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@ContributesRobot code generator
Add a new KSP code generator that generates the code for `@ContributesRobot` using Metro. The implementation is almost equivalent to the kotlin-inject implementation, except for that it's using Metro APIs. The big difference is that kotlin-inject implements map-multibindings by returning a `Pair<Abc, Def>` whereas Metro uses a `@ClassKey` annotation similar to Dagger 2. Therefore, we had to introduce the `@RobotKey` annotation specifically for Metro. See #115
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‎metro-extensions/contribute/impl-code-generators/src/main/kotlin/software/amazon/app/platform/metro/KotlinInjectExtensionSymbolProcessorProvider.kt‎

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@ import com.google.devtools.ksp.processing.SymbolProcessorEnvironment
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import com.google.devtools.ksp.processing.SymbolProcessorProvider
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import software.amazon.app.platform.ksp.CompositeSymbolProcessor
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import software.amazon.app.platform.metro.processor.ContributesRendererProcessor
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import software.amazon.app.platform.metro.processor.ContributesRobotProcessor
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/** Entry point for KSP to pick up our [SymbolProcessor]. */
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@AutoService(SymbolProcessorProvider::class)
@@ -16,7 +17,11 @@ public class KotlinInjectExtensionSymbolProcessorProvider : SymbolProcessorProvi
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ContributesRendererProcessor(
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codeGenerator = environment.codeGenerator,
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logger = environment.logger,
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)
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),
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ContributesRobotProcessor(
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codeGenerator = environment.codeGenerator,
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logger = environment.logger,
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),
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)
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}
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}

‎metro-extensions/contribute/impl-code-generators/src/main/kotlin/software/amazon/app/platform/metro/MetroContextAware.kt‎

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Original file line numberDiff line numberDiff line change
@@ -1,5 +1,7 @@
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package software.amazon.app.platform.metro
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import com.google.devtools.ksp.symbol.KSAnnotation
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import com.google.devtools.ksp.symbol.KSType
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import dev.zacsweers.metro.Inject
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import dev.zacsweers.metro.Scope
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import software.amazon.app.platform.ksp.ContextAware
@@ -10,4 +12,16 @@ internal interface MetroContextAware : ContextAware {
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private val scopeFqName
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get() = Scope::class.requireQualifiedName()
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fun KSAnnotation.isMetroScopeAnnotation(): Boolean {
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return annotationType.resolve().isMetroScopeAnnotation()
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}
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private fun KSType.isMetroScopeAnnotation(): Boolean {
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return declaration.annotations.any {
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// Don't use requireQualifiedName(), because @ContributingAnnotation might not be
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// on the compile classpath.
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it.annotationType.resolve().declaration.qualifiedName?.asString() == scopeFqName
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}
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}
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}

