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 android
16
17import (
18	"fmt"
19	"reflect"
20
21	"github.com/google/blueprint/proptools"
22)
23
24func registerPathDepsMutator(ctx RegisterMutatorsContext) {
25	ctx.BottomUp("pathdeps", pathDepsMutator).Parallel()
26}
27
28// The pathDepsMutator automatically adds dependencies on any module that is listed with ":module" syntax in a
29// property that is tagged with android:"path".
30func pathDepsMutator(ctx BottomUpMutatorContext) {
31	m := ctx.Module().(Module)
32	if m == nil {
33		return
34	}
35
36	props := m.base().generalProperties
37
38	var pathProperties []string
39	for _, ps := range props {
40		pathProperties = append(pathProperties, pathPropertiesForPropertyStruct(ctx, ps)...)
41	}
42
43	pathProperties = FirstUniqueStrings(pathProperties)
44
45	for _, s := range pathProperties {
46		if m, t := SrcIsModuleWithTag(s); m != "" {
47			ctx.AddDependency(ctx.Module(), sourceOrOutputDepTag(t), m)
48		}
49	}
50}
51
52// pathPropertiesForPropertyStruct uses the indexes of properties that are tagged with android:"path" to extract
53// all their values from a property struct, returning them as a single slice of strings..
54func pathPropertiesForPropertyStruct(ctx BottomUpMutatorContext, ps interface{}) []string {
55	v := reflect.ValueOf(ps)
56	if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
57		panic(fmt.Errorf("type %s is not a pointer to a struct", v.Type()))
58	}
59	if v.IsNil() {
60		return nil
61	}
62	v = v.Elem()
63
64	pathPropertyIndexes := pathPropertyIndexesForPropertyStruct(ps)
65
66	var ret []string
67
68	for _, i := range pathPropertyIndexes {
69		sv := fieldByIndex(v, i)
70		if !sv.IsValid() {
71			continue
72		}
73
74		if sv.Kind() == reflect.Ptr {
75			if sv.IsNil() {
76				continue
77			}
78			sv = sv.Elem()
79		}
80		switch sv.Kind() {
81		case reflect.String:
82			ret = append(ret, sv.String())
83		case reflect.Slice:
84			ret = append(ret, sv.Interface().([]string)...)
85		default:
86			panic(fmt.Errorf(`field %s in type %s has tag android:"path" but is not a string or slice of strings, it is a %s`,
87				v.Type().FieldByIndex(i).Name, v.Type(), sv.Type()))
88		}
89	}
90
91	return ret
92}
93
94// fieldByIndex is like reflect.Value.FieldByIndex, but returns an invalid reflect.Value when traversing a nil pointer
95// to a struct.
96func fieldByIndex(v reflect.Value, index []int) reflect.Value {
97	if len(index) == 1 {
98		return v.Field(index[0])
99	}
100	for _, x := range index {
101		if v.Kind() == reflect.Ptr {
102			if v.IsNil() {
103				return reflect.Value{}
104			}
105			v = v.Elem()
106		}
107		v = v.Field(x)
108	}
109	return v
110}
111
112var pathPropertyIndexesCache OncePer
113
114// pathPropertyIndexesForPropertyStruct returns a list of all of the indexes of properties in property struct type that
115// are tagged with android:"path".  Each index is a []int suitable for passing to reflect.Value.FieldByIndex.  The value
116// is cached in a global cache by type.
117func pathPropertyIndexesForPropertyStruct(ps interface{}) [][]int {
118	key := NewCustomOnceKey(reflect.TypeOf(ps))
119	return pathPropertyIndexesCache.Once(key, func() interface{} {
120		return proptools.PropertyIndexesWithTag(ps, "android", "path")
121	}).([][]int)
122}
123