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