adding CodeGenerator.group

The `group` value allows for basic scheduling of code generators. All code generators with the same group will be executed in a loop together until no new code is generated.

Author: RBusarow

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Added
 
+- Added `CodeGenerator.group` for scheduling of code generators.  All code generators with the same group will be executed in a loop together until no new code is generated.
+
 ### Changed
 
 - Anvil's generated hints are now all generated to the same `anvil.hint` package, which simplifies hint lookups and better future-proofs future KSP work. Note that this is a user-invisible change, but it will require a one-time recompilation of any Anvil-generated hints.
@@ -22,24 +24,10 @@
 
 ## [2.5.0-beta07] - 2024-04-16
 
-### Added
-
-### Changed
-
-### Deprecated
-
-### Removed
-
 ### Fixed
 
 * Another mangled name workaround in KSP ([#966](https://github.com/square/anvil/pull/966))
 
-### Security
-
-### Custom Code Generator
-
-### Other Notes & Contributions
-
 ## [2.5.0-beta06] - 2024-04-16
 
 ### Deprecated

compiler-api/README.md

@@ -40,6 +40,10 @@ After that implement the `CodeGenerator` interface:
 ```kotlin
 @AutoService(CodeGenerator::class)
 class SampleCodeGenerator : CodeGenerator {
+  
+  // execute before any of the default Anvil code generators (in group 0)
+  override val group = -1
+  
   override fun isApplicable(context: AnvilContext): Boolean = true
 
   override fun generateCode(

compiler-api/api/compiler-api.api

@@ -48,10 +48,21 @@ public abstract interface class com/squareup/anvil/compiler/api/AnvilContext {
 }
 
 public abstract interface class com/squareup/anvil/compiler/api/CodeGenerator : com/squareup/anvil/compiler/api/AnvilApplicabilityChecker {
+	public static final field Companion Lcom/squareup/anvil/compiler/api/CodeGenerator$Companion;
+	public static final field GROUP_DEFAULT I
 	public abstract fun generateCode (Ljava/io/File;Lorg/jetbrains/kotlin/descriptors/ModuleDescriptor;Ljava/util/Collection;)Ljava/util/Collection;
+	public abstract fun getGroup ()I
 	public abstract fun isApplicable (Lcom/squareup/anvil/compiler/api/AnvilContext;)Z
 }
 
+public final class com/squareup/anvil/compiler/api/CodeGenerator$Companion {
+	public static final field GROUP_DEFAULT I
+}
+
+public final class com/squareup/anvil/compiler/api/CodeGenerator$DefaultImpls {
+	public static fun getGroup (Lcom/squareup/anvil/compiler/api/CodeGenerator;)I
+}
+
 public final class com/squareup/anvil/compiler/api/CodeGeneratorKt {
 	public static final fun createGeneratedFile (Lcom/squareup/anvil/compiler/api/CodeGenerator;Ljava/io/File;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)Lcom/squareup/anvil/compiler/api/GeneratedFile;
 	public static final fun createGeneratedFile (Lcom/squareup/anvil/compiler/api/CodeGenerator;Ljava/io/File;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/io/File;[Ljava/io/File;)Lcom/squareup/anvil/compiler/api/GeneratedFileWithSources;

compiler-api/src/main/java/com/squareup/anvil/compiler/api/CodeGenerator.kt

@@ -19,6 +19,18 @@ import java.io.File
 @ExperimentalAnvilApi
 public interface CodeGenerator : AnvilApplicabilityChecker {
 
+  /**
+   * The group in which this generator will be invoked.
+   *
+   * All code generators with the same group will be executed in a loop together,
+   * in ascending order of their fully qualified name, until no new code is generated.
+   * Lower numbers will be executed first,
+   * and will not execute again after their group has finished.
+   *
+   * The default group is 0.
+   */
+  public val group: Int get() = 0
+
   /**
    * Returns true if this code generator is applicable for the given [context] or false if not. This
    * will only be called _once_.
@@ -39,6 +51,14 @@ public interface CodeGenerator : AnvilApplicabilityChecker {
     module: ModuleDescriptor,
     projectFiles: Collection<KtFile>,
   ): Collection<FileWithContent>
+
+  public companion object {
+    /**
+     * The default [group][CodeGenerator.group] for code generators.
+     * A lower group value will be executed before any higher group value.
+     */
+    public const val GROUP_DEFAULT: Int = 0
+  }
 }
 
 /**

compiler/src/main/java/com/squareup/anvil/compiler/codegen/CheckOnlyCodeGenerator.kt

@@ -10,6 +10,8 @@ import java.io.File
  */
 internal abstract class CheckOnlyCodeGenerator : PrivateCodeGenerator() {
 
+  override val group: Int get() = Int.MAX_VALUE
+
   final override fun generateCodePrivate(
     codeGenDir: File,
     module: ModuleDescriptor,

compiler/src/main/java/com/squareup/anvil/compiler/codegen/CodeGenerationExtension.kt

@@ -29,7 +29,7 @@ import java.io.File
 import kotlin.LazyThreadSafetyMode.NONE
 
 internal class CodeGenerationExtension(
-  codeGenerators: List<CodeGenerator>,
+  private val codeGenerators: List<CodeGenerator>,
   private val commandLineOptions: CommandLineOptions,
   private val moduleDescriptorFactory: RealAnvilModuleDescriptor.Factory,
   private val projectDir: BaseDir.ProjectDir,
@@ -56,18 +56,6 @@ internal class CodeGenerationExtension(
   private var didRecompile = false
   private var didSyncGeneratedDir = false
 
-  private val codeGenerators = codeGenerators
-    .onEach {
-      check(it !is FlushingCodeGenerator || it !is PrivateCodeGenerator) {
-        "A code generator can't be a private code generator and flushing code generator at the " +
