Parse string

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
        List<string> rows = new List<string>();
        while (true)
        {
            string row = Console.ReadLine();
            rows.Add(row);
            if (row.StartsWith("?>"))
            {
                break;
            }
        }
        bool inNormalBrackets2 = false;
        bool inNormalBrackets = false;
        bool inComment = false; /* global */
        bool inDoubleQuotes = false; //
        bool inSingleQuotes = false;
        bool inBrackets = false;
        bool isVariable = false; //

        StringBuilder sb = new StringBuilder();
        List<string> variables = new List<string>();
        for (int i = 0; i < rows.Count; i++)
        {
            List<string> buffer = new List<string>();
            string nextRow;
            nextRow = rows[i];
            char nextChar;
            for (int pos = 0; pos < nextRow.Length; pos++)
            {
                nextChar = nextRow[pos];
                string test = nextChar.ToString();
                if (nextChar == ';')
                {
                    foreach (var item in buffer)
                    {
                        if (!variables.Contains(item))
                        {
                            variables.Add(item);
                        }
                    }
                }
                if (isVariable == true)
                {
                    if (sb.Length == 0)
                    {
                       if (Regex.Matches(test,"[a-zA-Z_]+").Count > 0)
                       {

                       }
                       else
                       {
                           isVariable = false;
                           continue;
                       }
                    }

                    if (Regex.Matches(test,"\\w+").Count == 0)
                    {
                        if (sb.Length > 0)
                        {
                            if (!buffer.Contains(sb.ToString()))
                            {
                                buffer.Add(sb.ToString());
                            }
                            sb.Clear();
                        }
                        isVariable = false;
                    }
                    else
                    {
                        sb.Append(nextChar);
                    }
                }
                if (nextChar == '#' && inSingleQuotes == false && inDoubleQuotes == false)
                {
                    break;
                }
                if (nextChar == '\\') //in test
                {
                    pos++;
                    continue;
                }
                if (nextChar == '/' && inSingleQuotes == false && inDoubleQuotes == false )
                {
                    if (pos < nextRow.Length - 1)
                    {
                        if (nextRow[pos + 1] == '/') // comment to the end
                        {
                            break;
                        }
                        else if (nextRow[pos + 1] == '*') /* */
                        {
                            inComment = true;
                            pos++;
                        }
                    }
                }
                if (nextChar == '\'') // inSingleQuote
                {
                    if (inSingleQuotes == true)
                    {
                        inSingleQuotes = false;
                    }
                    else
                    {
                        inSingleQuotes = true;
                    }
                }
                if (nextChar == '{')
                {
                    inBrackets = true;
                }
                if (nextChar == '}')
                {
                    inBrackets = false;
                }
                if (nextChar == '[')
                {
                    inNormalBrackets = true;
                }
                if (nextChar == ']')
                {
                    inNormalBrackets = true;
                }
                if (nextChar == '(')
                {
                    inNormalBrackets2 = true;
                }
                if (nextChar == ')')
                {
                    inNormalBrackets2 = false;
                }
                if (nextChar == '"') //inDoubleQuote
                {
                    if (inDoubleQuotes == true)
                    {
                        inDoubleQuotes = false;
                    }
                    else
                    {
                        inDoubleQuotes = true;
                    }
                }
                if (nextChar == '*' && inSingleQuotes == false && inDoubleQuotes == false)
                {
                    if (pos < nextRow.Length - 1)
                    {
                        if (nextRow[pos + 1] == '/') // end of comment
                        {
                            inComment = false;
                            pos++;
                        }
                    }
                }
                if (nextChar == '$' && inComment == false)
                {
                    if (inSingleQuotes == false)
                    {
                        isVariable = true;
                    }
                    else if (inSingleQuotes == true && inBrackets == true)
                    {
                        isVariable = true;
                    }
                    else if (inSingleQuotes == true && inNormalBrackets == true)
                    {
                        isVariable = true;
                    }
                    else if (inSingleQuotes == true && inNormalBrackets2 == true)
                    {
                        isVariable = true;
                    }
                }
            }

        }
        Console.WriteLine(variables.Count);
        variables.Sort();
        foreach (var item in variables)
        {
            Console.WriteLine(item);
        }
    }
}