/// <summary>
/// Reports the zero-based index of the first occurrence of the specified <paramref name="value"/> in the current <paramref name="span"/>.
/// <param name="span">The source span.</param>
/// <param name="value">The value to seek within the source span.</param>
/// <param name="comparisonType">One of the enumeration values that determines how the <paramref name="span"/> and <paramref name="value"/> are compared.</param>
/// </summary>
public static int IndexOf(this ReadOnlySpan <char> span, ReadOnlySpan <char> value, StringComparison comparisonType)
{
string.CheckStringComparison(comparisonType);
if (value.Length == 0)
{
return(0);
}
if (span.Length == 0)
{
return(-1);
}
switch (comparisonType)
{
case StringComparison.CurrentCulture:
return(SpanHelpers.IndexOfCultureHelper(span, value, CultureInfo.CurrentCulture.CompareInfo));
case StringComparison.CurrentCultureIgnoreCase:
return(SpanHelpers.IndexOfCultureIgnoreCaseHelper(span, value, CultureInfo.CurrentCulture.CompareInfo));
case StringComparison.InvariantCulture:
return(SpanHelpers.IndexOfCultureHelper(span, value, CompareInfo.Invariant));
case StringComparison.InvariantCultureIgnoreCase:
return(SpanHelpers.IndexOfCultureIgnoreCaseHelper(span, value, CompareInfo.Invariant));
case StringComparison.Ordinal:
return(SpanHelpers.IndexOfOrdinalHelper(span, value, ignoreCase: false));
case StringComparison.OrdinalIgnoreCase:
return(SpanHelpers.IndexOfOrdinalHelper(span, value, ignoreCase: true));
}
Debug.Fail("StringComparison outside range");
return(-1);
}