except: add custom base exception

CMakeLists.txt

@@ -251,6 +251,8 @@ list (
     encode/base.hpp
     endian.cpp
     endian.hpp
+    except.cpp
+    except.hpp
     exe.hpp
     extent.cpp
     extent.hpp

except.cpp

@@ -0,0 +1,17 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2018 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "except.hpp"
+
+
+///////////////////////////////////////////////////////////////////////////////
+std::ostream&
+cruft::operator<< (std::ostream &os, const cruft::error &obj)
+{
+    return obj.describe (os);
+}

except.hpp

@@ -0,0 +1,22 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2018 Danny Robson <danny@nerdcruft.net>
+ */
+
+#pragma once
+
+#include <iosfwd>
+
+namespace cruft {
+    class error {
+    public:
+        virtual ~error () = default;
+        virtual std::ostream& describe (std::ostream&) const noexcept = 0;
+    };
+
+
+    std::ostream& operator<< (std::ostream &os, error const&);
+}