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-rw-r--r--src/bytes/bytes.go1176
1 files changed, 1176 insertions, 0 deletions
diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
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+++ b/src/bytes/bytes.go
@@ -0,0 +1,1176 @@
+// 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 (
+ "internal/bytealg"
+ "unicode"
+ "unicode/utf8"
+)
+
+// Equal reports whether a and b
+// are the same length and contain the same bytes.
+// A nil argument is equivalent to an empty slice.
+func Equal(a, b []byte) bool {
+ // Neither cmd/compile nor gccgo allocates for these string conversions.
+ return string(a) == string(b)
+}
+
+// Compare returns an integer comparing two byte slices lexicographically.
+// The result will be 0 if a==b, -1 if a < b, and +1 if a > b.
+// A nil argument is equivalent to an empty slice.
+func Compare(a, b []byte) int {
+ return bytealg.Compare(a, b)
+}
+
+// explode splits s into a slice of UTF-8 sequences, one per Unicode code point (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:size]
+ s = s[size:]
+ na++
+ }
+ return a[0:na]
+}
+
+// Count counts the number of non-overlapping instances of sep in s.
+// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
+func Count(s, sep []byte) int {
+ // special case
+ if len(sep) == 0 {
+ return utf8.RuneCount(s) + 1
+ }
+ if len(sep) == 1 {
+ return bytealg.Count(s, sep[0])
+ }
+ n := 0
+ for {
+ i := Index(s, sep)
+ if i == -1 {
+ return n
+ }
+ n++
+ s = s[i+len(sep):]
+ }
+}
+
+// Contains reports whether subslice is within b.
+func Contains(b, subslice []byte) bool {
+ return Index(b, subslice) != -1
+}
+
+// ContainsAny reports whether any of the UTF-8-encoded code points in chars are within b.
+func ContainsAny(b []byte, chars string) bool {
+ return IndexAny(b, chars) >= 0
+}
+
+// ContainsRune reports whether the rune is contained in the UTF-8-encoded byte slice b.
+func ContainsRune(b []byte, r rune) bool {
+ return IndexRune(b, r) >= 0
+}
+
+// IndexByte returns the index of the first instance of c in b, or -1 if c is not present in b.
+func IndexByte(b []byte, c byte) int {
+ return bytealg.IndexByte(b, c)
+}
+
+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)
+ switch {
+ case n == 0:
+ return len(s)
+ case n == 1:
+ return LastIndexByte(s, sep[0])
+ case n == len(s):
+ if Equal(s, sep) {
+ return 0
+ }
+ return -1
+ case n > len(s):
+ return -1
+ }
+ // Rabin-Karp search from the end of the string
+ hashss, pow := bytealg.HashStrRevBytes(sep)
+ last := len(s) - n
+ var h uint32
+ for i := len(s) - 1; i >= last; i-- {
+ h = h*bytealg.PrimeRK + uint32(s[i])
+ }
+ if h == hashss && Equal(s[last:], sep) {
+ return last
+ }
+ for i := last - 1; i >= 0; i-- {
+ h *= bytealg.PrimeRK
+ h += uint32(s[i])
+ h -= pow * uint32(s[i+n])
+ if h == hashss && Equal(s[i:i+n], sep) {
+ return i
+ }
+ }
+ return -1
+}
+
+// LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.
+func LastIndexByte(s []byte, c byte) int {
+ for i := len(s) - 1; i >= 0; i-- {
+ if s[i] == c {
+ return i
+ }
+ }
+ return -1
+}
+
+// IndexRune interprets s as a sequence of UTF-8-encoded 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.
+// If r is utf8.RuneError, it returns the first instance of any
+// invalid UTF-8 byte sequence.
+func IndexRune(s []byte, r rune) int {
+ switch {
+ case 0 <= r && r < utf8.RuneSelf:
+ return IndexByte(s, byte(r))
+ case r == utf8.RuneError:
+ for i := 0; i < len(s); {
+ r1, n := utf8.DecodeRune(s[i:])
+ if r1 == utf8.RuneError {
+ return i
+ }
+ i += n
+ }
+ return -1
+ case !utf8.ValidRune(r):
+ return -1
+ default:
+ var b [utf8.UTFMax]byte
+ n := utf8.EncodeRune(b[:], r)
+ return Index(s, b[:n])
+ }
+}
+
+// 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 chars == "" {
+ // Avoid scanning all of s.
