Merge "Remove obsolete copy headers"
diff --git a/android/sdk.go b/android/sdk.go
index 533bd0e..7956434 100644
--- a/android/sdk.go
+++ b/android/sdk.go
@@ -15,6 +15,7 @@
 package android
 
 import (
+	"sort"
 	"strings"
 
 	"github.com/google/blueprint"
@@ -218,18 +219,24 @@
 // The basic implementation should look something like this, where ModuleType is
 // the name of the module type being supported.
 //
-//    var ModuleTypeSdkMemberType = newModuleTypeSdkMemberType()
-//
-//    func newModuleTypeSdkMemberType() android.SdkMemberType {
-//    	return &moduleTypeSdkMemberType{}
+//    type moduleTypeSdkMemberType struct {
+//        android.SdkMemberTypeBase
 //    }
 //
-//    type moduleTypeSdkMemberType struct {
+//    func init() {
+//        android.RegisterSdkMemberType(&moduleTypeSdkMemberType{
+//            SdkMemberTypeBase: android.SdkMemberTypeBase{
+//                PropertyName: "module_types",
+//            },
+//        }
 //    }
 //
 //    ...methods...
 //
 type SdkMemberType interface {
+	// The name of the member type property on an sdk module.
+	SdkPropertyName() string
+
 	// Add dependencies from the SDK module to all the variants the member
 	// contributes to the SDK. The exact set of variants required is determined
 	// by the SDK and its properties. The dependencies must be added with the
@@ -254,3 +261,66 @@
 	// IsInstance(Module) method returned true.
 	BuildSnapshot(sdkModuleContext ModuleContext, builder SnapshotBuilder, member SdkMember)
 }
+
+type SdkMemberTypeBase struct {
+	PropertyName string
+}
+
+func (b *SdkMemberTypeBase) SdkPropertyName() string {
+	return b.PropertyName
+}
+
+// Encapsulates the information about registered SdkMemberTypes.
+type SdkMemberTypesRegistry struct {
+	// The list of types sorted by property name.
+	list []SdkMemberType
+
+	// The key that uniquely identifies this registry instance.
+	key OnceKey
+}
+
+func (r *SdkMemberTypesRegistry) RegisteredTypes() []SdkMemberType {
+	return r.list
+}
+
+func (r *SdkMemberTypesRegistry) UniqueOnceKey() OnceKey {
+	// Use the pointer to the registry as the unique key.
+	return NewCustomOnceKey(r)
+}
+
+// The set of registered SdkMemberTypes.
+var SdkMemberTypes = &SdkMemberTypesRegistry{}
+
+// Register an SdkMemberType object to allow them to be used in the sdk and sdk_snapshot module
+// types.
+func RegisterSdkMemberType(memberType SdkMemberType) {
+	oldList := SdkMemberTypes.list
+
+	// Copy the slice just in case this is being read while being modified, e.g. when testing.
+	list := make([]SdkMemberType, 0, len(oldList)+1)
+	list = append(list, oldList...)
+	list = append(list, memberType)
+
+	// Sort the member types by their property name to ensure that registry order has no effect
+	// on behavior.
+	sort.Slice(list, func(i1, i2 int) bool {
+		t1 := list[i1]
+		t2 := list[i2]
+
+		return t1.SdkPropertyName() < t2.SdkPropertyName()
+	})
+
+	// Generate a key that identifies the slice of SdkMemberTypes by joining the property names
+	// from all the SdkMemberType .
+	var properties []string
+	for _, t := range list {
+		properties = append(properties, t.SdkPropertyName())
+	}
+	key := NewOnceKey(strings.Join(properties, "|"))
+
+	// Create a new registry so the pointer uniquely identifies the set of registered types.
+	SdkMemberTypes = &SdkMemberTypesRegistry{
+		list: list,
+		key:  key,
+	}
+}
diff --git a/cc/library_sdk_member.go b/cc/library_sdk_member.go
index 6b09c12..9319070 100644
--- a/cc/library_sdk_member.go
+++ b/cc/library_sdk_member.go
@@ -24,17 +24,28 @@
 
 // This file contains support for using cc library modules within an sdk.
 
