C++词法分析（C#描述）
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近来开始学习编译原来，这是词法分析最基础的，在网上看到很多高手的作品，我也照着做了一个,有错别介意
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.IO;namespace 词法分析成功改造3{ class Program { static void Main(string[] args) { StreamReader reader = new StreamReader("D:/test.txt"); string wholeText = reader.ReadToEnd(); Console.WriteLine(wholeText + "\n\n"); LexicalAnalysis manage = new LexicalAnalysis(); Console.WriteLine(manage.Analysis(wholeText)); Console.WriteLine("\n\n" + manage.ErrorNO()); Console.WriteLine(LexicalAnalysis.AllWrongText); Console.Read(); } #region 词法分析 class LexicalAnalysis { /// <summary> /// 记录字符位置 /// </summary> int i = 0, j = 0; /// <summary> /// 行号 /// </summary> public static int LineNo = 1; /// <summary> /// 记录识别出的单词 /// </summary> string token = ""; /// <summary> /// 记录每一次得到的完整信息 /// </summary> string text2 = ""; /// <summary> /// 用来记录错误信息 /// </summary> string text3 = ""; /// <summary> /// 记录异常信息 /// </summary> string wrong = ""; /// <summary> /// 错误字段的个数 /// </summary> public static int errors = 0; /// <summary> /// 记录错误的详细信息 /// </summary> public static string AllWrongText = ""; /// <summary> /// 标记成对出现的界符 /// </summary> int flag1 = 0, flag2 = 0, flag3, flag4, flag5, flag6 = 0; /// <summary> /// 关键字(部分) /// </summary> string[] keyWords = new string[32]{"auto", "double", "int","struct", "break", "else", "long","switch","case","enum","register","typedef","char","extern","return", "union","const","float","short","unsigned","continue","for","signed","void","default", "goto","sizeof","volatile","do","if","while","static" }; /// <summary> /// 运算符 /// </summary> string[] operatorWords = new string[28]{"+","-","*","/","%",">","<",">=","<=","==", "-=", "+=","*=","/=","!=","=","%=","&","&&","|","||","!","++","--","~","<<",">>","?:"}; /// <summary> /// 边界符 /// </summary> string[] boundWords = new string[15] { "{", "}", "[", "]", ";", ",", ".", "(", ")", ":", "\"", "#", ">", "<", "\'" }; /// <summary> /// 词法分析 /// </summary> /// <param name="str">所要分析的句子</param> /// <returns>经过分析之后的句子</returns> public string Analysis(string str) { string space = ""; //空格数 if (str.Length == 0) //判断字符串是否为空 return ""; try { while (str[i] != '\0') //读入字符判断，空格、字母、数字、界符 { if (str[i] == ' ' || str[i] == '\t' || str[i] == '\r') { i++; //跳过无意义的字符 } else if (str[i] == '\n')//如果是换行符，则行号加1 { LineNo++; i++; } else if (IsLetter(str[i]))//如果是字母 { i = RecogniseLetter(str, i); for (j = 0; j < keyWords.Length; j++) { if (token.CompareTo(keyWords[j]) == 0) { break; } } if (j >= keyWords.Length)//是普通的标志符 { for (int m = 0; m < 12 - token.Length; m++) { space = space + " "; } text2 = text2 + LineNo.ToString() + ": " + token + space + "标识符" + "\r\n"; token = ""; space = ""; } if (j < keyWords.Length)//是保留字 { for (int m = 0; m < 12 - token.Length; m++) space = space + " "; text2 = text2 + LineNo.ToString() + ": " + keyWords[j] + space + "关键字" + "\r\n"; ; token = ""; space = ""; } }//end else if else if (IsDigit(str[i]))//如果是数字 { i = RecogniseDigit(str, i); for (int m = 0; m < 12 - token.Length; m++) { space = space + " "; } text2 = text2 + LineNo.ToString() + ": " + token + space + "常量" + "\r\n"; token = ""; space = ""; }//end else if else if (IsBound(str[i])) //识别界符 { i = RecogniseBound(str, i); for (int m = 0; m < 12 - token.Length; m++) { space = space + " "; } text2 = text2 + LineNo.ToString() + ": " + token + space + "界符" + "\r\n"; ; token = ""; space = ""; }//end else if else if (IsOperator(str[i])) { i = RecogniseOperator(str, i); for (int m = 0; m < 12 - token.Length; m++) { space = space + " "; } text2 = text2 + LineNo.ToString() + ": " + token + space + "运算符" + "\r\n"; token = ""; space = ""; }//end else if else { error(0); i++; } }//end while }//end try catch (DivideByZeroException e1) { wrong = e1.Message; } catch (IndexOutOfRangeException e2) { wrong = e2.Message; } catch (Exception e) { wrong = e.Message; } return text2; } /// <summary> /// 判断字符是不是字母 /// </summary> /// <param name="ch">待定字符</param> /// <returns>是否</returns> public bool IsLetter(char ch) { if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) { return true; } else return false; } /// <summary> /// 判断字符是不是数字 /// </summary> /// <param name="ch">待定字符</param> /// <returns>是否</returns> public bool IsDigit(char ch) { if (ch >= '0' && ch <= '9') { return true; } else return false; } /// <summary> /// 判断字符是不是下划线 /// </summary> /// <param name="ch">待定字符</param> /// <returns>是否</returns> public bool IsUnderline(char ch) { if (ch == '_') return true; else return false; } /// <summary> /// 判断字符是不是边界符 /// </summary> /// <param name="ch">待定字符</param> /// <returns></returns> public bool IsBound(char ch) { for (int j = 0; j < boundWords.Length; j++) { if (ch.CompareTo(boundWords[j][0]) == 0) { return true; } } return false; } /// <summary> /// 判断字符是不是操作符 /// </summary> /// <param name="ch">待定字符</param> /// <returns>是否</returns> public bool IsOperator(char ch) { for (int i = 0; i < operatorWords.Length; i++) { if (ch == operatorWords[i][0]) { return true; } } return false; } /// <summary> /// 识别整个操作符 /// </summary> /// <param name="str">字符串</param> /// <param name="i">字符串中字符的位置</param> /// <returns>字符位置</returns> private int RecogniseOperator(string str, int i) { char state = '0'; string temp = ""; while (state != '2') { switch (state) { case '0': temp += str[i]; i++; state = '1'; break; case '1': //判断为双个运算符 if (str.Substring(i - 1, 2) == "++" || str.Substring(i - 1, 2) == "--" || str.Substring(i - 1, 2) == "<<" || str.Substring(i - 1, 2) == ">>" || str.Substring(i - 1, 2) == "+=" || str.Substring(i - 1, 2) == "-=" || str.Substring(i - 1, 2) == "*=" || str.Substring(i - 1, 2) == "/=" || str.Substring(i - 1, 2) == "!=" || str.Substring(i - 1, 2) == "%=") { temp += str[i]; i++; state = '2'; } //三目运算符 if (str[i - 1] == '?' && str[i] == ':') { temp += str[i]; i++; state = '2'; } //不是运算符 else { state = '2'; } break; }//end switch }//end while token = temp; return i; } /// <summary> /// 识别普通的标识符 /// </summary> /// <param name="str">用来识别的字符串</param> /// <param name="i">字符串中字符的位置</param> /// <returns>字符位置</returns> public int RecogniseLetter(string str, int i) //识别单词 { char state = '0'; string temp = ""; //记录单词 while (state != '2') { switch (state) { case '0': if (IsLetter(str[i])) { state = '1'; temp = temp + str[i]; i++; } break; case '1': if (IsLetter(str[i]) || IsDigit(str[i]) || IsUnderline(str[i])) { state = '1'; temp = temp + str[i]; i++; } else state = '2'; break; }//end switch }//end while token = temp; //记录识别的字符串 return i; } /// <summary> /// 识别整个常熟 /// </summary> /// <param name="str">待测字符串</param> /// <param name="i">字符串中字符的位置</param> /// <returns>字符位置</returns> public int RecogniseDigit(string str, int i) //识别常数 { char state = '0'; string temp = ""; while (state != '2') { switch (state) { case '0': if (IsDigit(str[i])) { temp += str[i]; state = '1'; i++; } break; case '1': if (IsDigit(str[i])) { temp += str[i]; state = '1'; i++; } else if (str[i] == '.' && IsDigit(str[i + 1])) //有小数点的数 { temp += str[i]; state = '1'; i++; } else state = '2'; break; }//end switch }//end while token = temp; return i; } /// <summary> /// 识别标识符 /// </summary> /// <param name="str">待测字符串</param> /// <param name="i">字符串中字符的位置</param> /// <returns>字符位置</returns> public int RecogniseBound(string str, int i) { string temp = ""; for (int k = 0; k < boundWords.Length; k++) { if (str[i].CompareTo(boundWords[k][0]) == 0) { temp += str[i]; i++; break; } else continue; }//end for token = temp; //这些标志数是用来等会做错误判断用的（没有成双出现就是错误） if (token == "{" || token == "}") flag1++; else if (token == "[" || token == "]") flag2++; else if (token == "(" || token == ")") flag3++; else if (token == "<" || token == ">") flag4++; else if (token == "\'") flag5++; else if (token == "\"") flag6++; return i; } /// <summary> /// 得到已经识别的字符串 /// </summary> /// <param name="str">字符串</param> /// <param name="k">字符位置</param> /// <returns>字符位置</returns> public int GetetToken(string str, int k) { switch (k) { case 1: for (int i = 0; i < keyWords.Length; i++) //关键字 { if (str == keyWords[i]) return i; } break; case 2: for (int i = 0; i < operatorWords.Length; i++) //运算符 { if (str == operatorWords[i]) return i + 32; //+32的原因是keyWords中有32个关键字 } break; case 3: for (int i = 0; i < boundWords.Length; i++) //界符 { if (str == boundWords[i]) return i + 60; //+60的原因是keyWords+operatorWords有60个 } break; }//end switch return 0; } /// <summary> /// 错误个数 /// </summary> /// <returns>错误信息</returns> public string ErrorNO() { error(1); text3 = errors.ToString() + " errors"; return text3; } /// <summary> /// 错误信息 /// </summary> /// <param name="k"></param> public void error(int k) { switch (k) { case 0: //输入了非法字符 AllWrongText = AllWrongText + LineNo.ToString() + ": " + "非法字符" + "\r\n"; errors++; break; case 1: //界符不匹配 if (flag1 % 2 != 0) { AllWrongText = AllWrongText + "{ 不匹配" + "\r\n"; errors++; } if (flag2 % 2 != 0) { AllWrongText = AllWrongText + "[ 不匹配" + "\r\n"; errors++; } if (flag3 % 2 != 0) { AllWrongText = AllWrongText + "( 不匹配" + "\r\n"; errors++; } if (flag4 % 2 != 0) { AllWrongText = AllWrongText + "< 不匹配" + "\r\n"; errors++; } if (flag5 % 2 != 0) { AllWrongText = AllWrongText + "' 不匹配" + "\r\n"; errors++; } if (flag6 % 2 != 0) { AllWrongText = AllWrongText + " \" 不匹配" + "\r\n"; errors++; } break; }//end switch } } #endregion }}- C++词法分析（C#描述）
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