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// 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 android
import (
"fmt"
"reflect"
"github.com/google/blueprint/proptools"
)
// This file implements support for automatically adding dependencies on any module referenced
// with the ":module" module reference syntax in a property that is annotated with `android:"path"`.
// The dependency is used by android.PathForModuleSrc to convert the module reference into the path
// to the output file of the referenced module.
func registerPathDepsMutator(ctx RegisterMutatorsContext) {
ctx.BottomUp("pathdeps", pathDepsMutator).Parallel()
}
// The pathDepsMutator automatically adds dependencies on any module that is listed with the
// ":module" module reference syntax in a property that is tagged with `android:"path"`.
func pathDepsMutator(ctx BottomUpMutatorContext) {
props := ctx.Module().base().generalProperties
addPathDepsForProps(ctx, props)
}
func addPathDepsForProps(ctx BottomUpMutatorContext, props []interface{}) {
// Iterate through each property struct of the module extracting the contents of all properties
// tagged with `android:"path"`.
var pathProperties []string
for _, ps := range props {
pathProperties = append(pathProperties, pathPropertiesForPropertyStruct(ps)...)
}
// Remove duplicates to avoid multiple dependencies.
pathProperties = FirstUniqueStrings(pathProperties)
// Add dependencies to anything that is a module reference.
for _, s := range pathProperties {
if m, t := SrcIsModuleWithTag(s); m != "" {
ctx.AddDependency(ctx.Module(), sourceOrOutputDepTag(m, t), m)
}
}
}
// pathPropertiesForPropertyStruct uses the indexes of properties that are tagged with
// android:"path" to extract all their values from a property struct, returning them as a single
// slice of strings.
func pathPropertiesForPropertyStruct(ps interface{}) []string {
v := reflect.ValueOf(ps)
if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
panic(fmt.Errorf("type %s is not a pointer to a struct", v.Type()))
}
// If the property struct is a nil pointer it can't have any paths set in it.
if v.IsNil() {
return nil
}
// v is now the reflect.Value for the concrete property struct.
v = v.Elem()
// Get or create the list of indexes of properties that are tagged with `android:"path"`.
pathPropertyIndexes := pathPropertyIndexesForPropertyStruct(ps)
var ret []string
for _, i := range pathPropertyIndexes {
var values []reflect.Value
fieldsByIndex(v, i, &values)
for _, sv := range values {
if !sv.IsValid() {
// Skip properties inside a nil pointer.
continue
}
// If the field is a non-nil pointer step into it.
if sv.Kind() == reflect.Ptr {
if sv.IsNil() {
continue
}
sv = sv.Elem()
}
// Collect paths from all strings and slices of strings.
switch sv.Kind() {
case reflect.String:
ret = append(ret, sv.String())
case reflect.Slice:
ret = append(ret, sv.Interface().([]string)...)
default:
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`,
v.Type().FieldByIndex(i).Name, v.Type(), sv.Type()))
}
}
}
return ret
}
// fieldsByIndex is similar to reflect.Value.FieldByIndex, but is more robust: it doesn't track
// nil pointers and it returns multiple values when there's slice of struct.
func fieldsByIndex(v reflect.Value, index []int, values *[]reflect.Value) {
// leaf case
if len(index) == 1 {
if isSliceOfStruct(v) {
for i := 0; i < v.Len(); i++ {
*values = append(*values, v.Index(i).Field(index[0]))
}
} else {
// Dereference it if it's a pointer.
if v.Kind() == reflect.Ptr {
if v.IsNil() {
return
}
v = v.Elem()
}
*values = append(*values, v.Field(index[0]))
}
return
}
// recursion
if v.Kind() == reflect.Ptr {
// don't track nil pointer
if v.IsNil() {
return
}
v = v.Elem()
} else if isSliceOfStruct(v) {
// do the recursion for all elements
for i := 0; i < v.Len(); i++ {
fieldsByIndex(v.Index(i).Field(index[0]), index[1:], values)
}
return
}
fieldsByIndex(v.Field(index[0]), index[1:], values)
return
}
func isSliceOfStruct(v reflect.Value) bool {
return v.Kind() == reflect.Slice && v.Type().Elem().Kind() == reflect.Struct
}
var pathPropertyIndexesCache OncePer
// pathPropertyIndexesForPropertyStruct returns a list of all of the indexes of properties in
// property struct type that are tagged with `android:"path"`. Each index is a []int suitable for
// passing to reflect.Value.FieldByIndex. The value is cached in a global cache by type.
func pathPropertyIndexesForPropertyStruct(ps interface{}) [][]int {
key := NewCustomOnceKey(reflect.TypeOf(ps))
return pathPropertyIndexesCache.Once(key, func() interface{} {
return proptools.PropertyIndexesWithTag(ps, "android", "path")
}).([][]int)
}