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-rw-r--r--libgo/go/strings/strings.go559
1 files changed, 559 insertions, 0 deletions
diff --git a/libgo/go/strings/strings.go b/libgo/go/strings/strings.go
new file mode 100644
index 000000000..98a0d5731
--- /dev/null
+++ b/libgo/go/strings/strings.go
@@ -0,0 +1,559 @@
+// 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.
+
+// A package of simple functions to manipulate strings.
+package strings
+
+import (
+ "unicode"
+ "utf8"
+)
+
+// explode splits s into an array of UTF-8 sequences, one per Unicode character (still strings) up to a maximum of n (n < 0 means no limit).
+// Invalid UTF-8 sequences become correct encodings of U+FFF8.
+func explode(s string, n int) []string {
+ if n == 0 {
+ return nil
+ }
+ l := utf8.RuneCountInString(s)
+ if n <= 0 || n > l {
+ n = l
+ }
+ a := make([]string, n)
+ var size, rune int
+ i, cur := 0, 0
+ for ; i+1 < n; i++ {
+ rune, size = utf8.DecodeRuneInString(s[cur:])
+ a[i] = string(rune)
+ cur += size
+ }
+ // add the rest, if there is any
+ if cur < len(s) {
+ a[i] = s[cur:]
+ }
+ return a
+}
+
+// Count counts the number of non-overlapping instances of sep in s.
+func Count(s, sep string) int {
+ if sep == "" {
+ return utf8.RuneCountInString(s) + 1
+ }
+ c := sep[0]
+ l := len(sep)
+ n := 0
+ if l == 1 {
+ // special case worth making fast
+ for i := 0; i < len(s); i++ {
+ if s[i] == c {
+ n++
+ }
+ }
+ return n
+ }
+ for i := 0; i+l <= len(s); i++ {
+ if s[i] == c && s[i:i+l] == sep {
+ n++
+ i += l - 1
+ }
+ }
+ return n
+}
+
+// Contains returns true if substr is within s.
+func Contains(s, substr string) bool {
+ return Index(s, substr) != -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 string) int {
+ n := len(sep)
+ if n == 0 {
+ return 0
+ }
+ c := sep[0]
+ if n == 1 {
+ // special case worth making fast
+ for i := 0; i < len(s); i++ {
+ if s[i] == c {
+ return i
+ }
+ }
+ return -1
+ }
+ // n > 1
+ for i := 0; i+n <= len(s); i++ {
+ if s[i] == c && s[i:i+n] == sep {
+ 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 string) int {
+ n := len(sep)
+ if n == 0 {
+ return len(s)
+ }
+ c := sep[0]
+ if n == 1 {
+ // special case worth making fast
+ for i := len(s) - 1; i >= 0; i-- {
+ if s[i] == c {
+ return i
+ }
+ }
+ return -1
+ }
+ // n > 1
+ for i := len(s) - n; i >= 0; i-- {
+ if s[i] == c && s[i:i+n] == sep {
+ return i
+ }
+ }
+ return -1
+}
+
+// IndexRune returns the index of the first instance of the Unicode code point
+// rune, or -1 if rune is not present in s.
+func IndexRune(s string, rune int) int {
+ for i, c := range s {
+ if c == rune {
+ return i
+ }
+ }
+ return -1
+}
+
+// IndexAny returns the index of the first instance of any Unicode code point
+// from chars in s, or -1 if no Unicode code point from chars is present in s.
+func IndexAny(s, chars string) int {
+ if len(chars) > 0 {
+ for i, c := range s {
+ for _, m := range chars {
+ if c == m {
+ return i
+ }
+ }
+ }
+ }
+ return -1
+}
+
+// LastIndexAny returns the index of the last instance of any Unicode code
+// point from chars in s, or -1 if no Unicode code point from chars is
+// present in s.
+func LastIndexAny(s, chars string) int {
+ if len(chars) > 0 {
+ for i := len(s); i > 0; {
+ rune, size := utf8.DecodeLastRuneInString(s[0:i])
+ i -= size
+ for _, m := range chars {
+ if rune == m {
+ return i
+ }
+ }
+ }
+ }
+ return -1
+}
+
+// Generic split: splits after each instance of sep,
+// including sepSave bytes of sep in the subarrays.
+func genSplit(s, sep string, sepSave, n int) []string {
+ if n == 0 {
+ return nil
+ }
+ if sep == "" {
+ return explode(s, n)
+ }
+ if n < 0 {
+ n = Count(s, sep) + 1
+ }
+ c := sep[0]
+ start := 0
+ a := make([]string, n)
+ na := 0
+ for i := 0; i+len(sep) <= len(s) && na+1 < n; i++ {
+ if s[i] == c && (len(sep) == 1 || 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]
+}
+
+// Split slices s into substrings separated by sep and returns a slice of
+// the substrings between those separators.
+// If sep is empty, Split splits after each UTF-8 sequence.
+// The count determines the number of substrings to return:
+// n > 0: at most n substrings; the last substring will be the unsplit remainder.
