/// <summary>
/// Helper method to count how many times the given string appears in this string.
/// </summary>
/// <param name="str">This <see cref="String"/>.</param>
/// <param name="substring">The string to search. May be <c>null</c>, in which case result is <c>0</c>.</param>
/// <param name="comparison">The <see cref="StringComparison"/> to use.</param>
/// <returns>The amount of times <paramref name="substring"/> appears in this <see cref="String"/>.</returns>
/// <exception cref="NullReferenceException">If this <see cref="String"/> is <c>null</c>.</exception>
public static Int32 CountOccurrances(this String str, String substring, StringComparison comparison)
{
ArgumentValidator.ValidateNotNullReference(str);
var count = 0;
if (!String.IsNullOrEmpty(substring))
{
var idx = 0;
while ((idx = str.IndexOf(substring, idx, comparison)) != -1)
{
idx += substring.Length;
++count;
}
}
return(count);
}
/// <summary>
/// Creates the default encoding information for given <see cref="Encoding"/>.
/// </summary>
/// <param name="encoding">This <see cref="Encoding"/>.</param>
/// <returns>A new instance of <see cref="IEncodingInfo"/>.</returns>
/// <exception cref="InvalidOperationException">If this method could not automatically deduct which <see cref="IEncodingInfo"/> to create.</exception>
public static IEncodingInfo CreateDefaultEncodingInfo(this Encoding encoding)
{
ArgumentValidator.ValidateNotNullReference(encoding);
switch (encoding)
{
#if !NETSTANDARD1_0 && !NETSTANDARD1_1
case ASCIIEncoding ascii:
return(ASCIIEncodingInfo.Instance);
#endif
case UTF8Encoding utf8:
return(new UTF8EncodingInfo(utf8));
case UnicodeEncoding utf16:
if (ReferenceEquals(utf16, Encoding.Unicode))
{
return(new UTF16LEEncodingInfo(utf16));
}
else if (ReferenceEquals(utf16, Encoding.BigEndianUnicode) || UTF16EncodingInfo.IsBigEndian(utf16))
{
return(new UTF16BEEncodingInfo(utf16));
}
else
{
return(new UTF16LEEncodingInfo(utf16));
}
#if NET_40 || NETSTANDARD1_5 || NET_45
case UTF32Encoding utf32:
return(new UTF32EncodingInfo(utf32));
#endif
case null:
return(null);
default:
throw new InvalidOperationException($"Could not create default encoding info for {encoding}.");
}
}