1// Copyright 2019 Google Inc. All rights reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package proptools
16
17import (
18	"fmt"
19	"reflect"
20	"strings"
21)
22
23// HasTag returns true if a StructField has a tag in the form `name:"foo,value"`.
24func HasTag(field reflect.StructField, name, value string) bool {
25	tag := field.Tag.Get(name)
26	for _, entry := range strings.Split(tag, ",") {
27		if entry == value {
28			return true
29		}
30	}
31
32	return false
33}
34
35// PropertyIndexesWithTag returns the indexes of all properties (in the form used by reflect.Value.FieldByIndex) that
36// are tagged with the given key and value, including ones found in embedded structs or pointers to structs.
37func PropertyIndexesWithTag(ps interface{}, key, value string) [][]int {
38	t := reflect.TypeOf(ps)
39	if !isStructPtr(t) {
40		panic(fmt.Errorf("type %s is not a pointer to a struct", t))
41	}
42	t = t.Elem()
43
44	return propertyIndexesWithTag(t, key, value)
45}
46func propertyIndexesWithTag(t reflect.Type, key, value string) [][]int {
47	var indexes [][]int
48
49	for i := 0; i < t.NumField(); i++ {
50		field := t.Field(i)
51		ft := field.Type
52		if isStruct(ft) || isStructPtr(ft) {
53			if ft.Kind() == reflect.Ptr {
54				ft = ft.Elem()
55			}
56			subIndexes := propertyIndexesWithTag(ft, key, value)
57			for _, sub := range subIndexes {
58				sub = append([]int{i}, sub...)
59				indexes = append(indexes, sub)
60			}
61		} else if HasTag(field, key, value) {
62			indexes = append(indexes, field.Index)
63		}
64	}
65
66	return indexes
67}
68