feat(validator): Add default validator

Change-Id: Ic15931951127e119daca629fd5d8223092416587

Author: andeya

validator/README.md

@@ -22,12 +22,10 @@ package validator_test
 import (
 	"fmt"
 
-	"github.com/bytedance/go-tagexpr/validator"
+	vd "github.com/bytedance/go-tagexpr/validator"
 )
 
 func Example() {
-	var vd = validator.New("vd")
-
 	type InfoRequest struct {
 		Name   string `vd:"($!='Alice'||(Age)$==18) && regexp('\\w')"`
 		Age    int    `vd:"$>0"`
@@ -93,7 +91,7 @@ func Example() {
 
 	fmt.Println(vd.Validate(map[string]*F{"a": f}))
 
-	fmt.Println(vd.Validate([]*F{f}))
+	fmt.Println(vd.Validate([][1]*F{{f}}))
 
 	f = nil
 	fmt.Println(vd.Validate(f))

validator/default.go

@@ -0,0 +1,24 @@
+package validator
+
+var defaultValidator = New("vd").SetErrorFactory(defaultErrorFactory)
+
+// Default returns the default validator.
+// NOTE:
+//  The tag name is 'vd'
+func Default() *Validator {
+	return defaultValidator
+}
+
+// Validate uses the default validator to validate whether the fields of value is valid.
+// NOTE:
+//  The tag name is 'vd'
+func Validate(value interface{}) error {
+	return defaultValidator.Validate(value)
+}
+
+// SetErrorFactory customizes the factory of validation error for the default validator.
+// NOTE:
+//  The tag name is 'vd'
+func SetErrorFactory(errFactory func(fieldSelector, msg string) error) {
+	defaultValidator.SetErrorFactory(errFactory)
+}

validator/example_test.go

@@ -3,12 +3,10 @@ package validator_test
 import (
 	"fmt"
 
-	"github.com/bytedance/go-tagexpr/validator"
+	vd "github.com/bytedance/go-tagexpr/validator"
 )
 
 func Example() {
-	var vd = validator.New("vd")
-
 	type InfoRequest struct {
 		Name   string `vd:"($!='Alice'||(Age)$==18) && regexp('\\w')"`
 		Age    int    `vd:"$>0"`