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// 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 strings
// Count UTF-8 sequences in s.
// Assumes s is well-formed.
export func utflen(s string) int {
n := 0;
for i := 0; i < len(s); i++ {
if s[i]&0xC0 != 0x80 {
n++
}
}
return n
}
// Split string into array of UTF-8 sequences (still strings)
export func explode(s string) *[]string {
a := new([]string, utflen(s));
j := 0;
for i := 0; i < len(a); i++ {
ej := j;
ej++;
for ej < len(s) && (s[ej]&0xC0) == 0x80 {
ej++
}
a[i] = s[j:ej];
j = ej
}
return a
}
// Count non-overlapping instances of sep in s.
export func count(s, sep string) int {
if sep == "" {
return utflen(s)+1
}
c := sep[0];
n := 0;
for i := 0; i+len(sep) <= len(s); i++ {
if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == sep) {
n++;
i += len(sep)-1
}
}
return n
}
// Return index of first instance of sep in s.
export func index(s, sep string) int {
if sep == "" {
return 0
}
c := sep[0];
for i := 0; i+len(sep) <= len(s); i++ {
if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == sep) {
return i
}
}
return -1
}
// Split string into list of strings at separators
export func split(s, sep string) *[]string {
if sep == "" {
return explode(s)
}
c := sep[0];
start := 0;
n := count(s, sep)+1;
a := new([]string, n);
na := 0;
for i := 0; i+len(sep) <= len(s); i++ {
if s[i] == c && (len(sep) == 1 || s[i:i+len(sep)] == sep) {
a[na] = s[start:i];
na++;
start = i+len(sep);
i += len(sep)-1
}
}
a[na] = s[start:len(s)];
return a
}
// Join list of strings with separators between them.
export 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 := new([]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)
}
// Convert decimal string to unsigned integer.
// TODO: Doesn't check for overflow.
export func atoui64(s string) (i uint64, ok bool) {
// empty string bad
if len(s) == 0 {
return 0, false
}
// pick off zero
if s == "0" {
return 0, true
}
// otherwise, leading zero bad
if s[0] == '0' {
return 0, false
}
// parse number
n := uint64(0);
for i := 0; i < len(s); i++ {
if s[i] < '0' || s[i] > '9' {
return 0, false
}
n = n*10 + uint64(s[i] - '0')
}
return n, true
}
// Convert decimal string to integer.
// TODO: Doesn't check for overflow.
export func atoi64(s string) (i int64, ok bool) {
// empty string bad
if len(s) == 0 {
return 0, false
}
// pick off leading sign
neg := false;
if s[0] == '+' {
s = s[1:len(s)]
} else if s[0] == '-' {
neg = true;
s = s[1:len(s)]
}
var un uint64;
un, ok = atoui64(s);
if !ok {
return 0, false
}
n := int64(un);
if neg {
n = -n
}
return n, true
}
export func atoui(s string) (i uint, ok bool) {
ii, okok := atoui64(s);
i = uint(ii);
return i, okok
}
export func atoi(s string) (i int, ok bool) {
ii, okok := atoi64(s);
i = int(ii);
return i, okok
}
export func ltoa(i int64) string {
if i == 0 {
return "0"
}
neg := false; // negative
u := uint(i);
if i < 0 {
neg = true;
u = -u;
}
// Assemble decimal in reverse order.
var b [32]byte;
bp := len(b);
for ; u > 0; u /= 10 {
bp--;
b[bp] = byte(u%10) + '0'
}
if neg { // add sign
bp--;
b[bp] = '-'
}
// BUG return string(b[bp:len(b)])
return string((&b)[bp:len(b)])
}
export func itoa(i int) string {
return ltoa(int64(i));
}
// Convert float64 to string. No control over format.
// Result not great; only useful for simple debugging.
export func dtoa(v float64) string {
var buf [20]byte;
const n = 7; // digits printed
e := 0; // exp
var sign byte = '+';
if(v != 0) {
// sign
if(v < 0) {
v = -v;
sign = '-';
}
// normalize
for v >= 10 {
e++;
v /= 10;
}
for v < 1 {
e--;
v *= 10;
}
// round
var h float64 = 5;
for i := 0; i < n; i++ {
h /= 10;
}
v += h;
if v >= 10 {
e++;
v /= 10;
}
}
// format +d.dddd+edd
buf[0] = sign;
for i := 0; i < n; i++ {
s := int64(v);
buf[i+2] = byte(s)+'0';
v -= float64(s);
v *= 10;
}
buf[1] = buf[2];
buf[2] = '.';
buf[n+2] = 'e';
buf[n+3] = '+';
if e < 0 {
e = -e;
buf[n+3] = '-';
}
// TODO: exponents > 99?
buf[n+4] = byte((e/10) + '0');
buf[n+5] = byte((e%10) + '0');
return string(buf)[0:n+6]; // TODO: should be able to slice buf
}
export func ftoa(v float) string {
return dtoa(float64(v));
}
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