1 files changed, 80 insertions, 0 deletions
diff --git a/libbutl/diagnostics.cxx b/libbutl/diagnostics.cxx
new file mode 100644
index 0000000..e73412b
--- /dev/null
+++ b/libbutl/diagnostics.cxx
@@ -0,0 +1,80 @@
+// file      : libbutl/diagnostics.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <libbutl/diagnostics.hxx>
+
+#include <mutex>
+#include <iostream> // cerr
+
+using namespace std;
+
+namespace butl
+{
+  ostream* diag_stream = &cerr;
+
+  static mutex diag_mutex;
+
+  diag_lock::diag_lock ()
+  {
+    diag_mutex.lock ();
+  }
+
+  diag_lock::~diag_lock ()
+  {
+    diag_mutex.unlock ();
+  }
+
+  void diag_record::
+  flush () const
+  {
+    if (!empty_)
+    {
+      if (epilogue_ == nullptr)
+      {
+        os.put ('\n');
+
+        {
+          diag_lock l;
+          *diag_stream << os.str ();
+        }
+
+        // We can endup flushing the result of several writes. The last one may
+        // possibly be incomplete, but that's not a problem as it will also be
+        // followed by the flush() call.
+        //
+        diag_stream->flush ();
+
+        empty_ = true;
+      }
+      else
+      {
+        // Clear the epilogue in case it calls us back.
+        //
+        auto e (epilogue_);
+        epilogue_ = nullptr;
+        e (*this); // Can throw.
+        flush ();  // Call ourselves to write the data in case it returns.
+      }
+    }
+  }
+
+  diag_record::
+  ~diag_record () noexcept (false)
+  {
+    // Don't flush the record if this destructor was called as part of the
+    // stack unwinding.
+    //
+#ifdef __cpp_lib_uncaught_exceptions
+    if (uncaught_ == std::uncaught_exceptions ())
+      flush ();
+#else
+    // Fallback implementation. Right now this means we cannot use this
+    // mechanism in destructors, which is not a big deal, except for one
+    // place: exception_guard. Thus the ugly special check.
+    //
+    if (!std::uncaught_exception () || exception_unwinding_dtor ())
+      flush ();
+#endif
+  }
+}