+// n == 0: the result is nil (zero substrings)
+// n < 0: all substrings
+func Split(s, sep string, n int) []string { return genSplit(s, sep, 0, n) }
+
+// SplitAfter slices s into substrings after each instance of sep and
+// returns a slice of those substrings.
+// If sep is empty, Split splits after each UTF-8 sequence.
+// The count determines the number of substrings to return:
+// n > 0: at most n substrings; the last substring will be the unsplit remainder.
+// n == 0: the result is nil (zero substrings)
+// n < 0: all substrings
+func SplitAfter(s, sep string, n int) []string {
+ return genSplit(s, sep, len(sep), n)
+}
+
+// Fields splits the string s around each instance of one or more consecutive white space
+// characters, returning an array of substrings of s or an empty list if s contains only white space.
+func Fields(s string) []string {
+ return FieldsFunc(s, unicode.IsSpace)
+}
+
+// FieldsFunc splits the string s at each run of Unicode code points c satisfying f(c)
+// and returns an array of slices of s. If all code points in s satisfy f(c) or the
+// string is empty, an empty slice is returned.
+func FieldsFunc(s string, f func(int) bool) []string {
+ // First count the fields.
+ n := 0
+ inField := false
+ for _, rune := range s {
+ wasInField := inField
+ inField = !f(rune)
+ if inField && !wasInField {
+ n++
+ }
+ }
+
+ // Now create them.
+ a := make([]string, n)
+ na := 0
+ fieldStart := -1 // Set to -1 when looking for start of field.
+ for i, rune := range s {
+ if f(rune) {
+ if fieldStart >= 0 {
+ a[na] = s[fieldStart:i]
+ na++
+ fieldStart = -1
+ }
+ } else if fieldStart == -1 {
+ fieldStart = i
+ }
+ }
+ if fieldStart != -1 { // Last field might end at EOF.
+ a[na] = s[fieldStart:]
+ }
+ return a
+}
+
+// Join concatenates the elements of a to create a single string. The separator string
+// sep is placed between elements in the resulting string.
+func Join(a []string, sep string) string {
+ if len(a) == 0 {
+ return ""
+ }
+ if len(a) == 1 {
+ return a[0]
+ }
+ n := len(sep) * (len(a) - 1)
+ for i := 0; i < len(a); i++ {
+ n += len(a[i])
+ }
+
+ b := make([]byte, n)
+ bp := 0
+ for i := 0; i < len(a); i++ {
+ s := a[i]
+ for j := 0; j < len(s); j++ {
+ b[bp] = s[j]
+ bp++
+ }
+ if i+1 < len(a) {
+ s = sep
+ for j := 0; j < len(s); j++ {
+ b[bp] = s[j]
+ bp++
+ }
+ }
+ }
+ return string(b)
+}
+
+// HasPrefix tests whether the string s begins with prefix.
+func HasPrefix(s, prefix string) bool {
+ return len(s) >= len(prefix) && s[0:len(prefix)] == prefix
+}
+
+// HasSuffix tests whether the string s ends with suffix.
+func HasSuffix(s, suffix string) bool {
+ return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
+}
+
+// Map returns a copy of the string 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.
+func Map(mapping func(rune int) int, s string) string {
+ // In the worst case, the string 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 _, c := range s {
+ rune := mapping(c)
+ if rune >= 0 {
+ wid := 1
+ if rune >= utf8.RuneSelf {
+ wid = utf8.RuneLen(rune)
+ }
+ if nbytes+wid > 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], rune)
+ }
+ }
+ return string(b[0:nbytes])
+}
+
+// Repeat returns a new string consisting of count copies of the string s.
+func Repeat(s string, count int) string {
+ b := make([]byte, len(s)*count)
+ bp := 0
+ for i := 0; i < count; i++ {
+ for j := 0; j < len(s); j++ {
+ b[bp] = s[j]
+ bp++
+ }
+ }
+ return string(b)
+}
+
+
+// ToUpper returns a copy of the string s with all Unicode letters mapped to their upper case.
+func ToUpper(s string) string { return Map(unicode.ToUpper, s) }
+
+// ToLower returns a copy of the string s with all Unicode letters mapped to their lower case.
+func ToLower(s string) string { return Map(unicode.ToLower, s) }
+
+// ToTitle returns a copy of the string s with all Unicode letters mapped to their title case.
+func ToTitle(s string) string { return Map(unicode.ToTitle, s) }
+
+// ToUpperSpecial returns a copy of the string s with all Unicode letters mapped to their
+// upper case, giving priority to the special casing rules.
+func ToUpperSpecial(_case unicode.SpecialCase, s string) string {
+ return Map(func(r int) int { return _case.ToUpper(r) }, s)
+}
+
+// ToLowerSpecial returns a copy of the string s with all Unicode letters mapped to their
+// lower case, giving priority to the special casing rules.
+func ToLowerSpecial(_case unicode.SpecialCase, s string) string {
+ return Map(func(r int) int { return _case.ToLower(r) }, s)
+}
+
+// ToTitleSpecial returns a copy of the string s with all Unicode letters mapped to their
+// title case, giving priority to the special casing rules.
