form1.cs

一个用C#编写的解释器

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using Microsoft.VisualBasic.Devices;


namespace WindowsApplication6
{
    public partial class Form1 : Form
    {   
        const short ERROR = -1;
        const short BEGIN = 1;
        const short END = 2;
        const short IF = 3;
        const short THEN = 4;
        const short ELSE = 5;
        const short ID = 6;
        const short INT = 7;
        const short LT = 8;
        const short LE = 9;
        const short EQ = 10;
        const short NE = 11;
        const short GT = 12;
        const short GE = 13;
        public Form1()
        {
            InitializeComponent();
        }
        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }


        private void button1_Click(object sender, EventArgs e)
        {
            KeywordTable = new Keyword[5];
            KeywordTable[0] = new Keyword("BEGIN", BEGIN);
            KeywordTable[1] = new Keyword("END", END);
            KeywordTable[2] = new Keyword("IF", IF);
            KeywordTable[3] = new Keyword("THEN", THEN);
            KeywordTable[4] = new Keyword("ELSE", ELSE);
           
            textBox1.Clear();
            textBox4.Clear();
            try
            {
                string FILENAME = string.Empty;
                FILENAME = textBox2.Text;
                Computer MyComputer = new Computer();
                System.IO.StreamReader MyStreamReader;
                MyStreamReader = MyComputer.FileSystem.OpenTextFileReader(FILENAME, Encoding.Default);
                textBox4.Text = MyComputer.FileSystem.ReadAllText(FILENAME, Encoding.Default);
/////////////////////////////////////////////////////////////////////////////
                


                int c;
                char ch;
                string stemp = string.Empty;
                

                while (MyStreamReader.Peek()!=-1)
                {
                    stemp = string.Empty;
                    while(IsListSeparatorOrBlank((char)MyStreamReader.Peek()))
                    {
                        MyStreamReader.Read();
                    }
                    if (MyStreamReader.Peek() == -1)
                        continue;
                    ch = (char)MyStreamReader.Peek();

                    if (isalpha(ch))
                    {
                        stemp += ch;
                        MyStreamReader.Read();
                        ch = (char)MyStreamReader.Peek();
                        while (isalnum(ch))
                        {
                            stemp += ch;
                            MyStreamReader.Read();
                            ch = (char)MyStreamReader.Peek();
                        }
                        ch = (char)MyStreamReader.Peek();
                        if (MyStreamReader.Peek() == -1 | IsListSeparatorOrBlank(ch) | isrelationsign(ch))
                        {
                            c = lookup(stemp);
                            if (c == 0) Out(ID, stemp);
                            else Out(c, "");
                        }
                        else
                        {
                            stemp += ch;
                            MyStreamReader.Read();
                            ch = (char)MyStreamReader.Peek();
                            while (MyStreamReader.Peek() != -1 && !IsListSeparatorOrBlank((char)MyStreamReader.Peek()))
                            {
                                stemp += ch;
                                MyStreamReader.Read();
                                ch = (char)MyStreamReader.Peek();
                            }
                            Out(ERROR, stemp);
                        }
                    }
                    else if (isdigit(ch))
                    {
                        stemp += ch;
                        MyStreamReader.Read();
                        ch = (char)MyStreamReader.Peek();
                        while (isdigit(ch))
                        {
                            stemp += ch;
                            MyStreamReader.Read();
                            ch = (char)MyStreamReader.Peek();
                        }
                        ch = (char)MyStreamReader.Peek();
                        if (MyStreamReader.Peek() == -1 | IsListSeparatorOrBlank(ch) | isrelationsign(ch))
                        {
                            Out(INT, stemp);
                        }
                        else
                        {
                            stemp += ch;
                            MyStreamReader.Read();
                            ch = (char)MyStreamReader.Peek();
                            while (MyStreamReader.Peek() != -1 && !IsListSeparatorOrBlank((char)MyStreamReader.Peek()))
                            {
                                stemp += ch;
                                MyStreamReader.Read();
                                ch = (char)MyStreamReader.Peek();
                            }
                            Out(ERROR, stemp);
                        }
                    }
                    else switch (ch)
                        {
                            case '<':
                                
