Support sources located in an unnamed package

src/main/java/org/openrewrite/java/template/processor/RefasterTemplateProcessor.java

@@ -25,6 +25,7 @@
 import com.sun.tools.javac.tree.TreeMaker;
 import com.sun.tools.javac.tree.TreeScanner;
 import com.sun.tools.javac.util.Context;
+import com.sun.tools.javac.util.Name;
 import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.template.internal.FQNPretty;
 import org.openrewrite.java.template.internal.ImportDetector;
@@ -181,7 +182,9 @@ public void visitClassDef(JCTree.JCClassDecl classDecl) {
                     String after = descriptor.afterTemplate.getName().toString();
 
                     StringBuilder recipe = new StringBuilder();
-                    String refasterRuleClassName = classDecl.sym.fullname.toString().substring(classDecl.sym.packge().fullname.length() + 1);
+                    Symbol.PackageSymbol pkg = classDecl.sym.packge();
+                    String typeName = classDecl.sym.fullname.toString();
+                    String refasterRuleClassName = pkg.isUnnamed() ? typeName : typeName.substring(pkg.fullname.length() + 1);
                     recipe.append("/**\n * OpenRewrite recipe created for Refaster template {@code ").append(refasterRuleClassName).append("}.\n */\n");
                     String recipeName = templateFqn.substring(templateFqn.lastIndexOf('.') + 1);
                     recipe.append("@SuppressWarnings(\"all\")\n");
@@ -306,12 +309,15 @@ public void visitClassDef(JCTree.JCClassDecl classDecl) {
                 if (classDecl.sym != null && classDecl.sym.getNestingKind() == NestingKind.TOP_LEVEL && !recipes.isEmpty()) {
                     boolean outerClassRequired = descriptor == null;
                     try {
+                        Symbol.PackageSymbol pkg = classDecl.sym.packge();
                         String inputOuterFQN = outerClassRequired ? classDecl.sym.fullname.toString() : descriptor.classDecl.sym.fullname.toString();
                         String className = inputOuterFQN + (outerClassRequired ? "Recipes" : "Recipe");
                         JavaFileObject builderFile = processingEnv.getFiler().createSourceFile(className);
                         try (Writer out = new BufferedWriter(builderFile.openWriter())) {
-                            out.write("package " + classDecl.sym.packge().toString() + ";\n");
-                            out.write("\n");
+                            if (!pkg.isUnnamed()) {
+                                out.write("package " + pkg.fullname + ";\n");
+                                out.write("\n");
+                            }
                             out.write("import org.openrewrite.ExecutionContext;\n");
                             out.write("import org.openrewrite.Preconditions;\n");
                             out.write("import org.openrewrite.Recipe;\n");

src/main/java/org/openrewrite/java/template/processor/TemplateProcessor.java

@@ -140,9 +140,13 @@ public void visitApply(JCTree.JCMethodInvocation tree) {
 
                             String templateCode = TemplateCode.process(resolved.get(template.getBody()), parameters, false);
 
+                            Symbol.PackageSymbol pkg = classDecl.sym.packge();
                             JavaFileObject builderFile = processingEnv.getFiler().createSourceFile(templateFqn);
                             try (Writer out = new BufferedWriter(builderFile.openWriter())) {
-                                out.write("package " + classDecl.sym.packge().toString() + ";\n");
+                                if (!pkg.isUnnamed()) {
+                                    out.write("package " + pkg.fullname + ";\n");
+                                    out.write("\n");
+                                }
                                 out.write("import org.openrewrite.java.*;\n");
 
                                 out.write("\n");

src/test/java/org/openrewrite/java/template/RefasterTemplateProcessorTest.java

@@ -19,6 +19,7 @@
 import com.google.errorprone.refaster.annotation.BeforeTemplate;
 import com.google.testing.compile.Compilation;
 import com.google.testing.compile.JavaFileObjects;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 import org.openrewrite.java.template.processor.RefasterTemplateProcessor;
@@ -51,6 +52,16 @@ void generateRecipe(String recipeName) {
           .hasSourceEquivalentTo(JavaFileObjects.forResource("refaster/" + recipeName + "Recipe.java"));
     }
 
