87 lines
2.1 KiB
Plaintext
87 lines
2.1 KiB
Plaintext
%
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% VM.mcrl2
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%
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% A Simple Vending Machine.
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%
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% Copyright (c) 2019-2019 HS Emden-Leer
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% All Rights Reserved.
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% @version 1.00 - 01 Apr 2019 - GJV - initial version
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%
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% -----------------------------------------------------------------------------------------------------------------------
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% Definition of the coins
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sort
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Coin = struct _5c | _10c | _20c | _50c | Euro;
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map
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value: Coin -> Int; % the value of a coin as an integer
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next: Coin -> Coin;
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eqn
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value(_5c) = 5;
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value(_10c) = 10;
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value(_20c) = 20;
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value(_50c) = 50;
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value(Euro) = 100;
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next(Euro) = _50c;
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next(_50c) = _20c;
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next(_20c) = _10c;
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next(_10c) = _5c;
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% -----------------------------------------------------------------------------------------------------------------------
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%
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% Definition of the products
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sort
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Product = struct tea | coffee | cake | apple;
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map
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price: Product -> Int; % the price of a product as an integer
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eqn
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price(tea) = 10;
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price(coffee) = 25;
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price(cake) = 60;
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price(apple) = 80;
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% -----------------------------------------------------------------------------------------------------------------------
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%
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% Definition of the actions
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act
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accept: Coin; % accept a coin inserted into the machine
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return: Coin; % returns change
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offer: Product; % offer the possibility to order a certain product
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serve: Product; % serve a certain product
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returnChange: Int; % request to return the current credit as change
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%
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% Definition of the processes
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proc
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VendingMachine = VM(0);
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VM(credit : Int) =
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(credit < 200) -> sum c : Coin.accept(c).VM(credit + value(c))
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+ sum p : Product.(
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(credit > 0) -> returnChange(credit).ReturnChange(credit + price(p))
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)
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+ (credit > 0) -> returnChange(credit).ReturnChange(credit);
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ReturnChange(credit : Int) =
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sum c : Coin.((credit >= value(c) && credit < next(c)) -> return(c).(
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((credit - value(c)) >0) -> ReturnChange(credit - value(c)) <> VM(credit - value(c))
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));
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% -----------------------------------------------------------------------------------------------------------------------
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init
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VendingMachine
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;
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