adapters.coffee
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# The default `.` adapter thats comes with Rivets.js. Allows subscribing to
# properties on POJSOs, implemented in ES5 natives using
# `Object.defineProperty`.
Rivets.adapters['.'] =
id: '_rv'
counter: 0
weakmap: {}
weakReference: (obj) ->
unless obj[@id]?
id = @counter++
@weakmap[id] =
callbacks: {}
Object.defineProperty obj, @id, value: id
@weakmap[obj[@id]]
stubFunction: (obj, fn) ->
original = obj[fn]
map = @weakReference obj
weakmap = @weakmap
obj[fn] = ->
response = original.apply obj, arguments
for r, k of map.pointers
callback() for callback in weakmap[r]?.callbacks[k] ? []
response
observeMutations: (obj, ref, keypath) ->
if Array.isArray obj
map = @weakReference obj
unless map.pointers?
map.pointers = {}
functions = ['push', 'pop', 'shift', 'unshift', 'sort', 'reverse', 'splice']
@stubFunction obj, fn for fn in functions
map.pointers[ref] ?= []
unless keypath in map.pointers[ref]
map.pointers[ref].push keypath
unobserveMutations: (obj, ref, keypath) ->
if Array.isArray obj and obj[@id]?
if keypaths = @weakReference(obj).pointers?[ref]
keypaths.splice keypaths.indexOf(keypath), 1
subscribe: (obj, keypath, callback) ->
callbacks = @weakReference(obj).callbacks
unless callbacks[keypath]?
callbacks[keypath] = []
value = obj[keypath]
Object.defineProperty obj, keypath,
get: -> value
set: (newValue) =>
if newValue isnt value
value = newValue
callback() for callback in callbacks[keypath]
@observeMutations newValue, obj[@id], keypath
unless callback in callbacks[keypath]
callbacks[keypath].push callback
@observeMutations obj[keypath], obj[@id], keypath
unsubscribe: (obj, keypath, callback) ->
callbacks = @weakmap[obj[@id]].callbacks[keypath]
callbacks.splice callbacks.indexOf(callback), 1
@unobserveMutations obj[keypath], obj[@id], keypath
read: (obj, keypath) ->
obj[keypath]
publish: (obj, keypath, value) ->
obj[keypath] = value