TextUtils.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;

namespace LumiSoft.Net
{
	/// <summary>
	/// This class provides usefull text methods.
	/// </summary>
	public class TextUtils
	{      
		#region static method QuoteString

		/// <summary>
        /// Qoutes string and escapes fishy('\',"') chars.
        /// </summary>
        /// <param name="text">Text to quote.</param>
        /// <returns></returns>
        public static string QuoteString(string text)
        {
            // String is already quoted-string.
            if(text != null && text.StartsWith("\"") && text.EndsWith("\"")){
                return text;
            }

            StringBuilder retVal = new StringBuilder();

            for(int i=0;i<text.Length;i++){
                char c = text[i];

                if(c == '\\'){
                    retVal.Append("\\\\");
                }
                else if(c == '\"'){
                    retVal.Append("\\\"");
                }
                else{
                    retVal.Append(c);
                }
            }

            return "\"" + retVal.ToString() + "\"";
        }

		#endregion
         
        #region static method UnQuoteString

        /// <summary>
        /// Unquotes and unescapes escaped chars specified text. For example "xxx" will become to 'xxx', "escaped quote \"", will become to escaped 'quote "'.
        /// </summary>
        /// <param name="text">Text to unquote.</param>
        /// <returns></returns>
        public static string UnQuoteString(string text)
        {
            int startPosInText = 0;
            int endPosInText   = text.Length;
           
            //--- Trim. We can't use standard string.Trim(), it's slow. ----//
            for(int i=0;i<endPosInText;i++){
                char c = text[i];
                if(c == ' ' || c == '\t'){
                    startPosInText++;
                }
                else{
                    break;
                }
            }
            for(int i=endPosInText-1;i>0;i--){
                char c = text[i];
                if(c == ' ' || c == '\t'){
                    endPosInText--;
                }
                else{
                    break;
                }
            }
            //--------------------------------------------------------------//
         
            // All text trimmed
            if((endPosInText - startPosInText) <= 0){
                return "";
            }
            
            // Remove starting and ending quotes.         
            if(text[startPosInText] == '\"'){
				startPosInText++;
			}
			if(text[endPosInText - 1] == '\"'){
				endPosInText--;
			}

            // Just '"'
            if(endPosInText == startPosInText - 1){
                return "";
            }

            char[] chars = new char[endPosInText - startPosInText];
            
            int posInChars = 0;
            bool charIsEscaped = false;
            for(int i=startPosInText;i<endPosInText;i++){
                char c = text[i];

                // Escaping char
                if(!charIsEscaped && c == '\\'){
                    charIsEscaped = true;
                }
                // Escaped char
                else if(charIsEscaped){
                    // TODO: replace \n,\r,\t,\v ???
                    chars[posInChars] = c;
                    posInChars++;
                    charIsEscaped = false;
                }
                // Normal char
                else{
                    chars[posInChars] = c;
                    posInChars++;
                    charIsEscaped = false;
                }
            }

            return new string(chars,0,posInChars);
        }

        #endregion

        #region static method EscapeString

        /// <summary>
        /// Escapes specified chars in the specified string.
        /// </summary>
        /// <param name="text">Text to escape.</param>
        /// <param name="charsToEscape">Chars to escape.</param>
		public static string EscapeString(string text,char[] charsToEscape)
        {
            // Create worst scenario buffer, assume all chars must be escaped
            char[] buffer = new char[text.Length * 2];
            int nChars = 0;
            foreach(char c in text){
                foreach(char escapeChar in charsToEscape){
                    if(c == escapeChar){
                        buffer[nChars] = '\\';
                        nChars++;
                        break;
                    }
                }

                buffer[nChars] = c;
                nChars++;
            }

            return new string(buffer,0,nChars);
        }

        #endregion

        #region static method UnEscapeString

        /// <summary>
        /// Unescapes all escaped chars.
        /// </summary>
        /// <param name="text">Text to unescape.</param>
        /// <returns></returns>
        public static string UnEscapeString(string text)
        {
            // Create worst scenarion buffer, non of the chars escaped.
            char[] buffer = new char[text.Length];
            int nChars = 0;
            bool escapedCahr = false;
            foreach(char c in text){
                if(!escapedCahr && c == '\\'){
                    escapedCahr = true;
                }
                else{
                    buffer[nChars] = c;
                    nChars++;
                    escapedCahr = false;
                }                
            }

            return new string(buffer,0,nChars);
        }

        #endregion


		#region static method SplitQuotedString

        /// <summary>
		/// Splits string into string arrays. This split method won't split qouted strings, but only text outside of qouted string.
		/// For example: '"text1, text2",text3' will be 2 parts: "text1, text2" and text3.
		/// </summary>
		/// <param name="text">Text to split.</param>
		/// <param name="splitChar">Char that splits text.</param>
		/// <returns></returns>
		public static string[] SplitQuotedString(string text,char splitChar)
		{
            return SplitQuotedString(text,splitChar,false);
        }

		/// <summary>
		/// Splits string into string arrays. This split method won't split qouted strings, but only text outside of qouted string.
		/// For example: '"text1, text2",text3' will be 2 parts: "text1, text2" and text3.
		/// </summary>
		/// <param name="text">Text to split.</param>
		/// <param name="splitChar">Char that splits text.</param>
		/// <param name="unquote">If true, splitted parst will be unqouted if they are qouted.</param>
		/// <returns></returns>
		public static string[] SplitQuotedString(string text,char splitChar,bool unquote)
		{
			return SplitQuotedString(text,splitChar,unquote,int.MaxValue);
		}

