refactor(internal): compile regex once while clearing text

Regex and Replacer can be reused.
No need to recreate for each invocation.

Signed-off-by: ferhat elmas <elmas.ferhat@gmail.com>

pkg/htmltext/htmltext.go

@@ -34,38 +34,34 @@ import (
 	"github.com/mozillazg/go-pinyin"
 )
 
-// ClearText clear HTML, get the clear text
-func ClearText(html string) (text string) {
-	if len(html) == 0 {
-		text = html
-		return
-	}
+var (
+	reCode         = regexp.MustCompile(`(?ism)<(pre)>.*<\/pre>`)
+	reCodeReplace  = "{code...}"
+	reLink         = regexp.MustCompile(`(?ism)<a.*?[^<]>(.*)?<\/a>`)
+	reLinkReplace  = " [$1] "
+	reSpace        = regexp.MustCompile(` +`)
+	reSpaceReplace = " "
 
-	var (
-		re        *regexp.Regexp
-		codeReg   = `(?ism)<(pre)>.*<\/pre>`
-		codeRepl  = "{code...}"
-		linkReg   = `(?ism)<a.*?[^<]>(.*)?<\/a>`
-		linkRepl  = " [$1] "
-		spaceReg  = ` +`
-		spaceRepl = " "
-	)
-	re = regexp.MustCompile(codeReg)
-	html = re.ReplaceAllString(html, codeRepl)
-
-	re = regexp.MustCompile(linkReg)
-	html = re.ReplaceAllString(html, linkRepl)
-
-	text = strings.NewReplacer(
+	spaceReplacer = strings.NewReplacer(
 		"\n", " ",
 		"\r", " ",
 		"\t", " ",
-	).Replace(strip.StripTags(html))
+	)
+)
+
+// ClearText clear HTML, get the clear text
+func ClearText(html string) string {
+	if html == "" {
+		return html
+	}
+
+	html = reCode.ReplaceAllString(html, reCodeReplace)
+	html = reLink.ReplaceAllString(html, reLinkReplace)
+
+	text := spaceReplacer.Replace(strip.StripTags(html))
 
 	// replace multiple spaces to one space
-	re = regexp.MustCompile(spaceReg)
-	text = strings.TrimSpace(re.ReplaceAllString(text, spaceRepl))
-	return
+	return strings.TrimSpace(reSpace.ReplaceAllString(text, reSpaceReplace))
 }
 
 func UrlTitle(title string) (text string) {