-var SharedLibrarySdkMemberType = &librarySdkMemberType{
-	prebuiltModuleType: "cc_prebuilt_library_shared",
-	linkTypes:          []string{"shared"},
-}
+func init() {
+	// Register sdk member types.
+	android.RegisterSdkMemberType(&librarySdkMemberType{
+		SdkMemberTypeBase: android.SdkMemberTypeBase{
+			PropertyName: "native_shared_libs",
+		},
+		prebuiltModuleType: "cc_prebuilt_library_shared",
+		linkTypes:          []string{"shared"},
+	})
 
-var StaticLibrarySdkMemberType = &librarySdkMemberType{
-	prebuiltModuleType: "cc_prebuilt_library_static",
-	linkTypes:          []string{"static"},
+	android.RegisterSdkMemberType(&librarySdkMemberType{
+		SdkMemberTypeBase: android.SdkMemberTypeBase{
+			PropertyName: "native_static_libs",
+		},
+		prebuiltModuleType: "cc_prebuilt_library_static",
+		linkTypes:          []string{"static"},
+	})
 }
 
 type librarySdkMemberType struct {
+	android.SdkMemberTypeBase
+
 	prebuiltModuleType string
 
 	// The set of link types supported, set of "static", "shared".
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 76cdaea..92f9246 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -40,6 +40,13 @@
 	android.RegisterModuleType("droidstubs_host", DroidstubsHostFactory)
 
 	android.RegisterModuleType("prebuilt_stubs_sources", PrebuiltStubsSourcesFactory)
+
+	// Register sdk member type.
+	android.RegisterSdkMemberType(&droidStubsSdkMemberType{
+		SdkMemberTypeBase: android.SdkMemberTypeBase{
+			PropertyName: "stubs_sources",
+		},
+	})
 }
 
 var (
@@ -1974,9 +1981,8 @@
 	return module
 }
 
-var DroidStubsSdkMemberType = &droidStubsSdkMemberType{}
-
 type droidStubsSdkMemberType struct {
+	android.SdkMemberTypeBase
 }
 
 func (mt *droidStubsSdkMemberType) AddDependencies(mctx android.BottomUpMutatorContext, dependencyTag blueprint.DependencyTag, names []string) {
diff --git a/java/java.go b/java/java.go
index f58e5ba..d8db5f8 100644
--- a/java/java.go
+++ b/java/java.go
@@ -52,6 +52,23 @@
 
 	android.RegisterSingletonType("logtags", LogtagsSingleton)
 	android.RegisterSingletonType("kythe_java_extract", kytheExtractJavaFactory)
+
+	// Register sdk member types.
+	android.RegisterSdkMemberType(&headerLibrarySdkMemberType{
+		librarySdkMemberType{
+			android.SdkMemberTypeBase{
+				PropertyName: "java_header_libs",
+			},
+		},
+	})
+
+	android.RegisterSdkMemberType(&implLibrarySdkMemberType{
+		librarySdkMemberType{
+			android.SdkMemberTypeBase{
+				PropertyName: "java_libs",
+			},
+		},
+	})
 }
 
 func (j *Module) checkSdkVersion(ctx android.ModuleContext) {
@@ -1721,6 +1738,7 @@
 }
 
 type librarySdkMemberType struct {
+	android.SdkMemberTypeBase
 }
 
 func (mt *librarySdkMemberType) AddDependencies(mctx android.BottomUpMutatorContext, dependencyTag blueprint.DependencyTag, names []string) {
@@ -1764,8 +1782,6 @@
 	module.AddProperty("jars", []string{snapshotRelativeJavaLibPath})
 }
 
-var HeaderLibrarySdkMemberType = &headerLibrarySdkMemberType{}
-
 type headerLibrarySdkMemberType struct {
 	librarySdkMemberType
 }
@@ -1781,8 +1797,6 @@
 	})
 }
 
-var ImplLibrarySdkMemberType = &implLibrarySdkMemberType{}
-
 type implLibrarySdkMemberType struct {
 	librarySdkMemberType
 }
diff --git a/sdk/sdk.go b/sdk/sdk.go
index cd9aafa..62bc06f 100644
--- a/sdk/sdk.go
+++ b/sdk/sdk.go
@@ -17,6 +17,7 @@
 import (
 	"fmt"
 	"io"
+	"reflect"
 	"strconv"
 
