beholder.lua/beholder.lua
2012-03-04 23:56:41 +01:00

175 lines
4.7 KiB
Lua

-- beholder.lua - v2.1.0 (2011-11)
-- Copyright (c) 2011 Enrique García Cota
-- Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
-- The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN callback OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
local function copy(t)
local c={}
for i=1,#t do c[i]=t[i] end
return c
end
local function hash2array(t)
local arr, i = {}, 0
for _,v in pairs(t) do
i = i+1
arr[i] = v
end
return arr, i
end
-- private Node class
local nodesById = nil
local root = nil
local function newNode()
return { callbacks = {}, children = setmetatable({}, {__mode="k"}) }
end
local function findNodeById(id)
return nodesById[id]
end
local function findOrCreateChildNode(self, key)
self.children[key] = self.children[key] or newNode()
return self.children[key]
end
local function findOrCreateDescendantNode(self, keys)
local node = self
for i=1, #keys do
node = findOrCreateChildNode(node, keys[i])
end
return node
end
local function invokeNodeCallbacks(self, params)
-- copy the hash into an array, for safety (self-erasures)
local callbacks, count = hash2array(self.callbacks)
for i=1,#callbacks do
callbacks[i](unpack(params))
end
return count
end
local function invokeAllNodeCallbacksInSubTree(self, params)
local counter = invokeNodeCallbacks(self, params)
for _,child in pairs(self.children) do
counter = counter + invokeAllNodeCallbacksInSubTree(child, params)
end
return counter
end
local function invokeNodeCallbacksFromPath(self, path)
local node = self
local params = copy(path)
local counter = invokeNodeCallbacks(node, params)
for i=1, #path do
node = node.children[path[i]]
if not node then break end
table.remove(params, 1)
counter = counter + invokeNodeCallbacks(node, params)
end
return counter
end
local function addCallbackToNode(self, callback)
local id = {}
self.callbacks[id] = callback
nodesById[id] = self
return id
end
local function removeCallbackFromNode(self, id)
self.callbacks[id] = nil
nodesById[id] = nil
end
------ beholder table
local beholder = {}
-- beholder private functions/vars
local groups = nil
local currentGroupId = nil
local function addIdToCurrentGroup(id)
if currentGroupId then
groups[currentGroupId] = groups[currentGroupId] or {}
local group = groups[currentGroupId]
group[#group + 1] = id
end
return id
end
local function stopObservingGroup(group)
local count = #group
for i=1,count do
beholder.stopObserving(group[i])
end
return count
end
local function falseIfZero(n)
return n > 0 and n
end
local function extractEventAndCallbackFromParams(params)
assert(#params > 0, "beholder.observe requires at least one parameter - the callback. You usually want to use two, i.e.: beholder.observe('EVENT', callback)")
local callback = table.remove(params, #params)
return params, callback
end
------ Public interface
function beholder.observe(...)
local event, callback = extractEventAndCallbackFromParams({...})
local node = findOrCreateDescendantNode(root, event)
return addIdToCurrentGroup(addCallbackToNode(node, callback))
end
function beholder.stopObserving(id)
local node = findNodeById(id)
if node then removeCallbackFromNode(node, id) end
local group, count = groups[id], 0
if group then count = stopObservingGroup(group) end
return (node or count > 0) and true or false
end
function beholder.group(groupId, f)
assert(not currentGroupId, "beholder.group can not be nested!")
currentGroupId = groupId
f()
currentGroupId = nil
end
function beholder.trigger(...)
return falseIfZero( invokeNodeCallbacksFromPath(root, {...}) )
end
function beholder.triggerAll(...)
return falseIfZero( invokeAllNodeCallbacksInSubTree(root, {...}) )
end
function beholder.reset()
root = newNode()
nodesById = setmetatable({}, {__mode="k"})
groups = {}
currentGroupId = nil
end
beholder.reset()
return beholder