+func ToTitleSpecial(_case unicode.SpecialCase, s string) string {
+ return Map(func(r int) int { 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(rune int) bool {
+ // ASCII alphanumerics and underscore are not separators
+ if rune <= 0x7F {
+ switch {
+ case '0' <= rune && rune <= '9':
+ return false
+ case 'a' <= rune && rune <= 'z':
+ return false
+ case 'A' <= rune && rune <= 'Z':
+ return false
+ case rune == '_':
+ return false
+ }
+ return true
+ }
+ // Letters and digits are not separators
+ if unicode.IsLetter(rune) || unicode.IsDigit(rune) {
+ return false
+ }
+ // Otherwise, all we can do for now is treat spaces as separators.
+ return unicode.IsSpace(rune)
+}
+
+// BUG(r): The rule Title uses for word boundaries does not handle Unicode punctuation properly.
+
+// Title returns a copy of the string s with all Unicode letters that begin words
+// mapped to their title case.
+func Title(s string) string {
+ // 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 int) int {
+ if isSeparator(prev) {
+ prev = r
+ return unicode.ToTitle(r)
+ }
+ prev = r
+ return r
+ },
+ s)
+}
+
+// TrimLeftFunc returns a slice of the string s with all leading
+// Unicode code points c satisfying f(c) removed.
+func TrimLeftFunc(s string, f func(r int) bool) string {
+ i := indexFunc(s, f, false)
+ if i == -1 {
+ return ""
+ }
+ return s[i:]
+}
+
+// TrimRightFunc returns a slice of the string s with all trailing
+// Unicode code points c satisfying f(c) removed.
+func TrimRightFunc(s string, f func(r int) bool) string {
+ i := lastIndexFunc(s, f, false)
+ if i >= 0 && s[i] >= utf8.RuneSelf {
+ _, wid := utf8.DecodeRuneInString(s[i:])
+ i += wid
+ } else {
+ i++
+ }
+ return s[0:i]
+}
+
+// TrimFunc returns a slice of the string s with all leading
+// and trailing Unicode code points c satisfying f(c) removed.
+func TrimFunc(s string, f func(r int) bool) string {
+ return TrimRightFunc(TrimLeftFunc(s, f), f)
+}
+
+// IndexFunc returns the index into s of the first Unicode
+// code point satisfying f(c), or -1 if none do.
+func IndexFunc(s string, f func(r int) bool) int {
+ return indexFunc(s, f, true)
+}
+
+// LastIndexFunc returns the index into s of the last
+// Unicode code point satisfying f(c), or -1 if none do.
+func LastIndexFunc(s string, f func(r int) 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 string, f func(r int) bool, truth bool) int {
+ start := 0
+ for start < len(s) {
+ wid := 1
+ rune := int(s[start])
+ if rune >= utf8.RuneSelf {
+ rune, wid = utf8.DecodeRuneInString(s[start:])
+ }
+ if f(rune) == 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 string, f func(r int) bool, truth bool) int {
+ for i := len(s); i > 0; {
+ rune, size := utf8.DecodeLastRuneInString(s[0:i])
+ i -= size
+ if f(rune) == truth {
+ return i
+ }
+ }
+ return -1
+}
+
+func makeCutsetFunc(cutset string) func(rune int) bool {
+ return func(rune int) bool { return IndexRune(cutset, rune) != -1 }
+}
+
+// Trim returns a slice of the string s with all leading and
+// trailing Unicode code points contained in cutset removed.
+func Trim(s string, cutset string) string {
+ if s == "" || cutset == "" {
+ return s
+ }
+ return TrimFunc(s, makeCutsetFunc(cutset))
+}
+
+// TrimLeft returns a slice of the string s with all leading
+// Unicode code points contained in cutset removed.
+func TrimLeft(s string, cutset string) string {
+ if s == "" || cutset == "" {
+ return s
+ }
+ return TrimLeftFunc(s, makeCutsetFunc(cutset))
+}
+
+// TrimRight returns a slice of the string s, with all trailing
+// Unicode code points contained in cutset removed.
+func TrimRight(s string, cutset string) string {
+ if s == "" || cutset == "" {
+ return s
+ }
+ return TrimRightFunc(s, makeCutsetFunc(cutset))
+}
+
+// TrimSpace returns a slice of the string s, with all leading
+// and trailing white space removed, as defined by Unicode.
+func TrimSpace(s string) string {
+ return TrimFunc(s, unicode.IsSpace)
+}
+
+// Replace returns a copy of the string s with the first n
+// non-overlapping instances of old replaced by new.
+// If n < 0, there is no limit on the number of replacements.
+func Replace(s, old, new string, n int) string {
+ if old == new || n == 0 {
+ return s // avoid allocation
+ }
+
+ // Compute number of replacements.
+ if m := Count(s, old); m == 0 {
+ return s // avoid allocation
+ } else 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.DecodeRuneInString(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 string(t[0:w])
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-02 08:50:18 +0000