 	"github.com/google/blueprint"
@@ -26,8 +27,6 @@
 	// This package doesn't depend on the apex package, but import it to make its mutators to be
 	// registered before mutators in this package. See RegisterPostDepsMutators for more details.
 	_ "android/soong/apex"
-	"android/soong/cc"
-	"android/soong/java"
 )
 
 func init() {
@@ -38,20 +37,19 @@
 	android.RegisterModuleType("sdk_snapshot", SnapshotModuleFactory)
 	android.PreDepsMutators(RegisterPreDepsMutators)
 	android.PostDepsMutators(RegisterPostDepsMutators)
-
-	// Populate the dependency tags for each member list property.  This needs to
-	// be done here to break an initialization cycle.
-	for _, memberListProperty := range sdkMemberListProperties {
-		memberListProperty.dependencyTag = &sdkMemberDependencyTag{
-			memberListProperty: memberListProperty,
-		}
-	}
 }
 
 type sdk struct {
 	android.ModuleBase
 	android.DefaultableModuleBase
 
+	// The dynamically generated information about the registered SdkMemberType
+	dynamicSdkMemberTypes *dynamicSdkMemberTypes
+
+	// The dynamically created instance of the properties struct containing the sdk member
+	// list properties, e.g. java_libs.
+	dynamicMemberTypeListProperties interface{}
+
 	properties sdkProperties
 
 	snapshotFile android.OptionalPath
@@ -61,92 +59,141 @@
 }
 
 type sdkProperties struct {
-	// For module types from the cc package
-
-	// The list of shared native libraries in this SDK
-	Native_shared_libs []string
-
-	// The list of static native libraries in this SDK
-	Native_static_libs []string
-
-	// For module types from the java package
-
-	// The list of java header libraries in this SDK
-	//
-	// This should be used for java libraries that are provided separately at runtime,
-	// e.g. through an APEX.
-	Java_header_libs []string
-
-	// The list of java implementation libraries in this SDK
-	Java_libs []string
-
-	// The list of stub sources in this SDK
-	Stubs_sources []string
-
 	Snapshot bool `blueprint:"mutated"`
 }
 
 type sdkMemberDependencyTag struct {
 	blueprint.BaseDependencyTag
-	memberListProperty *sdkMemberListProperty
+	memberType android.SdkMemberType
 }
 
 // Contains information about the sdk properties that list sdk members, e.g.
 // Java_header_libs.
 type sdkMemberListProperty struct {
-	// the name of the property as used in a .bp file
-	name string
-
 	// getter for the list of member names
-	getter func(properties *sdkProperties) []string
+	getter func(properties interface{}) []string
 
 	// the type of member referenced in the list
 	memberType android.SdkMemberType
 
-	// the dependency tag used for items in this list.
+	// the dependency tag used for items in this list that can be used to determine the memberType
+	// for a resolved dependency.
 	dependencyTag *sdkMemberDependencyTag
 }
 
