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// Copyright (C) 2021 The Android Open Source Project
//
// 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 sdk
import (
"reflect"
"android/soong/android"
"github.com/google/blueprint/proptools"
)
// Contains information about the sdk properties that list sdk members by trait, e.g.
// native_bridge.
type sdkMemberTraitListProperty struct {
// getter for the list of member names
getter func(properties interface{}) []string
// the trait of member referenced in the list
memberTrait android.SdkMemberTrait
}
// Cache of dynamically generated dynamicSdkMemberTraits objects. The key is the pointer
// to a slice of SdkMemberTrait instances returned by android.RegisteredSdkMemberTraits().
var dynamicSdkMemberTraitsMap android.OncePer
// A dynamically generated set of member list properties and associated structure type.
//
// Instances of this are created by createDynamicSdkMemberTraits.
type dynamicSdkMemberTraits struct {
// The dynamically generated structure type.
//
// Contains one []string exported field for each SdkMemberTrait returned by android.RegisteredSdkMemberTraits(). The name of
// the field is the exported form of the value returned by SdkMemberTrait.SdkPropertyName().
propertiesStructType reflect.Type
// Information about each of the member trait specific list properties.
memberTraitListProperties []*sdkMemberTraitListProperty
}
func (d *dynamicSdkMemberTraits) createMemberTraitListProperties() interface{} {
return reflect.New(d.propertiesStructType).Interface()
}
func getDynamicSdkMemberTraits(key android.OnceKey, registeredTraits []android.SdkMemberTrait) *dynamicSdkMemberTraits {
// Get the cached value, creating new instance if necessary.
return dynamicSdkMemberTraitsMap.Once(key, func() interface{} {
return createDynamicSdkMemberTraits(registeredTraits)
}).(*dynamicSdkMemberTraits)
}
// Create the dynamicSdkMemberTraits from the list of registered member traits.
//
// A struct is created which contains one exported field per member trait corresponding to
// the SdkMemberTrait.SdkPropertyName() value.
//
// A list of sdkMemberTraitListProperty instances is created, one per member trait that provides:
// * a reference to the member trait.
// * a getter for the corresponding field in the properties struct.
func createDynamicSdkMemberTraits(sdkMemberTraits []android.SdkMemberTrait) *dynamicSdkMemberTraits {
var listProperties []*sdkMemberTraitListProperty
memberTraitToProperty := map[android.SdkMemberTrait]*sdkMemberTraitListProperty{}
var fields []reflect.StructField
// Iterate over the member traits creating StructField and sdkMemberTraitListProperty objects.
nextFieldIndex := 0
for _, memberTrait := range sdkMemberTraits {
p := memberTrait.SdkPropertyName()
var getter func(properties interface{}) []string
// Create a dynamic exported field for the member trait's property.
fields = append(fields, reflect.StructField{
Name: proptools.FieldNameForProperty(p),
Type: reflect.TypeOf([]string{}),
})
// Copy the field index for use in the getter func as using the loop variable directly will
// cause all funcs to use the last value.
fieldIndex := nextFieldIndex
nextFieldIndex += 1
getter = func(properties interface{}) []string {
// The properties is expected to be of the following form (where
// <Module_traits> is the name of an SdkMemberTrait.SdkPropertyName().
// properties *struct {<Module_traits> []string, ....}
//
// Although it accesses the field by index the following reflection code is equivalent to:
// *properties.<Module_traits>
//
list := reflect.ValueOf(properties).Elem().Field(fieldIndex).Interface().([]string)
return list
}
// Create an sdkMemberTraitListProperty for the member trait.
memberListProperty := &sdkMemberTraitListProperty{
getter: getter,
memberTrait: memberTrait,
}
memberTraitToProperty[memberTrait] = memberListProperty
listProperties = append(listProperties, memberListProperty)
}
// Create a dynamic struct from the collated fields.
propertiesStructType := reflect.StructOf(fields)
return &dynamicSdkMemberTraits{
memberTraitListProperties: listProperties,
propertiesStructType: propertiesStructType,
}
}
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