Imported Upstream version 1.4upstream/1.4

1 files changed, 703 insertions, 0 deletions

diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
new file mode 100644
index 000000000..7634707b3
--- /dev/null
+++ b/src/bytes/bytes.go
@@ -0,0 +1,703 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package bytes implements functions for the manipulation of byte slices.
+// It is analogous to the facilities of the strings package.
+package bytes
+
+import (
+	"unicode"
+	"unicode/utf8"
+)
+
+func equalPortable(a, b []byte) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i, c := range a {
+		if c != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// explode splits s into a slice of UTF-8 sequences, one per Unicode character (still slices of bytes),
+// up to a maximum of n byte slices. Invalid UTF-8 sequences are chopped into individual bytes.
+func explode(s []byte, n int) [][]byte {
+	if n <= 0 {
+		n = len(s)
+	}
+	a := make([][]byte, n)
+	var size int
+	na := 0
+	for len(s) > 0 {
+		if na+1 >= n {
+			a[na] = s
+			na++
+			break
+		}
+		_, size = utf8.DecodeRune(s)
+		a[na] = s[0:size]
+		s = s[size:]
+		na++
+	}
+	return a[0:na]
+}
+
+// Count counts the number of non-overlapping instances of sep in s.
+func Count(s, sep []byte) int {
+	n := len(sep)
+	if n == 0 {
+		return utf8.RuneCount(s) + 1
+	}
+	if n > len(s) {
+		return 0
+	}
+	count := 0
+	c := sep[0]
+	i := 0
+	t := s[:len(s)-n+1]
+	for i < len(t) {
+		if t[i] != c {
+			o := IndexByte(t[i:], c)
+			if o < 0 {
+				break
+			}
+			i += o
+		}
+		if n == 1 || Equal(s[i:i+n], sep) {
+			count++
+			i += n
+			continue
+		}
+		i++
+	}
+	return count
+}
+
+// Contains reports whether subslice is within b.
+func Contains(b, subslice []byte) bool {
+	return Index(b, subslice) != -1
+}
+
+// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
+func Index(s, sep []byte) int {
+	n := len(sep)
+	if n == 0 {
+		return 0
+	}
+	if n > len(s) {
+		return -1
+	}
+	c := sep[0]
+	if n == 1 {
+		return IndexByte(s, c)
+	}
+	i := 0
+	t := s[:len(s)-n+1]
+	for i < len(t) {
+		if t[i] != c {
+			o := IndexByte(t[i:], c)
+			if o < 0 {
+				break
+			}
+			i += o
+		}
+		if Equal(s[i:i+n], sep) {
+			return i
+		}
+		i++
+	}
+	return -1
+}
+
+func indexBytePortable(s []byte, c byte) int {
+	for i, b := range s {
+		if b == c {
+			return i
+		}
+	}
+	return -1
+}
+
+// LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s.
+func LastIndex(s, sep []byte) int {
+	n := len(sep)
+	if n == 0 {
+		return len(s)
+	}
+	c := sep[0]
+	for i := len(s) - n; i >= 0; i-- {
+		if s[i] == c && (n == 1 || Equal(s[i:i+n], sep)) {
+			return i
+		}
+	}
+	return -1
+}
+
+// IndexRune interprets s as a sequence of UTF-8-encoded Unicode code points.
+// It returns the byte index of the first occurrence in s of the given rune.
+// It returns -1 if rune is not present in s.
+func IndexRune(s []byte, r rune) int {
+	for i := 0; i < len(s); {
+		r1, size := utf8.DecodeRune(s[i:])
+		if r == r1 {
+			return i
+		}
+		i += size
+	}
+	return -1
+}
+
+// IndexAny interprets s as a sequence of UTF-8-encoded Unicode code points.
+// It returns the byte index of the first occurrence in s of any of the Unicode
+// code points in chars.  It returns -1 if chars is empty or if there is no code
+// point in common.
+func IndexAny(s []byte, chars string) int {
+	if len(chars) > 0 {
+		var r rune
+		var width int
+		for i := 0; i < len(s); i += width {
+			r = rune(s[i])
+			if r < utf8.RuneSelf {
+				width = 1
+			} else {
+				r, width = utf8.DecodeRune(s[i:])
+			}
+			for _, ch := range chars {
+				if r == ch {
+					return i
+				}
+			}
+		}
+	}
+	return -1
+}
+
+// LastIndexAny interprets s as a sequence of UTF-8-encoded Unicode code
+// points.  It returns the byte index of the last occurrence in s of any of
+// the Unicode code points in chars.  It returns -1 if chars is empty or if
+// there is no code point in common.
