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78 lines
3.3 KiB
OCaml
78 lines
3.3 KiB
OCaml
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(*
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copyright (c) 2013, simon cruanes
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all rights reserved.
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redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer. redistributions in binary
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form must reproduce the above copyright notice, this list of conditions and the
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following disclaimer in the documentation and/or other materials provided with
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the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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(** {1 Distributed Algorithms} *)
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type ('s, -'i, +'o) t = 's -> 'i -> 's * 'o list
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(** Transition function of an event automaton *)
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type ('s, 'i, 'o) instance
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(** Instance of an automaton, with a concrete state, and connections to other
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automaton instances. *)
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module EventQueue : sig
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type t
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(** Stateful value used to store the event (pending transitions) that remain
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* to process, using an in-memory queue and processing pending tasks until
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* none remains. A default global queue is provided, see {!default}. *)
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val default : t
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(** Default event queue *)
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val create : unit -> t
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end
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val instantiate : ?queue:EventQueue.t ->
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f:('s, 'i, 'o) t -> 's -> ('s, 'i, 'o) instance
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(** [instantiate ~f init] creates an instance of [f] with initial state
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[init]. The [queue] is used to process transitions of this automaton.
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@param queue event queue used to process transitions of the automaton
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upon calls to {!send}. Default value is {!EventQueue.default}. *)
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val transition : ('s, 'i, 'o) instance -> 'i -> ('s * 'o list)
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(** Compute the transition function for the given input *)
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val state : ('s, _, _) instance -> 's
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(** Current state of the automaton instance *)
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val on_transition : ('s, 'i, 'o) instance -> ('s -> 'i -> 's * 'o list -> bool) -> unit
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(** [on_state_change a k] calls [k] with the previous state, input,
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new state and ouputs of [a] every time [a] changes state.
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The callback [k] returns a boolean to signal whether it wants to continue
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being called ([true]) or stop being called ([false]). *)
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val connect : left:(_, _, 'a) instance -> right:(_, 'a, _) instance -> unit
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(** [connect ~left ~right] connects the ouput of [left] to the input of [right].
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Outputs of [left] will be fed to [right]. *)
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val send : (_, 'i, _) instance -> 'i -> unit
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(** [send a i] uses [a]'s transition function to update [a] with the input
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event [i]. The output of the transition function (a list of outputs) is
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recursively processed.
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This may not terminate, if the automata keep on creating new outputs that
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trigger other outputs forever. *)
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