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