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|
package util
import (
"fmt"
"unicode"
"unicode/utf8"
"unsafe"
)
const (
overflow64 uint64 = 0x8080808080808080
overflow32 uint32 = 0x80808080
)
type Chars struct {
slice []byte // or []rune
inBytes bool
trimLengthKnown bool
trimLength uint16
// XXX Piggybacking item index here is a horrible idea. But I'm trying to
// minimize the memory footprint by not wasting padded spaces.
Index int32
}
func checkAscii(bytes []byte) (bool, int) {
i := 0
for ; i <= len(bytes)-8; i += 8 {
if (overflow64 & *(*uint64)(unsafe.Pointer(&bytes[i]))) > 0 {
return false, i
}
}
for ; i <= len(bytes)-4; i += 4 {
if (overflow32 & *(*uint32)(unsafe.Pointer(&bytes[i]))) > 0 {
return false, i
}
}
for ; i < len(bytes); i++ {
if bytes[i] >= utf8.RuneSelf {
return false, i
}
}
return true, 0
}
// ToChars converts byte array into rune array
func ToChars(bytes []byte) Chars {
inBytes, bytesUntil := checkAscii(bytes)
if inBytes {
return Chars{slice: bytes, inBytes: inBytes}
}
runes := make([]rune, bytesUntil, len(bytes))
for i := 0; i < bytesUntil; i++ {
runes[i] = rune(bytes[i])
}
for i := bytesUntil; i < len(bytes); {
r, sz := utf8.DecodeRune(bytes[i:])
i += sz
runes = append(runes, r)
}
return RunesToChars(runes)
}
func RunesToChars(runes []rune) Chars {
return Chars{slice: *(*[]byte)(unsafe.Pointer(&runes)), inBytes: false}
}
func (chars *Chars) IsBytes() bool {
return chars.inBytes
}
func (chars *Chars) Bytes() []byte {
return chars.slice
}
func (chars *Chars) optionalRunes() []rune {
if chars.inBytes {
return nil
}
return *(*[]rune)(unsafe.Pointer(&chars.slice))
}
func (chars *Chars) Get(i int) rune {
if runes := chars.optionalRunes(); runes != nil {
return runes[i]
}
return rune(chars.slice[i])
}
func (chars *Chars) Length() int {
if runes := chars.optionalRunes(); runes != nil {
return len(runes)
}
return len(chars.slice)
}
// String returns the string representation of a Chars object.
func (chars *Chars) String() string {
return fmt.Sprintf("Chars{slice: []byte(%q), inBytes: %v, trimLengthKnown: %v, trimLength: %d, Index: %d}", chars.slice, chars.inBytes, chars.trimLengthKnown, chars.trimLength, chars.Index)
}
// TrimLength returns the length after trimming leading and trailing whitespaces
func (chars *Chars) TrimLength() uint16 {
if chars.trimLengthKnown {
return chars.trimLength
}
chars.trimLengthKnown = true
var i int
len := chars.Length()
for i = len - 1; i >= 0; i-- {
char := chars.Get(i)
if !unicode.IsSpace(char) {
break
}
}
// Completely empty
if i < 0 {
return 0
}
var j int
for j = 0; j < len; j++ {
char := chars.Get(j)
if !unicode.IsSpace(char) {
break
}
}
chars.trimLength = AsUint16(i - j + 1)
return chars.trimLength
}
func (chars *Chars) LeadingWhitespaces() int {
whitespaces := 0
for i := 0; i < chars.Length(); i++ {
char := chars.Get(i)
if !unicode.IsSpace(char) {
break
}
whitespaces++
}
return whitespaces
}
func (chars *Chars) TrailingWhitespaces() int {
whitespaces := 0
for i := chars.Length() - 1; i >= 0; i-- {
char := chars.Get(i)
if !unicode.IsSpace(char) {
break
}
whitespaces++
}
return whitespaces
}
func (chars *Chars) TrimTrailingWhitespaces() {
whitespaces := chars.TrailingWhitespaces()
chars.slice = chars.slice[0 : len(chars.slice)-whitespaces]
}
func (chars *Chars) ToString() string {
if runes := chars.optionalRunes(); runes != nil {
return string(runes)
}
return unsafe.String(unsafe.SliceData(chars.slice), len(chars.slice))
}
func (chars *Chars) ToRunes() []rune {
if runes := chars.optionalRunes(); runes != nil {
return runes
}
bytes := chars.slice
runes := make([]rune, len(bytes))
for idx, b := range bytes {
runes[idx] = rune(b)
}
return runes
}
func (chars *Chars) CopyRunes(dest []rune) {
if runes := chars.optionalRunes(); runes != nil {
copy(dest, runes)
return
}
for idx, b := range chars.slice[:len(dest)] {
dest[idx] = rune(b)
}
}
func (chars *Chars) Prepend(prefix string) {
if runes := chars.optionalRunes(); runes != nil {
runes = append([]rune(prefix), runes...)
chars.slice = *(*[]byte)(unsafe.Pointer(&runes))
} else {
chars.slice = append([]byte(prefix), chars.slice...)
}
}
|
