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strings and bytes.Split: make count of 0 mean 0, not infinite.

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Use a count of -1 for infinity.  Ditto for Replace.

R=rsc
CC=golang-dev
https://golang.org/cl/1704044
This commit is contained in:
Rob Pike 2010-07-01 14:08:14 -07:00
parent 285312a05c
commit 38f1231f3e
24 changed files with 123 additions and 98 deletions
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22
src/pkg/strings/strings.go
View file

@ -10,9 +10,12 @@ import (
"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).
// 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
@ -135,10 +138,13 @@ func IndexAny(s, chars string) int {
// 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 {
if n < 0 {
n = Count(s, sep) + 1
}
c := sep[0]
@ -159,12 +165,14 @@ func genSplit(s, sep string, sepSave, n int) []string {
// Split splits the string s around each instance of sep, returning an array of substrings of s.
// If sep is empty, Split splits s after each UTF-8 sequence.
// If n > 0, Split splits s into at most n substrings; the last substring will be the unsplit remainder.
// If n >= 0, Split splits s into at most n substrings; the last substring will be the unsplit remainder.
// Thus if n == 0, the result will be nil.
func Split(s, sep string, n int) []string { return genSplit(s, sep, 0, n) }
// SplitAfter splits the string s after each instance of sep, returning an array of substrings of s.
// If sep is empty, SplitAfter splits s after each UTF-8 sequence.
// If n > 0, SplitAfter splits s into at most n substrings; the last substring will be the unsplit remainder.
// If n >= 0, SplitAfter splits s into at most n substrings; the last substring will be the unsplit remainder.
// Thus if n == 0, the result will be nil.
func SplitAfter(s, sep string, n int) []string {
return genSplit(s, sep, len(sep), n)
}
@ -462,16 +470,16 @@ func TrimSpace(s string) string {
// 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.
// If n < 0, there is no limit on the number of replacements.
func Replace(s, old, new string, n int) string {
if old == new {
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 {
} else if n < 0 || m < n {
n = m
}