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@@ -0,0 +1,1296 @@
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+// Copyright 2009 The Go Authors. All rights reserved.
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+// Use of this source code is governed by a BSD-style
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+// license that can be found in the LICENSE file.
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+
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+// Package bytes implements functions for the manipulation of byte slices.
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+// It is analogous to the facilities of the strings package.
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+package bytes
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+
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+import (
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+ "internal/bytealg"
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+ "unicode"
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+ "unicode/utf8"
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+)
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+
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+// Equal reports whether a and b
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+// are the same length and contain the same bytes.
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+// A nil argument is equivalent to an empty slice.
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+func Equal(a, b []byte) bool {
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+ // Neither cmd/compile nor gccgo allocates for these string conversions.
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+ return string(a) == string(b)
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+}
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+
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+// Compare returns an integer comparing two byte slices lexicographically.
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+// The result will be 0 if a == b, -1 if a < b, and +1 if a > b.
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+// A nil argument is equivalent to an empty slice.
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+func Compare(a, b []byte) int {
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+ return bytealg.Compare(a, b)
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+}
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+
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+// explode splits s into a slice of UTF-8 sequences, one per Unicode code point (still slices of bytes),
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+// up to a maximum of n byte slices. Invalid UTF-8 sequences are chopped into individual bytes.
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+func explode(s []byte, n int) [][]byte {
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+ if n <= 0 {
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+ n = len(s)
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+ }
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+ a := make([][]byte, n)
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+ var size int
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+ na := 0
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+ for len(s) > 0 {
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+ if na+1 >= n {
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+ a[na] = s
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+ na++
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+ break
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+ }
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+ _, size = utf8.DecodeRune(s)
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+ a[na] = s[0:size:size]
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+ s = s[size:]
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+ na++
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+ }
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+ return a[0:na]
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+}
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+
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+// Count counts the number of non-overlapping instances of sep in s.
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+// If sep is an empty slice, Count returns 1 + the number of UTF-8-encoded code points in s.
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+func Count(s, sep []byte) int {
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+ // special case
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+ if len(sep) == 0 {
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+ return utf8.RuneCount(s) + 1
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+ }
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+ if len(sep) == 1 {
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+ return bytealg.Count(s, sep[0])
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+ }
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+ n := 0
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+ for {
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+ i := Index(s, sep)
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+ if i == -1 {
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+ return n
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+ }
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+ n++
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+ s = s[i+len(sep):]
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+ }
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+}
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+
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+// Contains reports whether subslice is within b.
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+func Contains(b, subslice []byte) bool {
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+ return Index(b, subslice) != -1
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+}
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+
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+// ContainsAny reports whether any of the UTF-8-encoded code points in chars are within b.
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+func ContainsAny(b []byte, chars string) bool {
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+ return IndexAny(b, chars) >= 0
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+}
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+
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+// ContainsRune reports whether the rune is contained in the UTF-8-encoded byte slice b.
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+func ContainsRune(b []byte, r rune) bool {
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+ return IndexRune(b, r) >= 0
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+}
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+
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+// IndexByte returns the index of the first instance of c in b, or -1 if c is not present in b.
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+func IndexByte(b []byte, c byte) int {
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+ return bytealg.IndexByte(b, c)
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+}
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+
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+func indexBytePortable(s []byte, c byte) int {
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+ for i, b := range s {
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+ if b == c {
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+ return i
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+ }
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+ }
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+ return -1
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+}
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+
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+// LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s.
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+func LastIndex(s, sep []byte) int {
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+ n := len(sep)
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+ switch {
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+ case n == 0:
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+ return len(s)
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+ case n == 1:
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+ return LastIndexByte(s, sep[0])
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+ case n == len(s):
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+ if Equal(s, sep) {
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+ return 0
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+ }
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+ return -1
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+ case n > len(s):
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+ return -1
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+ }
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+ // Rabin-Karp search from the end of the string
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+ hashss, pow := bytealg.HashStrRevBytes(sep)
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+ last := len(s) - n
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+ var h uint32
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+ for i := len(s) - 1; i >= last; i-- {
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+ h = h*bytealg.PrimeRK + uint32(s[i])
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+ }
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+ if h == hashss && Equal(s[last:], sep) {
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+ return last
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+ }
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+ for i := last - 1; i >= 0; i-- {
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+ h *= bytealg.PrimeRK
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+ h += uint32(s[i])
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+ h -= pow * uint32(s[i+n])
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+ if h == hashss && Equal(s[i:i+n], sep) {
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+ return i
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+ }
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+ }
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+ return -1
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+}
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+
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+// LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s.
