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64 lines
2.0 KiB
Lua

local Subject = require "rx.subjects.subject"
local Observer = require "rx.observer"
local util = require "rx.util"
--- @class ReplaySubject
-- @description A Subject that provides new Subscribers with some or all of the most recently
-- produced values upon subscription.
local ReplaySubject = setmetatable({}, Subject)
ReplaySubject.__index = ReplaySubject
ReplaySubject.__tostring = util.constant("ReplaySubject")
--- Creates a new ReplaySubject.
-- @arg {number=} bufferSize - The number of values to send to new subscribers. If nil, an infinite
-- buffer is used (note that this could lead to memory issues).
-- @returns {ReplaySubject}
function ReplaySubject.create(n)
local self = {
observers = {},
stopped = false,
buffer = {},
bufferSize = n,
}
return setmetatable(self, ReplaySubject)
end
--- Creates a new Observer and attaches it to the ReplaySubject. Immediately broadcasts the most
-- contents of the buffer to the Observer.
-- @arg {function} onNext - Called when the ReplaySubject produces a value.
-- @arg {function} onError - Called when the ReplaySubject terminates due to an error.
-- @arg {function} onCompleted - Called when the ReplaySubject completes normally.
function ReplaySubject:subscribe(onNext, onError, onCompleted)
local observer
if util.isa(onNext, Observer) then
observer = onNext
else
observer = Observer.create(onNext, onError, onCompleted)
end
local subscription = Subject.subscribe(self, observer)
for i = 1, #self.buffer do
observer:onNext(util.unpack(self.buffer[i]))
end
return subscription
end
--- Pushes zero or more values to the ReplaySubject. They will be broadcasted to all Observers.
-- @arg {*...} values
function ReplaySubject:onNext(...)
table.insert(self.buffer, util.pack(...))
if self.bufferSize and #self.buffer > self.bufferSize then
table.remove(self.buffer, 1)
end
return Subject.onNext(self, ...)
end
ReplaySubject.__call = ReplaySubject.onNext
return ReplaySubject