msvc_sink.h

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// Copyright(c) 2016 Alexander Dalshov & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
 
#pragma once
 
#if defined(_WIN32)
 
#include <spdlog/details/null_mutex.h>
#if defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT)
#include <spdlog/details/os.h>
#endif
#include <spdlog/sinks/base_sink.h>
 
#include <mutex>
#include <string>
 
// Avoid including windows.h (https://stackoverflow.com/a/30741042)
#if defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT)
extern "C" __declspec(dllimport) void __stdcall OutputDebugStringW(const wchar_t* lpOutputString);
#else
extern "C" __declspec(dllimport) void __stdcall OutputDebugStringA(const char* lpOutputString);
#endif
extern "C" __declspec(dllimport) int __stdcall IsDebuggerPresent();
 
namespace spdlog
{
    namespace sinks
    {
        /*
         * MSVC sink (logging using OutputDebugStringA)
         */
        template <typename Mutex>
        class msvc_sink : public base_sink<Mutex>
        {
        public:
            msvc_sink() = default;
            msvc_sink(bool check_debugger_present)
                : check_debugger_present_{check_debugger_present} {};
 
        protected:
            void sink_it_(const details::log_msg& msg) override
            {
                if (check_debugger_present_ && !IsDebuggerPresent())
                {
                    return;
                }
                memory_buf_t formatted;
                base_sink<Mutex>::formatter_->format(msg, formatted);
                formatted.push_back('\0'); // add a null terminator for OutputDebugString
#if defined(SPDLOG_WCHAR_TO_UTF8_SUPPORT)
                wmemory_buf_t wformatted;
                details::os::utf8_to_wstrbuf(string_view_t(formatted.data(), formatted.size()), wformatted);
                OutputDebugStringW(wformatted.data());
#else
                OutputDebugStringA(formatted.data());
#endif
            }
 
            void flush_() override
            {
            }
 
            bool check_debugger_present_ = true;
        };
 
        using msvc_sink_mt = msvc_sink<std::mutex>;
        using msvc_sink_st = msvc_sink<details::null_mutex>;
 
        using windebug_sink_mt = msvc_sink_mt;
        using windebug_sink_st = msvc_sink_st;
 
    } // namespace sinks
} // namespace spdlog
 
#endif