+ return -1
+ }
+ if len(s) == 1 {
+ r := rune(s[0])
+ if r >= utf8.RuneSelf {
+ // search utf8.RuneError.
+ for _, r = range chars {
+ if r == utf8.RuneError {
+ return 0
+ }
+ }
+ return -1
+ }
+ if bytealg.IndexByteString(chars, s[0]) >= 0 {
+ return 0
+ }
+ return -1
+ }
+ if len(chars) == 1 {
+ r := rune(chars[0])
+ if r >= utf8.RuneSelf {
+ r = utf8.RuneError
+ }
+ return IndexRune(s, r)
+ }
+ if len(s) > 8 {
+ if as, isASCII := makeASCIISet(chars); isASCII {
+ for i, c := range s {
+ if as.contains(c) {
+ return i
+ }
+ }
+ return -1
+ }
+ }
+ var width int
+ for i := 0; i < len(s); i += width {
+ r := rune(s[i])
+ if r < utf8.RuneSelf {
+ if bytealg.IndexByteString(chars, s[i]) >= 0 {
+ return i
+ }
+ width = 1
+ continue
+ }
+ r, width = utf8.DecodeRune(s[i:])
+ if r != utf8.RuneError {
+ // r is 2 to 4 bytes
+ if len(chars) == width {
+ if chars == string(r) {
+ return i
+ }
+ continue
+ }
+ // Use bytealg.IndexString for performance if available.
+ if bytealg.MaxLen >= width {
+ if bytealg.IndexString(chars, string(r)) >= 0 {
+ return i
+ }
+ continue
+ }
+ }
+ 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 chars == "" {
+ // Avoid scanning all of s.
+ return -1
+ }
+ if len(s) > 8 {
+ if as, isASCII := makeASCIISet(chars); isASCII {
+ for i := len(s) - 1; i >= 0; i-- {
+ if as.contains(s[i]) {
+ return i
+ }
+ }
+ return -1
+ }
+ }
+ if len(s) == 1 {
+ r := rune(s[0])
+ if r >= utf8.RuneSelf {
+ for _, r = range chars {
+ if r == utf8.RuneError {
+ return 0
+ }
+ }
+ return -1
+ }
+ if bytealg.IndexByteString(chars, s[0]) >= 0 {
+ return 0
+ }
+ return -1
+ }
+ if len(chars) == 1 {
+ cr := rune(chars[0])
+ if cr >= utf8.RuneSelf {
+ cr = utf8.RuneError
+ }
+ for i := len(s); i > 0; {
+ r, size := utf8.DecodeLastRune(s[:i])
+ i -= size
+ if r == cr {
+ return i
+ }
+ }
+ return -1
+ }
+ for i := len(s); i > 0; {
+ r := rune(s[i-1])
+ if r < utf8.RuneSelf {
+ if bytealg.IndexByteString(chars, s[i-1]) >= 0 {
+ return i - 1
+ }
+ i--
+ continue
+ }
+ r, size := utf8.DecodeLastRune(s[:i])
+ i -= size
+ if r != utf8.RuneError {
+ // r is 2 to 4 bytes
+ if len(chars) == size {
+ if chars == string(r) {
+ return i
+ }
+ continue
+ }
+ // Use bytealg.IndexString for performance if available.
+ if bytealg.MaxLen >= size {
+ if bytealg.IndexString(chars, string(r)) >= 0 {
+ return i
+ }
+ continue
+ }
+ }
+ 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
+ }
+
+ a := make([][]byte, n)
+ n--
+ i := 0
+ for i < n {
+ m := Index(s, sep)
+ if m < 0 {
+ break
+ }
+ a[i] = s[: m+sepSave : m+sepSave]
+ s = s[m+len(sep):]
+ i++
+ }
+ a[i] = s
+ return a[:i+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)
+}
+
+var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}
+
+// Fields interprets s as a sequence of UTF-8-encoded code points.
