mirror of
https://github.com/golang/go
synced 2024-10-05 10:21:22 -06:00
199 lines
3.4 KiB
Go
199 lines
3.4 KiB
Go
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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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package strings
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// Count UTF-8 sequences in s.
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// Assumes s is well-formed.
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export func utflen(s string) int {
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n := 0;
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for i := 0; i < len(s); i++ {
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if s[i]&0xC0 != 0x80 {
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n++
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}
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}
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return n
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}
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// Split string into array of UTF-8 sequences (still strings)
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export func explode(s string) *[]string {
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a := new([]string, utflen(s));
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j := 0;
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for i := 0; i < len(a); i++ {
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ej := j;
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ej++;
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for ej < len(s) && (s[ej]&0xC0) == 0x80 {
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ej++
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}
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a[i] = s[j:ej];
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j = ej
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}
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return a
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}
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// Count non-overlapping instances of sep in s.
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export func count(s, sep string) int {
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if sep == "" {
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return utflen(s)+1
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}
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c := sep[0];
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n := 0;
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for i := 0; i+len(sep) <= len(s); i++ {
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if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == sep) {
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n++;
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i += len(sep)-1
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}
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}
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return n
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}
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// Return index of first instance of sep in s.
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export func index(s, sep string) int {
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if sep == "" {
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return 0
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}
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c := sep[0];
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for i := 0; i+len(sep) <= len(s); i++ {
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if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == 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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// Split string into list of strings at separators
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export func split(s, sep string) *[]string {
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if sep == "" {
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return explode(s)
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}
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c := sep[0];
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start := 0;
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n := count(s, sep)+1;
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a := new([]string, n);
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na := 0;
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for i := 0; i+len(sep) <= len(s); i++ {
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if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == sep) {
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a[na] = s[start:i];
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na++;
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start = i+len(sep);
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i += len(sep)-1
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}
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}
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a[na] = s[start:len(s)];
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return a
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}
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// Join list of strings with separators between them.
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export func join(a *[]string, sep string) string {
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if len(a) == 0 {
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return 0
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}
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if len(a) == 1 {
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return a[0]
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}
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n := len(sep) * (len(a)-1);
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for i := 0; i < len(a); i++ {
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n += len(a[i])
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}
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b := new([]byte, n);
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bp := 0;
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for i := 0; i < len(a); i++ {
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s := a[i];
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for j := 0; j < len(s); j++ {
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b[bp] = s[j];
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bp++
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}
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if i + 1 < len(a) {
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s = sep;
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for j := 0; j < len(s); j++ {
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b[bp] = s[j];
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bp++
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}
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}
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}
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return string(b)
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}
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// Convert decimal string to integer.
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// TODO: Doesn't check for overflow.
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export func atoi(s string) (i int, ok bool) {
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// empty string bad
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if len(s) == 0 {
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return 0, false
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}
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// pick off leading sign
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neg := false;
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if s[0] == '+' {
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s = s[1:len(s)]
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} else if s[0] == '-' {
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neg = true;
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s = s[1:len(s)]
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}
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// empty string bad
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if len(s) == 0 {
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return 0, false
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}
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// pick off zero
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if s == "0" {
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return 0, true
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}
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// otherwise, leading zero bad
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if s[0] == '0' {
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return 0, false
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}
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// parse number
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n := 0;
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for i := 0; i < len(s); i++ {
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if s[i] < '0' || s[i] > '9' {
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return 0, false
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}
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n = n*10 + int(s[i] - '0')
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}
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if neg {
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n = -n
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}
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return n, true
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}
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export func itoa(i int) string {
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if i == 0 {
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return "0"
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}
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neg := false; // negative
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bigneg := false; // largest negative number
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if i < 0 {
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neg = true;
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i = -i;
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if i < 0 {
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bigneg = true; // is largest negative int
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i-- // now positive
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}
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}
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// Assemble decimal in reverse order.
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var b [32]byte;
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bp := len(b);
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for ; i > 0; i /= 10 {
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bp--;
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b[bp] = byte(i%10) + '0'
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}
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if neg { // add sign
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bp--;
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b[bp] = '-'
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}
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if bigneg { // account for i-- above
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b[len(b)-1]++
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}
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// BUG return string(b[bp:len(b)])
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return string((&b)[bp:len(b)])
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}
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