95 lines
2.6 KiB
CoffeeScript
95 lines
2.6 KiB
CoffeeScript
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#
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# An object that holds all applied operations.
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#
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# @note The HistoryBuffer is commonly abbreviated to HB.
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#
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class HistoryBuffer
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#
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# Creates an empty HB.
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# @param {Object} user_id Creator of the HB.
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#
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constructor: (@user_id)->
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@operation_counter = {}
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@buffer = {}
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@change_listeners = []
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#
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# Get the user id with wich the History Buffer was initialized.
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#
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getUserId: ()->
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@user_id
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#
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# There is only one reserved unique identifier (uid), so use it wisely.
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# I propose to use it in your Framework, to create something like a root element.
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# An operation with this identifier is not propagated to other clients.
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# This is why everybode must create the same operation with this uid.
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#
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getReservedUniqueIdentifier: ()->
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{
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creator : '_'
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op_number : '_'
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}
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#
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# Get the operation counter that describes the current state of the document.
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#
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getOperationCounter: ()->
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res = {}
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for user,ctn of @operation_counter
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res[user] = ctn
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res
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_encode: ()->
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json = []
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for u_name,user of @buffer
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for o_number,o of user
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if not isNaN(parseInt(o_number))
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json.push o._encode()
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json
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#
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# Get the number of operations that were created by a user.
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# Accordingly you will get the next operation number that is expected from that user.
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# This will increment the operation counter.
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#
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getNextOperationIdentifier: (user_id)->
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if not user_id?
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user_id = @user_id
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if not @operation_counter[user_id]?
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@operation_counter[user_id] = 0
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uid = {
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'creator' : user_id
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'op_number' : @operation_counter[user_id]
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}
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@operation_counter[user_id]++
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uid
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# Retrieve an operation from a unique id.
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getOperation: (uid)->
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if uid instanceof Object
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@buffer[uid.creator]?[uid.op_number]
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else if not uid?
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else
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throw new Error "This type of uid is not defined!"
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# Add an operation to the HB. Note that this will not link it against
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# other operations (it wont executed)
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addOperation: (o)->
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if not @buffer[o.creator]?
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@buffer[o.creator] = {}
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if not @operation_counter[o.creator]?
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@operation_counter[o.creator] = 0
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#if @operation_counter[o.creator] isnt o.op_number and typeof o.op_number is 'number'
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# throw new Error "You don't receive operations in the proper order. Try counting like this 0,1,2,3,4,.. ;)"
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if @buffer[o.creator][o.op_number]?
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throw new Error "You must not overwrite operations!"
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@buffer[o.creator][o.op_number] = o
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if typeof o.op_number is 'number' and o.creator isnt @getUserId()
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@operation_counter[o.creator]++
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o
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module.exports = HistoryBuffer
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