1 files changed, 43 insertions, 0 deletions
diff --git a/.config/nvim/lua/leaf/calendar.lua b/.config/nvim/lua/leaf/calendar.lua
new file mode 100644
index 0000000..f998785
--- /dev/null
+++ b/.config/nvim/lua/leaf/calendar.lua
@@ -0,0 +1,43 @@
+local M = {}
+
+
+local floor = math.floor
+
+
+M.MON = 1
+M.TUE = 2
+M.WED = 3
+M.THU = 4
+M.FRI = 5
+M.SAT = 6
+M.SUN = 7
+
+
+function M.calc_week_of_day(y, m, d)
+   -- Zeller's congruence
+   if m == 1 or m == 2 then
+      m = m + 12
+      y = y - 1
+   end
+   local C = floor(y / 100)
+   local Y = y % 100
+   local G = 5*C + floor(C/4)
+   return 1 + (d + floor(26 * (m+1) / 10) + Y + floor(Y/4) + G + 5) % 7
+end
+
+
+function M.translate_week_of_day(w, locale)
+   -- assert(locale == 'ja_JP')
+   return ({
+      [M.MON] = '月',
+      [M.TUE] = '火',
+      [M.WED] = '水',
+      [M.THU] = '木',
+      [M.FRI] = '金',
+      [M.SAT] = '土',
+      [M.SUN] = '日',
+   })[w]
+end
+
+
+return M