Improve Color.Equals performance from O(n²) to O(n)

Author: UnSubble

color.go

@@ -20,7 +20,7 @@ var (
 	// colors. For more control over each color block use the methods
 	// DisableColor() individually.
 	NoColor = noColorIsSet() || os.Getenv("TERM") == "dumb" ||
-		(!isatty.IsTerminal(os.Stdout.Fd()) && !isatty.IsCygwinTerminal(os.Stdout.Fd()))
+	(!isatty.IsTerminal(os.Stdout.Fd()) && !isatty.IsCygwinTerminal(os.Stdout.Fd()))
 
 	// Output defines the standard output of the print functions. By default,
 	// os.Stdout is used.
@@ -404,11 +404,11 @@ func (c *Color) SprintlnFunc() func(a ...interface{}) string {
 // an example output might be: "1;36" -> bold cyan
 func (c *Color) sequence() string {
 	format := make([]string, len(c.params))
-	for i, v := range c.params {
-		format[i] = strconv.Itoa(int(v))
-	}
+		for i, v := range c.params {
+			format[i] = strconv.Itoa(int(v))
+		}
 
-	return strings.Join(format, ";")
+		return strings.Join(format, ";")
 }
 
 // wrap wraps the s string with the colors attributes. The string is ready to
@@ -429,15 +429,15 @@ func (c *Color) unformat() string {
 	//return fmt.Sprintf("%s[%dm", escape, Reset)
 	//for each element in sequence let's use the specific reset escape, or the generic one if not found
 	format := make([]string, len(c.params))
-	for i, v := range c.params {
-		format[i] = strconv.Itoa(int(Reset))
-		ra, ok := mapResetAttributes[v]
-		if ok {
-			format[i] = strconv.Itoa(int(ra))
+		for i, v := range c.params {
+			format[i] = strconv.Itoa(int(Reset))
+				ra, ok := mapResetAttributes[v]
+				if ok {
+					format[i] = strconv.Itoa(int(ra))
+				}
 		}
-	}
 
-	return fmt.Sprintf("%s[%sm", escape, strings.Join(format, ";"))
+		return fmt.Sprintf("%s[%sm", escape, strings.Join(format, ";"))
 }
 
 // DisableColor disables the color output. Useful to not change any existing
@@ -471,27 +471,24 @@ func (c *Color) Equals(c2 *Color) bool {
 	if c == nil || c2 == nil {
 		return false
 	}
+
 	if len(c.params) != len(c2.params) {
 		return false
 	}
 
+	counts := make(map[Attribute]int, len(c.params))
 	for _, attr := range c.params {
-		if !c2.attrExists(attr) {
-			return false
-		}
+		counts[attr]++
 	}
 
-	return true
-}
-
-func (c *Color) attrExists(a Attribute) bool {
-	for _, attr := range c.params {
-		if attr == a {
-			return true
+	for _, attr := range c2.params {
+		if counts[attr] == 0 {
+			return false
 		}
+		counts[attr]--
 	}
 
-	return false
+	return true
 }
 
 func boolPtr(v bool) *bool {