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LibTSM/Util/Future.lua

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+-- ------------------------------------------------------------------------------ --
+--                                TradeSkillMaster                                --
+--                          https://tradeskillmaster.com                          --
+--    All Rights Reserved - Detailed license information included with addon.     --
+-- ------------------------------------------------------------------------------ --
+
+--- Future Functions.
+-- @module Future
+
+local _, TSM = ...
+local Future = TSM.Init("Util.Future")
+local private = {
+	context = {},
+}
+
+
+
+-- ============================================================================
+-- Metatable
+-- ============================================================================
+
+local FUTURE_MT = {
+	__index = {
+		GetName = function(self)
+			local context = private.context[self]
+			return context.name
+		end,
+		SetScript = function(self, script, handler)
+			assert(type(handler) == "function")
+			local context = private.context[self]
+			if script == "OnDone" then
+				assert(context.state ~= "DONE")
+				assert(not context.onDone)
+				context.onDone = handler
+			elseif script == "OnCleanup" then
+				assert(not context.onCleanup)
+				context.onCleanup = handler
+			else
+				error("Unknown script: "..tostring(script))
+			end
+		end,
+		Start = function(self)
+			local context = private.context[self]
+			assert(context.state == "RESET")
+			context.state = "STARTED"
+		end,
+		Cancel = function(self)
+			local context = private.context[self]
+			assert(context.state ~= "RESET")
+			private.Reset(self)
+		end,
+		Done = function(self, value)
+			local context = private.context[self]
+			assert(context.state == "STARTED")
+			context.state = "DONE"
+			context.value = value
+			if context.onDone then
+				context.onDone(self)
+			end
+		end,
+		IsDone = function(self)
+			local context = private.context[self]
+			assert(context.state ~= "RESET")
+			return context.state == "DONE"
+		end,
+		GetValue = function(self)
+			local context = private.context[self]
+			assert(context.state == "DONE")
+			local value = context.value
+			private.Reset(self)
+			return value
+		end,
+	},
+	__newindex = function(self, key, value) error("Future cannot be modified") end,
+	__metatable = false,
+}
+
+
+
+-- ============================================================================
+-- Module Functions
+-- ============================================================================
+
+--- Create a new future.
+-- @tparam string name The name of the future for debugging purposes
+-- @treturn Future The future object
+function Future.New(name)
+	local future = setmetatable({}, FUTURE_MT)
+	private.context[future] = {
+		name = name,
+	}
+	private.Reset(future)
+	return future
+end
+
+
+
+-- ============================================================================
+-- Private Helper Functions
+-- ============================================================================
+
+function private.Reset(future)
+	local context = private.context[future]
+	context.state = "RESET"
+	context.value = nil
+	context.onDone = nil
+	if context.onCleanup then
+		context.onCleanup()
+	end
+end