+// 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.
+func Fields(s []byte) [][]byte {
+ // First count the fields.
+ // This is an exact count if s is ASCII, otherwise it is an approximation.
+ n := 0
+ wasSpace := 1
+ // setBits is used to track which bits are set in the bytes of s.
+ 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
+ // Skip spaces in the front of the input.
+ for i < len(s) && asciiSpace[s[i]] != 0 {
+ i++
+ }
+ fieldStart = i
+ for i < len(s) {
+ if asciiSpace[s[i]] == 0 {
+ i++
+ continue
+ }
+ a[na] = s[fieldStart:i:i]
+ na++
+ i++
+ // Skip spaces in between fields.
+ for i < len(s) && asciiSpace[s[i]] != 0 {
+ i++
+ }
+ fieldStart = i
+ }
+ if fieldStart < len(s) { // Last field might end at EOF.
+ a[na] = s[fieldStart:len(s):len(s)]
+ }
+ return a
+}
+
+// FieldsFunc interprets s as a sequence of UTF-8-encoded 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)
+// and assumes that f always returns the same value for a given c.
+func FieldsFunc(s []byte, f func(rune) bool) [][]byte {
+ // A span is used to record a slice of s of the form s[start:end].
+ // The start index is inclusive and the end index is exclusive.
+ type span struct {
+ start int
+ end int
+ }
+ spans := make([]span, 0, 32)
+
+ // Find the field start and end indices.
+ // Doing this in a separate pass (rather than slicing the string s
+ // and collecting the result substrings right away) is significantly
+ // more efficient, possibly due to cache effects.
+ start := -1 // valid span start if >= 0
+ for i := 0; i < len(s); {
+ size := 1
+ r := rune(s[i])
+ if r >= utf8.RuneSelf {
+ r, size = utf8.DecodeRune(s[i:])
+ }
+ if f(r) {
+ if start >= 0 {
+ spans = append(spans, span{start, i})
+ start = -1
+ }
+ } else {
+ if start < 0 {
+ start = i
+ }
+ }
+ i += size
+ }
+
+ // Last field might end at EOF.
+ if start >= 0 {
+ spans = append(spans, span{start, len(s)})
+ }
+
+ // Create subslices from recorded field indices.
+ a := make([][]byte, len(spans))
+ for i, span := range spans {
+ a[i] = s[span.start:span.end:span.end]
+ }
+
+ return a
+}
+
+// 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 byte slice with no replacement. The characters in s and the
+// output are interpreted as UTF-8-encoded 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.
+//
+// It panics if count is negative or if
+// the result of (len(b) * count) overflows.
+func Repeat(b []byte, count int) []byte {
+ if count == 0 {
+ return []byte{}
+ }
+ // Since we cannot return an error on overflow,
+ // we should panic if the repeat will generate
+ // an overflow.
+ // See Issue golang.org/issue/16237.
+ if count < 0 {
+ panic("bytes: negative Repeat count")
+ } else if len(b)*count/count != len(b) {
+ panic("bytes: Repeat count causes overflow")
+ }
+
+ 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 {
+ isASCII, hasLower := true, false
+ for i := 0; i < len(s); i++ {
+ c := s[i]
+ if c >= utf8.RuneSelf {
+ isASCII = false
+ break
+ }
+ hasLower = hasLower || ('a' <= c && c <= 'z')
+ }
+
+ if isASCII { // optimize for ASCII-only byte slices.
+ if !hasLower {
+ // Just return a copy.
+ return append([]byte(""), s...)
+ }
+ b := make([]byte, len(s))
+ for i := 0; i < len(s); i++ {
+ c := s[i]
+ if 'a' <= c && c <= 'z' {
+ c -= 'a' - 'A'
+ }
+ b[i] = c
+ }
+ return b
+ }
+ 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 {
+ isASCII, hasUpper := true, false
+ for i := 0; i < len(s); i++ {
+ c := s[i]
+ if c >= utf8.RuneSelf {
+ isASCII = false
+ break
+ }
+ hasUpper = hasUpper || ('A' <= c && c <= 'Z')
+ }
+
+ if isASCII { // optimize for ASCII-only byte slices.
