF)
 cpr_option(CPR_BUILD_TESTS "Set to ON to build cpr tests." OFF)
 cpr_option(CPR_BUILD_TESTS_SSL "Set to ON to build cpr ssl tests" ${CPR_BUILD_TESTS})
 cpr_option(CPR_BUILD_TESTS_PROXY "Set to ON to build proxy tests. They fail in case there is no valid proxy server available in proxy_tests.cpp" OFF)
@@ -322,6 +323,10 @@ else()
     set(CURL_LIB CURL::libcurl)
 endif()
 
+if(CPR_BUILD_MODULES)
+    add_subdirectory(modules)
+endif()
+
 # GTest configuration
 if(CPR_BUILD_TESTS)
     if(CPR_USE_SYSTEM_GTEST)

README.md

@@ -221,6 +221,7 @@ The only explicit requirements are:
 
 * A `C++17` compatible compiler such as Clang or GCC. The minimum required version of GCC is unknown, so if anyone has trouble building this library with a specific version of GCC, do let us know.
 * In case you only have a `C++11` compatible compiler available, all versions below cpr 1.9.x are for you. The 1.10.0 release of cpr switches to `C++17` as a requirement.
+* If you would like to use cpr as a C++20 module, you must have CMake 3.28 enabled. Enable `CPR_BUILD_MODULES` to activate the feature.
 * If you would like to perform https requests `OpenSSL` and its development libraries are required.
 * If you do not use the built-in version of [curl](https://github.com/curl/curl) but instead use your systems version, make sure you use a version `>= 7.71.0`. Lower versions are not supported. This means you need Debian `>= 11` or Ubuntu `>= 22.04 LTS`.
 * [`The Meson Build System`](https://mesonbuild.com/) is required build PSL from source ([PSL support for curl](https://everything.curl.dev/build/deps.html#libpsl)). For more information take a look at the `CPR_CURL_USE_LIBPSL` and `CPR_USE_SYSTEM_LIB_PSL` CMake options.

include/cpr/accept_encoding.h

@@ -18,7 +18,7 @@ enum class AcceptEncodingMethods {
 };
 
 // NOLINTNEXTLINE(cert-err58-cpp)
-static const std::map<AcceptEncodingMethods, std::string> AcceptEncodingMethodsStringMap{{AcceptEncodingMethods::identity, "identity"}, {AcceptEncodingMethods::deflate, "deflate"}, {AcceptEncodingMethods::zlib, "zlib"}, {AcceptEncodingMethods::gzip, "gzip"}, {AcceptEncodingMethods::disabled, "disabled"}};
+inline const std::map<AcceptEncodingMethods, std::string> AcceptEncodingMethodsStringMap{{AcceptEncodingMethods::identity, "identity"}, {AcceptEncodingMethods::deflate, "deflate"}, {AcceptEncodingMethods::zlib, "zlib"}, {AcceptEncodingMethods::gzip, "gzip"}, {AcceptEncodingMethods::disabled, "disabled"}};
 
 class AcceptEncoding {
   public:

include/cpr/cookies.h

@@ -12,7 +12,7 @@ namespace cpr {
  * EXPIRES_STRING_SIZE is an explicitly static and const variable that could be only accessed within the same namespace and is immutable.
  * To be used for "std::array", the expression must have a constant value, so EXPIRES_STRING_SIZE must be a const value.
  **/
-static const std::size_t EXPIRES_STRING_SIZE = 100;
+inline const std::size_t EXPIRES_STRING_SIZE = 100;
 
 class Cookie {
   public:

include/cpr/cpr.h

@@ -10,7 +10,9 @@
 #include "cpr/connection_pool.h"
 #include "cpr/cookies.h"
 #include "cpr/cprtypes.h"
+#ifndef CPR_AS_MODULE
 #include "cpr/cprver.h"
+#endif
 #include "cpr/curl_container.h"
 #include "cpr/curlholder.h"
 #include "cpr/error.h"

