////////////////////////////////////////////////////////////////////////////
/// Automaton for recognizing valid C identifiers
/// @author Suradet Jitprapaikulsarn
/// @date   2005 June 28
/// @remark Microsoft Visual C++ 2003
/// @note   Copyright (C) 2005 Suradet Jitprapaikulsarn
////////////////////////////////////////////////////////////////////////////

#include "State.h"
#include "InputSymbol.h"
#include <cctype>
#include <iostream>
#include <fstream>
#include <string>

//**************************************************************************
// Prototypes
//**************************************************************************
bool scan(const std::string & fileName);
InputSymbol checkType(char ch);

//**************************************************************************
// main
//**************************************************************************
int main()
{
    std::string fileName;
    std::cout << "Please enter the C source file name : ";
    std::cin >> fileName;
    if ( !scan(fileName) )
    {
        std::cerr << "Error!!!  Failed to scan the file " << fileName << "\n";
    }

    return 0;
}

//==========================================================================
// @description scan a file for valid C idenifiers assuming there is no comment
// @param fileName the name of the input file
// @return true if success, false otherwise
// @contract scan: string -> bool
// @example scan("test.c") == false
// @example scan("scan.cpp") == true
// @example scan("state.h") == true
//==========================================================================
bool scan(const std::string & fileName)
{
    std::ifstream   ifs(fileName.c_str());

    // Check if the file can be opened
    if ( !ifs ) return false;

    char ch;
    State currentState = s0;
    InputSymbol type;
    std::string token = "";
    while (ifs)
    {
        ch = ifs.get();
        type = checkType(ch);
        switch (currentState)
        {
        case s0:
            switch (type)
            {
            case English:
                token += ch;
                currentState = s1;
                break;
            case Underscore:
                token += ch;
                currentState = s1;
                break;
            case Number:
                break;
            case Others:
                break;
            default:
                std::cerr << "Invalid type of symbols\n";
            } // switch type
            break;
        case s1:
            switch (type)
            {
            case English:
                token += ch;
                break;
            case Underscore:
                token += ch;
                break;
            case Number:
                token += ch;
                break;
            case Others:
                std::cout << "token = " << token << "\n";
                currentState = s0;
                token = "";
                break;
            default:
                std::cerr << "Invalid type of symbols\n";
            } // switch type
            break;
        default:
            std::cerr << "Invalid state\n";
        } // switch state
    } // while

    return true;
}

//==========================================================================
// @description determine the group of symbols of the input character
// @param ch the input character
// @return the name of the group of symbols
// @contract checkType : int -> InputSymbol
// @example checkType('c') == English
// @example checkType('_') == Underscore
// @example checkType('5') == Number
// @example checkType(' ') == Others
//==========================================================================
InputSymbol checkType(char ch)
{
    if ( std::isalpha(ch) )
    {
        return English;
    }
    else if ( ch == '_' )
    {
        return Underscore;
    }
    else if ( std::isdigit(ch) )
    {
        return Number;
    }
    else
    {
        return Others;
    }
}