format some codes style (#1165)

context.go

@@ -33,9 +33,7 @@ const (
 	MIMEMultipartPOSTForm = binding.MIMEMultipartPOSTForm
 )
 
-const (
-	abortIndex int8 = math.MaxInt8 / 2
-)
+const abortIndex int8 = math.MaxInt8 / 2
 
 // Context is the most important part of gin. It allows us to pass variables between middleware,
 // manage the flow, validate the JSON of a request and render a JSON response for example.
@@ -105,8 +103,7 @@ func (c *Context) Handler() HandlerFunc {
 // See example in GitHub.
 func (c *Context) Next() {
 	c.index++
-	s := int8(len(c.handlers))
-	for ; c.index < s; c.index++ {
+	for s := int8(len(c.handlers)); c.index < s; c.index++ {
 		c.handlers[c.index](c)
 	}
 }
@@ -521,11 +518,11 @@ func (c *Context) ClientIP() string {
 			clientIP = clientIP[0:index]
 		}
 		clientIP = strings.TrimSpace(clientIP)
-		if len(clientIP) > 0 {
+		if clientIP != "" {
 			return clientIP
 		}
 		clientIP = strings.TrimSpace(c.requestHeader("X-Real-Ip"))
-		if len(clientIP) > 0 {
+		if clientIP != "" {
 			return clientIP
 		}
 	}
@@ -588,7 +585,7 @@ func (c *Context) Status(code int) {
 // It writes a header in the response.
 // If value == "", this method removes the header `c.Writer.Header().Del(key)`
 func (c *Context) Header(key, value string) {
-	if len(value) == 0 {
+	if value == "" {
 		c.Writer.Header().Del(key)
 	} else {
 		c.Writer.Header().Set(key, value)

gin.go

@@ -403,8 +403,8 @@ func redirectTrailingSlash(c *Context) {
 		code = 307
 	}
 
-	if len(path) > 1 && path[len(path)-1] == '/' {
-		req.URL.Path = path[:len(path)-1]
+	if length := len(path); length > 1 && path[length-1] == '/' {
+		req.URL.Path = path[:length-1]
 	} else {
 		req.URL.Path = path + "/"
 	}

json/json.go

@@ -6,9 +6,7 @@
 
 package json
 
-import (
-	"encoding/json"
-)
+import "encoding/json"
 
 var (
 	Marshal       = json.Marshal

json/jsoniter.go

@@ -6,9 +6,7 @@
 
 package json
 
-import (
-	"github.com/json-iterator/go"
-)
+import "github.com/json-iterator/go"
 
 var (
 	json          = jsoniter.ConfigCompatibleWithStandardLibrary