include/cpr/status_codes.h

@@ -1,82 +1,81 @@
 #ifndef CPR_STATUS_CODES
 #define CPR_STATUS_CODES
-namespace cpr {
-namespace status {
+namespace cpr::status {
 // Information responses
-constexpr long HTTP_CONTINUE = 100;
-constexpr long HTTP_SWITCHING_PROTOCOL = 101;
-constexpr long HTTP_PROCESSING = 102;
-constexpr long HTTP_EARLY_HINTS = 103;
+inline constexpr long HTTP_CONTINUE = 100;
+inline constexpr long HTTP_SWITCHING_PROTOCOL = 101;
+inline constexpr long HTTP_PROCESSING = 102;
+inline constexpr long HTTP_EARLY_HINTS = 103;
 // Successful responses
-constexpr long HTTP_OK = 200;
-constexpr long HTTP_CREATED = 201;
-constexpr long HTTP_ACCEPTED = 202;
-constexpr long HTTP_NON_AUTHORITATIVE_INFORMATION = 203;
-constexpr long HTTP_NO_CONTENT = 204;
-constexpr long HTTP_RESET_CONTENT = 205;
-constexpr long HTTP_PARTIAL_CONTENT = 206;
-constexpr long HTTP_MULTI_STATUS = 207;
-constexpr long HTTP_ALREADY_REPORTED = 208;
-constexpr long HTTP_IM_USED = 226;
+inline constexpr long HTTP_OK = 200;
+inline constexpr long HTTP_CREATED = 201;
+inline constexpr long HTTP_ACCEPTED = 202;
+inline constexpr long HTTP_NON_AUTHORITATIVE_INFORMATION = 203;
+inline constexpr long HTTP_NO_CONTENT = 204;
+inline constexpr long HTTP_RESET_CONTENT = 205;
+inline constexpr long HTTP_PARTIAL_CONTENT = 206;
+inline constexpr long HTTP_MULTI_STATUS = 207;
+inline constexpr long HTTP_ALREADY_REPORTED = 208;
+inline constexpr long HTTP_IM_USED = 226;
 // Redirection messages
-constexpr long HTTP_MULTIPLE_CHOICE = 300;
-constexpr long HTTP_MOVED_PERMANENTLY = 301;
-constexpr long HTTP_FOUND = 302;
-constexpr long HTTP_SEE_OTHER = 303;
-constexpr long HTTP_NOT_MODIFIED = 304;
-constexpr long HTTP_USE_PROXY = 305;
-constexpr long HTTP_UNUSED = 306;
-constexpr long HTTP_TEMPORARY_REDIRECT = 307;
-constexpr long HTTP_PERMANENT_REDIRECT = 308;
+inline constexpr long HTTP_MULTIPLE_CHOICE = 300;
+inline constexpr long HTTP_MOVED_PERMANENTLY = 301;
+inline constexpr long HTTP_FOUND = 302;
+inline constexpr long HTTP_SEE_OTHER = 303;
+inline constexpr long HTTP_NOT_MODIFIED = 304;
+inline constexpr long HTTP_USE_PROXY = 305;
+inline constexpr long HTTP_UNUSED = 306;
+inline constexpr long HTTP_TEMPORARY_REDIRECT = 307;
+inline constexpr long HTTP_PERMANENT_REDIRECT = 308;
 // Client error responses
-constexpr long HTTP_BAD_REQUEST = 400;
-constexpr long HTTP_UNAUTHORIZED = 401;
-constexpr long HTTP_PAYMENT_REQUIRED = 402;
-constexpr long HTTP_FORBIDDEN = 403;
-constexpr long HTTP_NOT_FOUND = 404;
-constexpr long HTTP_METHOD_NOT_ALLOWED = 405;
-constexpr long HTTP_NOT_ACCEPTABLE = 406;
-constexpr long HTTP_PROXY_AUTHENTICATION_REQUIRED = 407;
-constexpr long HTTP_REQUEST_TIMEOUT = 408;
-constexpr long HTTP_CONFLICT = 409;
-constexpr long HTTP_GONE = 410;
-constexpr long HTTP_LENGTH_REQUIRED = 411;
-constexpr long HTTP_PRECONDITION_FAILED = 412;
-constexpr long HTTP_PAYLOAD_TOO_LARGE = 413;
-constexpr long HTTP_URI_TOO_LONG = 414;
-constexpr long HTTP_UNSUPPORTED_MEDIA_TYPE = 415;
-constexpr long HTTP_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
-constexpr long HTTP_EXPECTATION_FAILED = 417;
-constexpr long HTTP_IM_A_TEAPOT = 418;
