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interpreter

admin 11月 12, 2020 0

GoF Definition:

Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.

概念

建立一个解释器，对于特定的计算机程序设计语言，用来解释预先定义的文法。简单地说，解释器模式是一种简单的语法解释器构架。

例子

编程语言的解释器。

代码实现

public interface  {
    void interpret(Context context);
}

public class IntToWords implements  {
    private String s;

    public IntToWords(String s) {
        this.s = s;
    }

    
    public void interpret(Context context) {
        context.printInWords(s);
    }
}

public class StringToBinaryExp implements  {
    private String s;

    public StringToBinaryExp(String s) {
        this.s = s;
    }

    
    public void interpret(Context context) {
        context.getBinaryForm(s);
    }
}

public class Context {
    public String input;

    public Context(String input) {
        this.input = input;
    }

    public void getBinaryForm(String input) {
        int i = Integer.parseInt(input);
        String binaryString = Integer.toBinaryString(i);
        System.out.print("Binary equivalent of " + input + " is " + binaryString);
    }

    public void printInWords(String input) {
        this.input = input;
        System.out.print("Printing the input in words:");
        char[] c = input.toCharArray();
        for (int i = 0; i < c.length; ++i) {
            switch (c[i]) {
                case '1':
                    System.out.print("One ");
                    break;
                case '2':
                    System.out.print("Two ");
                    break;
                case '3':
                    System.out.print("Three ");
                    break;
                case '4':
                    System.out.print("Four ");
                    break;
                case '5':
                    System.out.print("Five ");
                    break;
                case '6':
                    System.out.print("Six ");
                    break;
                case '7':
                    System.out.print("Seven ");
                    break;
                case '8':
                    System.out.print("Eight ");
                    break;
                case '9':
                    System.out.print("Nine ");
                    break;
                case '0':
                    System.out.print("Ten");
                    break;
                default:
                    System.out.print("# ");
                    break;
            }
        }
    }
}