lexicalanalyze.cs

用microsoft vc++6.0制作

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;

namespace Analyzer
{
    class LexicalAnalyze
    {
        private int typeofkey;          //关键字的类型
        private int row;                //当前编译的行数
		private string text;            //此法分析类构造时传入要处理的代码
        private int length;             //代码长度
        private int pointer;            //指向下一个要处理的字符    
		private char c;                 //当前正在处理的字符
		private char bC;                //当前处理的字符的前一个字符
		private int state;              //处理状态
		private string str;             //当前处理行,处理后的结果
        private string result;          //最后处理完所有代码结果存放在result中等待返回

        public LexicalAnalyze(string t)//构造函数初始化
		{
            this.text = t;
            length = text.Length;
            pointer = 0;
            typeofkey = -1;
            row = 0;
			c=' ';
			bC=' ';
			state = 0;
            str = "";
            result = "";
		}

		public string getSymbolTable()//处理入口
		{
			c = nextChar();//取下一个字符
			analyzer();//开始分析
			return result;//返回结果输出在richtexbox中
		}

		private void analyzer()
		{
			bool flag=true;//标志是否继续执行

			while(flag)
			{
				switch (state)
				{
					case 0:			
						if(c==' ')            //空格
						{
						}
						else if((int)c==10)   //回车
						{
                            row++;
                            result +="第"+row.ToString()+"行"+ str + "\n";
                            str = "";
						}
						else if(c=='~')       //结束符
						{
							return;
						}
						else if(c=='+')       //操作符+
						{
							install("操作符","+",1);
						} 
						else if(c=='-')       //操作符-
						{
							install("操作符","-",2);
						}
						else if(c=='=')       //操作符=
						{ 
							state = 2;
						}
						else if(c=='<')       //操作符<
						{
							state = 3;
						}
						else if(c=='>')       //操作符>
						{
							state = 4;
						}
						else if(c=='!')       //操作符!
						{
							state = 5;
						}
						else if(c=='{')       //分隔符{
						{
							install("分隔符","{",3);
						}
						else if(c=='}')       //分隔符}
						{
							install("分隔符","}",4);
						}
						else if(c=='(')		  //分隔符(
						{
							install("分隔符","(",5);
						}
						else if(c==')')		  //分隔符)
						{
							install("分隔符",")",6);
						}
						else if(c==';')       //分隔符;
						{
							install("分隔符",";",7);
						}
						else if(isLetter(c))  //读到了字符
						{
							bC = c;
							state = 6;
						}
						else if(isDigit(c))   //读到了数字
						{
							bC = c;
							state = 7;
						}
						else if(c=='#')
						{
                           state=8;
						}
						else 
						{
							state=0;
							flag=false;
							fail(0);
						}
						c = nextChar();
						break;

					case 2:
                
						if(c=='=')           //表示操作符==
						{
							state = 0;
							install("操作符","==",8);
							c = nextChar();
						}
						else 
						{
							state = 0;
							install("操作符","=",9);
						}

						break;
					case 3:
						if(c=='=')          //表示操作符<=
						{
							state = 0;
							install("操作符","<=",10);
							c = nextChar();
						}
						else 
						{
							state = 0;
							install("操作符","<",11);
						}
                
						break;
					case 4:
						if(c=='=')          //表示操作符>=
						{
							state = 0;
							install("操作符",">=",12);
							c = nextChar();
						}
						else 
						{
							state = 0;
							install("操作符",">",13);
						}

						break;
					case 5:
						if(c=='=')         // 表示操作符!=
						{
							state = 0;
							install("操作符","!=",14);
							c = nextChar();
						}
						else 
						{
							state = 0;
							flag=false;
							fail(1);
						}
						break;
				
						//读入标识符,后面是 数字符和字母才是对的
					case 6:                      
						string id = bC.ToString();
						while(isLetter(c)||isDigit(c))
						{
                            id += c.ToString() ;
							c = nextChar();
						}
						if(isKey(id))
							install("关键字",id,typeofkey);
						else
							install("标识符",id,15);
						state = 0;
						break;

						//读入数字符,后面是 数字符(循环); 
					case 7:                         
                        string digit = bC.ToString();
						while(isDigit(c))            
						{
							digit+=c;
							c=nextChar();
						}
						state = 0;
						install("数字符",digit,16);
						break;
                    case 8: //声明部分

                        string temp = "";
                        install("操作符", "#", 17);
						while(isLetter(c))
						{
                            temp += c;
							c = nextChar();
						}
                        if (temp == "include" && c == '<')
						{
                            install("关键字", "include", 18);
                            install("操作符", c.ToString(), 11);
							c = nextChar();
							while(isLetter(c)||this.isDigit(c))
							{
								c = nextChar();
							}
							if(c=='>')
							{                                
                                install("操作符", c.ToString(), 13);
								c = nextChar();
							}
							else
							 fail(2);//如果不是">"则出错                                         
						}
						else
							fail(0);
						state = 0;
						break;	
				}  
			}
		}
 
		private void fail(int i) //出错处理函数
		{
			string typeerror="";;
			switch(i)
			{
				case 0:
					typeerror="输入非法字符错误";
					break;
				case 1:
					typeerror="操作符错误";
					break;
				case 2:
					typeerror="声明错误";
					break;
			}
            MessageBox.Show(typeerror, "出现错误!", MessageBoxButtons.OK, MessageBoxIcon.Error);
		}

		private char nextChar()
		{
			if(pointer>=length)return '~';//如果读完最后一个字符返回"~"表示结束
            return text[pointer++];//取下一个字符
		}
    
		private void install(string type,string value,int n)
		{
            //str += type + n +" \"" + aValue + "\" " +  "->" ;
            str += " "+n + "\"" + value + "\" " + "->";//格式输出
		}
 
		private bool isLetter(char checkChar)
		{
            int checkInt = Convert.ToInt32(checkChar);//转换为asc码,判断是否是字符
			if((checkInt<=122&&checkInt>=97)||(checkInt>=65&&checkInt<=90))
			return true;
			else return false;
		}
    
		private bool isDigit(char checkChar)
		{
            int checkInt = Convert.ToInt32(checkChar); //转换为asc码,判断是否是数字
            if (checkInt >= 48 && checkInt <= 57) return true;
            else return false;
		}
    
		private bool isKey(string key)//判断是否为关键字
		{
            switch (key)//关键字分开编码
            {                                   //分别对应关键字编码
                case "if": typeofkey = 19; break;
                case "else": typeofkey = 20; break;
                case "return": typeofkey = 21; break;
                case "int": typeofkey = 22; break;
                case "main": typeofkey = 23; break;
                case "printf": typeofkey = 24; break;
                default: return false;
            }
            return true;
            //关键字统一编码
            //if(checkKey.Equals("if")||checkKey.Equals("return")||
            //    checkKey.Equals("else")||checkKey.Equals("int")||
            //    checkKey.Equals("main") || checkKey.Equals("printf"))
            //{
            //    return true;
            //}
            //return false;
		}
	}
}