yufafenzx.txt

语法分析 用C编写的

#include   <iostream>   
  #include   <fstream>   
  #include   <string>   
  #include   <string.h>   
  #include   <ctype.h>   
  using   namespace   std;   
  //   保留字数组定义   
  char*   ReserveWords[35]   =   {   
      "and",   "array",   "begin",   "case",   "const",   "div",   "do",   "downto",   "else",   "end",   "file",   
      "for",   "function",   "goto",   "if",   "in",   "label",   "mod",   "nil",   "not",   "of",   "or",   "packed",   
      "procedure",   "program",   "record",   "repeat",   "set",   "then",   "to",   "type",   "until",   "var",   
      "while",   "with"   
  };   
  char   arrow[]   =   "   ----->   ";   
  char   enter[]   =   "\r\n";   
  //   读入ch   
  char   GetChar(ifstream&   src)   
  {   
      char   cRet;   
      src.get(cRet);   
      return   cRet;   
  }   
  //   读入空格   
  char   GetBC(ifstream&   src)   
  {   
      char   cRet;   
      src.get(cRet);   
      while   (cRet   ==   '   ')   
          src.get(cRet);   
      return   cRet;   
  }   
  //   连接单词符号   
  void   Concat(char   *str,   char   c)   
  {   
      size_t   n   =   strlen(str);   
      str[n++]   =   c;   
      str[n]   =   '\0';   
  }   
  //   判断是否为保留字   
  bool   Reserve(const   char*   str)   
  {   
      bool   bRet   =   false;   
      for   (int   i   =   0;   i   <   35;   i++)   
      {   
          if   (_stricmp(ReserveWords[i],   str)   ==   0)   
          {   
              bRet   =   true;   
              break;   
          }   
      }   
      return   bRet;   
  }   
  //   回调字符   
  char   Retract(ifstream&   src)   
  {   
      src.seekg(-1,   ios::cur);   
      return   '\0';   
  }   
  //   分析函数   
  void   Analyzer(ifstream&   src,   ofstream&   dst)   
  {   
      char   ch;   
      char   strToken[1024]   =   "";   
      ch   =   GetBC(src);   
      //   判断标识符的情况   
      if   (isalpha(ch))   
      {   
          while   (isalpha(ch)   ||   isdigit(ch)   ||   ch   ==   '_')   
          {   
              Concat(strToken,   ch);   
              ch   =   GetChar(src);   
          }   
          ch   =   Retract(src);   
          if   (Reserve(strToken))   
              dst   <<   strToken   <<   arrow   <<   "Reserve   Word"   <<   enter;   
          else   
              dst   <<   strToken   <<   arrow   <<   "Identifier"   <<   enter;   
      }   
      //   判断数值的情况   
      else   if   (isdigit(ch))   
      {   
          while   (isdigit(ch))   
          {   
              Concat(strToken,   ch);   
              ch   =   GetChar(src);   
          }   
          Retract(src);   
          dst   <<   strToken   <<   arrow   <<   "Number"   <<   enter;   
      }   
      //   判断字符串的情况   
      else   if   (ch   ==   '\'')   
      {   
          Concat(strToken,   ch);   
          ch   =   GetChar(src);   
          while   (ch   !=   '\'')   
          {   
              Concat(strToken,   ch);   
              ch   =   GetChar(src);   
          }   
          if   (ch   !=   '\'')   
              cerr   <<   "String   is   too   long   -   more   than   1024   bytes!"   <<   endl;   
          else   
          {   
              Concat(strToken,   ch);   
              dst   <<   strToken   <<   arrow   <<   "String"   <<   enter;   
          }   
      }   
      //   过滤注释   
      else   if   (ch   ==   '{')   
      {   
          while   (GetChar(src)   !=   '}')   
              ;   
      }   
      //   判断所有没有歧义的单目运算符   
      else   if   (ch   ==   '+')   
          dst   <<   ch   <<   arrow   <<   "Plus"   <<   enter;   
      else   if   (ch   ==   '-')   
          dst   <<   ch   <<   arrow   <<   "Minus"   <<   enter;   