+func LastIndexAny(s []byte, chars string) int {
+	if len(chars) > 0 {
+		for i := len(s); i > 0; {
+			r, size := utf8.DecodeLastRune(s[0:i])
+			i -= size
+			for _, ch := range chars {
+				if r == ch {
+					return i
+				}
+			}
+		}
+	}
+	return -1
+}
+
+// Generic split: splits after each instance of sep,
+// including sepSave bytes of sep in the subslices.
+func genSplit(s, sep []byte, sepSave, n int) [][]byte {
+	if n == 0 {
+		return nil
+	}
+	if len(sep) == 0 {
+		return explode(s, n)
+	}
+	if n < 0 {
+		n = Count(s, sep) + 1
+	}
+	c := sep[0]
+	start := 0
+	a := make([][]byte, n)
+	na := 0
+	for i := 0; i+len(sep) <= len(s) && na+1 < n; i++ {
+		if s[i] == c && (len(sep) == 1 || Equal(s[i:i+len(sep)], sep)) {
+			a[na] = s[start : i+sepSave]
+			na++
+			start = i + len(sep)
+			i += len(sep) - 1
+		}
+	}
+	a[na] = s[start:]
+	return a[0 : na+1]
+}
+
+// SplitN slices s into subslices separated by sep and returns a slice of
+// the subslices between those separators.
+// If sep is empty, SplitN splits after each UTF-8 sequence.
+// The count determines the number of subslices to return:
+//   n > 0: at most n subslices; the last subslice will be the unsplit remainder.
+//   n == 0: the result is nil (zero subslices)
+//   n < 0: all subslices
+func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }
+
+// SplitAfterN slices s into subslices after each instance of sep and
+// returns a slice of those subslices.
+// If sep is empty, SplitAfterN splits after each UTF-8 sequence.
+// The count determines the number of subslices to return:
+//   n > 0: at most n subslices; the last subslice will be the unsplit remainder.
+//   n == 0: the result is nil (zero subslices)
+//   n < 0: all subslices
+func SplitAfterN(s, sep []byte, n int) [][]byte {
+	return genSplit(s, sep, len(sep), n)
+}
+
+// Split slices s into all subslices separated by sep and returns a slice of
+// the subslices between those separators.
+// If sep is empty, Split splits after each UTF-8 sequence.
+// It is equivalent to SplitN with a count of -1.
+func Split(s, sep []byte) [][]byte { return genSplit(s, sep, 0, -1) }
+
+// SplitAfter slices s into all subslices after each instance of sep and
+// returns a slice of those subslices.
+// If sep is empty, SplitAfter splits after each UTF-8 sequence.
+// It is equivalent to SplitAfterN with a count of -1.
+func SplitAfter(s, sep []byte) [][]byte {
+	return genSplit(s, sep, len(sep), -1)
+}
+
+// Fields splits the slice s around each instance of one or more consecutive white space
+// characters, returning a slice of subslices of s or an empty list if s contains only white space.
+func Fields(s []byte) [][]byte {
+	return FieldsFunc(s, unicode.IsSpace)
+}
+
+// FieldsFunc interprets s as a sequence of UTF-8-encoded Unicode code points.
+// It splits the slice s at each run of code points c satisfying f(c) and
+// returns a slice of subslices of s.  If all code points in s satisfy f(c), or
+// len(s) == 0, an empty slice is returned.
+// FieldsFunc makes no guarantees about the order in which it calls f(c).
+// If f does not return consistent results for a given c, FieldsFunc may crash.
+func FieldsFunc(s []byte, f func(rune) bool) [][]byte {
+	n := 0
+	inField := false
+	for i := 0; i < len(s); {
+		r, size := utf8.DecodeRune(s[i:])
+		wasInField := inField
+		inField = !f(r)
+		if inField && !wasInField {
+			n++
+		}
+		i += size
+	}
+
+	a := make([][]byte, n)
+	na := 0
+	fieldStart := -1
+	for i := 0; i <= len(s) && na < n; {
+		r, size := utf8.DecodeRune(s[i:])
+		if fieldStart < 0 && size > 0 && !f(r) {
+			fieldStart = i
+			i += size
+			continue
+		}
+		if fieldStart >= 0 && (size == 0 || f(r)) {
+			a[na] = s[fieldStart:i]
+			na++
+			fieldStart = -1
+		}
+		if size == 0 {
+			break
+		}
+		i += size
+	}
+	return a[0:na]
+}
+
+// Join concatenates the elements of s to create a new byte slice. The separator
+// sep is placed between elements in the resulting slice.