‎metro-extensions/contribute/impl-code-generators/src/main/kotlin/software/amazon/app/platform/metro/processor/ContributesRobotProcessor.kt‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,168 @@
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package software.amazon.app.platform.metro.processor
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import com.google.devtools.ksp.KspExperimental
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import com.google.devtools.ksp.getAllSuperTypes
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import com.google.devtools.ksp.isAnnotationPresent
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import com.google.devtools.ksp.processing.CodeGenerator
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import com.google.devtools.ksp.processing.KSPLogger
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import com.google.devtools.ksp.processing.Resolver
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import com.google.devtools.ksp.processing.SymbolProcessor
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import com.google.devtools.ksp.symbol.KSAnnotated
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import com.google.devtools.ksp.symbol.KSClassDeclaration
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import com.squareup.kotlinpoet.AnnotationSpec
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import com.squareup.kotlinpoet.ClassName
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import com.squareup.kotlinpoet.FileSpec
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import com.squareup.kotlinpoet.FunSpec
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import com.squareup.kotlinpoet.ParameterizedTypeName.Companion.parameterizedBy
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import com.squareup.kotlinpoet.TypeSpec
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import com.squareup.kotlinpoet.asClassName
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import com.squareup.kotlinpoet.ksp.addOriginatingKSFile
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import com.squareup.kotlinpoet.ksp.toClassName
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import com.squareup.kotlinpoet.ksp.writeTo
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import dev.zacsweers.metro.AppScope
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import dev.zacsweers.metro.ContributesTo
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import dev.zacsweers.metro.Inject
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import dev.zacsweers.metro.IntoMap
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import dev.zacsweers.metro.Provider
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import dev.zacsweers.metro.Provides
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import software.amazon.app.platform.inject.robot.ContributesRobot
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import software.amazon.app.platform.ksp.decapitalize
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import software.amazon.app.platform.metro.METRO_LOOKUP_PACKAGE
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import software.amazon.app.platform.metro.MetroContextAware
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import software.amazon.app.platform.renderer.metro.RobotKey
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/**
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* Generates the necessary code in order to support [ContributesRobot].
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*
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* If you use `@ContributesRobot(AbcScope::class)`, then this processor will generate a graph
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* interface, which gets contributed to this scope.
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*
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* ```
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* package app.platform.inject.metro.software.amazon.test
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*
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* @ContributesTo(scope = AbcScope::class)
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* public interface AbcRobotGraph {
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* @Provide
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* fun provideAbcRobot(): AbcRobot = AbcRobot()
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*
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* @Provides
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* @IntoMap
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* @RobotKey(AbcRobot::class)
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* fun provideAbcRobotIntoMap(
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* robot: Provider<AbcRobot>,
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* ): Robot = robot()
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* }
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* ```
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*/
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@OptIn(KspExperimental::class)
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internal class ContributesRobotProcessor(
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private val codeGenerator: CodeGenerator,
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override val logger: KSPLogger,
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) : SymbolProcessor, MetroContextAware {
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private val robotClassName = ClassName("software.amazon.app.platform.robot", "Robot")
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private val robotFqName = robotClassName.canonicalName
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private val robotKey = RobotKey::class.asClassName()
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override fun process(resolver: Resolver): List<KSAnnotated> {
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resolver
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.getSymbolsWithAnnotation(ContributesRobot::class)
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.filterIsInstance<KSClassDeclaration>()
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.onEach {
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checkIsPublic(it)
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checkHasInjectAnnotation(it)
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checkNotSingleton(it)
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checkSuperType(it)
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checkAppScope(it)
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}
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.forEach { generateGraph(it) }
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return emptyList()
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}
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private fun generateGraph(clazz: KSClassDeclaration) {
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val packageName = "${METRO_LOOKUP_PACKAGE}.${clazz.packageName.asString()}"
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val graphClassName = ClassName(packageName, "${clazz.innerClassNames()}Graph")
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val fileSpec =
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FileSpec.builder(graphClassName)
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.addType(
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TypeSpec.interfaceBuilder(graphClassName)
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.addOriginatingKSFile(clazz.requireContainingFile())
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.addAnnotation(
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AnnotationSpec.builder(ContributesTo::class)
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.addMember("%T::class", clazz.scope().type.toClassName())
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.build()
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)
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.apply {
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if (!clazz.isAnnotationPresent(Inject::class)) {
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addFunction(
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FunSpec.builder("provide${clazz.innerClassNames()}")
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.addAnnotation(Provides::class)
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.returns(clazz.toClassName())
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.addStatement("return %T()", clazz.toClassName())
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.build()
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)
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}
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}
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.addFunction(
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FunSpec.builder("provide${clazz.innerClassNames()}IntoMap")
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.addAnnotation(Provides::class)
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.addAnnotation(IntoMap::class)
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.addAnnotation(
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AnnotationSpec.builder(robotKey)
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.addMember("%T::class", clazz.toClassName())
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.build()
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)
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.addParameter(
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name = "robot",
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type = Provider::class.asClassName().parameterizedBy(clazz.toClassName()),
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)
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.returns(robotClassName)
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.addStatement("return robot()")
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.build()
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)
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.addProperty(name = clazz.innerClassNames().decapitalize(), type = clazz.toClassName())
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.build()
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)
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.build()
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fileSpec.writeTo(codeGenerator, aggregating = false)
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}
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private fun checkHasInjectAnnotation(clazz: KSClassDeclaration) {
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if (clazz.primaryConstructor?.parameters?.isNotEmpty() == true) {
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check(clazz.annotations.any { it.isAnnotation(injectFqName) }, clazz) {
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"${clazz.simpleName.asString()} must be annotated with @Inject when " +
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"injecting arguments into a robot."
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}
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}
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}
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private fun checkNotSingleton(clazz: KSClassDeclaration) {
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check(clazz.annotations.none { it.isMetroScopeAnnotation() }, clazz) {
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"It's not allowed allowed for a robot to be a singleton, because the lifetime " +
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"of the robot is scoped to the robot() factory function. Remove the @" +
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clazz.annotations.first { it.isMetroScopeAnnotation() }.shortName.asString() +
148+
" annotation."
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}
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}
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private fun checkSuperType(clazz: KSClassDeclaration) {
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val extendsRobot =
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clazz.getAllSuperTypes().any { it.declaration.requireQualifiedName() == robotFqName }
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check(extendsRobot, clazz) {
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"In order to use @ContributesRobot, ${clazz.simpleName.asString()} must " +
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"implement $robotFqName."
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}
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}
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162+
private fun checkAppScope(clazz: KSClassDeclaration) {
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val scope = clazz.scope().type.declaration.requireQualifiedName()
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check(scope == AppScope::class.requireQualifiedName(), clazz) {
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"Robots can only be contributed to the AppScope for now. Scope $scope is unsupported."
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}
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}
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}

‎metro-extensions/contribute/impl-code-generators/src/test/kotlin/software/amazon/app/platform/inject/metro/CommonSourceCode.kt‎

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Original file line numberDiff line numberDiff line change
@@ -5,6 +5,7 @@ package software.amazon.app.platform.inject.metro
55
import com.tschuchort.compiletesting.JvmCompilationResult
66
import org.jetbrains.kotlin.compiler.plugin.ExperimentalCompilerApi
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import software.amazon.test.TestRendererGraph
8+
import software.amazon.test.TestRobotGraph
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910
internal val JvmCompilationResult.graphInterface: Class<*>
1011
get() = classLoader.loadClass("software.amazon.test.GraphInterface")
@@ -17,3 +18,12 @@ internal fun Class<*>.newTestRendererGraph(): TestRendererGraph {
1718
.single { it.name == "create" }
1819
.invoke(companionObject) as TestRendererGraph
1920
}
21+
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internal fun Class<*>.newTestRobotGraph(): TestRobotGraph {
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val companionObject = fields.single().get(null)
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return classes
25+
.single { it.simpleName == "Companion" }
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.declaredMethods
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.single { it.name == "create" }
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.invoke(companionObject) as TestRobotGraph
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}

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