using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Lab_Final
{
    struct wt
    {
        public string Word;
        public string Type;

        public wt(string w, string t)
        {
            Word = w;
            Type = t;
        }
    }
    class Lexical
    {
        public static ArrayList ALLex = new ArrayList();

        public static void Lex(string st)
        {
            int i = 0;
            char c;
            char[] ch = st.ToCharArray(0, st.Length);
            string w = "";

            c = getchar(ref i, ch);
            while (c != '$')
            {
                w = "";
                if ((c == ' ') || (c == '\r') || (c == '\n') || (c == '\t'))
                {
                    c = getchar(ref i, ch);
                    continue;
                }
                else if (char.IsLetter(c))
                {
                    w += c;
                    c = getchar(ref i, ch);
                    while (char.IsLetter(c))
                    {
                        w += c;
                        c = getchar(ref i, ch);
                    }
                    if (RW(w))
                    {
                        ALLex.Add(new wt(w, "RW"));
                        w = "";
                    }
                    else
                    {
                        ALLex.Add(new wt(w, "ID"));
                    }
                    unget(ref i, ch);

                }
                else if (char.IsDigit(c))
                {
                    w += c;
                    c = getchar(ref i, ch);
                    while (char.IsDigit(c))
                    {
                        w += c;
                        c = getchar(ref i, ch);
                    }
                    if (c == '.')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        while (char.IsDigit(c))
                        {
                            w += c;
                            c = getchar(ref i, ch);
                        }
                        unget(ref i, ch);
                        ALLex.Add(new wt(w, "float_const"));
                    }
                    else
                    {
                        ALLex.Add(new wt(w, "int_const"));
                        unget(ref i, ch);
                    }
                }
                else if (OP(c))
                {
                    if (c == '=')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        if (c == '=')
                        {
                            w += c;
                            ALLex.Add(new wt(w, "OP"));
                        }
                        else
                        {
                            ALLex.Add(new wt(w, "OP"));
                            unget(ref i, ch);
                        }
                    }
                    else if (c == '!')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        if (c == '=')
                        {
                            w += c;
                            ALLex.Add(new wt(w, "OP"));
                        }
                        else
                        {
                            ALLex.Add(new wt(w, "OP"));
                            unget(ref i, ch);
                        }
                    }
                    else if (c == '<')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        if (c == '=')
                        {
                            w += c;
                            ALLex.Add(new wt(w, "OP"));
                        }
                        else
                        {
                            ALLex.Add(new wt(w, "OP"));
                            unget(ref i, ch);
                        }
                    }
                    else if (c == '>')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        if (c == '=')
                        {
                            w += c;
                            ALLex.Add(new wt(w, "OP"));
                        }
                        else
                        {
                            ALLex.Add(new wt(w, "OP"));
                            unget(ref i, ch);
                        }
                    }
                    else if (c == '|')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        if (c == '|')
                        {
                            w += c;
                            ALLex.Add(new wt(w, "OP"));
                        }
                        else
                        {

                        }
                        unget(ref i, ch);
                    }
                    else if (c == '&')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                        if (c == '&')
                        {
                            w += c;
                            ALLex.Add(new wt(w, "OP"));
                        }
                        else
                        {

                        }
                        unget(ref i, ch);
                    }
                    else
                    {
                        w += c;
                        ALLex.Add(new wt(w, "OP"));
                    }
                }
                else if (c == '"')
                {
                    w += c;
                    c = getchar(ref i, ch);
                    while (c != '"')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                    }
                    w += c;
                    ALLex.Add(new wt(w, "string_const"));
                }
                else if (c == '@')
                {
                    w += c;
                    c = getchar(ref i, ch);
                    while (c != '@')
                    {
                        w += c;
                        c = getchar(ref i, ch);
                    }
                    w += c;
                }
                c = getchar(ref i, ch);
            }
            ALLex.Add(new wt("$", "$"));
        }
        public static char getchar(ref int i, char[] ch)
        {
            char c;
            c = ch[i];
            i++;
            return c;
        }
        public static char unget(ref int i, char[] ch)
        {
            i--;
            char c;
            c = ch[i];
            return c;
        }
        public static void print()
        {
            foreach (wt tk in ALLex)
            {
                Console.WriteLine("\t" + tk.Word + "\t" + tk.Type);
            }
        }
        public static bool RW(string s)
        {
            switch (s)
            {
                case "int":
                case "float":
                case "string":
                case "Program":
                case "begin":
                case "end":
                case "fun":
                case "call":
                case "while":
                    return true;
                default:
                    return false;
            }
        }
        public static bool OP(char c)
        {
            switch (c)
            {
                case '=':
                case '+':
                case '-':
                case '*':
                case '/':
                case '(':
                case ')':
                case ';':
                case ',':
                case '<':
                case '>':
                case '!':
                case '|':
                case '&':
                    return true;
                default:
                    return false;
            }
        }
    }
}