-// Information about how to handle each member list property.
+func (p *sdkMemberListProperty) propertyName() string {
+	return p.memberType.SdkPropertyName()
+}
+
+// Cache of dynamically generated dynamicSdkMemberTypes objects. The key is the pointer
+// to a slice of SdkMemberType instances held in android.SdkMemberTypes.
+var dynamicSdkMemberTypesMap android.OncePer
+
+// A dynamically generated set of member list properties and associated structure type.
+type dynamicSdkMemberTypes struct {
+	// The dynamically generated structure type.
+	//
+	// Contains one []string exported field for each android.SdkMemberTypes. The name of the field
+	// is the exported form of the value returned by SdkMemberType.SdkPropertyName().
+	propertiesStructType reflect.Type
+
+	// Information about each of the member type specific list properties.
+	memberListProperties []*sdkMemberListProperty
+}
+
+func (d *dynamicSdkMemberTypes) createMemberListProperties() interface{} {
+	return reflect.New(d.propertiesStructType).Interface()
+}
+
+func getDynamicSdkMemberTypes(registry *android.SdkMemberTypesRegistry) *dynamicSdkMemberTypes {
+
+	// Get a key that uniquely identifies the registry contents.
+	key := registry.UniqueOnceKey()
+
+	// Get the registered types.
+	registeredTypes := registry.RegisteredTypes()
+
+	// Get the cached value, creating new instance if necessary.
+	return dynamicSdkMemberTypesMap.Once(key, func() interface{} {
+		return createDynamicSdkMemberTypes(registeredTypes)
+	}).(*dynamicSdkMemberTypes)
+}
+
+// Create the dynamicSdkMemberTypes from the list of registered member types.
 //
-// It is organized first by package and then by name within the package.
-// Packages are in alphabetical order and properties are in alphabetical order
-// within each package.
-var sdkMemberListProperties = []*sdkMemberListProperty{
-	// Members from cc package.
-	{
-		name:       "native_shared_libs",
-		getter:     func(properties *sdkProperties) []string { return properties.Native_shared_libs },
-		memberType: cc.SharedLibrarySdkMemberType,
-	},
-	{
-		name:       "native_static_libs",
-		getter:     func(properties *sdkProperties) []string { return properties.Native_static_libs },
-		memberType: cc.StaticLibrarySdkMemberType,
-	},
-	// Members from java package.
-	{
-		name:       "java_header_libs",
-		getter:     func(properties *sdkProperties) []string { return properties.Java_header_libs },
-		memberType: java.HeaderLibrarySdkMemberType,
-	},
-	{
-		name:       "java_libs",
-		getter:     func(properties *sdkProperties) []string { return properties.Java_libs },
-		memberType: java.ImplLibrarySdkMemberType,
-	},
-	{
-		name:       "stubs_sources",
-		getter:     func(properties *sdkProperties) []string { return properties.Stubs_sources },
-		memberType: java.DroidStubsSdkMemberType,
-	},
+// A struct is created which contains one exported field per member type corresponding to
+// the SdkMemberType.SdkPropertyName() value.
+//
+// A list of sdkMemberListProperty instances is created, one per member type that provides:
+// * a reference to the member type.
+// * a getter for the corresponding field in the properties struct.
+// * a dependency tag that identifies the member type of a resolved dependency.
+//
+func createDynamicSdkMemberTypes(sdkMemberTypes []android.SdkMemberType) *dynamicSdkMemberTypes {
+	var listProperties []*sdkMemberListProperty
+	var fields []reflect.StructField
+
+	// Iterate over the member types creating StructField and sdkMemberListProperty objects.
+	for f, memberType := range sdkMemberTypes {
+		p := memberType.SdkPropertyName()
+
+		// Create a dynamic exported field for the member type'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 := f
+
+		// Create an sdkMemberListProperty for the member type.
+		memberListProperty := &sdkMemberListProperty{
+			getter: func(properties interface{}) []string {
+				// The properties is expected to be of the following form (where
+				// <Module_types> is the name of an SdkMemberType.SdkPropertyName().
+				//     properties *struct {<Module_types> []string, ....}
+				//
+				// Although it accesses the field by index the following reflection code is equivalent to:
+				//    *properties.<Module_types>
+				//
+				list := reflect.ValueOf(properties).Elem().Field(fieldIndex).Interface().([]string)
+				return list
+			},
+
+			memberType: memberType,
+
+			dependencyTag: &sdkMemberDependencyTag{
+				memberType: memberType,
+			},
+		}
+
+		listProperties = append(listProperties, memberListProperty)
+	}
+
+	// Create a dynamic struct from the collated fields.
+	propertiesStructType := reflect.StructOf(fields)
+
+	return &dynamicSdkMemberTypes{
+		memberListProperties: listProperties,
+		propertiesStructType: propertiesStructType,
+	}
 }
 