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+func LastIndexByte(s []byte, c byte) int {
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+ for i := len(s) - 1; i >= 0; i-- {
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+ if s[i] == c {
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+ return i
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+ }
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+ }
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+ return -1
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+}
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+
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+// IndexRune interprets s as a sequence of UTF-8-encoded code points.
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+// It returns the byte index of the first occurrence in s of the given rune.
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+// It returns -1 if rune is not present in s.
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+// If r is utf8.RuneError, it returns the first instance of any
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+// invalid UTF-8 byte sequence.
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+func IndexRune(s []byte, r rune) int {
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+ switch {
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+ case 0 <= r && r < utf8.RuneSelf:
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+ return IndexByte(s, byte(r))
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+ case r == utf8.RuneError:
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+ for i := 0; i < len(s); {
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+ r1, n := utf8.DecodeRune(s[i:])
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+ if r1 == utf8.RuneError {
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+ return i
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+ }
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+ i += n
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+ }
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+ return -1
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+ case !utf8.ValidRune(r):
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+ return -1
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+ default:
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+ var b [utf8.UTFMax]byte
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+ n := utf8.EncodeRune(b[:], r)
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+ return Index(s, b[:n])
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+ }
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+}
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+
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+// IndexAny interprets s as a sequence of UTF-8-encoded Unicode code points.
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+// It returns the byte index of the first occurrence in s of any of the Unicode
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+// code points in chars. It returns -1 if chars is empty or if there is no code
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+// point in common.
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+func IndexAny(s []byte, chars string) int {
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+ if chars == "" {
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+ // Avoid scanning all of s.
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+ return -1
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+ }
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+ if len(s) == 1 {
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+ r := rune(s[0])
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+ if r >= utf8.RuneSelf {
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+ // search utf8.RuneError.
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+ for _, r = range chars {
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+ if r == utf8.RuneError {
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+ return 0
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+ }
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+ }
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+ return -1
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+ }
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+ if bytealg.IndexByteString(chars, s[0]) >= 0 {
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+ return 0
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+ }
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+ return -1
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+ }
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+ if len(chars) == 1 {
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+ r := rune(chars[0])
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+ if r >= utf8.RuneSelf {
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+ r = utf8.RuneError
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+ }
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+ return IndexRune(s, r)
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+ }
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+ if len(s) > 8 {
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+ if as, isASCII := makeASCIISet(chars); isASCII {
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+ for i, c := range s {
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+ if as.contains(c) {
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+ return i
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+ }
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+ }
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+ return -1
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+ }
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+ }
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+ var width int
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+ for i := 0; i < len(s); i += width {
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+ r := rune(s[i])
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+ if r < utf8.RuneSelf {
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+ if bytealg.IndexByteString(chars, s[i]) >= 0 {
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+ return i
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+ }
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+ width = 1
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+ continue
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+ }
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+ r, width = utf8.DecodeRune(s[i:])
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+ if r != utf8.RuneError {
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+ // r is 2 to 4 bytes
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+ if len(chars) == width {
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+ if chars == string(r) {
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+ return i
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+ }
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+ continue
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+ }
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+ // Use bytealg.IndexString for performance if available.
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+ if bytealg.MaxLen >= width {
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+ if bytealg.IndexString(chars, string(r)) >= 0 {
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+ return i
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+ }
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+ continue
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+ }
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+ }
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+ for _, ch := range chars {
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+ if r == ch {
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+ return i
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+ }
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+ }
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+ }
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+ return -1
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+}
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+
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+// LastIndexAny interprets s as a sequence of UTF-8-encoded Unicode code
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+// points. It returns the byte index of the last occurrence in s of any of
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+// the Unicode code points in chars. It returns -1 if chars is empty or if
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+// there is no code point in common.
