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127 lines
3.3 KiB
Lua
127 lines
3.3 KiB
Lua
-- Copyright (c) 2021 Maksim Tuprikov <insality@gmail.com>. This code is licensed under MIT license
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--- Druid Event Module
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--
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-- The Event module provides a simple class for handling callbacks. It is used in many Druid components.
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--
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-- You can subscribe to an event using the `:subscribe` method and unsubscribe using the `:unsubscribe` method.
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-- @module DruidEvent
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-- @alias druid.event
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local class = require("druid.system.middleclass")
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local DruidEvent = class("druid.event")
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--- DruidEvent constructor
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-- @tparam DruidEvent self @{DruidEvent}
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-- @tparam function|nil initial_callback Subscribe the callback on new event, if callback exist
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-- @usage
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-- local Event = require("druid.event")
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-- ...
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-- local event = Event(initial_callback)
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function DruidEvent.initialize(self, initial_callback)
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self._callbacks = nil -- initialize later
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if initial_callback then
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self:subscribe(initial_callback)
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end
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end
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--- Subscribe callback on event
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-- @tparam DruidEvent self @{DruidEvent}
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-- @tparam function callback Callback itself
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-- @tparam any|nil context Additional context as first param to callback call, usually it's self
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-- @usage
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-- local function on_long_callback(self)
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-- print("Long click!")
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-- end
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-- ...
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-- local button = self.druid:new_button("button", callback)
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-- button.on_long_click:subscribe(on_long_callback, self)
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function DruidEvent.subscribe(self, callback, context)
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assert(type(self) == "table", "You should subscribe to event with : syntax")
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assert(type(callback) == "function", "Callback should be function")
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self._callbacks = self._callbacks or {}
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table.insert(self._callbacks, {
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callback = callback,
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context = context
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})
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return callback
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end
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--- Unsubscribe callback on event
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-- @tparam DruidEvent self @{DruidEvent}
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-- @tparam function callback Callback itself
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-- @tparam any|nil context Additional context as first param to callback call
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-- @usage
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-- local function on_long_callback(self)
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-- print("Long click!")
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-- end
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-- ...
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-- button.on_long_click:unsubscribe(on_long_callback, self)
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function DruidEvent.unsubscribe(self, callback, context)
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if not self._callbacks then
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return
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end
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for index, callback_info in ipairs(self._callbacks) do
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if callback_info.callback == callback and callback_info.context == context then
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table.remove(self._callbacks, index)
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return
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end
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end
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end
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--- Return true, if event have at lease one handler
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-- @tparam DruidEvent self @{DruidEvent}
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-- @treturn boolean True if event have handlers
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-- @usage
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-- local is_long_click_handler_exists = button.on_long_click:is_exist()
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function DruidEvent.is_exist(self)
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if not self._callbacks then
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return false
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end
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return #self._callbacks > 0
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end
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--- Clear the all event handlers
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-- @tparam DruidEvent self @{DruidEvent}
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-- @usage
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-- button.on_long_click:clear()
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function DruidEvent.clear(self)
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self._callbacks = nil
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end
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--- Trigger the event and call all subscribed callbacks
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-- @tparam DruidEvent self @{DruidEvent}
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-- @tparam any ... All event params
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-- @usage
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-- local Event = require("druid.event")
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-- ...
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-- local event = Event()
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-- event:trigger("Param1", "Param2")
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function DruidEvent.trigger(self, ...)
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if not self._callbacks then
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return false
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end
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for _, callback_info in ipairs(self._callbacks) do
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if callback_info.context then
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callback_info.callback(callback_info.context, ...)
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else
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callback_info.callback(...)
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end
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end
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end
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return DruidEvent
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