+ if !hasUpper {
+ return append([]byte(""), s...)
+ }
+ b := make([]byte, len(s))
+ for i := 0; i < len(s); i++ {
+ c := s[i]
+ if 'A' <= c && c <= 'Z' {
+ c += 'a' - 'A'
+ }
+ b[i] = c
+ }
+ return b
+ }
+ return Map(unicode.ToLower, s)
+}
+
+// ToTitle treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their title case.
+func ToTitle(s []byte) []byte { return Map(unicode.ToTitle, s) }
+
+// ToUpperSpecial treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their
+// upper case, giving priority to the special casing rules.
+func ToUpperSpecial(c unicode.SpecialCase, s []byte) []byte {
+ return Map(c.ToUpper, s)
+}
+
+// ToLowerSpecial treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their
+// lower case, giving priority to the special casing rules.
+func ToLowerSpecial(c unicode.SpecialCase, s []byte) []byte {
+ return Map(c.ToLower, s)
+}
+
+// ToTitleSpecial treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their
+// title case, giving priority to the special casing rules.
+func ToTitleSpecial(c unicode.SpecialCase, s []byte) []byte {
+ return Map(c.ToTitle, s)
+}
+
+// ToValidUTF8 treats s as UTF-8-encoded bytes and returns a copy with each run of bytes
+// representing invalid UTF-8 replaced with the bytes in replacement, which may be empty.
+func ToValidUTF8(s, replacement []byte) []byte {
+ b := make([]byte, 0, len(s)+len(replacement))
+ invalid := false // previous byte was from an invalid UTF-8 sequence
+ for i := 0; i < len(s); {
+ c := s[i]
+ if c < utf8.RuneSelf {
+ i++
+ invalid = false
+ b = append(b, byte(c))
+ continue
+ }
+ _, wid := utf8.DecodeRune(s[i:])
+ if wid == 1 {
+ i++
+ if !invalid {
+ invalid = true
+ b = append(b, replacement...)
+ }
+ continue
+ }
+ invalid = false
+ b = append(b, s[i:i+wid]...)
+ i += wid
+ }
+ return b
+}
+
+// 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 treats s as UTF-8-encoded bytes and returns a copy with all Unicode letters that begin
+// words mapped to their title case.
+//
+// BUG(rsc): 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 treats s as UTF-8-encoded bytes and returns a subslice of s by slicing off
+// all leading UTF-8-encoded 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 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 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 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 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
+}
+
+// asciiSet is a 32-byte value, where each bit represents the presence of a
+// given ASCII character in the set. The 128-bits of the lower 16 bytes,
+// starting with the least-significant bit of the lowest word to the
+// most-significant bit of the highest word, map to the full range of all
+// 128 ASCII characters. The 128-bits of the upper 16 bytes will be zeroed,
+// ensuring that any non-ASCII character will be reported as not in the set.
+type asciiSet [8]uint32
+
+// makeASCIISet creates a set of ASCII characters and reports whether all
+// characters in chars are ASCII.
+func makeASCIISet(chars string) (as asciiSet, ok bool) {
+ for i := 0; i < len(chars); i++ {
+ c := chars[i]
+ if c >= utf8.RuneSelf {
+ return as, false
+ }
+ as[c>>5] |= 1 << uint(c&31)
+ }
+ return as, true
+}
+
+// contains reports whether c is inside the set.
