// Bytes returns a slice of length b.Len() holding the unread portion of the buffer.
// The slice is valid for use only until the next buffer modification (that is,
// only until the next call to a method like [Buffer.Read], [Buffer.Write], [Buffer.Reset], or [Buffer.Truncate]).
// The slice aliases the buffer content at least until the next buffer modification,
// so immediate changes to the slice will affect the result of future reads.

                Arguments.of(makeSeq(8), 0, 8, 0), // full copy at index 0
                Arguments.of(makeSeq(10), 2, 5, 3), // middle slice, non-zero dst index
                Arguments.of(makeSeq(4), 4, 0, 0), // zero-length slice at end
                Arguments.of(makeSeq(16), 7, 3, 0), // small slice from middle
                Arguments.of(makeSeq(16), 0, 0, 5) // zero-length with non-zero dst index
        );
    }

// It splits the slice s around each instance of one or more consecutive white space
// characters, as defined by [unicode.IsSpace], returning a slice of subslices of s or an
// empty slice if s contains only white space. Every element of the returned slice is
// non-empty. Unlike [Split], leading and trailing runs of white space characters
// are discarded.
func Fields(s []byte) [][]byte {

// scanning lines, a [SplitFunc] can return (0, nil, nil) to signal the
// [Scanner] to read more data into the slice and try again with a
// longer slice starting at the same point in the input.
//
// The function is never called with an empty data slice unless atEOF
// is true. If atEOF is true, however, data may be non-empty and,
// as always, holds unprocessed text.

	return predicate{
		func(r rune) bool {
			return !p.f(r)
		},
		"not " + p.name,
	}
}

var trimFuncTests = []TrimFuncTest{
	{isSpace, space + " hello " + space,
		[]byte("hello"),
		[]byte("hello " + space),
		[]byte(space + " hello")},
	{isDigit, "\u0e50\u0e5212hello34\u0e50\u0e51",
		[]byte("hello"),
		[]byte("hello34\u0e50\u0e51"),
		[]byte("\u0e50\u0e5212hello")},

}

// parsePAXRecord parses the input PAX record string into a key-value pair.
// If parsing is successful, it will slice off the currently read record and
// return the remainder as r.
func parsePAXRecord(s string) (k, v, r string, err error) {
	// The size field ends at the first space.
	nStr, rest, ok := strings.Cut(s, " ")
	if !ok {
		return "", "", s, ErrHeader
	}

	nameIndexMap map[string]int64       // name to column index
	current      [][]string             // current block of results to be returned
	recordsRead  int                    // number of records read in current slice
	input        chan *queueItem        // input for workers
	queue        chan *queueItem        // output from workers in order
	err          error                  // global error state, only touched by Reader.Read

	return &RingBuffer{
		buf:  b,
		size: len(b),
	}
}

// SetBlocking sets the blocking mode of the ring buffer.
// If block is true, Read and Write will block when there is no data to read or no space to write.
// If block is false, Read and Write will return ErrIsEmpty or ErrIsFull immediately.
// By default, the ring buffer is not blocking.
// This setting should be called before any Read or Write operation or after a Reset.

	if signFields[0] != "Signature" {
		return "", ErrMissingSignTag
	}
	if signFields[1] == "" {
		return "", ErrMissingFields
	}
	signature := signFields[1]
	return signature, ErrNone
}

// Parse slice of signed headers from signed headers tag.
func parseSignedHeader(signedHdrElement string) ([]string, APIErrorCode) {
	signedHdrFields := strings.Split(strings.TrimSpace(signedHdrElement), "=")
	if len(signedHdrFields) != 2 {

The <i>capacity</i> is a measure of that extent: it is the sum of
the length of the slice and the length of the array beyond the slice;
a slice of length up to that capacity can be created by
<a href="#Slice_expressions"><i>slicing</i></a> a new one from the original slice.
The capacity of a slice <code>a</code> can be discovered using the
built-in function <a href="#Length_and_capacity"><code>cap(a)</code></a>.
</p>