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70 lines
2.1 KiB
Lua
70 lines
2.1 KiB
Lua
local Subject = require "rx.subjects.subject"
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local Observer = require "rx.observer"
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local util = require "rx.util"
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--- @class BehaviorSubject
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-- @description A Subject that tracks its current value. Provides an accessor to retrieve the most
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-- recent pushed value, and all subscribers immediately receive the latest value.
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local BehaviorSubject = setmetatable({}, Subject)
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BehaviorSubject.__index = BehaviorSubject
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BehaviorSubject.__tostring = util.constant("BehaviorSubject")
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--- Creates a new BehaviorSubject.
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-- @arg {*...} value - The initial values.
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-- @returns {BehaviorSubject}
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function BehaviorSubject.create(...)
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local self = {
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observers = {},
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stopped = false,
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}
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if select("#", ...) > 0 then
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self.value = util.pack(...)
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end
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return setmetatable(self, BehaviorSubject)
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end
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--- Creates a new Observer and attaches it to the BehaviorSubject. Immediately broadcasts the most
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-- recent value to the Observer.
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-- @arg {function} onNext - Called when the BehaviorSubject produces a value.
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-- @arg {function} onError - Called when the BehaviorSubject terminates due to an error.
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-- @arg {function} onCompleted - Called when the BehaviorSubject completes normally.
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function BehaviorSubject:subscribe(onNext, onError, onCompleted)
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local observer
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if util.isa(onNext, Observer) then
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observer = onNext
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else
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observer = Observer.create(onNext, onError, onCompleted)
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end
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local subscription = Subject.subscribe(self, observer)
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if self.value then
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observer:onNext(util.unpack(self.value))
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end
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return subscription
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end
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--- Pushes zero or more values to the BehaviorSubject. They will be broadcasted to all Observers.
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-- @arg {*...} values
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function BehaviorSubject:onNext(...)
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self.value = util.pack(...)
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return Subject.onNext(self, ...)
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end
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--- Returns the last value emitted by the BehaviorSubject, or the initial value passed to the
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-- constructor if nothing has been emitted yet.
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-- @returns {*...}
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function BehaviorSubject:getValue()
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if self.value ~= nil then
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return util.unpack(self.value)
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end
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end
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BehaviorSubject.__call = BehaviorSubject.onNext
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return BehaviorSubject
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