+func (as *asciiSet) contains(c byte) bool {
+ return (as[c>>5] & (1 << uint(c&31))) != 0
+}
+
+func makeCutsetFunc(cutset string) func(r rune) bool {
+ if len(cutset) == 1 && cutset[0] < utf8.RuneSelf {
+ return func(r rune) bool {
+ return r == rune(cutset[0])
+ }
+ }
+ if as, isASCII := makeASCIISet(cutset); isASCII {
+ return func(r rune) bool {
+ return r < utf8.RuneSelf && as.contains(byte(r))
+ }
+ }
+ 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 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 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 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 {
+ // Fast path for ASCII: look for the first ASCII non-space byte
+ start := 0
+ for ; start < len(s); start++ {
+ c := s[start]
+ if c >= utf8.RuneSelf {
+ // If we run into a non-ASCII byte, fall back to the
+ // slower unicode-aware method on the remaining bytes
+ return TrimFunc(s[start:], unicode.IsSpace)
+ }
+ if asciiSpace[c] == 0 {
+ break
+ }
+ }
+
+ // Now look for the first ASCII non-space byte from the end
+ stop := len(s)
+ for ; stop > start; stop-- {
+ c := s[stop-1]
+ if c >= utf8.RuneSelf {
+ return TrimFunc(s[start:stop], unicode.IsSpace)
+ }
+ if asciiSpace[c] == 0 {
+ break
+ }
+ }
+
+ // At this point s[start:stop] starts and ends with an ASCII
+ // non-space bytes, so we're done. Non-ASCII cases have already
+ // been handled above.
+ if start == stop {
+ // Special case to preserve previous TrimLeftFunc behavior,
+ // returning nil instead of empty slice if all spaces.
+ return nil
+ }
+ return s[start:stop]
+}
+
+// Runes interprets s as a sequence of UTF-8-encoded code points.
+// It 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]
+}
+
+// ReplaceAll returns a copy of the slice s with all
+// 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.
+func ReplaceAll(s, old, new []byte) []byte {
+ return Replace(s, old, new, -1)
+}
+
+// EqualFold reports whether s and t, interpreted as UTF-8 strings,
+// are equal under Unicode case-folding, which is a more general
+// form of case-insensitivity.
+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 {
+ // ASCII only, sr/tr must be upper/lower case
+ if 'A' <= sr && sr <= 'Z' && 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)
+}
+
+// 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)
+ switch {
+ case n == 0:
+ return 0
+ case n == 1:
+ return IndexByte(s, sep[0])
+ case n == len(s):
+ if Equal(sep, s) {
+ return 0
+ }
+ return -1
+ case n > len(s):
+ return -1
+ case n <= bytealg.MaxLen:
+ // Use brute force when s and sep both are small
+ if len(s) <= bytealg.MaxBruteForce {
+ return bytealg.Index(s, sep)
+ }
+ c0 := sep[0]
+ c1 := sep[1]
+ i := 0
+ t := len(s) - n + 1
+ fails := 0
+ for i < t {
+ if s[i] != c0 {
+ // IndexByte is faster than bytealg.Index, so use it as long as
+ // we're not getting lots of false positives.
+ o := IndexByte(s[i+1:t], c0)
+ if o < 0 {
+ return -1
+ }
+ i += o + 1
+ }
+ if s[i+1] == c1 && Equal(s[i:i+n], sep) {
+ return i
+ }
+ fails++
+ i++
+ // Switch to bytealg.Index when IndexByte produces too many false positives.
+ if fails > bytealg.Cutover(i) {
+ r := bytealg.Index(s[i:], sep)
+ if r >= 0 {
+ return r + i
+ }
+ return -1
+ }
+ }
+ return -1
+ }
+ c0 := sep[0]
+ c1 := sep[1]
+ i := 0
+ fails := 0
+ t := len(s) - n + 1
+ for i < t {
+ if s[i] != c0 {
+ o := IndexByte(s[i+1:t], c0)
+ if o < 0 {
+ break
+ }
+ i += o + 1
+ }
+ if s[i+1] == c1 && Equal(s[i:i+n], sep) {
+ return i
+ }
+ i++
+ fails++
+ if fails >= 4+i>>4 && i < t {
+ // Give up on IndexByte, it isn't skipping ahead
+ // far enough to be better than Rabin-Karp.
+ // Experiments (using IndexPeriodic) suggest
+ // the cutover is about 16 byte skips.
+ // TODO: if large prefixes of sep are matching
+ // we should cutover at even larger average skips,
+ // because Equal becomes that much more expensive.
+ // This code does not take that effect into account.
+ j := bytealg.IndexRabinKarpBytes(s[i:], sep)
+ if j < 0 {
+ return -1
+ }
+ return i + j
+ }
+ }
+ return -1
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-23 09:51:51 +0000