automatic console output logging facility

Author: cherubrock-seb

include/core/Version.hpp

@@ -4,7 +4,7 @@
 #include <string>
 
 namespace core {
-    const std::string PRMERS_VERSION = "4.15.58-alpha";
+    const std::string PRMERS_VERSION = "4.15.59-alpha";
 } // namespace core
 
 #endif // VERSION_HPP

src/main.cpp

@@ -20,7 +20,60 @@
  * This code is released as free software. 
  */
 #include "core/App.hpp"
+#include <fstream>
+#include <streambuf>
+#include <iostream>
+#include <string>
+
+class TeeBuf : public std::streambuf {
+    std::streambuf* a_;
+    std::streambuf* b_;
+public:
+    TeeBuf(std::streambuf* a, std::streambuf* b) : a_(a), b_(b) {}
+protected:
+    int overflow(int ch) override {
+        if (ch == EOF) return !EOF;
+        const int r1 = a_ ? a_->sputc(ch) : ch;
+        const int r2 = b_ ? b_->sputc(ch) : ch;
+        return (r1 == EOF || r2 == EOF) ? EOF : ch;
+    }
+    int sync() override {
+        const int s1 = a_ ? a_->pubsync() : 0;
+        const int s2 = b_ ? b_->pubsync() : 0;
+        return (s1 == 0 && s2 == 0) ? 0 : -1;
+    }
+};
+
+struct LogTee {
+    std::ofstream file;
+    std::streambuf *oldCout = nullptr, *oldCerr = nullptr, *oldClog = nullptr;
+    TeeBuf *teeCout = nullptr, *teeCerr = nullptr, *teeClog = nullptr;
+
+    explicit LogTee(const std::string& path) : file(path, std::ios::app) {
+        if (!file) return;
+        oldCout = std::cout.rdbuf();
+        oldCerr = std::cerr.rdbuf();
+        oldClog = std::clog.rdbuf();
+        teeCout = new TeeBuf(oldCout, file.rdbuf());
+        teeCerr = new TeeBuf(oldCerr, file.rdbuf());
+        teeClog = new TeeBuf(oldClog, file.rdbuf());
+        std::cout.rdbuf(teeCout);
+        std::cerr.rdbuf(teeCerr);
+        std::clog.rdbuf(teeClog);
+        std::cout.setf(std::ios::unitbuf);
+        std::cerr.setf(std::ios::unitbuf);
+        std::clog.setf(std::ios::unitbuf);
+    }
+
+    ~LogTee() {
+        if (teeCout) { std::cout.rdbuf(oldCout); delete teeCout; }
+        if (teeCerr) { std::cerr.rdbuf(oldCerr); delete teeCerr; }
+        if (teeClog) { std::clog.rdbuf(oldClog); delete teeClog; }
+        if (file) file.flush();
+    }
+};
 
 int main(int argc, char** argv) {
+    LogTee _tee("prmers.log");
     return core::App(argc, argv).run();
 }