Some code improvements (gin-gonic#1909)

* strings.ToLower comparison changed to strings.EqualFold.
* Rewrite switch statement with only one case as if.

binding/form_mapping.go

@@ -126,9 +126,7 @@ func tryToSetValue(value reflect.Value, field reflect.StructField, setter setter
 	for len(opts) > 0 {
 		opt, opts = head(opts, ",")
 
-		k, v := head(opt, "=")
-		switch k {
-		case "default":
+		if k, v := head(opt, "="); k == "default" {
 			setOpt.isDefaultExists = true
 			setOpt.defaultValue = v
 		}

context.go

@@ -671,7 +671,7 @@ func (c *Context) ContentType() string {
 // handshake is being initiated by the client.
 func (c *Context) IsWebsocket() bool {
 	if strings.Contains(strings.ToLower(c.requestHeader("Connection")), "upgrade") &&
-		strings.ToLower(c.requestHeader("Upgrade")) == "websocket" {
+		strings.EqualFold(c.requestHeader("Upgrade"), "websocket") {
 		return true
 	}
 	return false

tree.go

@@ -514,7 +514,7 @@ func (n *node) findCaseInsensitivePath(path string, fixTrailingSlash bool) (ciPa
 	ciPath = make([]byte, 0, len(path)+1) // preallocate enough memory
 
 	// Outer loop for walking the tree
-	for len(path) >= len(n.path) && strings.ToLower(path[:len(n.path)]) == strings.ToLower(n.path) {
+	for len(path) >= len(n.path) && strings.EqualFold(path[:len(n.path)], n.path) {
 		path = path[len(n.path):]
 		ciPath = append(ciPath, n.path...)
 
@@ -618,7 +618,7 @@ func (n *node) findCaseInsensitivePath(path string, fixTrailingSlash bool) (ciPa
 			return ciPath, true
 		}
 		if len(path)+1 == len(n.path) && n.path[len(path)] == '/' &&
-			strings.ToLower(path) == strings.ToLower(n.path[:len(path)]) &&
+			strings.EqualFold(path, n.path[:len(path)]) &&
 			n.handlers != nil {
 			return append(ciPath, n.path...), true
 		}