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LibTSM/Util/SmartMap.lua

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+-- ------------------------------------------------------------------------------ --
+--                                TradeSkillMaster                                --
+--                          https://tradeskillmaster.com                          --
+--    All Rights Reserved - Detailed license information included with addon.     --
+-- ------------------------------------------------------------------------------ --
+
+--- Smart Map.
+-- @module SmartMap
+
+local _, TSM = ...
+local SmartMap = TSM.Init("Util.SmartMap")
+local private = {
+	mapContext = {},
+	readerContext = {},
+}
+local VALID_FIELD_TYPES = {
+	string = true,
+	number = true,
+	boolean = true,
+}
+
+
+
+-- ============================================================================
+-- Metatable Methods
+-- ============================================================================
+
+local SMART_MAP_MT = {
+	-- getter
+	__index = function(self, key)
+		if key == nil then
+			error("Attempt to get nil key")
+		end
+		if key == "ValueChanged" then
+			return private.MapValueChanged
+		elseif key == "SetCallbacksPaused" then
+			return private.MapSetCallbacksPaused
+		elseif key == "CreateReader" then
+			return private.MapCreateReader
+		elseif key == "GetKeyType" then
+			return private.MapGetKeyType
+		elseif key == "GetValueType" then
+			return private.MapGetValueType
+		elseif key == "Iterator" then
+			return private.MapIterator
+		else
+			error("Invalid map method: "..tostring(key), 2)
+		end
+	end,
+
+	-- setter
+	__newindex = function(self, key, value)
+		error("Map cannot be written to directly", 2)
+	end,
+
+	__tostring = function(self)
+		return "SmartMap:"..strmatch(tostring(private.mapContext[self]), "table:[^0-9a-fA-F]*([0-9a-fA-F]+)")
+	end,
+
+	__metatable = false,
+}
+
+local READER_MT = {
+	-- getter
+	__index = function(self, key)
+		-- check if the map already has the value for this key cached
+		local readerContext = private.readerContext[self]
+		local map = readerContext.map
+		local mapContext = private.mapContext[map]
+		if mapContext.data[key] ~= nil then
+			return mapContext.data[key]
+		end
+
+		-- get the value for this key
+		local value = mapContext.func(key)
+		if value == nil then
+			error(format("No value for key (%s)", tostring(key)))
+		elseif type(value) ~= mapContext.valueType then
+			error(format("Invalid type of value (got %s, expected %s): %s", type(value), mapContext.valueType, tostring(value)))
+		end
+
+		-- cache the value both on the map and on this reader
+		mapContext.data[key] = value
+		rawset(self, key, value)
+
+		return value
+	end,
+
+	-- setter
+	__newindex = function(self, key, value)
+		error("Reader is read-only", 2)
+	end,
+
+	__tostring = function(self)
+		return "SmartMapReader:"..strmatch(tostring(private.readerContext[self]), "table:[^0-9a-fA-F]*([0-9a-fA-F]+)")
+	end,
+
+	__metatable = false,
+}
+
+
+
+-- ============================================================================
+-- Module Functions
+-- ============================================================================
+
+function SmartMap.New(keyType, valueType, callable)
+	assert(VALID_FIELD_TYPES[keyType] and VALID_FIELD_TYPES[valueType])
+	local map = setmetatable({}, SMART_MAP_MT)
+	private.mapContext[map] = {
+		keyType = keyType,
+		valueType = valueType,
+		func = callable,
+		data = {},
+		readers = {},
+		callbacksPaused = 0,
+		hasReaderCallback = false,
+	}
+	return map
+end
+
+
+
+-- ============================================================================
+-- Private Helper Functions
+-- ============================================================================
+
+function private.MapValueChanged(self, key)
+	local mapContext = private.mapContext[self]
+	local oldValue = mapContext.data[key]
+	if oldValue == nil then
+		-- nobody cares about this value
+		return
+	end
+
+	if not mapContext.hasReaderCallback then
+		-- no reader has registered a callback, so just clear the value
+		mapContext.data[key] = nil
+		for _, reader in ipairs(mapContext.readers) do
+			rawset(reader, key, nil)
+		end
+		return
+	end
+
+	-- get the new value
+	local newValue = mapContext.func(key)
+	if type(newValue) ~= mapContext.valueType then
+		error(format("Invalid type (got %s, expected %s)", type(newValue), mapContext.valueType))
+	end
+	if oldValue == newValue then
+		-- the value didn't change
+		return
+	end
+
+	-- update the data
+	mapContext.data[key] = newValue
+
+	for _, reader in ipairs(mapContext.readers) do
+		local readerContext = private.readerContext[reader]
+		local prevValue = rawget(reader, key)
+		if prevValue ~= nil then
+			rawset(reader, key, newValue)
+			if readerContext.callback then
+				readerContext.pendingChanges[key] = prevValue
+				if mapContext.callbacksPaused == 0 then
+					readerContext.callback(reader, readerContext.pendingChanges)
+					wipe(readerContext.pendingChanges)
+				end
+			end
+		end
+	end
+end
+
+function private.MapSetCallbacksPaused(self, paused)
+	local mapContext = private.mapContext[self]
+	if paused then
+		mapContext.callbacksPaused = mapContext.callbacksPaused + 1
+	else
+		mapContext.callbacksPaused = mapContext.callbacksPaused - 1
+		assert(mapContext.callbacksPaused >= 0)
+		if mapContext.callbacksPaused == 0 then
+			for _, reader in ipairs(mapContext.readers) do
+				local readerContext = private.readerContext[reader]
+				if readerContext.callback and next(readerContext.pendingChanges) then
+					readerContext.callback(reader, readerContext.pendingChanges)
+					wipe(readerContext.pendingChanges)
+				end
+			end
+		end
+	end
+end
+
+function private.MapCreateReader(self, callback)
+	assert(callback == nil or type(callback) == "function")
+	local reader = setmetatable({}, READER_MT)
+	local mapContext = private.mapContext[self]
+	tinsert(mapContext.readers, reader)
+	mapContext.hasReaderCallback = mapContext.hasReaderCallback or (callback and true or false)
+	private.readerContext[reader] = {
+		map = self,
+		callback = callback,
+		pendingChanges = {},
+	}
+	return reader
+end
+
+function private.MapGetKeyType(self)
+	return private.mapContext[self].keyType
+end
+
+function private.MapGetValueType(self)
+	return private.mapContext[self].valueType
+end
+
+function private.MapIterator(self)
+	return pairs(private.mapContext[self].data)
+end