1 files changed, 84 insertions, 0 deletions
diff --git a/asl/format.hpp b/asl/format.hpp
new file mode 100644
index 0000000..6cffd3a
--- /dev/null
+++ b/asl/format.hpp
@@ -0,0 +1,84 @@
+#pragma once
+
+#include "asl/integers.hpp"
+#include "asl/meta.hpp"
+#include "asl/utility.hpp"
+
+namespace asl
+{
+
+// @Todo Move this to io
+class writer
+{
+public:
+    writer() = default;
+    ASL_DELETE_COPY_MOVE(writer);
+    virtual ~writer() = default;
+    
+    // @Todo Use string view, or span of bytes?
+    virtual void write(const char* str, int64_t len) = 0;
+};
+
+class formatter;
+
+template<typename T>
+concept formattable = requires (formatter& f, const T& value)
+{
+    AslFormat(f, value);
+};
+
+namespace format_internals
+{
+
+struct type_erased_arg
+{
+    const void* data;
+    void (*fn)(formatter&, const void*);
+
+    template<formattable T>
+    static constexpr void erased_fn(formatter& f, const void* data)
+    {
+        AslFormat(f, *reinterpret_cast<const T*>(data));
+    }
+
+    template<formattable T>
+    explicit constexpr type_erased_arg(const T& arg)
+        : data{&arg}
+        , fn{erased_fn<T>}
+    {}
+};
+
+// @Todo Use span
+void format(writer*, const char* fmt, const type_erased_arg* args, int64_t arg_count);
+
+} // internals
+
+class formatter
+{
+    writer* m_writer;
+
+public:
+    explicit constexpr formatter(writer* writer)
+        : m_writer{writer}
+    {}
+
+    // @Todo Use string_view
+    constexpr void write(const char* s, int64_t len)
+    {
+        m_writer->write(s, len);
+    }
+};
+
+// @Todo Use string_view
+template<typename... Args>
+void format(writer* w, const char* fmt, const Args&... args)
+{
+    auto type_erased_args[] = {
+        format_internals::type_erased_arg(args)...
+    };
+
+    // @Todo Use array extent
+    format_internals::format(w, fmt, type_erased_args, types_count<Args...>);
+}
+
+} // namespace asl