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tokenizer.go
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tokenizer.go
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package logstorage
import (
"sync"
"unicode"
"unicode/utf8"
)
// tokenizeStrings extracts word tokens from a, appends them to dst and returns the result.
//
// the order of returned tokens is unspecified.
func tokenizeStrings(dst, a []string) []string {
t := getTokenizer()
for i, s := range a {
if i > 0 && s == a[i-1] {
// This string has been already tokenized
continue
}
dst = t.tokenizeString(dst, s)
}
putTokenizer(t)
return dst
}
type tokenizer struct {
m map[string]struct{}
}
func (t *tokenizer) reset() {
clear(t.m)
}
func (t *tokenizer) tokenizeString(dst []string, s string) []string {
if !isASCII(s) {
// Slow path - s contains unicode chars
return t.tokenizeStringUnicode(dst, s)
}
// Fast path for ASCII s
m := t.m
i := 0
for i < len(s) {
// Search for the next token.
start := len(s)
for i < len(s) {
if !isTokenChar(s[i]) {
i++
continue
}
start = i
i++
break
}
// Search for the end of the token.
end := len(s)
for i < len(s) {
if isTokenChar(s[i]) {
i++
continue
}
end = i
i++
break
}
if end <= start {
break
}
// Register the token.
token := s[start:end]
if _, ok := m[token]; !ok {
m[token] = struct{}{}
dst = append(dst, token)
}
}
return dst
}
func (t *tokenizer) tokenizeStringUnicode(dst []string, s string) []string {
m := t.m
for len(s) > 0 {
// Search for the next token.
n := len(s)
for offset, r := range s {
if isTokenRune(r) {
n = offset
break
}
}
s = s[n:]
// Search for the end of the token.
n = len(s)
for offset, r := range s {
if !isTokenRune(r) {
n = offset
break
}
}
if n == 0 {
break
}
// Register the token
token := s[:n]
s = s[n:]
if _, ok := m[token]; !ok {
m[token] = struct{}{}
dst = append(dst, token)
}
}
return dst
}
func isASCII(s string) bool {
for i := range s {
if s[i] >= utf8.RuneSelf {
return false
}
}
return true
}
func isTokenChar(c byte) bool {
return c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' || c == '_'
}
func isTokenRune(c rune) bool {
return unicode.IsLetter(c) || unicode.IsDigit(c) || c == '_'
}
func getTokenizer() *tokenizer {
v := tokenizerPool.Get()
if v == nil {
return &tokenizer{
m: make(map[string]struct{}),
}
}
return v.(*tokenizer)
}
func putTokenizer(t *tokenizer) {
t.reset()
tokenizerPool.Put(t)
}
var tokenizerPool sync.Pool
type tokensBuf struct {
A []string
}
func (tb *tokensBuf) reset() {
clear(tb.A)
tb.A = tb.A[:0]
}
func getTokensBuf() *tokensBuf {
v := tokensBufPool.Get()
if v == nil {
return &tokensBuf{}
}
return v.(*tokensBuf)
}
func putTokensBuf(tb *tokensBuf) {
tb.reset()
tokensBufPool.Put(tb)
}
var tokensBufPool sync.Pool