GenerateConstructorUsingFields refactoring operation

rewrite-core/src/main/java/com/netflix/rewrite/visitor/refactor/op/AddImport.java

@@ -16,10 +16,7 @@
 package com.netflix.rewrite.visitor.refactor.op;
 
 import com.netflix.rewrite.internal.lang.Nullable;
-import com.netflix.rewrite.tree.Formatting;
-import com.netflix.rewrite.tree.Tr;
-import com.netflix.rewrite.tree.TreeBuilder;
-import com.netflix.rewrite.tree.Type;
+import com.netflix.rewrite.tree.*;
 import com.netflix.rewrite.visitor.refactor.AstTransform;
 import com.netflix.rewrite.visitor.refactor.RefactorVisitor;
 import com.netflix.rewrite.visitor.search.FindType;
@@ -54,7 +51,6 @@ public class AddImport extends RefactorVisitor {
     private boolean hasReferences;
     private Tr.CompilationUnit cu;
 
-
     public AddImport(String clazz, @Nullable String staticMethod, boolean onlyIfReferenced) {
         this.clazz = clazz;
         this.staticMethod = staticMethod;

rewrite-core/src/main/java/com/netflix/rewrite/visitor/refactor/op/GenerateConstructorUsingFields.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2020 the original authors.
+ *
+ * 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
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.
+ */
+package com.netflix.rewrite.visitor.refactor.op;
+
+import com.netflix.rewrite.tree.*;
+import com.netflix.rewrite.visitor.refactor.AstTransform;
+import com.netflix.rewrite.visitor.refactor.ScopedRefactorVisitor;
+
+import java.util.List;
+import java.util.Set;
+import java.util.UUID;
+
+import static com.netflix.rewrite.tree.Formatting.*;
+import static com.netflix.rewrite.tree.Tr.randomId;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
+import static java.util.stream.Collectors.*;
+
+public class GenerateConstructorUsingFields extends ScopedRefactorVisitor {
+    private final List<Tr.VariableDecls> fields;
+
+    public GenerateConstructorUsingFields(UUID scope, List<Tr.VariableDecls> fields) {
+        super(scope);
+        this.fields = fields;
+    }
+
+    @Override
+    public List<AstTransform> visitClassDecl(Tr.ClassDecl classDecl) {
+        return maybeTransform(classDecl,
+                isScope(classDecl) && !hasRequiredArgsConstructor(classDecl),
+                super::visitClassDecl,
+                (cd, cursor) -> {
+                    List<Tree> statements = cd.getBody().getStatements();
+
+                    int lastField = 0;
+                    for (int i = 0; i < statements.size(); i++) {
+                        if (statements.get(i) instanceof Tr.VariableDecls) {
+                            lastField = i;
+                        }
+                    }
+
+                    List<Statement> constructorParams = fields.stream()
+                            .map(mv -> new Tr.VariableDecls(randomId(),
+                                    emptyList(),
+                                    emptyList(),
+                                    mv.getTypeExpr() != null ? mv.getTypeExpr().withFormatting(EMPTY) : null,
+                                    null,
+                                    formatFirstPrefix(mv.getDimensionsBeforeName(), ""),
+                                    formatFirstPrefix(mv.getVars(), " "),
+                                    EMPTY))
+                            .collect(toList());
+
+                    for (int i = 1; i < constructorParams.size(); i++) {
+                        constructorParams.set(i, constructorParams.get(i).withFormatting(format(" ")));
+                    }
+
+                    Formatting constructorFormatting = formatter().format(cd.getBody());
+                    Tr.MethodDecl constructor = new Tr.MethodDecl(randomId(), emptyList(),
+                            singletonList(new Tr.Modifier.Public(randomId(), EMPTY)),
+                            null,
+                            null,
+                            Tr.Ident.build(randomId(), cd.getSimpleName(), cd.getType(), format(" ")),
+                            new Tr.MethodDecl.Parameters(randomId(), constructorParams, EMPTY),
+                            null,
+                            new Tr.Block<>(randomId(), null, emptyList(), format(" "),
+                                    formatter().findIndent(cd.getBody().getIndent(), cd.getBody().getStatements().toArray(Tree[]::new)).getPrefix()),
+                            null,
+                            constructorFormatting.withPrefix("\n" + constructorFormatting.getPrefix()));
+
+                    // add assignment statements to constructor
+                    andThen(new ScopedRefactorVisitor(constructor.getId()) {
+                        @Override
+                        public List<AstTransform> visitMethod(Tr.MethodDecl method) {
+                            return maybeTransform(method,
+                                    isScope(method),
+                                    super::visitMethod,
+                                    Tr.MethodDecl::getBody,
+                                    (body, cursor) -> body.withStatements(
+                                            TreeBuilder.buildSnippet(cursor.enclosingCompilationUnit(),
+                                                    cursor,
+                                                    fields.stream().map(mv -> {
+                                                        String name = mv.getVars().get(0).getSimpleName();
+                                                        return "this." + name + " = " + name + ";";
+                                                    }).collect(joining("\n", "", "\n"))
+                                            ))
+                            );
+                        }
+                    });
+
+                    statements.add(lastField + 1, constructor);
+
+                    return cd.withBody(cd.getBody().withStatements(statements));
+                });
+    }
+
+    private boolean hasRequiredArgsConstructor(Tr.ClassDecl cd) {
+        Set<String> injectedFieldNames = fields.stream().map(f -> f.getVars().get(0).getSimpleName()).collect(toSet());
+
+        return cd.getBody().getStatements().stream().anyMatch(stat -> stat.whenType(Tr.MethodDecl.class)
+                .filter(Tr.MethodDecl::isConstructor)
+                .map(md -> md.getParams().getParams().stream()
+                        .map(p -> p.whenType(Tr.VariableDecls.class)
+                                .map(mv -> mv.getVars().get(0).getSimpleName())
+                                .orElseThrow(() -> new RuntimeException("not possible to get here")))
+                        .allMatch(injectedFieldNames::contains))
+                .orElse(false));
+    }
+}

rewrite-core/src/test/kotlin/com/netflix/rewrite/visitor/refactor/op/GenerateConstructorUsingFieldsTest.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2020 the original authors.
+ *
+ * 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
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.
+ */
+package com.netflix.rewrite.visitor.refactor.op
+
+import com.netflix.rewrite.Parser
+import com.netflix.rewrite.assertRefactored
+import org.junit.Test
+
+class GenerateConstructorUsingFieldsTest: Parser() {
+    @Test
+    fun generateConstructorUsingFields() {
+        val a = parse("""
+            public class UsersController {
+                private final UsersService usersService;
+                private final UsernameService usernameService;
+            }
+        """.trimIndent())
+
+        val fixed = a.refactor().visit(GenerateConstructorUsingFields(a.classes[0].id, a.classes[0].fields))
+                .fix().fixed
+
+        assertRefactored(fixed, """
+            public class UsersController {
+                private final UsersService usersService;
+                private final UsernameService usernameService;
+            
+                public UsersController(UsersService usersService, UsernameService usernameService) {
+                    this.usersService = usersService;
+                    this.usernameService = usernameService;
+                }
+            }
+        """)
+    }
+}