publisher: Improve class collector for dynamic classes

E.g.

* AlpinesJS' :class="isTrue 'class1' : 'class2'"
* And dynamic classes with colon in them, e.g. `hover:bg-white`

publisher/htmlElementsCollector.go

@@ -32,7 +32,7 @@ const eof = -1
 
 var (
 	htmlJsonFixer = strings.NewReplacer(", ", "\n")
-	jsonAttrRe    = regexp.MustCompile(`'?(.*?)'?:.*`)
+	jsonAttrRe    = regexp.MustCompile(`'?(.*?)'?:\s.*`)
 	classAttrRe   = regexp.MustCompile(`(?i)^class$|transition`)
 
 	skipInnerElementRe = regexp.MustCompile(`(?i)^(pre|textarea|script|style)`)
@@ -404,21 +404,31 @@ func (w *htmlElementsCollectorWriter) parseHTMLElement(elStr string) (el htmlEle
 					if conf.DisableClasses {
 						continue
 					}
+
 					if classAttrRe.MatchString(a.Key) {
 						el.Classes = append(el.Classes, strings.Fields(a.Val)...)
 					} else {
 						key := strings.ToLower(a.Key)
 						val := strings.TrimSpace(a.Val)
-						if strings.Contains(key, "class") && strings.HasPrefix(val, "{") {
+
-							// This looks like a Vue or AlpineJS class binding.
+						if strings.Contains(key, ":class") {
-							val = htmlJsonFixer.Replace(strings.Trim(val, "{}"))
+							if strings.HasPrefix(val, "{") {
-							lines := strings.Split(val, "\n")
+								// This looks like a Vue or AlpineJS class binding.
-							for i, l := range lines {
+								val = htmlJsonFixer.Replace(strings.Trim(val, "{}"))
-								lines[i] = strings.TrimSpace(l)
+								lines := strings.Split(val, "\n")
+								for i, l := range lines {
+									lines[i] = strings.TrimSpace(l)
+								}
+								val = strings.Join(lines, "\n")
+
+								val = jsonAttrRe.ReplaceAllString(val, "$1")
+
+								el.Classes = append(el.Classes, strings.Fields(val)...)
 							}
-							val = strings.Join(lines, "\n")
+							// Also add single quoted strings.
-							val = jsonAttrRe.ReplaceAllString(val, "$1")
+							// This may introduce some false positives, but it covers some missing cases in the above.
-							el.Classes = append(el.Classes, strings.Fields(val)...)
+							// E.g. AlpinesJS' :class="isTrue 'class1' : 'class2'"
+							el.Classes = append(el.Classes, extractSingleQuotedStrings(val)...)
 						}
 					}
 				}
@@ -519,3 +529,29 @@ LOOP:
 func isSpace(b byte) bool {
 	return b == ' ' || b == '\t' || b == '\n'
 }
+
+func extractSingleQuotedStrings(s string) []string {
+	var (
+		inQuote bool
+		lo      int
+		hi      int
+	)
+
+	var words []string
+
+	for i, r := range s {
+		switch {
+		case r == '\'':
+			if !inQuote {
+				inQuote = true
+				lo = i + 1
+			} else {
+				inQuote = false
+				hi = i
+				words = append(words, strings.Fields(s[lo:hi])...)
+			}
+		}
+	}
+
+	return words
+}

publisher/htmlElementsCollector_test.go

@@ -99,6 +99,8 @@ func TestClassCollector(t *testing.T) {
                  pl-2: b == 3,
                 'text-gray-600': (a > 1)
                 }" class="block w-36 cursor-pointer pr-3 no-underline capitalize"></a>`, f("a", "block capitalize cursor-pointer no-underline pl-2 pl-3 pr-3 text-a text-b text-gray-600 w-36", "")},
+		{"AlpineJS bind 6", `<button :class="isActive(32) ? 'border-gray-500 bg-white pt border-t-2' : 'border-transparent hover:bg-gray-100'"></button>`, f("button", "bg-white border-gray-500 border-t-2 border-transparent hover:bg-gray-100 pt", "")},
+		{"AlpineJS bind 7", `<button :class="{ 'border-gray-500 bg-white pt border-t-2': isActive(32), 'border-transparent hover:bg-gray-100': !isActive(32) }"></button>`, f("button", "bg-white border-gray-500 border-t-2 border-transparent hover:bg-gray-100 pt", "")},
 		{"AlpineJS transition 1", `<div x-transition:enter-start="opacity-0 transform mobile:-translate-x-8 sm:-translate-y-8">`, f("div", "mobile:-translate-x-8 opacity-0 sm:-translate-y-8 transform", "")},
 		{"Vue bind", `<div v-bind:class="{ active: isActive }"></div>`, f("div", "active", "")},
 		// Issue #7746
@@ -136,7 +138,9 @@ func TestClassCollector(t *testing.T) {
 			{minify: true},
 		} {
 
-			c.Run(fmt.Sprintf("%s--minify-%t", test.name, variant.minify), func(c *qt.C) {
+			name := fmt.Sprintf("%s--minify-%t", test.name, variant.minify)
+
+			c.Run(name, func(c *qt.C) {
 				w := newHTMLElementsCollectorWriter(newHTMLElementsCollector(
 					config.BuildStats{Enable: true},
 				))