/// <summary>
/// Attempts to locate the target <paramref name="value"/> within this <see cref="Utf8Span"/> instance.
/// If <paramref name="value"/> is found, returns <see langword="true"/> and sets <paramref name="range"/> to
/// the location where <paramref name="value"/> occurs within this <see cref="Utf8Span"/> instance.
/// If <paramref name="value"/> is not found, returns <see langword="false"/> and sets <paramref name="range"/>
/// to <see langword="default"/>.
/// </summary>
/// <remarks>
/// An ordinal search is performed.
/// </remarks>
public bool TryFind(Rune value, out Range range)
{
if (value.IsAscii)
{
// Special-case ASCII since it's a simple single byte search.
int idx = Bytes.IndexOf((byte)value.Value);
if (idx < 0)
{
range = default;
return(false);
}
else
{
range = idx..(idx + 1);
return(true);
}
}
else
{
// Slower path: need to search a multi-byte sequence.
// TODO_UTF8STRING: As an optimization, we could use unsafe APIs below since we
// know Rune instances are well-formed and slicing is safe.
Span <byte> runeBytes = stackalloc byte[Utf8Utility.MaxBytesPerScalar];
int utf8ByteLengthOfRune = value.EncodeToUtf8(runeBytes);
return(TryFind(UnsafeCreateWithoutValidation(runeBytes.Slice(0, utf8ByteLengthOfRune)), out range));
}
}
/// <summary>
/// Returns a value stating whether the current <see cref="Utf8Span"/> instance contains
/// the specified <see cref="Rune"/>. An ordinal comparison is used.
/// </summary>
public bool Contains(Rune value)
{
// TODO_UTF8STRING: This should be split into two methods:
// One which operates on a single-byte (ASCII) search value,
// the other which operates on a multi-byte (non-ASCII) search value.
Span <byte> runeBytes = stackalloc byte[Utf8Utility.MaxBytesPerScalar];
int runeBytesWritten = value.EncodeToUtf8(runeBytes);
return(this.Bytes.IndexOf(runeBytes.Slice(0, runeBytesWritten)) >= 0);
}
/// <summary>
/// Attempts to locate the target <paramref name="value"/> within this <see cref="Utf8Span"/> instance.
/// If <paramref name="value"/> is found, returns <see langword="true"/> and sets <paramref name="range"/> to
/// the location where <paramref name="value"/> occurs within this <see cref="Utf8Span"/> instance.
/// If <paramref name="value"/> is not found, returns <see langword="false"/> and sets <paramref name="range"/>
/// to <see langword="default"/>.
/// </summary>
/// <remarks>
/// The search is performed using the specified <paramref name="comparisonType"/>.
/// </remarks>
public bool TryFind(Rune value, StringComparison comparisonType, out Range range)
{
if (comparisonType == StringComparison.Ordinal)
{
return(TryFind(value, out range));
}
else
{
// Slower path: not an ordinal comparison.
// TODO_UTF8STRING: As an optimization, we could use unsafe APIs below since we
// know Rune instances are well-formed and slicing is safe.
Span <byte> runeBytes = stackalloc byte[Utf8Utility.MaxBytesPerScalar];
int utf8ByteLengthOfRune = value.EncodeToUtf8(runeBytes);
return(TryFind(UnsafeCreateWithoutValidation(runeBytes.Slice(0, utf8ByteLengthOfRune)), comparisonType, out range));
}
}