// Determines whether two Strings match.
public static bool Equals(string?a, string?b)
{
// Transform 'str == ""' to 'str != null && str.Length == 0' if either a or b are jit-time
// constants. Otherwise, these two blocks are eliminated
if (RuntimeHelpers.IsKnownConstant(a) && a != null && a.Length == 0)
{
return(b != null && b.Length == 0);
}
if (RuntimeHelpers.IsKnownConstant(b) && b != null && b.Length == 0)
{
return(a != null && a.Length == 0);
}
if (object.ReferenceEquals(a, b))
{
return(true);
}
if (a is null || b is null || a.Length != b.Length)
{
return(false);
}
return(EqualsHelper(a, b));
}
public bool EndsWith(char value)
{
// If the string is empty, *(&_firstChar + length - 1) will deref within
// the _stringLength field, which will be all-zero. We must forbid '\0'
// from going down the optimized code path because otherwise empty strings
// would appear to end with '\0', which is incorrect.
// n.b. This optimization relies on the layout of string and is not valid
// for other data types like char[] or Span<char>.
if (RuntimeHelpers.IsKnownConstant(value) && value != '\0')
{
// deref Length now to front-load the null check; also take this time to zero-extend
// n.b. (localLength - 1) could be negative!
nuint localLength = (uint)Length;
return(Unsafe.Add(ref _firstChar, (nint)localLength - 1) == value);
}
int lastPos = Length - 1;
return(((uint)lastPos < (uint)Length) && this[lastPos] == value);
}