-          "same time. Private code generators don't impact other code generators, therefore " +
-          "they shouldn't need to flush files after other code generators generated code."
-      }
-    }
-    // Use a stable sort in case code generators depend on the order.
-    // At least don't make it random.
-    .sortedWith(compareBy({ it is PrivateCodeGenerator }, { it::class.qualifiedName }))
-
   override fun doAnalysis(
     project: Project,
     module: ModuleDescriptor,
@@ -196,11 +184,6 @@ internal class CodeGenerationExtension(
 
     val generatedFiles = mutableMapOf<String, FileWithContent>()
 
-    val (privateCodeGenerators, nonPrivateCodeGenerators) =
-      codeGenerators
-        .filter { it.isApplicable(anvilContext) }
-        .partition { it is PrivateCodeGenerator }
-
     fun onGenerated(
       generatedFile: FileWithContent,
       codeGenerator: CodeGenerator,
@@ -237,43 +220,23 @@ internal class CodeGenerationExtension(
           .toKtFiles(psiManager, anvilModule)
       }
 
-    fun Collection<FlushingCodeGenerator>.flush(): List<KtFile> =
-      flatMap { codeGenerator ->
-        codeGenerator.flush(generatedDir, anvilModule)
-          .onEach {
-            onGenerated(
-              generatedFile = it,
-              codeGenerator = codeGenerator,
-              // flushing code generators write the files but no content during normal rounds.
-              allowOverwrites = true,
-            )
-          }
-          .toKtFiles(psiManager, anvilModule)
-      }
-
-    fun List<CodeGenerator>.loopGeneration() {
-      var newFiles = generateAndCache(anvilModule.allFiles.toList())
-      while (newFiles.isNotEmpty()) {
-        // Parse the KtFile for each generated file. Then feed the code generators with the new
-        // parsed files until no new files are generated.
-        newFiles = generateAndCache(newFiles)
+    // Group the code generators by their group number,
+    // then sort them by their class name to keep the order stable.
+    // All generators in a group will be looped together until none of them generate new files.
+    codeGenerators
+      .filter { it.isApplicable(anvilContext) }
+      .groupBy { it.group }
+      .entries
+      .sortedBy { it.key }
+      .map { (_, generators) -> generators.sortedBy { it::class.qualifiedName } }
+      .forEach { generators ->
+        var newFiles = generators.generateAndCache(anvilModule.allFiles.toList())
+        while (newFiles.isNotEmpty()) {
+          // Parse the KtFile for each generated file. Then feed the code generators with the new
+          // parsed files until no new files are generated.
+          newFiles = generators.generateAndCache(newFiles)
+        }
       }
-    }
-
-    // All non-private code generators are batched together.
-    // They will execute against the initial set of files,
-    // then loop until no generator produces any new files.
-    nonPrivateCodeGenerators.loopGeneration()
-
-    // Flushing generators are next.
-    // They have already seen all generated code.
-    // Their output may be consumed by a private generator.
-    codeGenerators.filterIsInstance<FlushingCodeGenerator>().flush()
-
-    // Private generators do not affect each other, so they're invoked last.
-    // They may require multiple iterations of their own logic, though,
-    // so we loop them individually until there are no more changes.
-    privateCodeGenerators.forEach { listOf(it).loopGeneration() }
 
     return generatedFiles.values
   }

compiler/src/main/java/com/squareup/anvil/compiler/codegen/ContributesSubcomponentHandlerGenerator.kt

@@ -8,6 +8,7 @@ import com.squareup.anvil.compiler.PARENT_COMPONENT
 import com.squareup.anvil.compiler.SUBCOMPONENT_FACTORY
 import com.squareup.anvil.compiler.SUBCOMPONENT_MODULE
 import com.squareup.anvil.compiler.api.AnvilContext
+import com.squareup.anvil.compiler.api.CodeGenerator
 import com.squareup.anvil.compiler.api.GeneratedFileWithSources
 import com.squareup.anvil.compiler.api.createGeneratedFile
 import com.squareup.anvil.compiler.contributesSubcomponentFactoryFqName
@@ -62,7 +63,9 @@ import java.io.File
  */
 internal class ContributesSubcomponentHandlerGenerator(
   private val classScanner: ClassScanner,
-) : PrivateCodeGenerator() {
+) : CodeGenerator {
+
+  override val group: Int get() = 8
 
   private val triggers = mutableListOf<Trigger>()
   private val contributions = mutableSetOf<Contribution>()
@@ -73,7 +76,7 @@ internal class ContributesSubcomponentHandlerGenerator(
 
   override fun isApplicable(context: AnvilContext): Boolean = !context.generateFactoriesOnly
 
-  override fun generateCodePrivate(
+  override fun generateCode(
     codeGenDir: File,
     module: ModuleDescriptor,
     projectFiles: Collection<KtFile>,

compiler/src/main/java/com/squareup/anvil/compiler/codegen/FlushingCodeGenerator.kt

@@ -8,11 +8,12 @@ import java.io.File
 
 /**
  * Generates code that doesn't impact any other [CodeGenerator], meaning no other code generator
- * will process the generated code produced by this instance. A [PrivateCodeGenerator] is called
- * one last time after [FlushingCodeGenerator.flush] has been called to get a chance to evaluate
- * written results.
+ * will process the generated code produced by this instance.
  */
 internal abstract class PrivateCodeGenerator : CodeGenerator {
+
+  override val group: Int get() = 10
+
   final override fun generateCode(
     codeGenDir: File,
     module: ModuleDescriptor,