From 98c8fd5d39ee645922f071b6433308a813245500 Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Wed, 24 Apr 2024 00:29:16 +0200
Subject: Add custom formatter & use it on Status

---
 deimos/core/format.h | 39 +++++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

(limited to 'deimos/core/format.h')

diff --git a/deimos/core/format.h b/deimos/core/format.h
index 3424dc2..ba1a3e2 100644
--- a/deimos/core/format.h
+++ b/deimos/core/format.h
@@ -7,6 +7,14 @@ namespace deimos
 
 class IWriter;
 
+struct CustomFormatter
+{
+    using Callback = void (*)(IWriter*, const void* payload);
+    
+    const void* payload;
+    Callback    callback;
+};
+
 struct FormatArg
 {
     enum Type : uint8_t
@@ -14,42 +22,57 @@ struct FormatArg
         kInteger,
         kUnsignedInteger,
         kString,
+        kCustom,
     };
 
     Type type;
 
     union
     {
-        int64_t     integer;
-        uint64_t    unsigned_integer;
-        StringView  string;
+        int64_t         integer;
+        uint64_t        unsigned_integer;
+        StringView      string;
+        CustomFormatter custom;
     };
 
-    explicit FormatArg(std::signed_integral auto value) :
+    constexpr explicit FormatArg(std::signed_integral auto value) :
         type{kInteger},
         integer{value}
     {}
 
-    explicit FormatArg(std::unsigned_integral auto value) :
+    constexpr explicit FormatArg(std::unsigned_integral auto value) :
         type{kUnsignedInteger},
         unsigned_integer{value}
     {}
 
-    explicit FormatArg(StringView value) :
+    constexpr explicit FormatArg(StringView value) :
         type{kString},
         string{value}
     {}
+
+    template<typename T>
+    constexpr explicit FormatArg(const T& payload, CustomFormatter::Callback callback) :
+        type{kCustom},
+        custom{CustomFormatter{&payload, callback}}
+    {}
 };
 
 template<typename T>
-concept Formattable = requires (T value) { FormatArg(value); };
+deimos::FormatArg DeimosMakeFormatArg(T&& value)
+    requires std::is_constructible_v<deimos::FormatArg, T>
+{
+    return deimos::FormatArg(value);
+}
+
+template<typename T>
+concept Formattable = std::same_as<deimos::FormatArg, decltype(DeimosMakeFormatArg(std::declval<T>()))>;
 
 void FormatVa(IWriter*, gsl::czstring fmt, Span<const FormatArg>);
 
 template<Formattable... Args>
 void Format(IWriter* writer, gsl::czstring fmt, Args&&... args)
 {
-    FormatVa(writer, fmt, { FormatArg(std::forward<Args>(args))... });
+    FormatVa(writer, fmt, { DeimosMakeFormatArg(std::forward<Args>(args))... });
 }
 
 } // namespace deimos
-- 
cgit