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+func LastIndexAny(s []byte, chars string) int {
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+ if chars == "" {
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+ // Avoid scanning all of s.
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+ return -1
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+ }
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+ if len(s) > 8 {
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+ if as, isASCII := makeASCIISet(chars); isASCII {
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+ for i := len(s) - 1; i >= 0; i-- {
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+ if as.contains(s[i]) {
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+ return i
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+ }
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+ }
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+ return -1
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+ }
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+ }
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+ if len(s) == 1 {
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+ r := rune(s[0])
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+ if r >= utf8.RuneSelf {
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+ for _, r = range chars {
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+ if r == utf8.RuneError {
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+ return 0
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+ }
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+ }
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+ return -1
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+ }
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+ if bytealg.IndexByteString(chars, s[0]) >= 0 {
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+ return 0
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+ }
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+ return -1
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+ }
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+ if len(chars) == 1 {
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+ cr := rune(chars[0])
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+ if cr >= utf8.RuneSelf {
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+ cr = utf8.RuneError
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+ }
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+ for i := len(s); i > 0; {
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+ r, size := utf8.DecodeLastRune(s[:i])
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+ i -= size
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+ if r == cr {
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+ return i
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+ }
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+ }
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+ return -1
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+ }
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+ for i := len(s); i > 0; {
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+ r := rune(s[i-1])
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+ if r < utf8.RuneSelf {
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+ if bytealg.IndexByteString(chars, s[i-1]) >= 0 {
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+ return i - 1
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+ }
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+ i--
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+ continue
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+ }
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+ r, size := utf8.DecodeLastRune(s[:i])
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+ i -= size
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+ if r != utf8.RuneError {
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+ // r is 2 to 4 bytes
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+ if len(chars) == size {
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+ if chars == string(r) {
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+ return i
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+ }
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+ continue
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+ }
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+ // Use bytealg.IndexString for performance if available.
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+ if bytealg.MaxLen >= size {
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+ if bytealg.IndexString(chars, string(r)) >= 0 {
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+ return i
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+ }
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+ continue
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+ }
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+ }
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+ for _, ch := range chars {
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+ if r == ch {
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+ return i
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+ }
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+ }
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+ }
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+ return -1
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+}
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+
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+// Generic split: splits after each instance of sep,
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+// including sepSave bytes of sep in the subslices.
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+func genSplit(s, sep []byte, sepSave, n int) [][]byte {
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+ if n == 0 {
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+ return nil
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+ }
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+ if len(sep) == 0 {
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+ return explode(s, n)
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+ }
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+ if n < 0 {
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+ n = Count(s, sep) + 1
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+ }
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+
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+ a := make([][]byte, n)
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+ n--
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+ i := 0
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+ for i < n {
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+ m := Index(s, sep)
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+ if m < 0 {
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+ break
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+ }
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+ a[i] = s[: m+sepSave : m+sepSave]
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+ s = s[m+len(sep):]
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+ i++
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+ }
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+ a[i] = s
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+ return a[:i+1]
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+}
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+
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+// SplitN slices s into subslices separated by sep and returns a slice of
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+// the subslices between those separators.
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+// If sep is empty, SplitN splits after each UTF-8 sequence.
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+// The count determines the number of subslices to return:
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+// n > 0: at most n subslices; the last subslice will be the unsplit remainder.
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+// n == 0: the result is nil (zero subslices)
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+// n < 0: all subslices
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+//
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+// To split around the first instance of a separator, see Cut.
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+func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) }
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+
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+// SplitAfterN slices s into subslices after each instance of sep and
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+// returns a slice of those subslices.
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+// If sep is empty, SplitAfterN splits after each UTF-8 sequence.
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+// The count determines the number of subslices to return:
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+// n > 0: at most n subslices; the last subslice will be the unsplit remainder.
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+// n == 0: the result is nil (zero subslices)
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+// n < 0: all subslices
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+func SplitAfterN(s, sep []byte, n int) [][]byte {
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+ return genSplit(s, sep, len(sep), n)
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+}
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+
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+// Split slices s into all subslices separated by sep and returns a slice of
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+// the subslices between those separators.
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+// If sep is empty, Split splits after each UTF-8 sequence.
