用C语言代码实现

以下是一个用C语言实现右线性文法构造有穷自动机的示例代码：

#include<stdio.h>
#include<string.h>

#define MAX_STATES 1000
#define MAX_SYMBOLS 1000

// 定义状态转移表
int transition_table[MAX_STATES][MAX_SYMBOLS];

// 定义终态和终态数量
int final_states[MAX_STATES], num_final_states = 0;

// 定义字符集和字符集大小
char symbols[MAX_SYMBOLS];
int num_symbols = 0;

// 添加字符到字符集
void add_symbol(char symbol)
{
    int i;
    for(i = 0; i < num_symbols; i++)
    {
        if(symbols[i] == symbol)
            return;
    }
    symbols[num_symbols++] = symbol;
}

// 判断是否为终态
int is_final_state(int state)
{
    int i;
    for(i = 0; i < num_final_states; i++)
    {
        if(final_states[i] == state)
            return 1;
    }
    return 0;
}

// 添加终态
void add_final_state(int state)
{
    final_states[num_final_states++] = state;
}

// 打印状态转移表
void print_transition_table(int num_states)
{
    int i, j;
    printf("Transition table:\n");
    printf("State\t");
    for(i = 0; i < num_symbols; i++)
        printf("%c\t", symbols[i]);
    printf("\n");
    for(i = 0; i < num_states; i++)
    {
        printf("%d\t", i);
        for(j = 0; j < num_symbols; j++)
        {
            printf("%d\t", transition_table[i][j]);
        }
        printf("\n");
    }
}

// 构造有穷自动机
void construct_finite_automaton(char* grammar)
{
    int i, j, k, len;
    int num_states = 1;
    int state_stack[MAX_STATES], top = 0;
    int symbol_stack[MAX_SYMBOLS], num_symbol_stack = 0;
    int current_state, next_state;
    char symbol;

    // 初始化状态转移表
    memset(transition_table, -1, sizeof(transition_table));

    // 初始化终态和字符集
    num_final_states = 0;
    num_symbols = 0;

    // 开始构造有穷自动机
    len = strlen(grammar);
    for(i = 0; i < len; i++)
    {
        if(grammar[i] == '-')
        {
            // 左右两边分别为状态和符号
            current_state = state_stack[top-1];
            symbol = grammar[i+1];
            next_state = num_states++;

            // 添加符号到字符集
            add_symbol(symbol);

            // 添加转移
            transition_table[current_state][symbol] = next_state;

            // 压入状态栈和符号栈
            state_stack[top++] = next_state;
            symbol_stack[num_symbol_stack++] = symbol;
        }
        else if(grammar[i] == '|')
        {
            // 左边为状态，右边为符号
            current_state = state_stack[top-1];
            symbol = symbol_stack[num_symbol_stack-1];
            next_state = num_states++;

            // 添加转移
            transition_table[current_state][symbol] = next_state;

            // 压入状态栈
            state_stack[top-1] = next_state;
        }
        else if(grammar[i] == '>')
        {
            // 左边为状态，右边为终态
            current_state = state_stack[top-1];
            add_final_state(current_state);
        }
        else if(grammar[i] == ' ')
        {
            // 空格表示一个新的产生式
            top = 1;
            num_symbol_stack = 0;
            state_stack[0] = 0;
        }
    }
    // 最后一个状态是终态
    add_final_state(num_states-1);

    // 打印状态转移表
    print_transition_table(num_states);
}

int main()
{
    char grammar[] = "0 - a 1 | b 2 > 3 | c 4 >";
    construct_finite_automaton(grammar);
    return 0;
}

以上代码实现了一个简单的右线性文法构造有穷自动机的过程，可以根据具体的需求进行修改和扩展。