My string helper class in C#

Keywords: C#, string helper class.

下面的类是我经常会使用到的, 它是用来帮助从一个string中提取substring. 我在设计这些代码时, 主要考虑的是代码的易用性, 并没有太多地在意执行效率的问题. 注意:这些功能通常也可以通过正则表达式来实现, 但不如下面的代码来的快.

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

namespace LiuHarry.Utils.Foundation
{
    public class StrHelper
    {


        /// <summary>
        /// return the first nested-substring of source string be contained in enveloped pattern.
        /// </summary>
        /// <param name="sourceStr">the entire source string</param>
        /// <param name="leftSeparator">left separator string of pattern</param>
        /// <param name="rightSeparator">right separator string of pattern</param>
        /// <param name="patternEndIndex">pattern end index in source string </param>
        /// <returns>nested-substring</returns>
        private static string GetNestedString(string sourceStr, string leftSeparator, string rightSeparator, out int patternEndIndex)
        {
            patternEndIndex = -1; 
            if (String.IsNullOrEmpty(sourceStr)  )
                return null ;

            int startIndex = sourceStr.IndexOf(leftSeparator);
            if (startIndex<0)
                return null ;
            else
            {
                startIndex = startIndex + leftSeparator.Length;
            }
            int endIndex = sourceStr.IndexOf(rightSeparator, startIndex + 1);
            if (endIndex<0)
            {
                return null;
            }
            else // "123##"67"
            {
                patternEndIndex = endIndex + rightSeparator.Length - 1;
            }
            string result = sourceStr.Substring(startIndex, endIndex - startIndex);
            return result;
        }


        /// <summary>
        /// return the first nested-substring of source string be contained in enveloped pattern in sourceStr.
        /// </summary>
        /// <param name="sourceStr">the entire source string</param>
        /// <param name="leftSeparator">left separator string of pattern</param>
        /// <param name="rightSeparator">right separator string of pattern</param>
        /// <returns>nested-substring</returns>
        public static string GetNestedSubString(string sourceStr,  string leftSeparator, string rightSeparator)
        {
            int patternEndIndex;
            return GetNestedString(sourceStr, leftSeparator, rightSeparator, out patternEndIndex);
        }




        /// <summary>
        /// return given ignoreMatchedCount nested-substring of source string be contained in enveloped pattern
        /// </summary>
        /// <param name="sourceStr">the entire source string</param>
        /// <param name="leftSeparator">left separator string of pattern</param>
        /// <param name="rightSeparator">right separator string of pattern</param>
        /// /// <param name="ignoreMatchedCount">ignore the match pattern count</param>
        /// <returns>nested-substring</returns>
        public static string GetNestedSubString(string sourceStr,string leftSeparator,string rightSeparator,int ignoreMatchedCount)
        {
            int patternEndIndex;
            string tempStr = sourceStr;
            string resultStr = null ;
            for (int i=0;i<=ignoreMatchedCount;i++)
            {
                resultStr = GetNestedString(tempStr, leftSeparator, rightSeparator, out patternEndIndex);
                tempStr = tempStr.Substring(patternEndIndex+1);
            }
            return resultStr;
        }



        /// <summary>
        /// return all nested-substring of source string be contained in  enveloped pattern
        /// </summary>
        /// <param name="sourceStr">the entire source string </param>
        /// <param name="leftSeparator">left separator string of pattern</param>
        /// <param name="rightSeparator">right separator string of pattern</param>
        /// <returns>a List<string> collection of all nested-substring </returns>
        public static List<string> GetAllNestedSubString(string sourceStr, string leftSeparator, string rightSeparator)
        {
            List<string> listNestedSubStr = new List<string>();
            int ignoreMatchedCount= 0 ;
            string nestSubStr=null ;
            while (true )
            {   
                nestSubStr=GetNestedSubString( sourceStr, leftSeparator, rightSeparator,ignoreMatchedCount);
                if (nestSubStr==null)
                    break ;
                else
                {
                    listNestedSubStr.Add(nestSubStr);
                    ignoreMatchedCount = ignoreMatchedCount+1;
                }
            }
            return listNestedSubStr ;
        }
    }
}