C#索引属性使用范例源码

将开发过程中常用的内容记录起来，下面的资料是关于C#索引属性使用范例的代码。

using System;

public class Document { public class WordCollection {

    internal WordCollection(Document d)
    {
       document = d;
    }

    private bool GetWord(char[] text, int begin, int wordCount, 

out int start, out int length) { int end = text.Length; int count = 0; int inWord = -1; start = length = 0;

        for (int i = begin; i <= end; ++i) 
        {
            bool isLetter = i < end && Char.IsLetterOrDigit(text[i]);

            if (inWord >= 0) 
            {
                if (!isLetter) 
                {
                    if (count++ == wordCount) 
                    {
                        start = inWord;
                        length = i - inWord;
                        return true;
                    }
                    inWord = -1;
                }
            }
            else 
            {
                if (isLetter)
                    inWord = i;
            }
        }
        return false;
    }

    public string this[int index] 
    {
        get 
        { 
            int start, length;
            if (GetWord(document.TextArray, 0, index, out start, 
                  out length))
                return new string(document.TextArray, start, length);
            else
                throw new IndexOutOfRangeException();
        }
        set 
        {
            int start, length;
            if (GetWord(document.TextArray, 0, index, out start, 
                 out length)) 
            {
                if (length == value.Length) 
                {
                    Array.Copy(value.ToCharArray(), 0, 
                             document.TextArray, start, length);
                }
                else 
                {
                    char[] newText = 
                        new char[document.TextArray.Length + 
   value.Length - length];
                    Array.Copy(document.TextArray, 0, newText, 
                0, start);
                    Array.Copy(value.ToCharArray(), 0, newText, 
     start, value.Length);
                    Array.Copy(document.TextArray, start + length,
                               newText, start + value.Length,
                              document.TextArray.Length - start
                    - length);
                    document.TextArray = newText;
                }
            }                    
            else
                throw new IndexOutOfRangeException();
        }
    }

    public int Count 
    {
        get 
        { 
            int count = 0, start = 0, length = 0;
            while (GetWord(document.TextArray, start + length, 0, 
      out start, out length))
                ++count;
            return count; 
        }
    }
}

public class CharacterCollection
{

    internal CharacterCollection(Document d)
    {
      document = d; 
    }

    public char this[int index] 
    {
        get 
        { 
            return document.TextArray[index]; 
        }
        set 
        { 
            document.TextArray[index] = value; 
        }
    }

    public int Count 
    {
        get 
        { 
            return document.TextArray.Length; 
        }
    }
}

public WordCollection Words;
public CharacterCollection Characters;


public Document(string initialText)
{
    TextArray = initialText.ToCharArray();
    Words = new WordCollection(this);
    Characters = new CharacterCollection(this);
}

public string Text 
{
    get 
    { 
       return new string(TextArray); 
    }
}

}

class Test { static void Main() { Document d = new Document( "peter piper picked a peck of pickled peppers. How many pickled peppers did peter piper pick?" );

    for (int i = 0; i < d.Words.Count; ++i) 
    {
        if (d.Words[i] == "peter") 
            d.Words[i] = "penelope";
    }

    for (int i = 0; i < d.Characters.Count; ++i) 
    {
        if (d.Characters[i] == 'p')
            d.Characters[i] = 'P';
    }
    
    Console.WriteLine(d.Text);
}

}