        /// <summary>
		/// Splits string into string arrays. This split method won't split qouted strings, but only text outside of qouted string.
		/// For example: '"text1, text2",text3' will be 2 parts: "text1, text2" and text3.
		/// </summary>
		/// <param name="text">Text to split.</param>
		/// <param name="splitChar">Char that splits text.</param>
		/// <param name="unquote">If true, splitted parst will be unqouted if they are qouted.</param>
        /// <param name="count">Maximum number of substrings to return.</param>
		/// <returns>Returns splitted string.</returns>
        /// <exception cref="ArgumentNullException">Is raised when <b>text</b> is null reference.</exception>
		public static string[] SplitQuotedString(string text,char splitChar,bool unquote,int count)
		{
            if(text == null){
                throw new ArgumentNullException("text");
            }

			List<string>  splitParts     = new List<string>();  // Holds splitted parts
            int           startPos       = 0;
			bool          inQuotedString = false;               // Holds flag if position is quoted string or not
            char          lastChar       = '0';

            for(int i=0;i<text.Length;i++){
			    char c = text[i];

                // We have exceeded maximum allowed splitted parts.
                if((splitParts.Count + 1) >= count){
                    break;
                }

                // We have quoted string start/end.
                if(lastChar != '\\' && c == '\"'){
                    inQuotedString = !inQuotedString;
                }
                // We have escaped or normal char.
                //else{

                // We igonre split char in quoted-string.
                if(!inQuotedString){
                    // We have split char, do split.
                    if(c == splitChar){
                        if(unquote){
					        splitParts.Add(UnQuoteString(text.Substring(startPos,i - startPos)));
                        }
                        else{                        
                            splitParts.Add(text.Substring(startPos,i - startPos));
                        }
                                               
                        // Store new split part start position.
                        startPos = i + 1;                        
                    }
                }
                //else{

                lastChar = c;
			}
                        
			// Add last split part to splitted parts list
            if(unquote){
			    splitParts.Add(UnQuoteString(text.Substring(startPos,text.Length - startPos)));
            }
            else{
                splitParts.Add(text.Substring(startPos,text.Length - startPos));
            }

			return splitParts.ToArray();
		}

		#endregion


		#region method QuotedIndexOf

		/// <summary>
		/// Gets first index of specified char. The specified char in quoted string is skipped.
		/// Returns -1 if specified char doesn't exist.
		/// </summary>
		/// <param name="text">Text in what to check.</param>
		/// <param name="indexChar">Char what index to get.</param>
		/// <returns></returns>
		public static int QuotedIndexOf(string text,char indexChar)
		{
			int  retVal         = -1;
			bool inQuotedString = false; // Holds flag if position is quoted string or not			
			for(int i=0;i<text.Length;i++){
				char c = text[i];

				if(c == '\"'){
					// Start/end quoted string area
					inQuotedString = !inQuotedString;
				}

				// Current char is what index we want and it isn't in quoted string, return it's index
				if(!inQuotedString && c == indexChar){
					return i;
				}
			}

			return retVal;
		}

		#endregion


		#region static method SplitString

		/// <summary>
		/// Splits string into string arrays.
		/// </summary>
		/// <param name="text">Text to split.</param>
		/// <param name="splitChar">Char Char that splits text.</param>
		/// <returns></returns>
		public static string[] SplitString(string text,char splitChar)
		{
			ArrayList splitParts = new ArrayList();  // Holds splitted parts

			int lastSplitPoint = 0;
			int textLength     = text.Length;
			for(int i=0;i<textLength;i++){
				if(text[i] == splitChar){
					// Add current currentSplitBuffer value to splitted parts list
					splitParts.Add(text.Substring(lastSplitPoint,i - lastSplitPoint));

					lastSplitPoint = i + 1;
				}
			}
			// Add last split part to splitted parts list
			if(lastSplitPoint <= textLength){
				splitParts.Add(text.Substring(lastSplitPoint));
			}

			string[] retVal = new string[splitParts.Count];
			splitParts.CopyTo(retVal,0);

			return retVal;
		}

		#endregion


        #region static method IsToken

        /// <summary>
        /// Gets if specified string is valid "token" value.
        /// </summary>
        /// <param name="value">String value to check.</param>
        /// <returns>Returns true if specified string value is valid "token" value.</returns>
        /// <exception cref="ArgumentNullException">Is raised if <b>value</b> is null.</exception>
        public static bool IsToken(string value)
        {
            if(value == null){
                throw new ArgumentNullException(value);
            }

            /* This syntax is taken from rfc 3261, but token must be universal so ... .
                token    =  1*(alphanum / "-" / "." / "!" / "%" / "*" / "_" / "+" / "`" / "'" / "~" )
                alphanum = ALPHA / DIGIT
                ALPHA    =  %x41-5A / %x61-7A   ; A-Z / a-z
                DIGIT    =  %x30-39             ; 0-9
            */

            char[] tokenChars = new char[]{'-','.','!','%','*','_','+','`','\'','~'};
            foreach(char c in value){
                // We don't have letter or digit, so we only may have token char.
                if(!((c >= 0x41 && c <= 0x5A) || (c >= 0x61 && c <= 0x7A) || (c >= 0x30 && c <= 0x39))){
                    bool validTokenChar = false;
                    foreach(char tokenChar in tokenChars){
                        if(c == tokenChar){
                            validTokenChar = true;
                            break;
                        }
                    }
                    if(!validTokenChar){
                        return false;
                    }
                }
            }

            return true;
        }

        #endregion
    }
}