From a60021403a35802d3e0a404ffea969f1492f91b2 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Thu, 10 Nov 2022 13:08:28 +0100
Subject: add a working fmtlib operator""_cf()

---
 compat/format.hpp | 22 ++++++++++++++++++++++
 editor/imgui.cpp  |  8 ++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/compat/format.hpp b/compat/format.hpp
index d3b06521..0ebb3e18 100644
--- a/compat/format.hpp
+++ b/compat/format.hpp
@@ -2,8 +2,30 @@
 #include <fmt/core.h>
 #include <fmt/compile.h>
 
+namespace floormat::detail::fmt {
+
+template<std::size_t N>
+struct fmt_string final {
+    static constexpr std::size_t size = N;
+    char data[N];
+
+    template <std::size_t... Is>
+    consteval fmt_string(const char (&arr)[N]) noexcept {
+        for (std::size_t i = 0; i < N; i++)
+            data[i] = arr[i];
+    }
+};
+
+} // namespace floormat::detail::fmt
+
 namespace floormat {
 
+template<detail::fmt::fmt_string s>
+consteval auto operator""_cf() noexcept
+{
+    return FMT_COMPILE(s.data);
+}
+
 template<std::size_t N, typename Fmt, typename... Xs>
 std::size_t snformat(char(&buf)[N], Fmt&& fmt, Xs&&... args)
 {
diff --git a/editor/imgui.cpp b/editor/imgui.cpp
index b29c4f6c..df1f07b3 100644
--- a/editor/imgui.cpp
+++ b/editor/imgui.cpp
@@ -107,7 +107,7 @@ static void draw_editor_pane_atlas(tile_editor& ed, StringView name, const std::
             ImGui::SameLine();
             text(" (selected)");
         }
-        const auto len = snformat(buf, FMT_COMPILE("{:d}"), N);
+        const auto len = snformat(buf, "{:d}"_cf, N);
         ImGui::SameLine(window_width - ImGui::CalcTextSize(buf).x - style.FramePadding.x - 4);
         text(buf, len);
     };
@@ -134,7 +134,7 @@ static void draw_editor_pane_atlas(tile_editor& ed, StringView name, const std::
                 perm_selected ? push_style_color(ImGuiCol_ButtonHovered, color_perm_selected) : raii_wrapper{},
             };
 
-            snformat(buf, FMT_COMPILE("##item_{}"), i);
+            snformat(buf, "##item_{}"_cf, i);
             const auto uv = atlas->texcoords_for_id(i);
             constexpr ImVec2 size_2 = { TILE_SIZE[0]*.5f, TILE_SIZE[1]*.5f };
             ImGui::ImageButton(buf, (void*)&atlas->texture(), size_2,
@@ -193,7 +193,7 @@ void app::draw_fps()
     const auto frame_time = M->smoothed_dt();
     char buf[16];
     const double hz = frame_time > 1e-6f ? (int)std::round(10./(double)frame_time + .05) * .1 : 9999;
-    snformat(buf, FMT_COMPILE("{:.1f} FPS"), hz);
+    snformat(buf, "{:.1f} FPS"_cf, hz);
     const ImVec2 size = ImGui::CalcTextSize(buf);
     ImDrawList& draw = *ImGui::GetForegroundDrawList();
     draw.AddText({M->window_size()[0] - size.x - 4, 3}, ImGui::ColorConvertFloat4ToU32({0, 1, 0, 1}), buf);
@@ -208,7 +208,7 @@ void app::draw_tile_under_cursor()
     const auto coord = *cursor.tile;
     const auto chunk = coord.chunk();
     const auto local = coord.local();
-    snformat(buf, FMT_COMPILE("{}:{} - {}:{}"), chunk.x, chunk.y, local.x, local.y);
+    snformat(buf, "{}:{} - {}:{}"_cf, chunk.x, chunk.y, local.x, local.y);
     const auto size = ImGui::CalcTextSize(buf);
     const auto window_size = M->window_size();
 
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