-constexpr long HTTP_MISDIRECTED_REQUEST = 421;
-constexpr long HTTP_UNPROCESSABLE_ENTITY = 422;
-constexpr long HTTP_LOCKED = 423;
-constexpr long HTTP_FAILED_DEPENDENCY = 424;
-constexpr long HTTP_TOO_EARLY = 425;
-constexpr long HTTP_UPGRADE_REQUIRED = 426;
-constexpr long HTTP_PRECONDITION_REQUIRED = 428;
-constexpr long HTTP_TOO_MANY_REQUESTS = 429;
-constexpr long HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE = 431;
-constexpr long HTTP_UNAVAILABLE_FOR_LEGAL_REASONS = 451;
+inline constexpr long HTTP_BAD_REQUEST = 400;
+inline constexpr long HTTP_UNAUTHORIZED = 401;
+inline constexpr long HTTP_PAYMENT_REQUIRED = 402;
+inline constexpr long HTTP_FORBIDDEN = 403;
+inline constexpr long HTTP_NOT_FOUND = 404;
+inline constexpr long HTTP_METHOD_NOT_ALLOWED = 405;
+inline constexpr long HTTP_NOT_ACCEPTABLE = 406;
+inline constexpr long HTTP_PROXY_AUTHENTICATION_REQUIRED = 407;
+inline constexpr long HTTP_REQUEST_TIMEOUT = 408;
+inline constexpr long HTTP_CONFLICT = 409;
+inline constexpr long HTTP_GONE = 410;
+inline constexpr long HTTP_LENGTH_REQUIRED = 411;
+inline constexpr long HTTP_PRECONDITION_FAILED = 412;
+inline constexpr long HTTP_PAYLOAD_TOO_LARGE = 413;
+inline constexpr long HTTP_URI_TOO_LONG = 414;
+inline constexpr long HTTP_UNSUPPORTED_MEDIA_TYPE = 415;
+inline constexpr long HTTP_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
+inline constexpr long HTTP_EXPECTATION_FAILED = 417;
+inline constexpr long HTTP_IM_A_TEAPOT = 418;
+inline constexpr long HTTP_MISDIRECTED_REQUEST = 421;
+inline constexpr long HTTP_UNPROCESSABLE_ENTITY = 422;
+inline constexpr long HTTP_LOCKED = 423;
+inline constexpr long HTTP_FAILED_DEPENDENCY = 424;
+inline constexpr long HTTP_TOO_EARLY = 425;
+inline constexpr long HTTP_UPGRADE_REQUIRED = 426;
+inline constexpr long HTTP_PRECONDITION_REQUIRED = 428;
+inline constexpr long HTTP_TOO_MANY_REQUESTS = 429;
+inline constexpr long HTTP_REQUEST_HEADER_FIELDS_TOO_LARGE = 431;
+inline constexpr long HTTP_UNAVAILABLE_FOR_LEGAL_REASONS = 451;
 // Server response errors
-constexpr long HTTP_INTERNAL_SERVER_ERROR = 500;
-constexpr long HTTP_NOT_IMPLEMENTED = 501;
-constexpr long HTTP_BAD_GATEWAY = 502;
-constexpr long HTTP_SERVICE_UNAVAILABLE = 503;
-constexpr long HTTP_GATEWAY_TIMEOUT = 504;
-constexpr long HTTP_HTTP_VERSION_NOT_SUPPORTED = 505;
-constexpr long HTTP_VARIANT_ALSO_NEGOTIATES = 506;
-constexpr long HTTP_INSUFFICIENT_STORAGE = 507;
-constexpr long HTTP_LOOP_DETECTED = 508;
-constexpr long HTTP_NOT_EXTENDED = 510;
-constexpr long HTTP_NETWORK_AUTHENTICATION_REQUIRED = 511;
+inline constexpr long HTTP_INTERNAL_SERVER_ERROR = 500;
+inline constexpr long HTTP_NOT_IMPLEMENTED = 501;
+inline constexpr long HTTP_BAD_GATEWAY = 502;
+inline constexpr long HTTP_SERVICE_UNAVAILABLE = 503;
+inline constexpr long HTTP_GATEWAY_TIMEOUT = 504;
+inline constexpr long HTTP_HTTP_VERSION_NOT_SUPPORTED = 505;
+inline constexpr long HTTP_VARIANT_ALSO_NEGOTIATES = 506;
+inline constexpr long HTTP_INSUFFICIENT_STORAGE = 507;
+inline constexpr long HTTP_LOOP_DETECTED = 508;
+inline constexpr long HTTP_NOT_EXTENDED = 510;
+inline constexpr long HTTP_NETWORK_AUTHENTICATION_REQUIRED = 511;
 
