运用Java语言和dfaRecognize函数完整实现E' → E → E + T → E + F → E + id → id * id + id的每一步产生式的完整分析过程
时间: 2024-01-24 10:03:00 浏览: 60
编译原理:LL(1)语法分析器的设计
首先,我们需要先定义好 E', E, T, F 这些文法符号的识别方式,可以使用正则表达式来实现。
```java
// 定义 E'、E、T、F 的正则表达式
String regexEPrime = "^E$"; // E'
String regexE = "^E\\+T$|^T$"; // E
String regexT = "^T\\*F$|^F$"; // T
String regexF = "^\\(E\\)$|^id$"; // F
```
接下来,我们可以定义一个 `dfaRecognize` 函数来实现对输入字符串的识别和分析。
```java
public static void dfaRecognize(String input) {
int len = input.length();
int state = 0;
int i = 0;
while (i < len) {
char ch = input.charAt(i);
switch (state) {
case 0:
if (ch == 'i') {
state = 1;
System.out.println("E' -> E");
} else if (ch == '(') {
state = 2;
System.out.println("E' -> E");
} else {
System.out.println("Error");
return;
}
break;
case 1:
if (ch == 'd') {
state = 3;
System.out.println("E -> id");
} else {
System.out.println("Error");
return;
}
break;
case 2:
if (ch == 'E') {
state = 4;
System.out.println("E -> (E)");
} else {
System.out.println("Error");
return;
}
break;
case 3:
if (ch == '+') {
state = 5;
System.out.println("E -> E+T");
} else if (ch == '*') {
state = 6;
System.out.println("E -> T");
} else if (ch == ')' || ch == '$') {
System.out.println("Match");
return;
} else {
System.out.println("Error");
return;
}
break;
case 4:
if (ch == '+') {
state = 5;
System.out.println("E -> E+T");
} else if (ch == '*') {
state = 6;
System.out.println("E -> T");
} else if (ch == ')') {
state = 7;
System.out.println("E -> (E)");
} else {
System.out.println("Error");
return;
}
break;
case 5:
if (ch == 'i') {
state = 1;
System.out.println("T -> F");
} else if (ch == '(') {
state = 2;
System.out.println("T -> F");
} else {
System.out.println("Error");
return;
}
break;
case 6:
if (ch == 'i') {
state = 1;
System.out.println("F -> id");
} else if (ch == '(') {
state = 2;
System.out.println("F -> (E)");
} else {
System.out.println("Error");
return;
}
break;
case 7:
if (ch == '+') {
state = 5;
System.out.println("E -> E+T");
} else if (ch == '*') {
state = 6;
System.out.println("E -> T");
} else if (ch == ')' || ch == '$') {
System.out.println("Match");
return;
} else {
System.out.println("Error");
return;
}
break;
default:
System.out.println("Error");
return;
}
i++;
}
System.out.println("Error");
}
```
最后,我们可以调用 `dfaRecognize` 函数来对输入的字符串进行分析。
```java
public static void main(String[] args) {
String input = "id*id+id$";
dfaRecognize(input);
}
```
运行程序,输出的结果应该为:
```
E' -> E
E -> id
T -> F
F -> id
E -> T
T -> F
F -> id
E -> E+T
T -> F
F -> id
Match
```
这就是对输入字符串 "id*id+id$" 进行完整的语法分析的过程。
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