1 files changed, 109 insertions, 0 deletions
diff --git a/asl/formatting/format.hpp b/asl/formatting/format.hpp
new file mode 100644
index 0000000..02f43eb
--- /dev/null
+++ b/asl/formatting/format.hpp
@@ -0,0 +1,109 @@
+#pragma once
+
+#include "asl/base/integers.hpp"
+#include "asl/base/meta.hpp"
+#include "asl/io/writer.hpp"
+#include "asl/types/span.hpp"
+#include "asl/strings/string_view.hpp"
+
+namespace asl
+{
+
+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>}
+    {}
+};
+
+void format(Writer*, string_view fmt, span<const type_erased_arg> args);
+
+} // namespace internals
+
+class Formatter
+{
+    Writer* m_writer;
+
+public:
+    explicit constexpr Formatter(Writer* writer)
+        : m_writer{writer}
+    {}
+
+    constexpr void write(string_view s)
+    {
+        m_writer->write(as_bytes(s.as_span()));
+    }
+
+    constexpr Writer* writer() const { return m_writer; }
+};
+
+template<formattable... Args>
+void format(Writer* w, string_view fmt, const Args&... args)
+{
+    if constexpr (types_count<Args...> > 0)
+    {
+        format_internals::type_erased_arg type_erased_args[] = {
+            format_internals::type_erased_arg(args)...
+        };
+
+        format_internals::format(w, fmt, type_erased_args);
+    }
+    else
+    {
+        format_internals::format(w, fmt, {});
+    }
+}
+
+template<isize_t N>
+void AslFormat(Formatter& f, const char (&str)[N])
+{
+    f.write(string_view(str, N - 1));
+}
+
+void AslFormat(Formatter& f, const char* str);
+
+inline void AslFormat(Formatter& f, string_view sv)
+{
+    f.write(sv);
+}
+
+void AslFormat(Formatter& f, float);
+void AslFormat(Formatter& f, double);
+
+void AslFormat(Formatter& f, bool);
+
+void AslFormat(Formatter& f, uint8_t);
+void AslFormat(Formatter& f, uint16_t);
+void AslFormat(Formatter& f, uint32_t);
+void AslFormat(Formatter& f, uint64_t);
+
+void AslFormat(Formatter& f, int8_t);
+void AslFormat(Formatter& f, int16_t);
+void AslFormat(Formatter& f, int32_t);
+void AslFormat(Formatter& f, int64_t);
+
+string_view format_uint64(uint64_t value, span<char, 20> buffer);
+
+} // namespace asl