chore: add some annotations (#1550)

ref #1075 should all annotations and can close #1075 .

errors.go

@@ -12,18 +12,24 @@ import (
 	"github.com/gin-gonic/gin/internal/json"
 )
 
+// ErrorType is an unsigned 64-bit error code as defined in the gin spec.
 type ErrorType uint64
 
 const (
-	ErrorTypeBind    ErrorType = 1 << 63 // used when c.Bind() fails
-	ErrorTypeRender  ErrorType = 1 << 62 // used when c.Render() fails
+	// ErrorTypeBind is used when Context.Bind() fails.
+	ErrorTypeBind ErrorType = 1 << 63
+	// ErrorTypeRender is used when Context.Render() fails.
+	ErrorTypeRender ErrorType = 1 << 62
+	// ErrorTypePrivate indicates a private error.
 	ErrorTypePrivate ErrorType = 1 << 0
-	ErrorTypePublic  ErrorType = 1 << 1
-
+	// ErrorTypePublic indicates a public error.
+	ErrorTypePublic ErrorType = 1 << 1
+	// ErrorTypeAny indicates other any error.
 	ErrorTypeAny ErrorType = 1<<64 - 1
 	ErrorTypeNu            = 2
 )
 
+// Error represents a error's specification.
 type Error struct {
 	Err  error
 	Type ErrorType
@@ -34,11 +40,13 @@ type errorMsgs []*Error
 
 var _ error = &Error{}
 
+// SetType sets the error's type.
 func (msg *Error) SetType(flags ErrorType) *Error {
 	msg.Type = flags
 	return msg
 }
 
+// SetMeta sets the error's meta data.
 func (msg *Error) SetMeta(data interface{}) *Error {
 	msg.Meta = data
 	return msg
@@ -70,11 +78,12 @@ func (msg *Error) MarshalJSON() ([]byte, error) {
 	return json.Marshal(msg.JSON())
 }
 
-// Error implements the error interface
+// Error implements the error interface.
 func (msg Error) Error() string {
 	return msg.Err.Error()
 }
 
+// IsType judges one error.
 func (msg *Error) IsType(flags ErrorType) bool {
 	return (msg.Type & flags) > 0
 }
@@ -138,6 +147,7 @@ func (a errorMsgs) JSON() interface{} {
 	}
 }
 
+// MarshalJSON implements the json.Marshaller interface.
 func (a errorMsgs) MarshalJSON() ([]byte, error) {
 	return json.Marshal(a.JSON())
 }