+func Join(s [][]byte, sep []byte) []byte {
+	if len(s) == 0 {
+		return []byte{}
+	}
+	if len(s) == 1 {
+		// Just return a copy.
+		return append([]byte(nil), s[0]...)
+	}
+	n := len(sep) * (len(s) - 1)
+	for _, v := range s {
+		n += len(v)
+	}
+
+	b := make([]byte, n)
+	bp := copy(b, s[0])
+	for _, v := range s[1:] {
+		bp += copy(b[bp:], sep)
+		bp += copy(b[bp:], v)
+	}
+	return b
+}
+
+// HasPrefix tests whether the byte slice s begins with prefix.
+func HasPrefix(s, prefix []byte) bool {
+	return len(s) >= len(prefix) && Equal(s[0:len(prefix)], prefix)
+}
+
+// HasSuffix tests whether the byte slice s ends with suffix.
+func HasSuffix(s, suffix []byte) bool {
+	return len(s) >= len(suffix) && Equal(s[len(s)-len(suffix):], suffix)
+}
+
+// Map returns a copy of the byte slice s with all its characters modified
+// according to the mapping function. If mapping returns a negative value, the character is
+// dropped from the string with no replacement.  The characters in s and the
+// output are interpreted as UTF-8-encoded Unicode code points.
+func Map(mapping func(r rune) rune, s []byte) []byte {
+	// In the worst case, the slice can grow when mapped, making
+	// things unpleasant.  But it's so rare we barge in assuming it's
+	// fine.  It could also shrink but that falls out naturally.
+	maxbytes := len(s) // length of b
+	nbytes := 0        // number of bytes encoded in b
+	b := make([]byte, maxbytes)
+	for i := 0; i < len(s); {
+		wid := 1
+		r := rune(s[i])
+		if r >= utf8.RuneSelf {
+			r, wid = utf8.DecodeRune(s[i:])
+		}
+		r = mapping(r)
+		if r >= 0 {
+			rl := utf8.RuneLen(r)
+			if rl < 0 {
+				rl = len(string(utf8.RuneError))
+			}
+			if nbytes+rl > maxbytes {
+				// Grow the buffer.
+				maxbytes = maxbytes*2 + utf8.UTFMax
+				nb := make([]byte, maxbytes)
+				copy(nb, b[0:nbytes])
+				b = nb
+			}
+			nbytes += utf8.EncodeRune(b[nbytes:maxbytes], r)
+		}
+		i += wid
+	}
+	return b[0:nbytes]
+}
+
+// Repeat returns a new byte slice consisting of count copies of b.
+func Repeat(b []byte, count int) []byte {
+	nb := make([]byte, len(b)*count)
+	bp := copy(nb, b)
+	for bp < len(nb) {
+		copy(nb[bp:], nb[:bp])
+		bp *= 2
+	}
+	return nb
+}
+
+// ToUpper returns a copy of the byte slice s with all Unicode letters mapped to their upper case.
+func ToUpper(s []byte) []byte { return Map(unicode.ToUpper, s) }
+
+// ToLower returns a copy of the byte slice s with all Unicode letters mapped to their lower case.
+func ToLower(s []byte) []byte { return Map(unicode.ToLower, s) }
+
+// ToTitle returns a copy of the byte slice s with all Unicode letters mapped to their title case.
+func ToTitle(s []byte) []byte { return Map(unicode.ToTitle, s) }
+
+// ToUpperSpecial returns a copy of the byte slice s with all Unicode letters mapped to their
+// upper case, giving priority to the special casing rules.
+func ToUpperSpecial(_case unicode.SpecialCase, s []byte) []byte {
+	return Map(func(r rune) rune { return _case.ToUpper(r) }, s)
+}
+
+// ToLowerSpecial returns a copy of the byte slice s with all Unicode letters mapped to their
+// lower case, giving priority to the special casing rules.
+func ToLowerSpecial(_case unicode.SpecialCase, s []byte) []byte {
+	return Map(func(r rune) rune { return _case.ToLower(r) }, s)
+}
+
+// ToTitleSpecial returns a copy of the byte slice s with all Unicode letters mapped to their
+// title case, giving priority to the special casing rules.
+func ToTitleSpecial(_case unicode.SpecialCase, s []byte) []byte {
+	return Map(func(r rune) rune { return _case.ToTitle(r) }, s)
+}
+
+// isSeparator reports whether the rune could mark a word boundary.
+// TODO: update when package unicode captures more of the properties.