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+// It is equivalent to SplitN with a count of -1.
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+//
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+// To split around the first instance of a separator, see Cut.
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+func Split(s, sep []byte) [][]byte { return genSplit(s, sep, 0, -1) }
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+
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+// SplitAfter slices s into all subslices after each instance of sep and
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+// returns a slice of those subslices.
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+// If sep is empty, SplitAfter splits after each UTF-8 sequence.
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+// It is equivalent to SplitAfterN with a count of -1.
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+func SplitAfter(s, sep []byte) [][]byte {
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+ return genSplit(s, sep, len(sep), -1)
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+}
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+
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+var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}
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+
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+// Fields interprets s as a sequence of UTF-8-encoded code points.
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+// It splits the slice s around each instance of one or more consecutive white space
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+// characters, as defined by unicode.IsSpace, returning a slice of subslices of s or an
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+// empty slice if s contains only white space.
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+func Fields(s []byte) [][]byte {
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+ // First count the fields.
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+ // This is an exact count if s is ASCII, otherwise it is an approximation.
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+ n := 0
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+ wasSpace := 1
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+ // setBits is used to track which bits are set in the bytes of s.
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+ setBits := uint8(0)
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+ for i := 0; i < len(s); i++ {
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+ r := s[i]
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+ setBits |= r
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+ isSpace := int(asciiSpace[r])
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+ n += wasSpace & ^isSpace
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+ 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, 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.
|
|
|
+//
|
|
|
+// Deprecated: The rule Title uses for word boundaries does not handle Unicode
|
|
|
+// punctuation properly. Use golang.org/x/text/cases instead.
|
|
|
+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.
|
|
|
+// This allocates a total of 32 bytes even though the upper half
|
|
|
+// is unused to avoid bounds checks in asciiSet.contains.
|
|
|
+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/32] |= 1 << (c % 32)
|
|
|
+ }
|
|
|
+ return as, true
|
|
|
+}
|
|
|
+
|
|
|
+// contains reports whether c is inside the set.
|
|
|
+func (as *asciiSet) contains(c byte) bool {
|
|
|
+ return (as[c/32] & (1 << (c % 32))) != 0
|
|
|
+}
|
|
|
+
|
|
|
+// containsRune is a simplified version of strings.ContainsRune
|
|
|
+// to avoid importing the strings package.
|
|
|
+// We avoid bytes.ContainsRune to avoid allocating a temporary copy of s.
|
|
|
+func containsRune(s string, r rune) bool {
|
|
|
+ for _, c := range s {
|
|
|
+ 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 {
|
|
|
+ if len(s) == 0 {
|
|
|
+ // This is what we've historically done.
|
|
|
+ return nil
|
|
|
+ }
|
|
|
+ if cutset == "" {
|
|
|
+ return s
|
|
|
+ }
|
|
|
+ if len(cutset) == 1 && cutset[0] < utf8.RuneSelf {
|
|
|
+ return trimLeftByte(trimRightByte(s, cutset[0]), cutset[0])
|
|
|
+ }
|
|
|
+ if as, ok := makeASCIISet(cutset); ok {
|
|
|
+ return trimLeftASCII(trimRightASCII(s, &as), &as)
|
|
|
+ }
|
|
|
+ return trimLeftUnicode(trimRightUnicode(s, cutset), 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 {
|
|
|
+ if len(s) == 0 {
|
|
|
+ // This is what we've historically done.
|
|
|
+ return nil
|
|
|
+ }
|
|
|
+ if cutset == "" {
|
|
|
+ return s
|
|
|
+ }
|
|
|
+ if len(cutset) == 1 && cutset[0] < utf8.RuneSelf {
|
|
|
+ return trimLeftByte(s, cutset[0])
|
|
|
+ }
|
|
|
+ if as, ok := makeASCIISet(cutset); ok {
|
|
|
+ return trimLeftASCII(s, &as)
|
|
|
+ }
|
|
|
+ return trimLeftUnicode(s, cutset)
|
|
|
+}
|
|
|
+
|
|
|
+func trimLeftByte(s []byte, c byte) []byte {
|
|
|
+ for len(s) > 0 && s[0] == c {
|
|
|
+ s = s[1:]
|
|
|
+ }
|
|
|
+ if len(s) == 0 {
|
|
|
+ // This is what we've historically done.
