initial commit

src/mods/Events.lua

@@ -0,0 +1,35 @@
+local Events = {}
+Events.__index = Events
+
+function Events.new()
+  return setmetatable({ listeners = {}, sealed = false }, Events)
+end
+
+function Events:on(name, callback, priority)
+  assert(not self.sealed, "mod events are sealed")
+  assert(type(name) == "string" and name ~= "", "event name is required")
+  assert(type(callback) == "function", "event callback must be a function")
+  local list = self.listeners[name] or {}
+  self.listeners[name] = list
+  local entry = { callback = callback, priority = priority or 0 }
+  list[#list + 1] = entry
+  table.sort(list, function(a, b) return a.priority > b.priority end)
+  return function()
+    for i, candidate in ipairs(list) do
+      if candidate == entry then table.remove(list, i) break end
+    end
+  end
+end
+
+function Events:emit(name, payload)
+  local list = self.listeners[name] or {}
+  for _, entry in ipairs(list) do
+    entry.callback(payload)
+  end
+end
+
+function Events:seal()
+  self.sealed = true
+end
+
+return Events