+func isSeparator(r rune) bool {
+	// ASCII alphanumerics and underscore are not separators
+	if r <= 0x7F {
+		switch {
+		case '0' <= r && r <= '9':
+			return false
+		case 'a' <= r && r <= 'z':
+			return false
+		case 'A' <= r && r <= 'Z':
+			return false
+		case r == '_':
+			return false
+		}
+		return true
+	}
+	// Letters and digits are not separators
+	if unicode.IsLetter(r) || unicode.IsDigit(r) {
+		return false
+	}
+	// Otherwise, all we can do for now is treat spaces as separators.
+	return unicode.IsSpace(r)
+}
+
+// Title returns a copy of s with all Unicode letters that begin words
+// mapped to their title case.
+//
+// BUG: The rule Title uses for word boundaries does not handle Unicode punctuation properly.
+func Title(s []byte) []byte {
+	// Use a closure here to remember state.
+	// Hackish but effective. Depends on Map scanning in order and calling
+	// the closure once per rune.
+	prev := ' '
+	return Map(
+		func(r rune) rune {
+			if isSeparator(prev) {
+				prev = r
+				return unicode.ToTitle(r)
+			}
+			prev = r
+			return r
+		},
+		s)
+}
+
+// TrimLeftFunc returns a subslice of s by slicing off all leading UTF-8-encoded
+// Unicode code points c that satisfy f(c).
+func TrimLeftFunc(s []byte, f func(r rune) bool) []byte {
+	i := indexFunc(s, f, false)
+	if i == -1 {
+		return nil
+	}
+	return s[i:]
+}
+
+// TrimRightFunc returns a subslice of s by slicing off all trailing UTF-8
+// encoded Unicode code points c that satisfy f(c).
+func TrimRightFunc(s []byte, f func(r rune) bool) []byte {
+	i := lastIndexFunc(s, f, false)
+	if i >= 0 && s[i] >= utf8.RuneSelf {
+		_, wid := utf8.DecodeRune(s[i:])
+		i += wid
+	} else {
+		i++
+	}
+	return s[0:i]
+}
+
+// TrimFunc returns a subslice of s by slicing off all leading and trailing
+// UTF-8-encoded Unicode code points c that satisfy f(c).
+func TrimFunc(s []byte, f func(r rune) bool) []byte {
+	return TrimRightFunc(TrimLeftFunc(s, f), f)
+}
+
+// TrimPrefix returns s without the provided leading prefix string.
+// If s doesn't start with prefix, s is returned unchanged.
+func TrimPrefix(s, prefix []byte) []byte {
+	if HasPrefix(s, prefix) {
+		return s[len(prefix):]
+	}
+	return s
+}
+
+// TrimSuffix returns s without the provided trailing suffix string.
+// If s doesn't end with suffix, s is returned unchanged.
+func TrimSuffix(s, suffix []byte) []byte {
+	if HasSuffix(s, suffix) {
+		return s[:len(s)-len(suffix)]
+	}
+	return s
+}
+
+// IndexFunc interprets s as a sequence of UTF-8-encoded Unicode code points.
+// It returns the byte index in s of the first Unicode
+// code point satisfying f(c), or -1 if none do.
+func IndexFunc(s []byte, f func(r rune) bool) int {
+	return indexFunc(s, f, true)
+}
+
+// LastIndexFunc interprets s as a sequence of UTF-8-encoded Unicode code points.
+// It returns the byte index in s of the last Unicode
+// code point satisfying f(c), or -1 if none do.
+func LastIndexFunc(s []byte, f func(r rune) bool) int {
+	return lastIndexFunc(s, f, true)
+}
+
+// indexFunc is the same as IndexFunc except that if
+// truth==false, the sense of the predicate function is
+// inverted.
+func indexFunc(s []byte, f func(r rune) bool, truth bool) int {
+	start := 0
+	for start < len(s) {
+		wid := 1
+		r := rune(s[start])
+		if r >= utf8.RuneSelf {
+			r, wid = utf8.DecodeRune(s[start:])
+		}
+		if f(r) == truth {
+			return start
+		}
+		start += wid
+	}
+	return -1
+}
+
+// lastIndexFunc is the same as LastIndexFunc except that if
+// truth==false, the sense of the predicate function is
+// inverted.