|
|
|
+ return nil
|
|
|
+ }
|
|
|
+ return s
|
|
|
+}
|
|
|
+
|
|
|
+func trimLeftASCII(s []byte, as *asciiSet) []byte {
|
|
|
+ for len(s) > 0 {
|
|
|
+ if !as.contains(s[0]) {
|
|
|
+ break
|
|
|
+ }
|
|
|
+ s = s[1:]
|
|
|
+ }
|
|
|
+ if len(s) == 0 {
|
|
|
+ // This is what we've historically done.
|
|
|
+ return nil
|
|
|
+ }
|
|
|
+ return s
|
|
|
+}
|
|
|
+
|
|
|
+func trimLeftUnicode(s []byte, cutset string) []byte {
|
|
|
+ for len(s) > 0 {
|
|
|
+ r, n := rune(s[0]), 1
|
|
|
+ if r >= utf8.RuneSelf {
|
|
|
+ r, n = utf8.DecodeRune(s)
|
|
|
+ }
|
|
|
+ if !containsRune(cutset, r) {
|
|
|
+ break
|
|
|
+ }
|
|
|
+ s = s[n:]
|
|
|
+ }
|
|
|
+ if len(s) == 0 {
|
|
|
+ // This is what we've historically done.
|
|
|
+ return nil
|
|
|
+ }
|
|
|
+ return s
|
|
|
+}
|
|
|
+
|
|
|
+// 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 {
|
|
|
+ if len(s) == 0 || cutset == "" {
|
|
|
+ return s
|
|
|
+ }
|
|
|
+ if len(cutset) == 1 && cutset[0] < utf8.RuneSelf {
|
|
|
+ return trimRightByte(s, cutset[0])
|
|
|
+ }
|
|
|
+ if as, ok := makeASCIISet(cutset); ok {
|
|
|
+ return trimRightASCII(s, &as)
|
|
|
+ }
|
|
|
+ return trimRightUnicode(s, cutset)
|
|
|
+}
|
|
|
+
|
|
|
+func trimRightByte(s []byte, c byte) []byte {
|
|
|
+ for len(s) > 0 && s[len(s)-1] == c {
|
|
|
+ s = s[:len(s)-1]
|
|
|
+ }
|
|
|
+ return s
|
|
|
+}
|
|
|
+
|
|
|
+func trimRightASCII(s []byte, as *asciiSet) []byte {
|
|
|
+ for len(s) > 0 {
|
|
|
+ if !as.contains(s[len(s)-1]) {
|
|
|
+ break
|
|
|
+ }
|
|
|
+ s = s[:len(s)-1]
|
|
|
+ }
|
|
|
+ return s
|
|
|
+}
|
|
|
+
|
|
|
+func trimRightUnicode(s []byte, cutset string) []byte {
|
|
|
+ for len(s) > 0 {
|
|
|
+ r, n := rune(s[len(s)-1]), 1
|
|
|
+ if r >= utf8.RuneSelf {
|
|
|
+ r, n = utf8.DecodeLastRune(s)
|
|
|
+ }
|
|
|
+ if !containsRune(cutset, r) {
|
|
|
+ break
|
|
|
+ }
|
|
|
+ s = s[:len(s)-n]
|
|
|
+ }
|
|
|
+ return s
|
|
|
+}
|
|
|
+
|
|
|
+// 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
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|
|
+ // 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
|
|
|
+}
|
|
|
+
|
|
|
+// Cut slices s around the first instance of sep,
|
|
|
+// returning the text before and after sep.
|
|
|
+// The found result reports whether sep appears in s.
|
|
|
+// If sep does not appear in s, cut returns s, nil, false.
|
|
|
+//
|
|
|
+// Cut returns slices of the original slice s, not copies.
|
|
|
+func Cut(s, sep []byte) (before, after []byte, found bool) {
|
|
|
+ if i := Index(s, sep); i >= 0 {
|
|
|
+ return s[:i], s[i+len(sep):], true
|
|
|
+ }
|
|
|
+ return s, nil, false
|
|
|
+}
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alexv-smirnov