public static string Truncate(this string text, int maxLength, TextTruncateType textTruncateType, string trailerText)
{
if (string.IsNullOrEmpty(text))
{
return(string.Empty); //? throw new ArgumentNullException("text");
}
if (maxLength < 0)
{
throw new ArgumentOutOfRangeException("maxLength");
}
if (string.IsNullOrEmpty(trailerText))
{
throw new ArgumentNullException("trailerText");
}
var trailerTextLength = trailerText.Length;
switch (textTruncateType)
{
case TextTruncateType.Normal:
return(text.Length > maxLength ? (maxLength > trailerTextLength ? text.Substring(0, maxLength - trailerTextLength) + trailerText : text.Substring(0, maxLength)) : text);
case TextTruncateType.LastWhitespace:
if (text.Length > maxLength)
{
if (maxLength > trailerTextLength)
{
var truncatedText = text.Substring(0, maxLength - trailerTextLength);
var whiteIndex = truncatedText.LastIndexOf(' ');
string truncatedTextUntilWhite;
return(((whiteIndex > 0) && ((truncatedTextUntilWhite = truncatedText.Substring(0, whiteIndex).Trim()).Length > 0) ? truncatedTextUntilWhite : truncatedText) + trailerText);
}
return(text.Substring(0, maxLength));
}
return(text);
case TextTruncateType.FromAtomSite:
// Add room for a word not breaking and the trailer
var b = new StringBuilder(maxLength + 20);
var words = text.Split(new char[] { ' ' });
var index = 0;
while (b.Length + words[index].Length + trailerTextLength < maxLength - trailerTextLength && index < words.GetUpperBound(0))
{
b.Append(words[index]);
b.Append(" ");
index++;
}
// We exited the loop before reaching the end of the array - which would normally be the case.
if (index < words.GetUpperBound(0))
{
// Remove the ending space before attaching the trailer.
b.Remove(b.Length - 1, 1);
b.Append(trailerText);
}
else
{
b.Append(words[index]);
}
return(b.ToString());
default:
throw new InvalidOperationException();
}
}
/// <summary>
/// Truncates the specified text.
/// </summary>
/// <param name="text">The text.</param>
/// <param name="maxLength">Length of the max.</param>
/// <param name="textTruncateType">Type of the text truncate.</param>
/// <returns></returns>
public static string Truncate(this string text, int maxLength, TextTruncateType textTruncateType)
{
return(Truncate(text, maxLength, textTruncateType, "..."));
}
