nestlog: + terminal colors for entry/exit/code location

include/nestlog/code_location.hpp

@@ -0,0 +1,56 @@
+/* @file code_location.hpp */
+
+#pragma once
+
+#include "filename.hpp"
+#include "color.hpp"
+
+namespace xo {
+    /* Example:
+     *   os << code_location("/path/to/foo.cpp", 123)
+     * writes
+     *   foo.cpp:123
+     * on stream os
+     */
+
+    /* Tag to drive header-only expression */
+    template <typename Tag>
+    class code_location_impl {
+    public:
+        code_location_impl(std::string_view file,
+                           std::uint32_t line,
+                           color_encoding encoding = CE_Ansi,
+                           std::uint32_t color = 31 /*red*/)
+            : file_{file}, line_{line}, encoding_{encoding}, color_{color} {}
+
+        void print_code_location(std::ostream & os) const {
+            os << "["
+               << with_color(encoding_, color_, basename(file_))
+               << ":"
+               << line_
+               << "]";
+        } /*print_code_location*/
+
+    private:
+        /* __FILE__ */
+        std::string_view file_;
+        /* __LINE__ */
+        std::uint32_t line_ = 0;
+        /* color encoding for file,line */
+        color_encoding encoding_ = CE_Ansi;
+        /* color for file,line */
+        std::uint32_t color_ = 0;
+    }; /*code_location_impl*/
+
+    using code_location = code_location_impl<class code_location_impl_tag>;
+
+    inline std::ostream &
+    operator<<(std::ostream & os,
+               code_location const & x)
+    {
+        x.print_code_location(os);
+        return os;
+    }
+} /*namespace xo*/
+
+/* end code_location.hpp */