-constexpr long INFO_CODE_OFFSET = 100;
-constexpr long SUCCESS_CODE_OFFSET = 200;
-constexpr long REDIRECT_CODE_OFFSET = 300;
-constexpr long CLIENT_ERROR_CODE_OFFSET = 400;
-constexpr long SERVER_ERROR_CODE_OFFSET = 500;
-constexpr long MISC_CODE_OFFSET = 600;
+inline constexpr long INFO_CODE_OFFSET = 100;
+inline constexpr long SUCCESS_CODE_OFFSET = 200;
+inline constexpr long REDIRECT_CODE_OFFSET = 300;
+inline constexpr long CLIENT_ERROR_CODE_OFFSET = 400;
+inline constexpr long SERVER_ERROR_CODE_OFFSET = 500;
+inline constexpr long MISC_CODE_OFFSET = 600;
 
 constexpr bool is_informational(const long code) {
     return (code >= INFO_CODE_OFFSET && code < SUCCESS_CODE_OFFSET);
@@ -93,7 +92,5 @@ constexpr bool is_client_error(const long code) {
 constexpr bool is_server_error(const long code) {
     return (code >= SERVER_ERROR_CODE_OFFSET && code < MISC_CODE_OFFSET);
 }
-
-} // namespace status
-} // namespace cpr
+} // namespace cpr::status
 #endif

include/cpr/threadpool.h

@@ -15,8 +15,8 @@
 
 #define CPR_DEFAULT_THREAD_POOL_MAX_THREAD_NUM std::thread::hardware_concurrency()
 
-constexpr size_t CPR_DEFAULT_THREAD_POOL_MIN_THREAD_NUM = 1;
-constexpr std::chrono::milliseconds CPR_DEFAULT_THREAD_POOL_MAX_IDLE_TIME{250};
+inline constexpr size_t CPR_DEFAULT_THREAD_POOL_MIN_THREAD_NUM = 1;
+inline constexpr std::chrono::milliseconds CPR_DEFAULT_THREAD_POOL_MAX_IDLE_TIME{250};
 
 namespace cpr {
 

include/cpr/timeout.h

@@ -18,6 +18,7 @@ class Timeout {
 
     // No way around since curl uses a long here.
     // NOLINTNEXTLINE(google-runtime-int)
+    [[nodiscard]]
     long Milliseconds() const;
 
     std::chrono::milliseconds ms;

include/cpr/unix_socket.h

@@ -10,6 +10,7 @@ class UnixSocket {
     // NOLINTNEXTLINE(google-explicit-constructor, hicpp-explicit-conversions)
     UnixSocket(std::string unix_socket) : unix_socket_(std::move(unix_socket)) {}
 
+    [[nodiscard]]
     const char* GetUnixSocketString() const noexcept;
 
   private:

modules/CMakeLists.txt

@@ -0,0 +1,27 @@
+cmake_minimum_required(VERSION 3.28)
+
+add_library(cpr_module)
+
+target_sources(cpr_module
+    PUBLIC
+        FILE_SET CXX_MODULES FILES
+            cpr.cppm
+)
+
+target_compile_features(cpr_module PUBLIC cxx_std_20)
+
+target_include_directories(cpr_module PUBLIC
+    $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
+    $<INSTALL_INTERFACE:include>
+)
+
+add_library(cpr::module ALIAS cpr_module)
+
+# Installation
+install(TARGETS cpr_module
+    EXPORT ${PROJECT_NAME}Targets
+    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+    FILE_SET CXX_MODULES DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/module
+)