Interpreterパターン調査ドキュメント

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11

Client ──────────────────────────────────────────────────────────────
    │
    ├── Context（共有情報）
    │
    └── AbstractExpression（抽象/インターフェース）
            │
            ├── TerminalExpression（終端：リーフ）
            │
            └── NonterminalExpression（非終端：複合）
                    │
                    └── 子Expression（再帰的に構成）

1
2
3
4

// Java 11+
public interface Expression {
    boolean interpret(String context);
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13

// Java 11+
public class TerminalExpression implements Expression {
    private String data;

    public TerminalExpression(String data) {
        this.data = data;
    }

    @Override
    public boolean interpret(String context) {
        return context.contains(data);
    }
}

 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

// Java 11+
public class AndExpression implements Expression {
    private Expression expr1;
    private Expression expr2;

    public AndExpression(Expression expr1, Expression expr2) {
        this.expr1 = expr1;
        this.expr2 = expr2;
    }

    @Override
    public boolean interpret(String context) {
        return expr1.interpret(context) && expr2.interpret(context);
    }
}

public class OrExpression implements Expression {
    private Expression expr1;
    private Expression expr2;

    public OrExpression(Expression expr1, Expression expr2) {
        this.expr1 = expr1;
        this.expr2 = expr2;
    }

    @Override
    public boolean interpret(String context) {
        return expr1.interpret(context) || expr2.interpret(context);
    }
}

 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

// Java 11+
public class InterpreterDemo {
    public static void main(String[] args) {
        // 終端式を作成
        Expression isJava = new TerminalExpression("Java");
        Expression isPattern = new TerminalExpression("Pattern");

        // 非終端式を作成（Java AND Pattern）
        Expression isJavaPattern = new AndExpression(isJava, isPattern);

        // コンテキスト（入力文字列）
        String context = "Java Design Pattern";

        // 解釈を実行
        System.out.println("Context: " + context);
        System.out.println("Java AND Pattern? " + isJavaPattern.interpret(context));
        // 出力: Java AND Pattern? true

        // OR式の例
        Expression isPython = new TerminalExpression("Python");
        Expression isJavaOrPython = new OrExpression(isJava, isPython);
        System.out.println("Java OR Python? " + isJavaOrPython.interpret(context));
        // 出力: Java OR Python? true
    }
}

 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
45
46
47
48
49
50

# Python 3.8+
from abc import ABC, abstractmethod

# AbstractExpression
class Expression(ABC):
    @abstractmethod
    def interpret(self, context: str) -> bool:
        pass

# TerminalExpression
class TerminalExpression(Expression):
    def __init__(self, data: str):
        self.data = data

    def interpret(self, context: str) -> bool:
        return self.data in context

# NonterminalExpression: AND
class AndExpression(Expression):
    def __init__(self, expr1: Expression, expr2: Expression):
        self.expr1 = expr1
        self.expr2 = expr2

    def interpret(self, context: str) -> bool:
        return self.expr1.interpret(context) and self.expr2.interpret(context)

# NonterminalExpression: OR
class OrExpression(Expression):
    def __init__(self, expr1: Expression, expr2: Expression):
        self.expr1 = expr1
        self.expr2 = expr2

    def interpret(self, context: str) -> bool:
        return self.expr1.interpret(context) or self.expr2.interpret(context)

# Client
if __name__ == "__main__":
    context = "Java Design Pattern"

    is_java = TerminalExpression("Java")
    is_pattern = TerminalExpression("Pattern")

    # Java AND Pattern
    is_java_pattern = AndExpression(is_java, is_pattern)
    print(f"Java AND Pattern? {is_java_pattern.interpret(context)}")  # True

    # Java OR Python
    is_python = TerminalExpression("Python")
    is_java_or_python = OrExpression(is_java, is_python)
    print(f"Java OR Python? {is_java_or_python.interpret(context)}")  # True

1
2
3
4
5
6

        [Add]
       /    \
    [Num]   [Mul]
      5     /    \
        [Num]   [Num]
          3       2