 // sdk defines an SDK which is a logical group of modules (e.g. native libs, headers, java libs, etc.)
 // which Mainline modules like APEX can choose to build with.
 func ModuleFactory() android.Module {
 	s := &sdk{}
-	s.AddProperties(&s.properties)
+
+	// Get the dynamic sdk member type data for the currently registered sdk member types.
+	s.dynamicSdkMemberTypes = getDynamicSdkMemberTypes(android.SdkMemberTypes)
+
+	// Create an instance of the dynamically created struct that contains all the
+	// properties for the member type specific list properties.
+	s.dynamicMemberTypeListProperties = s.dynamicSdkMemberTypes.createMemberListProperties()
+
+	s.AddProperties(&s.properties, s.dynamicMemberTypeListProperties)
+
 	android.InitAndroidMultiTargetsArchModule(s, android.HostAndDeviceSupported, android.MultilibCommon)
 	android.InitDefaultableModule(s)
 	android.AddLoadHook(s, func(ctx android.LoadHookContext) {
@@ -235,9 +282,9 @@
 
 // Step 1: create dependencies from an SDK module to its members.
 func memberMutator(mctx android.BottomUpMutatorContext) {
-	if m, ok := mctx.Module().(*sdk); ok {
-		for _, memberListProperty := range sdkMemberListProperties {
-			names := memberListProperty.getter(&m.properties)
+	if s, ok := mctx.Module().(*sdk); ok {
+		for _, memberListProperty := range s.dynamicSdkMemberTypes.memberListProperties {
+			names := memberListProperty.getter(s.dynamicMemberTypeListProperties)
 			tag := memberListProperty.dependencyTag
 			memberListProperty.memberType.AddDependencies(mctx, tag, names)
 		}
diff --git a/sdk/update.go b/sdk/update.go
index 52d21ed..d31fa30 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -105,21 +105,20 @@
 // Collect all the members.
 //
 // The members are first grouped by type and then grouped by name. The order of
-// the types is the order they are referenced in sdkMemberListProperties. The
+// the types is the order they are referenced in android.SdkMemberTypes. The
 // names are in order in which the dependencies were added.
-func collectMembers(ctx android.ModuleContext) []*sdkMember {
+func (s *sdk) collectMembers(ctx android.ModuleContext) []*sdkMember {
 	byType := make(map[android.SdkMemberType][]*sdkMember)
 	byName := make(map[string]*sdkMember)
 
 	ctx.VisitDirectDeps(func(m android.Module) {
 		tag := ctx.OtherModuleDependencyTag(m)
 		if memberTag, ok := tag.(*sdkMemberDependencyTag); ok {
-			memberListProperty := memberTag.memberListProperty
-			memberType := memberListProperty.memberType
+			memberType := memberTag.memberType
 
 			// Make sure that the resolved module is allowed in the member list property.
 			if !memberType.IsInstance(m) {
-				ctx.ModuleErrorf("module %q is not valid in property %s", ctx.OtherModuleName(m), memberListProperty.name)
+				ctx.ModuleErrorf("module %q is not valid in property %s", ctx.OtherModuleName(m), memberType.SdkPropertyName())
 			}
 
 			name := ctx.OtherModuleName(m)
@@ -136,7 +135,7 @@
 	})
 
 	var members []*sdkMember
-	for _, memberListProperty := range sdkMemberListProperties {
+	for _, memberListProperty := range s.dynamicSdkMemberTypes.memberListProperties {
 		membersOfType := byType[memberListProperty.memberType]
 		members = append(members, membersOfType...)
 	}
@@ -191,7 +190,7 @@
 	}
 	s.builderForTests = builder
 
-	for _, member := range collectMembers(ctx) {
+	for _, member := range s.collectMembers(ctx) {
 		member.memberType.BuildSnapshot(ctx, builder, member)
 	}
 
@@ -220,10 +219,10 @@
 	}
 
 	addHostDeviceSupportedProperties(&s.ModuleBase, snapshotModule)
-	for _, memberListProperty := range sdkMemberListProperties {
-		names := memberListProperty.getter(&s.properties)
+	for _, memberListProperty := range s.dynamicSdkMemberTypes.memberListProperties {
+		names := memberListProperty.getter(s.dynamicMemberTypeListProperties)
 		if len(names) > 0 {
-			snapshotModule.AddProperty(memberListProperty.name, builder.versionedSdkMemberNames(names))
+			snapshotModule.AddProperty(memberListProperty.propertyName(), builder.versionedSdkMemberNames(names))
 		}
 	}
 	bpFile.AddModule(snapshotModule)