      else   if   (ch   ==   '*')   
          dst   <<   ch   <<   arrow   <<   "Multiply"   <<   enter;   
      else   if   (ch   ==   '/')   
          dst   <<   ch   <<   arrow   <<   "Divide"   <<   enter;   
      else   if   (ch   ==   '=')   
          dst   <<   ch   <<   arrow   <<   "Equal"   <<   enter;   
      else   if   (ch   ==   '[')   
          dst   <<   ch   <<   arrow   <<   "Left   Square   Brackets"   <<   enter;   
      else   if   (ch   ==   ']')   
          dst   <<   ch   <<   arrow   <<   "Right   Square   Brackets"   <<   enter;   
      else   if   (ch   ==   ',')   
          dst   <<   ch   <<   arrow   <<   "Comma"   <<   enter;   
      else   if   (ch   ==   '^')   
          dst   <<   ch   <<   arrow   <<   "Pointer"   <<   enter;   
      else   if   (ch   ==   ';')   
          dst   <<   ch   <<   arrow   <<   "Semicolon"   <<   enter;   
      else   if   (ch   ==   '(')   
          dst   <<   ch   <<   arrow   <<   "Left   Parenthesis"   <<   enter;   
      else   if   (ch   ==   ')')   
          dst   <<   ch   <<   arrow   <<   "Right   Parenthesis"   <<   enter;   
      //   判断<、<>和<=   
      else   if   (ch   ==   '<')   
      {   
          ch   =   GetChar(src);   
          if   (ch   ==   '>')   
              dst   <<   "<>"   <<   arrow   <<   "Unequal"   <<   enter;   
          else   if   (ch   ==   '=')   
              dst   <<   "<="   <<   arrow   <<   "Less   or   Equal"   <<   enter;   
          else   
          {   
              dst   <<   '<'   <<   arrow   <<   "Less"   <<   enter;   
              Retract(src);   
          }   
      }   
      //   判断>和>=   
      else   if   (ch   ==   '>')   
      {   
          ch   =   GetChar(src);   
          if   (ch   ==   '=')   
              dst   <<   ">="   <<   arrow   <<   "Greater   or   Equal"   <<   enter;   
          else   
          {   
              dst   <<   '>'   <<   arrow   <<   "Greater"   <<   enter;   
              Retract(src);   
          }   
      }   
      //   判断.和..   
      else   if   (ch   ==   '.')   
      {   
          ch   =   GetChar(src);   
          if   (ch   ==   '.')   
              dst   <<   ".."   <<   arrow   <<   "Bound"   <<   enter;   
          else   
          {   
              dst   <<   '.'   <<   arrow   <<   "Point"   <<   enter;   
              Retract(src);   
          }   
      }   
      //   判断:和:=   
      else   if   (ch   ==   ':')   
      {   
          ch   =   GetChar(src);   
          if   (ch   ==   '=')   
              dst   <<   ":="   <<   arrow   <<   "Assign"   <<   enter;   
          else   
          {   
              dst   <<   ':'   <<   arrow   <<   "Colon"   <<   enter;   
              Retract(src);   
          }   
      }   
  }   
  int   main(int   argc,   char*   argv[])   
  {   
      string   strSrc;   
      //   命令行的支持   
      if   (argc   ==   1)   
      {   
          cout   <<   "Please   input   PASCAL   source   file   name:   ";   
          getline(cin,   strSrc);   
      }   
      else   
          strSrc   =   argv[1];   
      //   打开文件   
      ifstream   src(strSrc.c_str());   
      if   (src.fail())   
      {   
          cerr   <<   "\aFailed   openning   \""   <<   strSrc   <<   "\"!"   <<   endl;   
          return   1;   
      }   
      ofstream   dst("Result.txt");   
      //   开始解析   
      while   (!src.eof())   
          Analyzer(src,   dst);   
      //   收尾工作   
      dst.close();   
      src.close();   
      cout   <<   "The   result   of   Analyzing   is   written   into   Result.txt."   <<   endl;   
      return   0;   
  }