traefik/pkg/provider/label/internal/nodes_metadata.go

169 lines
3.9 KiB
Go
Raw Normal View History

2018-12-04 13:24:04 +00:00
package internal
import (
"errors"
"fmt"
"reflect"
"strings"
)
// AddMetadata Adds metadata to a node.
// nodes + element -> nodes
func AddMetadata(structure interface{}, node *Node) error {
if node == nil {
return nil
}
2018-12-04 13:24:04 +00:00
if len(node.Children) == 0 {
return fmt.Errorf("invalid node %s: no child", node.Name)
}
if structure == nil {
return errors.New("nil structure")
}
rootType := reflect.TypeOf(structure)
node.Kind = rootType.Kind()
return browseChildren(rootType, node)
}
func addMetadata(rootType reflect.Type, node *Node) error {
rType := rootType
if rootType.Kind() == reflect.Ptr {
rType = rootType.Elem()
}
field, err := findTypedField(rType, node)
if err != nil {
return err
}
if err = isSupportedType(field); err != nil {
return err
}
fType := field.Type
node.Kind = fType.Kind()
if fType.Kind() == reflect.Struct || fType.Kind() == reflect.Ptr && fType.Elem().Kind() == reflect.Struct ||
fType.Kind() == reflect.Map {
if len(node.Children) == 0 && field.Tag.Get(TagLabel) != "allowEmpty" {
return fmt.Errorf("node %s (type %s) must have children", node.Name, fType)
}
node.Disabled = len(node.Value) > 0 && !strings.EqualFold(node.Value, "true") && field.Tag.Get(TagLabel) == "allowEmpty"
2018-12-04 13:24:04 +00:00
}
if len(node.Children) == 0 {
return nil
}
if fType.Kind() == reflect.Struct || fType.Kind() == reflect.Ptr && fType.Elem().Kind() == reflect.Struct {
return browseChildren(fType, node)
}
if fType.Kind() == reflect.Map {
for _, child := range node.Children {
// elem is a map entry value type
elem := fType.Elem()
child.Kind = elem.Kind()
if elem.Kind() == reflect.Map || elem.Kind() == reflect.Struct ||
(elem.Kind() == reflect.Ptr && elem.Elem().Kind() == reflect.Struct) {
if err = browseChildren(elem, child); err != nil {
return err
}
}
}
return nil
}
// only for struct/Ptr with label-slice-as-struct tag
if fType.Kind() == reflect.Slice {
return browseChildren(fType.Elem(), node)
}
return fmt.Errorf("invalid node %s: %v", node.Name, fType.Kind())
}
func findTypedField(rType reflect.Type, node *Node) (reflect.StructField, error) {
for i := 0; i < rType.NumField(); i++ {
cField := rType.Field(i)
fieldName := cField.Tag.Get(TagLabelSliceAsStruct)
if len(fieldName) == 0 {
fieldName = cField.Name
}
if isExported(cField) && strings.EqualFold(fieldName, node.Name) {
node.FieldName = cField.Name
return cField, nil
}
}
return reflect.StructField{}, fmt.Errorf("field not found, node: %s", node.Name)
}
func browseChildren(fType reflect.Type, node *Node) error {
for _, child := range node.Children {
if err := addMetadata(fType, child); err != nil {
return err
}
}
return nil
}
// isExported return true is a struct field is exported, else false
// https://golang.org/pkg/reflect/#StructField
func isExported(f reflect.StructField) bool {
if f.PkgPath != "" && !f.Anonymous {
return false
}
return true
}
func isSupportedType(field reflect.StructField) error {
fType := field.Type
if fType.Kind() == reflect.Slice {
switch fType.Elem().Kind() {
case reflect.String,
reflect.Bool,
reflect.Int,
reflect.Int8,
reflect.Int16,
reflect.Int32,
reflect.Int64,
reflect.Uint,
reflect.Uint8,
reflect.Uint16,
reflect.Uint32,
reflect.Uint64,
reflect.Uintptr,
reflect.Float32,
reflect.Float64:
return nil
default:
if len(field.Tag.Get(TagLabelSliceAsStruct)) > 0 {
return nil
}
return fmt.Errorf("unsupported slice type: %v", fType)
}
}
if fType.Kind() == reflect.Ptr && fType.Elem().Kind() != reflect.Struct {
return fmt.Errorf("unsupported pointer type: %v", fType.Elem())
}
if fType.Kind() == reflect.Map && fType.Key().Kind() != reflect.String {
return fmt.Errorf("unsupported map key type: %v", fType.Key())
}
if fType.Kind() == reflect.Func {
return fmt.Errorf("unsupported type: %v", fType)
}
return nil
}