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 len(tag) > 0 {
27		idx := strings.Index(tag, ",")
28
29		if idx < 0 {
30			return tag == value
31		}
32		if tag[:idx] == value {
33			return true
34		}
35
36		tag = tag[idx+1:]
37	}
38
39	return false
40}
41
42// PropertyIndexesWithTag returns the indexes of all properties (in the form used by reflect.Value.FieldByIndex) that
43// are tagged with the given key and value, including ones found in embedded structs or pointers to structs.
44func PropertyIndexesWithTag(ps interface{}, key, value string) [][]int {
45	t := reflect.TypeOf(ps)
46	if !isStructPtr(t) {
47		panic(fmt.Errorf("type %s is not a pointer to a struct", t))
48	}
49	t = t.Elem()
50
51	return propertyIndexesWithTag(t, key, value)
52}
53func propertyIndexesWithTag(t reflect.Type, key, value string) [][]int {
54	var indexes [][]int
55
56	for i := 0; i < t.NumField(); i++ {
57		field := t.Field(i)
58		ft := field.Type
59		if isStruct(ft) || isStructPtr(ft) || isSliceOfStruct(ft) {
60			if ft.Kind() == reflect.Ptr || ft.Kind() == reflect.Slice {
61				ft = ft.Elem()
62			}
63			subIndexes := propertyIndexesWithTag(ft, key, value)
64			for _, sub := range subIndexes {
65				sub = append([]int{i}, sub...)
66				indexes = append(indexes, sub)
67			}
68		} else if HasTag(field, key, value) {
69			indexes = append(indexes, field.Index)
70		}
71	}
72
73	return indexes
74}
75