+func lastIndexFunc(s []byte, f func(r rune) bool, truth bool) int {
+	for i := len(s); i > 0; {
+		r, size := rune(s[i-1]), 1
+		if r >= utf8.RuneSelf {
+			r, size = utf8.DecodeLastRune(s[0:i])
+		}
+		i -= size
+		if f(r) == truth {
+			return i
+		}
+	}
+	return -1
+}
+
+func makeCutsetFunc(cutset string) func(r rune) bool {
+	return func(r rune) bool {
+		for _, c := range cutset {
+			if c == r {
+				return true
+			}
+		}
+		return false
+	}
+}
+
+// Trim returns a subslice of s by slicing off all leading and
+// trailing UTF-8-encoded Unicode code points contained in cutset.
+func Trim(s []byte, cutset string) []byte {
+	return TrimFunc(s, makeCutsetFunc(cutset))
+}
+
+// TrimLeft returns a subslice of s by slicing off all leading
+// UTF-8-encoded Unicode code points contained in cutset.
+func TrimLeft(s []byte, cutset string) []byte {
+	return TrimLeftFunc(s, makeCutsetFunc(cutset))
+}
+
+// TrimRight returns a subslice of s by slicing off all trailing
+// UTF-8-encoded Unicode code points that are contained in cutset.
+func TrimRight(s []byte, cutset string) []byte {
+	return TrimRightFunc(s, makeCutsetFunc(cutset))
+}
+
+// TrimSpace returns a subslice of s by slicing off all leading and
+// trailing white space, as defined by Unicode.
+func TrimSpace(s []byte) []byte {
+	return TrimFunc(s, unicode.IsSpace)
+}
+
+// Runes returns a slice of runes (Unicode code points) equivalent to s.
+func Runes(s []byte) []rune {
+	t := make([]rune, utf8.RuneCount(s))
+	i := 0
+	for len(s) > 0 {
+		r, l := utf8.DecodeRune(s)
+		t[i] = r
+		i++
+		s = s[l:]
+	}
+	return t
+}
+
+// Replace returns a copy of the slice s with the first n
+// non-overlapping instances of old replaced by new.
+// If old is empty, it matches at the beginning of the slice
+// and after each UTF-8 sequence, yielding up to k+1 replacements
+// for a k-rune slice.
+// If n < 0, there is no limit on the number of replacements.
+func Replace(s, old, new []byte, n int) []byte {
+	m := 0
+	if n != 0 {
+		// Compute number of replacements.
+		m = Count(s, old)
+	}
+	if m == 0 {
+		// Just return a copy.
+		return append([]byte(nil), s...)
+	}
+	if n < 0 || m < n {
+		n = m
+	}
+
+	// Apply replacements to buffer.
+	t := make([]byte, len(s)+n*(len(new)-len(old)))
+	w := 0
+	start := 0
+	for i := 0; i < n; i++ {
+		j := start
+		if len(old) == 0 {
+			if i > 0 {
+				_, wid := utf8.DecodeRune(s[start:])
+				j += wid
+			}
+		} else {
+			j += Index(s[start:], old)
+		}
+		w += copy(t[w:], s[start:j])
+		w += copy(t[w:], new)
+		start = j + len(old)
+	}
+	w += copy(t[w:], s[start:])
+	return t[0:w]
+}
+
+// EqualFold reports whether s and t, interpreted as UTF-8 strings,
+// are equal under Unicode case-folding.
+func EqualFold(s, t []byte) bool {
+	for len(s) != 0 && len(t) != 0 {
+		// Extract first rune from each.
+		var sr, tr rune
+		if s[0] < utf8.RuneSelf {
+			sr, s = rune(s[0]), s[1:]
+		} else {
+			r, size := utf8.DecodeRune(s)
+			sr, s = r, s[size:]
+		}
+		if t[0] < utf8.RuneSelf {
+			tr, t = rune(t[0]), t[1:]
+		} else {
+			r, size := utf8.DecodeRune(t)
+			tr, t = r, t[size:]
+		}
+
+		// If they match, keep going; if not, return false.
+
+		// Easy case.
+		if tr == sr {
+			continue
+		}
+
+		// Make sr < tr to simplify what follows.
+		if tr < sr {
+			tr, sr = sr, tr
+		}
+		// Fast check for ASCII.
+		if tr < utf8.RuneSelf && 'A' <= sr && sr <= 'Z' {
+			// ASCII, and sr is upper case.  tr must be lower case.
+			if tr == sr+'a'-'A' {
+				continue
+			}
+			return false
+		}
+
+		// General case.  SimpleFold(x) returns the next equivalent rune > x
+		// or wraps around to smaller values.
+		r := unicode.SimpleFold(sr)
+		for r != sr && r < tr {
+			r = unicode.SimpleFold(r)
+		}
+		if r == tr {
+			continue
+		}
+		return false
+	}
+
+	// One string is empty.  Are both?
+	return len(s) == len(t)
+}