C# 正则表达式验证器：NFA、DFA 和 MFA 生成器

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.IO; using System.Linq; using System.Reflection.Emit; using System.Security.Cryptography; using System.Text; using System.Text.RegularExpressions; using System.Threading.Tasks; using System.Windows.Forms; using static System.Windows.Forms.VisualStyles.VisualStyleElement;

namespace byyljxfzxt { public partial class Form3 : Form { public Form3() { InitializeComponent(); }

    public bool rep(char x, string s)//判断是否重复
    {
        int i = 0;
        if (s.Length == 0)
        {
            return true;
        }
        while (i < s.Length)
        {
            if (s[i] == x)
                return false;
            i++;
        }
        return true;
    }

    string s3 = "";
    public int countap(string s)//统计字母个数
    {
        int i = 0;
        while (i < s.Length)
        {
            if (s[i] <= 'z' && s[i] >= 'a')
            {
                if (rep(s[i], s3))
                    s3 = s3 + s[i];
            }
            i++;
        }
        return s3.Length;
    }

    private void listView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        ListViewItem item = new ListViewItem();
        item.Text = Convert.ToString(listView1.Items.Count + 1);
        item.SubItems.Add("0");
        item.SubItems.Add("1");
        item.SubItems.Add("2");
        listView1.Items.Add(item);
    }

    private void button1_Click(object sender, EventArgs e)
    {
        string s = richTextBox1.Text;
        int i, count = 0;//count用来标记（和）
        countap(s);
        if (s == "")//如果输入为空白
        {
            MessageBox.Show("正确的输入");
            return;
        }

        if (s[0] == '|' || s[0] == '*' || s[s.Length - 1] == '|' || s[s.Length - 1] == '(')//不能以|、*开头，也不能以|、（结尾
        {
            MessageBox.Show("错误的输入");
            return;
        }

        for (i = 0; i < s.Length; i++)//做循环判断
        {
            if ((s[i] >= 'a' && s[i] <= 'z') || (s[i] >= 'A' && s[i] <= 'Z') || s[i] == '*' || s[i] == '|' || s[i] == '(' || s[i] == ')')
            //当前为大写（小写）字母或者*、|、（、）
            {
                switch (s[i])
                {
                    case '(': 
                        if ((i + 1) < s.Length)
                        {
                            if (s[i + 1] == '*' || s[i + 1] == '|')//（）内开头也不可以是闭包 
                            {
                                MessageBox.Show("错误的输入");
                                return;
                            }
                            if (s[i + 1] == ')')
                            {
                                MessageBox.Show("错误的输入");
                                return;
                            }
                        }
                        count++;
                        break;
                    case '|':
                        if ((i + 1) < s.Length)
                        {
                            if (s[i + 1] == '*' || s[i + 1] == '|' || s[i + 1] == ')')
                            {
                                MessageBox.Show("错误的输入");
                                return;
                            }
                        }
                        break;
                    case '*':
                        if ((i + 1) < s.Length)
                        {
                            if (s[i + 1] == '*')
                            {
                                MessageBox.Show("错误的输入");
                                return;
                            }
                        }
                        break;
                    case ')':
                        count--;
                        break;
                }
            }
            else
            {
                MessageBox.Show("错误的输入");
                return;
            }
            if (count < 0)//只要出现）数量大于（时，一定是错误情况
            {
                MessageBox.Show("错误的输入");
                return;
            }
        }
        if (count != 0)//最终循环结束时，count=0才是括号匹配
        {
            MessageBox.Show("错误的输入");
            return;
        }
        //CreateNFA.Enabled = true;
        button4.Enabled = true;
        MessageBox.Show("正确的输入");
    }

    private void button2_Click(object sender, EventArgs e)
    {
        richTextBox1.Text = " ";
    }

    private void button3_Click(object sender, EventArgs e)//读入NFA文件显示在listView1容器中
    {
        
    }

  private void button5_Click(object sender, EventArgs e)//保存NFA文件
    {
        
    }

    private void button6_Click(object sender, EventArgs e)//读入DFA文件显示在listView2容器中
    {
        
    }

    private void button8_Click(object sender, EventArgs e)//保存DFA文件
    {
        
    }

    private void button7_Click(object sender, EventArgs e)//生成DFA文件显示在listView2容器中
    {
    }

    private void button9_Click(object sender, EventArgs e)//生成MFA文件显示在listView3容器中
    {

    }

}

}

// 统计字符串s中不同的字母个数并返回该值 private string s3 = ""; public int countap(string s) { int i = 0; while (i < s.Length) { if (s[i] <= 'z' && s[i] >= 'a') { if (rep(s[i], s3)) s3 = s3 + s[i]; } i++; } return s3.Length; }

// 判断字符x是否在字符串s中出现过，若出现过返回false，否则返回true public bool rep(char x, string s) { int i = 0; if (s.Length == 0) { return true; } while (i < s.Length) { if (s[i] == x) return false; i++; } return true; }