Codegen Gradle: add toggle to activate JavaGenerator implementation

Summary:
JavaGenerator is a Java-based implementation for generating codegen output from the parsed schema file. Right now the output is a hardcoded Java file. In the next commits, proper JavaGenerator impl will be added.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D23100171

fbshipit-source-id: 1bef23e3dba4d8c222ebdece0edeb4435d388cd4

RNTester/android/app/build.gradle

@@ -229,4 +229,5 @@ react {
     enableCodegen = System.getenv("USE_CODEGEN") ?: false
     jsRootDir = file("$rootDir/RNTester")
     reactNativeRootDir = file("$rootDir")
+    useJavaGenerator = System.getenv("USE_CODEGEN_JAVAPOET") ?: false
 }

ReactAndroid/build.gradle

@@ -476,4 +476,5 @@ react {
     enableCodegen = System.getenv("USE_CODEGEN") ?: false
     jsRootDir = file("../Libraries")
     reactNativeRootDir = file("$rootDir")
+    useJavaGenerator = System.getenv("USE_CODEGEN_JAVAPOET") ?: false
 }

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/src/main/java/com/facebook/react/codegen/generator/JavaGenerator.java

@@ -10,23 +10,24 @@ package com.facebook.react.codegen.generator;
 import com.squareup.javapoet.JavaFile;
 import com.squareup.javapoet.MethodSpec;
 import com.squareup.javapoet.TypeSpec;
+import java.io.File;
 import java.io.IOException;
-import java.nio.file.Paths;
 import javax.lang.model.element.Modifier;
 
 // TODO: Implement proper generator - this is a sample usage of JavaPoet
 public final class JavaGenerator {
+  private final File mSchemaFile;
+  private final String mJavaPackageName;
+  private final File mOutputDir;
 
-  private String mSchemaFilePath;
-  private String mOutputDir;
-
-  public JavaGenerator(String schemaFilePath, String outputDir) {
-    mSchemaFilePath = schemaFilePath;
+  public JavaGenerator(final File schemaFile, final String javaPackageName, final File outputDir) {
+    mSchemaFile = schemaFile;
+    mJavaPackageName = javaPackageName;
     mOutputDir = outputDir;
   }
 
   public void build() throws IOException {
-    MethodSpec main =
+    final MethodSpec main =
         MethodSpec.methodBuilder("main")
             .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
             .returns(void.class)
@@ -34,18 +35,16 @@ public final class JavaGenerator {
             .addStatement("$T.out.println($S)", System.class, "Hello, JavaPoet!")
             .build();
 
-    TypeSpec helloWorld =
+    final TypeSpec helloWorld =
         TypeSpec.classBuilder("ReactNativeCodegen")
             .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
             .addMethod(main)
             .build();
 
-    JavaFile javaFile = JavaFile.builder("com.facebook.react.codegen", helloWorld).build();
+    final JavaFile javaFile = JavaFile.builder(mJavaPackageName, helloWorld).build();
 
     System.out.println(javaFile.toString());
 
-    if (!mOutputDir.isEmpty()) {
-      javaFile.writeToPath(Paths.get(mOutputDir));
-    }
+    javaFile.writeTo(mOutputDir);
   }
 }

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/src/main/java/com/facebook/react/codegen/plugin/CodegenPlugin.java

@@ -8,9 +8,11 @@
 package com.facebook.react.codegen.plugin;
 
 import com.android.build.gradle.BaseExtension;
+import com.facebook.react.codegen.generator.JavaGenerator;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import java.io.File;
+import java.io.IOException;
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
@@ -95,16 +97,25 @@ public class CodegenPlugin implements Plugin<Project> {
               task.getInputs().files(generatedSchemaFile);
               task.getOutputs().dir(outputDir);
 
-              ImmutableList<String> execCommands =
-                  new ImmutableList.Builder<String>()
-                      .add("yarn")
-                      .addAll(ImmutableList.copyOf(extension.nodeExecutableAndArgs))
-                      .add(extension.codegenGenerateNativeModuleSpecsCLI().getAbsolutePath())
-                      .add("android")
-                      .add(generatedSchemaFile.getAbsolutePath())
-                      .add(outputDir.getAbsolutePath())
-                      .build();
-              task.commandLine(execCommands);
+              if (extension.useJavaGenerator) {
+                generateJavaFromSchemaWithJavaGenerator(
+                    generatedSchemaFile,
+                    extension.codegenJavaPackageName,
+                    new File(generatedSrcDir, "java"));
+                // TODO: generate JNI C++ files.
+                task.commandLine("echo");
+              } else {
+                ImmutableList<String> execCommands =
+                    new ImmutableList.Builder<String>()
+                        .add("yarn")
+                        .addAll(ImmutableList.copyOf(extension.nodeExecutableAndArgs))
+                        .add(extension.codegenGenerateNativeModuleSpecsCLI().getAbsolutePath())
+                        .add("android")
+                        .add(generatedSchemaFile.getAbsolutePath())
+                        .add(outputDir.getAbsolutePath())
+                        .build();
+                task.commandLine(execCommands);
+              }
             });
 
     // 4. Add dependencies & generated sources to the project.
@@ -140,4 +151,16 @@ public class CodegenPlugin implements Plugin<Project> {
           // TODO: Add JNI sources.
         });
   }
+
+  // Use Java-based generator implementation to produce the source files, instead of using the
+  // JS-based generator.
+  private void generateJavaFromSchemaWithJavaGenerator(
+      final File schemaFile, final String javaPackageName, final File outputDir) {
+    final JavaGenerator generator = new JavaGenerator(schemaFile, javaPackageName, outputDir);
+    try {
+      generator.build();
+    } catch (final IOException e) {
+      // Ignore for now.
+    }
+  }
 }

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/src/main/java/com/facebook/react/codegen/plugin/CodegenPluginExtension.java

@@ -13,12 +13,13 @@ import org.gradle.api.Project;
 public class CodegenPluginExtension {
   // TODO: Remove beta.
   public String codegenJavaPackageName = "com.facebook.fbreact.specs.beta";
-  public boolean enableCodegen;
+  public boolean enableCodegen = false;
   public File jsRootDir;
   public String[] nodeExecutableAndArgs = {"node"};
   public File reactNativeRootDir;
+  public boolean useJavaGenerator = false;
 
-  public CodegenPluginExtension(Project project) {
+  public CodegenPluginExtension(final Project project) {
     this.reactNativeRootDir = new File(project.getRootDir(), "node_modules/react-native");
   }