+    @Test
+    void generateRecipeInDefaultPackage() {
+        Compilation compilation = compile("refaster/UnnamedPackage.java");
+        assertThat(compilation).succeeded();
+        assertThat(compilation).hadNoteCount(0);
+        assertThat(compilation)
+          .generatedSourceFile("UnnamedPackageRecipe")
+          .hasSourceEquivalentTo(JavaFileObjects.forResource("refaster/UnnamedPackageRecipe.java"));
+    }
+
     @ParameterizedTest
     @ValueSource(strings = {
       "OrElseGetGet",

src/test/java/org/openrewrite/java/template/TemplateProcessorTest.java

@@ -74,4 +74,13 @@ void throwNew() {
           .generatedSourceFile("template/ThrowNewRecipe$1_template")
           .hasSourceEquivalentTo(JavaFileObjects.forResource("template/ThrowNewRecipe$1_template.java"));
     }
+
+    @Test
+    void unnamedPackage() {
+        Compilation compilation = compile("template/UnnamedPackage.java", new TemplateProcessor());
+        assertThat(compilation).succeeded();
+        assertThat(compilation)
+          .generatedSourceFile("UnnamedPackage$1_message")
+          .hasSourceEquivalentTo(JavaFileObjects.forResource("template/UnnamedPackage$1_message.java"));
+    }
 }

src/test/resources/refaster/UnnamedPackage.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.
+ */
+import com.google.errorprone.refaster.annotation.AfterTemplate;
+import com.google.errorprone.refaster.annotation.BeforeTemplate;
+
+public class UnnamedPackage {
+    @BeforeTemplate
+    String before() {
+        return "This class is located in the default package";
+    }
+
+    @AfterTemplate
+    String after() {
+        return "And that doesn't cause any problems";
+    }
+}

src/test/resources/refaster/UnnamedPackageRecipe.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.
+ */
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Preconditions;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.internal.lang.NonNullApi;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.JavaVisitor;
+import org.openrewrite.java.search.*;
+import org.openrewrite.java.template.Primitive;
+import org.openrewrite.java.template.Semantics;
+import org.openrewrite.java.template.function.*;
+import org.openrewrite.java.template.internal.AbstractRefasterJavaVisitor;
+import org.openrewrite.java.tree.*;
+
+import java.util.*;
+
+import static org.openrewrite.java.template.internal.AbstractRefasterJavaVisitor.EmbeddingOption.*;
+
+
+/**
+ * OpenRewrite recipe created for Refaster template {@code UnnamedPackage}.
+ */
+@SuppressWarnings("all")
+@NonNullApi
+public class UnnamedPackageRecipe extends Recipe {
+
+    /**
+     * Instantiates a new instance.
+     */
+    public UnnamedPackageRecipe() {}
+
+    @Override
+    public String getDisplayName() {
+        return "Refaster template `UnnamedPackage`";
+    }
+
+    @Override
+    public String getDescription() {
+        return "Recipe created for the following Refaster template:\n```java\npublic class UnnamedPackage {\n    \n    @BeforeTemplate()\n    String before() {\n        return \"This class is located in the default package\";\n    }\n    \n    @AfterTemplate()\n    String after() {\n        return \"And that doesn\\'t cause any problems\";\n    }\n}\n```\n.";
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        JavaVisitor<ExecutionContext> javaVisitor = new AbstractRefasterJavaVisitor() {
+            final JavaTemplate before = Semantics.expression(this, "before", () -> "This class is located in the default package").build();
+            final JavaTemplate after = Semantics.expression(this, "after", () -> "And that doesn\'t cause any problems").build();
+
+            @Override
+            public J visitExpression(Expression elem, ExecutionContext ctx) {
+                JavaTemplate.Matcher matcher;
+                if ((matcher = before.matcher(getCursor())).find()) {
+                    return embed(after.apply(getCursor(), elem.getCoordinates().replace()), getCursor(), ctx);
+                }
+                return super.visitExpression(elem, ctx);
+            }
+
+        };
+        return javaVisitor;
+    }
+}

src/test/resources/template/UnnamedPackage$1_message.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.
+ */
+import org.openrewrite.java.*;
+
+/**
+ * OpenRewrite `message` template created for {@code UnnamedPackage$1}.
+ */
+@SuppressWarnings("all")
+public class UnnamedPackage$1_message {
+    /**
+     * Instantiates a new instance.
+     */
+    public UnnamedPackage$1_message() {}
+
+    /**
+     * Get the {@code JavaTemplate.Builder} to match or replace.
+     * @return the JavaTemplate builder.
+     */
+    public static JavaTemplate.Builder getTemplate() {
+        return JavaTemplate
+                .builder("\"This class is located in the default package\"");
+    }
+}

src/test/resources/template/UnnamedPackage.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2024 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.
+ */
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.java.JavaIsoVisitor;
+import org.openrewrite.java.JavaTemplate;
+import org.openrewrite.java.template.Semantics;
+
+public class UnnamedPackage {
+    JavaIsoVisitor visitor = new JavaIsoVisitor<ExecutionContext>() {
+        JavaTemplate.Builder message = Semantics.expression(this, "message", () -> "This class is located in the default package");
+    };
+}