世界上并没有完美的程序，但是我们并不因此而沮丧，因为写程序就是一个不断追求完美的过程。
- 意图
根据语法规则解释语言 - 类图
- 实例
interface Expression {
/**
* 解释
* @param context
* @return
*/
Boolean interpret (String context);
}
static class Terminal implements Expression {
private String data;
public Terminal (String data) {
this.data = data;
}
@Override
public Boolean interpret(String context) {
if (null != context && context.contains(data)) {
return true;
}
return false;
}
}
static class And implements Expression {
private Expression expression1;
private Expression expression2;
public And (Expression expression1, Expression expression2) {
this.expression1 = expression1;
this.expression2 = expression2;
}
@Override
public Boolean interpret(String context) {
return expression1.interpret(context) && expression2.interpret(context);
}
}
static class Or implements Expression {
private Expression expression1;
private Expression expression2;
private Or (Expression expression1, Expression expression2) {
this.expression1 = expression1;
this.expression2 = expression2;
}
@Override
public Boolean interpret(String context) {
return expression1.interpret(context) || expression2.interpret(context);
}
}
interface Rule {
/**
* 获取男性
* @return
*/
Expression getMale ();
/**
* 获取已婚
* @return
*/
Expression getMarried ();
}
static class RuleImpl implements Rule {
@Override
public Expression getMale() {
Expression expression1 = new Terminal("Robot");
Expression expression2 = new Terminal("John");
return new Or(expression1, expression2);
}
@Override
public Expression getMarried() {
Expression expression1 = new Terminal("Julie");
Expression expression2 = new Terminal("Married");
return new And(expression1, expression2);
}
}
- 测试
public static void main(String[] args) {
Rule rule = new RuleImpl();
Expression male = rule.getMale();
Expression married = rule.getMarried();
boolean b1 = male.interpret("Is John a Robot?");
boolean b2 = married.interpret("Julie or Married?");
System.out.println("b1 --- " + b1 + ", b2 --- " + b2);
}
运行结果：
b1 --- true, b2 --- true
