nvim-cmp/lua/cmp/utils/event.lua

---@class cmp.Event
---@field private events table<string, function[]>
local event = {}

---Create vents
event.new = function()
  local self = setmetatable({}, { __index = event })
  self.events = {}
  return self
end

---Add event listener
---@param name string
---@param callback function
---@return function
event.on = function(self, name, callback)
  if not self.events[name] then
    self.events[name] = {}
  end
  table.insert(self.events[name], callback)
  return function()
    self:off(name, callback)
  end
end

---Remove event listener
---@param name string
---@param callback function
event.off = function(self, name, callback)
  for i, callback_ in ipairs(self.events[name] or {}) do
    if callback_ == callback then
      table.remove(self.events[name], i)
      break
    end
  end
end

---Remove all events
event.clear = function(self)
  self.events = {}
end

---Emit event
---@param name string
event.emit = function(self, name, ...)
  for _, callback in ipairs(self.events[name] or {}) do
    callback(...)
  end
end

return event