public static T[] Match2 <T>(this T[] source, Func <T, bool> condition)
{
if (source == null || source.Length == 0)
{
return(source);
}
if (source.Length > 2)
{
var matchStart = 0;
T[] matches = null;
var matchFound = false;
var i = 0;
while (i < source.Length)
{
matchFound = condition(source[i]);
if (!matchFound)
{
// for accumulated matched items
if (i != 0 && i > matchStart)
{
matches = ArrayTools.AppendTo(source, matchStart, i - matchStart, matches);
}
matchStart = i + 1; // guess the next match start will be after the non-matched item
}
++i;
}
// when last match was found but not all items are matched (hence matchStart != 0)
if (matchFound && matchStart != 0)
{
return(ArrayTools.AppendTo(source, matchStart, i - matchStart, matches));
}
if (matches != null)
{
return(matches);
}
if (matchStart != 0) // no matches
{
return(ArrayTools.Empty <T>());
}
return(source);
}
if (source.Length == 2)
{
var condition0 = condition(source[0]);
var condition1 = condition(source[1]);
return(condition0 && condition1 ? new[] { source[0], source[1] }
: condition0 ? new[] { source[0] }
: condition1 ? new[] { source[1] }
: ArrayTools.Empty <T>());
}
return(condition(source[0]) ? source : ArrayTools.Empty <T>());
}
