isSpace = removeLastDuplication(buf, alphanumSize, isSpace, termCache);
                            } else if (symbolSize > 0) {
                                isSpace = removeLastDuplication(buf, symbolSize, isSpace, termCache);
                            }
                        }
                        // space
                        if (!isSpace && !isLastSpaceChar(buf)) {

				isSpace = unicode.IsSpace(r)
			}
			if isSpace {
				if start >= 0 {
					if !yield(s[start:i:i]) {
						return
					}
					start = -1
				}
			} else if start < 0 {
				start = i
			}
			i += size
		}
		if start >= 0 {
			yield(s[start:len(s):len(s)])
		}
	}
}

// FieldsFuncSeq returns an iterator over substrings of s split around runs of

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bufio

// Exported for testing only.
import (
	"unicode/utf8"
)

var IsSpace = isSpace

const DefaultBufSize = defaultBufSize

func (s *Scanner) MaxTokenSize(n int) {
	if n < utf8.UTFMax || n > 1e9 {
		panic("bad max token size")
	}
	if n < len(s.buf) {
		s.buf = make([]byte, n)
	}

	}
	// Request more data.
	return 0, nil, nil
}

// isSpace reports whether the character is a Unicode white space character.
// We avoid dependency on the unicode package, but check validity of the implementation
// in the tests.
func isSpace(r rune) bool {
	if r <= '\u00FF' {
		// Obvious ASCII ones: \t through \r plus space. Plus two Latin-1 oddballs.
		switch r {
		case ' ', '\t', '\n', '\v', '\f', '\r':

- [SplitAfterSeq] returns an iterator
  over substrings of s split after each instance of sep.
- [FieldsSeq] returns an iterator over
  substrings of s split around runs of whitespace characters,
  as defined by unicode.IsSpace.
- [FieldsFuncSeq] returns an iterator

- [SplitAfterSeq] returns an iterator
  over substrings of s split after each instance of sep.
- [FieldsSeq] returns an iterator over
  substrings of s split around runs of whitespace characters,
  as defined by unicode.IsSpace.
- [FieldsFuncSeq] returns an iterator

	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")},

)

const smallMaxTokenSize = 256 // Much smaller for more efficient testing.

// Test white space table matches the Unicode definition.
func TestSpace(t *testing.T) {
	for r := rune(0); r <= utf8.MaxRune; r++ {
		if IsSpace(r) != unicode.IsSpace(r) {
			t.Fatalf("white space property disagrees: %#U should be %t", r, unicode.IsSpace(r))
		}
	}
}

var scanTests = []string{
	"",
	"a",
	"¼",
	"☹",

	setBits := uint8(0)
	for i := 0; i < len(s); i++ {
		r := s[i]
		setBits |= r
		isSpace := int(asciiSpace[r])
		n += wasSpace & ^isSpace
		wasSpace = isSpace
	}

	if setBits >= utf8.RuneSelf {
		// Some runes in the input slice are not ASCII.
		return FieldsFunc(s, unicode.IsSpace)
	}

	// ASCII fast path
	a := make([][]byte, n)
	na := 0
	fieldStart := 0
	i := 0

}

// Trim leading and trailing spaces and replace sequential spaces with one space, following Trimall()
// in http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
func signV4TrimAll(input string) string {
	// Compress adjacent spaces (a space is determined by
	// unicode.IsSpace() internally here) to one space and return
	return strings.Join(strings.Fields(input), " ")
}