本文系 Creating JVM language 翻译的第 20 篇。
原文中的代码和原文有不一致的地方均在新的代码仓库中更正过，建议参考新的代码仓库。

源码

Github

扑克牌洗牌模拟器

在之前的 19 篇博客中，我把实现编程语言的每一步都详细的记录下来了。如果不拿这门语言，练练手，做个东西玩，那就没什么意思了，对不？

我准备实现一个扑克牌的洗牌模拟器。思路是提供一定数量的玩家，指定每个玩家的扑克牌的数量。作为输出，每个玩家都能获得一定数量的随机扑克牌。

Card 类

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Card {

    string color
    string pattern

    Card(string cardColor,string cardPattern) {
        color = cardColor
        pattern = cardPattern
    }

    string getColor() {
        color
    }

    string getPattern() {
        pattern
    }

    string toString() {
        return "{" + color + "," + pattern + "}"
    }
}

没有黑科技，就是一个对象，并且是不可变的。

CardDrawer 类

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
CardDrawer {
    start {
        var cards = new List() //creates java.util.ArrayList 
        addNumberedCards(cards) //calling method with 3 arguments (last 2 are default)
        addCardWithAllColors("Ace",cards) 
        addCardWithAllColors("Queen",cards)
        addCardWithAllColors("King",cards)
        addCardWithAllColors("Jack",cards)
        //Calling with named arguments (and in differnet order)
        //The last parameter (cardsPerPlayer) is ommited (it's default value is 5)
        drawCardsForPlayers(playersAmount -> 5,cardsList -> cards) 
    }

    addNumberedCards(List cardsList,int first=2, int last=10) {
        for i from first to last {  //loop from first to last (inclusive)
            var numberString = new java.lang.Integer(i).toString()
            addCardWithAllColors(numberString,cardsList)
        }
    }

    addCardWithAllColors(string pattern,List cardsList) {
        cardsList.add(new Card("Clubs",pattern))
        cardsList.add(new Card("Diamonds",pattern))
        cardsList.add(new Card("Hearts",pattern))
        cardsList.add(new Card("Spades",pattern))
    }

    drawCardsForPlayers(List cardsList,int playersAmount = 3,int cardsPerPlayer = 5) {
        if(cardsList.size() < (playersAmount * cardsPerPlayer)) {
            print "ERROR - Not enough cards" //No exceptions yet :)
            return
        }
        var random = new java.util.Random()
        for i from 1 to playersAmount {
            var playernumberString = new java.lang.Integer(i).toString()
            print "player " + playernumberString  + " is drawing:"
            for j from 1 to cardsPerPlayer {
                var dawnCardIndex = random.nextInt(cardsList.size() - 1)
                var drawedCard = cardsList.remove(dawnCardIndex)
                print "    drawed:" + drawedCard
            }
        }
    }
}

运行

首先我们需要编译 Card 类。然后编译 CardDrawer 类。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
java -classpath compiler/target/compiler-1.0-SNAPSHOT-jar-with-dependencies.jar: com.kubadziworski.compiler.Compiler EnkelExamples/RealApp/Card.enk
java -classpath compiler/target/compiler-1.0-SNAPSHOT-jar-with-dependencies.jar:. com.kubadziworski.compiler.Compiler EnkelExamples/RealApp/CardDrawer.enk

kuba@kuba-laptop:~/repos/Enkel-JVM-language$ java CardDrawer 
player 1 is drawing:
    drawed:{Diamonds,Queen}
    drawed:{Spades,7}
    drawed:{Hearts,Jack}
    drawed:{Spades,4}
    drawed:{Hearts,2}
player 2 is drawing:
    drawed:{Diamonds,4}
    drawed:{Hearts,Ace}
    drawed:{Diamonds,Jack}
    drawed:{Spades,Queen}
    drawed:{Spades,King}
player 3 is drawing:
    drawed:{Diamonds,Ace}
    drawed:{Clubs,2}
    drawed:{Clubs,3}
    drawed:{Spades,8}
    drawed:{Clubs,7}
player 4 is drawing:
    drawed:{Spades,Ace}
    drawed:{Diamonds,3}
    drawed:{Clubs,4}
    drawed:{Clubs,6}
    drawed:{Diamonds,2}
player 5 is drawing:
    drawed:{Hearts,4}
    drawed:{Hearts,Queen}
    drawed:{Hearts,10}
    drawed:{Clubs,Jack}
    drawed:{Diamonds,8}

完美！

再见，Enkel

为了实现 Enkel 和分享整个过程我花费了大量的精力。写代码是一回事，能够表达和分享是另一回事（能够让读者通俗易懂本身就是一个很大的挑战）。

在这个过程中我学习到了很多，也希望屏幕前面的你也能有所收获。

很不幸的是，这是系列中的最后一篇了，这个项目将继续下去，所以，保持关注吧！