#include <iostream>
#include <fstream>
#include <string>
//#include <string.h>
#include <ctype.h>

using namespace std;
// 保留字?jǐn)?shù)組定義
char* ReserveWords[33] = {
  "and", "array", "begin", "case","char" "constant", "do",  "else", "end", "false",
  "for",  "if", "input", "integer", "not", "of", "or", "output","packed",
  "procedure", "program", "read", "real","repeat", "set", "then", "to", "type", "until", 
  "var","while", "with","write"
};
char arrow[] = " -----> ";
char enter[] = "\r\n";
// 讀入ch
char Get_char(ifstream& src)
{
  char cRet;
 // src.get(cRet);
  for(int i=0;i<src.size();i++)
  src.get(cRet);
  return cRet;
}
// 讀入空格
char Get_blank_char(ifstream& src)
{
  char cRet;
 // src.get(cRet);
  while (cRet == ' ')
    src.get(cRet);
  return cRet;
}
// 連接單詞符號
void Contact(char *str, char c)
{
  size_t n = strlen(str);
  str[n++] = c;
  str[n] = '\0';
}
// 判斷是否為保留字
bool Reserve_words(const char* str)
{
  bool bRet = false;
  for (int i = 0; i < 33; i++)
  {
    if (_stricmp(ReserveWords[i], str) == 0)
    {
      bRet = true;
      break;
    }
  }
  return bRet;
}
// 回調(diào)字符
char Retract(ifstream& src)
{
  src.seekg(-1, ios::cur);
  return '\0';
}
// 分析函數(shù)
void Analyzer(ifstream& src, ofstream& dst)
{
  char ch;
  char strToken[1024] = " ";
  ch = GetBC(src);
  // 判斷標(biāo)識符的情況
  if (isalpha(ch))
  {
    while (isalpha(ch) || isdigit(ch) || ch == '_')
    {
      Contact(strToken, ch);
      ch = Get_char(src);
    }
    ch = Retract(src);
    if (Reserve_words(strToken))
      dst << strToken << arrow << "Reserve Word" << enter;
    else
      dst << strToken << arrow << "Identifier" << enter;
  }
  // 判斷數(shù)值的情況
  else if (isdigit(ch))
  {
    while (isdigit(ch))
    {
      Contact(strToken, ch);
      ch = GetChar(src);
    }
    Retract(src);
    dst << strToken << arrow << "Number" << enter;
  }
  // 判斷字符串的情況
  else if (ch == '\'')
  {
    Contact(strToken, ch);
    ch = Get_char(src);
    while (ch != '\'')
    {
      Contact(strToken, ch);
      ch = Get_char(src);
    }
    if (ch != '\'')
      cerr << "String is too long - more than 1024 bytes!" << endl;
    else
    {
      Contact(strToken, ch);
      dst << strToken << arrow << "String" << enter;
    }
  }
  // 過濾注釋
  else if (ch == '{')
  {
    while (Get_char(src) != '}')
      ;
  }
  // 判斷所有沒有歧義的單目運算符
  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;
  // 判斷<、<>和<=
  else if (ch == '<')
  {
    ch = Get_char(src);
    if (ch == '>')
      dst << "<>" << arrow << "Unequal" << enter;
    else if (ch == '=')
      dst << "<=" << arrow << "Less or Equal" << enter;
    else
    {
      dst << '<' << arrow << "Less" << enter;
      Retract(src);
    }
  }
  // 判斷>和>=
  else if (ch == '>')
  {
    ch = Get_char(src);
    if (ch == '=')
      dst << ">=" << arrow << "Greater or Equal" << enter;
    else
    {
      dst << '>' << arrow << "Greater" << enter;
      Retract(src);
    }
  }
  // 判斷.和..
  else if (ch == '.')
  {
    ch = Get_char(src);
    if (ch == '.')
      dst << ".." << arrow << "Bound" << enter;
    else
    {
      dst << '.' << arrow << "Point" << enter;
      Retract(src);
    }
  }
  // 判斷:和:=
  else if (ch == ':')
  {
    ch = Get_char(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];
  // 打開文件
  ifstream src(strSrc.c_str());
  if (src.fail())
  {
    cerr << "\aFailed openning \"" << strSrc << "\"!" << endl;
    return 1;
  }
  ofstream dst("Result.txt");
  // 開始解析
  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;
}