1 files changed, 85 insertions, 0 deletions
diff --git a/log.h b/log.h
new file mode 100644
index 0000000..cfc4d4c
--- /dev/null
+++ b/log.h
@@ -0,0 +1,85 @@
+#pragma once
+
+#include <iostream>
+#include <ostream>
+#include <sstream>
+#include <string>
+
+class log_stream
+{
+public:
+  log_stream(): m_active(false), m_buffer(), m_log_lines() {}
+
+  void log_lines(int n) {
+    m_log_lines = n;
+  }
+
+  std::string get_log() {
+    return m_buffer.str();
+  }
+
+  // log to buffer
+  void activate()
+  {
+    m_active = true;
+  }
+
+  // log to plain console
+  void deactivate()
+  {
+    m_active = false;
+  }
+
+  template<typename T>
+  log_stream& operator<<(const T& arg) {
+    if (m_active) {
+      m_buffer << arg;
+      trim_buffer();
+    }
+    else
+    {
+      std::cout << arg;
+    }
+    return *this;
+  }
+
+  log_stream& operator<<(
+    std::basic_ostream<char>& (*func)
+        (std::basic_ostream<char>&) ) {
+    if (m_active) {
+      m_buffer << *func;
+      trim_buffer();
+    }
+    else
+    {
+      std::cout << *func;
+    }
+    return *this;
+  }
+
+private:
+  void trim_buffer()
+  {
+    std::string s = m_buffer.str();
+    size_t pos = s.npos;
+    for (int i = 0; i <= m_log_lines; ++i) {
+      pos = s.rfind("\n", pos);
+      if (pos == s.npos) {
+        // too few lines
+        return;
+      }
+      if (pos > 0) {
+        --pos;
+      }
+    }
+
+    m_buffer.str(s.substr((pos <= (s.size() - 2)) ? pos + 2 : pos));
+  }
+
+  bool m_active;
+  std::stringstream m_buffer;
+  int m_log_lines;
+};
+
+extern log_stream log_cout;
+