Aconfig rules

Test: m services_device_config (which runs sooong tests too)
Change-Id: I432e914d01d2bff77ba68de65ae5baea527090f5
diff --git a/device_config/device_config_value_set.go b/device_config/device_config_value_set.go
new file mode 100644
index 0000000..e406d20
--- /dev/null
+++ b/device_config/device_config_value_set.go
@@ -0,0 +1,92 @@
+// Copyright 2023 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 device_config
+
+import (
+	"android/soong/android"
+	"github.com/google/blueprint"
+)
+
+// Properties for "device_config_value_set"
+type ValueSetModule struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+
+	properties struct {
+		// device_config_values modules
+		Values []string
+	}
+}
+
+func ValueSetFactory() android.Module {
+	module := &ValueSetModule{}
+
+	android.InitAndroidModule(module)
+	android.InitDefaultableModule(module)
+	module.AddProperties(&module.properties)
+	// TODO: bp2build
+	//android.InitBazelModule(module)
+
+	return module
+}
+
+// Dependency tag for values property
+type valueSetType struct {
+	blueprint.BaseDependencyTag
+}
+
+var valueSetTag = valueSetType{}
+
+// Provider published by device_config_value_set
+type valueSetProviderData struct {
+	// The namespace of each of the
+	// (map of namespace --> device_config_module)
+	AvailableNamespaces map[string]android.Paths
+}
+
+var valueSetProviderKey = blueprint.NewProvider(valueSetProviderData{})
+
+func (module *ValueSetModule) DepsMutator(ctx android.BottomUpMutatorContext) {
+	deps := ctx.AddDependency(ctx.Module(), valueSetTag, module.properties.Values...)
+	for _, dep := range deps {
+		_, ok := dep.(*ValuesModule)
+		if !ok {
+			ctx.PropertyErrorf("values", "values must be a device_config_values module")
+			return
+		}
+	}
+}
+
+func (module *ValueSetModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Accumulate the namespaces of the values modules listed, and set that as an
+	// valueSetProviderKey provider that device_config modules can read and use
+	// to append values to their aconfig actions.
+	namespaces := make(map[string]android.Paths)
+	ctx.VisitDirectDeps(func(dep android.Module) {
+		if !ctx.OtherModuleHasProvider(dep, valuesProviderKey) {
+			// Other modules get injected as dependencies too, for example the license modules
+			return
+		}
+		depData := ctx.OtherModuleProvider(dep, valuesProviderKey).(valuesProviderData)
+
+		srcs := make([]android.Path, len(depData.Values))
+		copy(srcs, depData.Values)
+		namespaces[depData.Namespace] = srcs
+
+	})
+	ctx.SetProvider(valueSetProviderKey, valueSetProviderData{
+		AvailableNamespaces: namespaces,
+	})
+}