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Small performance improvements to the HTML tokenizer based on your 'TODO's.

R=nigeltao_golang
CC=golang-dev
https://golang.org/cl/1941042
This commit is contained in:
Kyle Consalus 2010-08-12 09:45:34 +10:00 committed by Nigel Tao
parent bca3151042
commit 8fcdc6a1e2
2 changed files with 48 additions and 12 deletions

View File

@ -5,6 +5,7 @@
package html
import (
"bytes"
"strings"
"utf8"
)
@ -60,18 +61,45 @@ func unescape(b []byte) []byte {
return b
}
const escapedChars = `&'<>"`
func escape(buf *bytes.Buffer, s string) {
i := strings.IndexAny(s, escapedChars)
for i != -1 {
buf.WriteString(s[0:i])
var esc string
switch s[i] {
case '&':
esc = "&amp;"
case '\'':
esc = "&apos;"
case '<':
esc = "&lt;"
case '>':
esc = "&gt;"
case '"':
esc = "&quot;"
default:
panic("unrecognized escape character")
}
s = s[i+1:]
buf.WriteString(esc)
i = strings.IndexAny(s, escapedChars)
}
buf.WriteString(s)
}
// EscapeString escapes special characters like "<" to become "&lt;". It
// escapes only five such characters: amp, apos, lt, gt and quot.
// UnescapeString(EscapeString(s)) == s always holds, but the converse isn't
// always true.
func EscapeString(s string) string {
// TODO(nigeltao): Do this much more efficiently.
s = strings.Replace(s, `&`, `&amp;`, -1)
s = strings.Replace(s, `'`, `&apos;`, -1)
s = strings.Replace(s, `<`, `&lt;`, -1)
s = strings.Replace(s, `>`, `&gt;`, -1)
s = strings.Replace(s, `"`, `&quot;`, -1)
return s
if strings.IndexAny(s, escapedChars) == -1 {
return s
}
buf := bytes.NewBuffer(nil)
escape(buf, s)
return buf.String()
}
// UnescapeString unescapes entities like "&lt;" to become "<". It unescapes a

View File

@ -5,6 +5,7 @@
package html
import (
"bytes"
"io"
"log"
"os"
@ -68,12 +69,19 @@ type Token struct {
// tagString returns a string representation of a tag Token's Data and Attr.
func (t Token) tagString() string {
// TODO(nigeltao): Don't use string concatenation; it is inefficient.
s := string(t.Data)
for _, a := range t.Attr {
s += ` ` + a.Key + `="` + EscapeString(a.Val) + `"`
if len(t.Attr) == 0 {
return t.Data
}
return s
buf := bytes.NewBuffer(nil)
buf.WriteString(t.Data)
for _, a := range t.Attr {
buf.WriteByte(' ')
buf.WriteString(a.Key)
buf.WriteString(`="`)
escape(buf, a.Val)
buf.WriteByte('"')
}
return buf.String()
}
// String returns a string representation of the Token.