| // Copyright 2019 Google Inc. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package proptools |
| |
| import ( |
| "fmt" |
| "reflect" |
| "strings" |
| ) |
| |
| // HasTag returns true if a StructField has a tag in the form `name:"foo,value"`. |
| func HasTag(field reflect.StructField, name, value string) bool { |
| tag := field.Tag.Get(name) |
| for len(tag) > 0 { |
| idx := strings.Index(tag, ",") |
| |
| if idx < 0 { |
| return tag == value |
| } |
| if tag[:idx] == value { |
| return true |
| } |
| |
| tag = tag[idx+1:] |
| } |
| |
| return false |
| } |
| |
| // PropertyIndexesWithTag returns the indexes of all properties (in the form used by reflect.Value.FieldByIndex) that |
| // are tagged with the given key and value, including ones found in embedded structs or pointers to structs. |
| func PropertyIndexesWithTag(ps interface{}, key, value string) [][]int { |
| t := reflect.TypeOf(ps) |
| if !isStructPtr(t) { |
| panic(fmt.Errorf("type %s is not a pointer to a struct", t)) |
| } |
| t = t.Elem() |
| |
| return propertyIndexesWithTag(t, key, value) |
| } |
| func propertyIndexesWithTag(t reflect.Type, key, value string) [][]int { |
| var indexes [][]int |
| |
| for i := 0; i < t.NumField(); i++ { |
| field := t.Field(i) |
| ft := field.Type |
| if isStruct(ft) || isStructPtr(ft) || isSliceOfStruct(ft) { |
| if ft.Kind() == reflect.Ptr || ft.Kind() == reflect.Slice { |
| ft = ft.Elem() |
| } |
| subIndexes := propertyIndexesWithTag(ft, key, value) |
| for _, sub := range subIndexes { |
| sub = append([]int{i}, sub...) |
| indexes = append(indexes, sub) |
| } |
| } else if HasTag(field, key, value) { |
| indexes = append(indexes, field.Index) |
| } |
| } |
| |
| return indexes |
| } |