                                    stemp += ch;
                                    MyStreamReader.Read();
                                    ch = (char)MyStreamReader.Peek();
                                    if (ch == '=')
                                    { stemp += ch; Out(LE, ""); MyStreamReader.Read(); }
                                    else if (ch == '>')
                                    { stemp += ch; Out(NE, ""); MyStreamReader.Read(); }
                                    else Out(LT, "");
                                    break;


                        case '=':
                                    stemp += ch; Out(EQ, ""); 
                                    MyStreamReader.Read();
                                    break;
                        case '>':
                            stemp += ch;
                            MyStreamReader.Read();
                            ch = (char)MyStreamReader.Peek();
                            if (ch == '=')
                            { stemp += ch; Out(LE, ""); MyStreamReader.Read(); }
                            else Out(GT, "");
                            break;

                        default :
                            stemp += ch;
                            MyStreamReader.Read();
                            ch = (char)MyStreamReader.Peek();
                            while (MyStreamReader.Peek() != -1 && !IsListSeparatorOrBlank((char)MyStreamReader.Peek()))
                            {
                                stemp += ch;
                                MyStreamReader.Read();
                                ch = (char)MyStreamReader.Peek();
                            }
                            Out(ERROR, stemp);
                            break;

                        }

                    

                   
                    
                }


                MyStreamReader.Close();   




////////////////////////////////////////////////////////////////////////////

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "错误",MessageBoxButtons.OK,MessageBoxIcon.Warning);
            
            }
            
        }

        
        
        private bool isalpha(int c)
        {
            if ((c <= 'z' && c >= 'a') | (c <= 'Z' && c >= 'A'))
                return true;
            else return false;
        }  //判断是否为大小写字母
        private bool isalnum(int c)
        {
            if ((c <= 'z' && c >= 'a') | (c <= 'Z' && c >= 'A') | (c <= '9' && c >= '0'))
                return true;
            else return false;
        }  //判断是否为大小写字母或数字
        private bool isdigit(int c)
        {
            if (c <= '9' && c >= '0')
                return true;
            else return false;
        }  //判断是否为数字
        private bool isrelationsign(int c)  //判断是否为关系符
        {
            if (c == '>' | c == '<' | c == '=')
                return true;
            else return false;
        }   


        class Keyword
        {
            public string key;
            public int value;
            public Keyword(string s, int v)
            {
                this.key = s;
                this.value = v;
            }
        }    //关键字类定义
        Keyword[] KeywordTable;
        
        private int lookup(string s)
        {
            
            foreach (Keyword t in KeywordTable)
            {
                if (s == t.key)
                    return t.value;

            }
            return 0;
        }   //判断输入串是否在关键字表中
        private void Out(int c, string s)
        {
            textBox1.Text += "（" + c + "，" + s + "） "+Environment.NewLine;
        }    //输出信息
        private bool IsBlank(char c)
        {
            if (c == ' ' | c == '\t' | c=='\n')
                return true;
            else return false;
        
        } //是空白符吗
        private bool IsListSeparatorOrBlank(char c)
        {
            if (c == ' ' | c == '\t' | c=='\n'|c==','|c==';'|c=='\r')
                return true;
            else return false;

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            
            textBox2.Text += (@"D:\T1.txt");
            textBox5.Text += (@"D:\T2.txt");
            textBox3.Text += "分析结果是形如(CLASS,VALUE)的二元表达式，CLASS为类型码，VALUE为其值。若当前分析的串为关键字，则VALUE为空。另外，我们约定CLASS为－1时表示此串为非法串（查错功能）";
        }

        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                string myText;
                myText = "*****原文件内容为*****" + textBox4.Text + Environment.NewLine + "**********************" + Environment.NewLine + Environment.NewLine + "****词法分析结果为****" + Environment.NewLine + textBox1.Text + "**********************" + Environment.NewLine + "建立文件时间：" + System.DateTime.Now.ToString() + Environment.NewLine; 
                File.WriteAllText(textBox5.Text, myText, Encoding.Default);
                MessageBox.Show("成功写入文件","操作成功",MessageBoxButtons.OK,MessageBoxIcon.Asterisk);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
        }
    }

}