/*
* Copyright (C) 2014 Google, Inc.
*
* 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.google.auto.value.processor;
import com.google.auto.common.SuperficialValidation;
import com.google.auto.service.AutoService;
import com.google.auto.value.AutoAnnotation;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.primitives.Primitives;
import java.io.IOException;
import java.io.Writer;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.Generated;
import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.Processor;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.type.ArrayType;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.PrimitiveType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.ElementFilter;
import javax.lang.model.util.Types;
import javax.tools.Diagnostic;
import javax.tools.JavaFileObject;
/**
* Javac annotation processor (compiler plugin) to generate annotation implementations. User code
* never references this class.
*
* @author emcmanus@google.com (Éamonn McManus)
*/
@AutoService(Processor.class)
public class AutoAnnotationProcessor extends AbstractProcessor {
public AutoAnnotationProcessor() {}
@Override
public Set<String> getSupportedAnnotationTypes() {
return ImmutableSet.of(AutoAnnotation.class.getName());
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
/**
* Issue a compilation error. This method does not throw an exception, since we want to
* continue processing and perhaps report other errors.
*/
private void reportError(Element e, String msg, Object... msgParams) {
String formattedMessage = String.format(msg, msgParams);
processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR, formattedMessage, e);
}
/**
* Issue a compilation error and return an exception that, when thrown, will cause the processing
* of this class to be abandoned. This does not prevent the processing of other classes.
*/
private AbortProcessingException abortWithError(String msg, Element e) {
reportError(e, msg);
return new AbortProcessingException();
}
private Types typeUtils;
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
typeUtils = processingEnv.getTypeUtils();
boolean claimed = (annotations.size() == 1
&& annotations.iterator().next().getQualifiedName().toString().equals(
AutoAnnotation.class.getName()));
if (claimed) {
process(roundEnv);
return true;
} else {
return false;
}
}
private void process(RoundEnvironment roundEnv) {
Collection<? extends Element> annotatedElements =
roundEnv.getElementsAnnotatedWith(AutoAnnotation.class);
List<ExecutableElement> methods = ElementFilter.methodsIn(annotatedElements);
if (!SuperficialValidation.validateElements(methods) || methodsAreOverloaded(methods)) {
return;
}
for (ExecutableElement method : methods) {
try {
processMethod(method);
} catch (AbortProcessingException e) {
// We abandoned this type, but continue with the next.
} catch (RuntimeException e) {
// Don't propagate this exception, which will confusingly crash the compiler.
// Instead, report a compiler error with the stack trace.
String trace = Throwables.getStackTraceAsString(e);
reportError(method, "@AutoAnnotation processor threw an exception: %s", trace);
}
}
}
private void processMethod(ExecutableElement method) {
if (!method.getModifiers().contains(Modifier.STATIC)) {
throw abortWithError("@AutoAnnotation method must be static", method);
}
TypeElement annotationElement = getAnnotationReturnType(method);
TypeMirror annotationTypeMirror = annotationElement.asType();
Set<Class<?>> wrapperTypesUsedInCollections = wrapperTypesUsedInCollections(method);
ImmutableMap<String, ExecutableElement> memberMethods = getMemberMethods(annotationElement);
Set<TypeMirror> memberTypes = getMemberTypes(memberMethods.values());
Set<TypeMirror> referencedTypes = getReferencedTypes(
annotationTypeMirror, method, memberTypes, wrapperTypesUsedInCollections);
TypeElement methodClass = (TypeElement) method.getEnclosingElement();
String pkg = TypeSimplifier.packageNameOf(methodClass);
TypeSimplifier typeSimplifier = new TypeSimplifier(
typeUtils, pkg, referencedTypes, annotationTypeMirror);
AnnotationDefaults annotationDefaults =
new AnnotationDefaults(processingEnv, typeSimplifier, method);
ImmutableMap<String, AnnotationValue> defaultValues = getDefaultValues(annotationElement);
ImmutableMap<String, Member> members =
getMembers(memberMethods, typeSimplifier, annotationDefaults);
ImmutableMap<String, Parameter> parameters =
getParameters(annotationElement, method, members, typeSimplifier);
validateParameters(annotationElement, method, members, parameters, defaultValues);
String generatedClassName = generatedClassName(method);
AutoAnnotationTemplateVars vars = new AutoAnnotationTemplateVars();
vars.annotationFullName = annotationElement.toString();
vars.annotationName = typeSimplifier.simplify(annotationElement.asType());
vars.className = generatedClassName;
vars.imports = typeSimplifier.typesToImport();
vars.generated = typeSimplifier.simplify(getTypeMirror(Generated.class));
vars.arrays = typeSimplifier.simplify(getTypeMirror(Arrays.class));
vars.members = members;
vars.params = parameters;
vars.pkg = pkg;
vars.wrapperTypesUsedInCollections = wrapperTypesUsedInCollections;
String text = vars.toText();
text = Reformatter.fixup(text);
writeSourceFile(pkg + "." + generatedClassName, text, methodClass);
}
private boolean methodsAreOverloaded(List<ExecutableElement> methods) {
boolean overloaded = false;
Set<String> classNames = new HashSet<String>();
for (ExecutableElement method : methods) {
if (!classNames.add(generatedClassName(method))) {
overloaded = true;
reportError(method, "@AutoAnnotation methods cannot be overloaded");
}
}
return overloaded;
}
private String generatedClassName(ExecutableElement method) {
TypeElement type = (TypeElement) method.getEnclosingElement();
String name = type.getSimpleName().toString();
while (type.getEnclosingElement() instanceof TypeElement) {
type = (TypeElement) type.getEnclosingElement();
name = type.getSimpleName() + "_" + name;
}
return "AutoAnnotation_" + name + "_" + method.getSimpleName();
}
private TypeElement getAnnotationReturnType(ExecutableElement method) {
TypeMirror returnTypeMirror = method.getReturnType();
if (returnTypeMirror.getKind() == TypeKind.DECLARED) {
Element returnTypeElement = typeUtils.asElement(method.getReturnType());
if (returnTypeElement.getKind() == ElementKind.ANNOTATION_TYPE) {
return (TypeElement) returnTypeElement;
}
}
throw abortWithError("Return type of @AutoAnnotation method must be an annotation type, not "
+ returnTypeMirror, method);
}
private ImmutableMap<String, ExecutableElement> getMemberMethods(TypeElement annotationElement) {
ImmutableMap.Builder<String, ExecutableElement> members = ImmutableMap.builder();
for (ExecutableElement member :
ElementFilter.methodsIn(annotationElement.getEnclosedElements())) {
String name = member.getSimpleName().toString();
members.put(name, member);
}
return members.build();
}
private ImmutableMap<String, Member> getMembers(
ImmutableMap<String, ExecutableElement> memberMethods,
TypeSimplifier typeSimplifier,
AnnotationDefaults annotationDefaults) {
ImmutableMap.Builder<String, Member> members = ImmutableMap.builder();
for (Map.Entry<String, ExecutableElement> entry : memberMethods.entrySet()) {
ExecutableElement memberMethod = entry.getValue();
String name = memberMethod.getSimpleName().toString();
members.put(name, new Member(memberMethod, typeSimplifier, annotationDefaults));
}
return members.build();
}
private ImmutableMap<String, AnnotationValue> getDefaultValues(TypeElement annotationElement) {
ImmutableMap.Builder<String, AnnotationValue> defaultValues = ImmutableMap.builder();
for (ExecutableElement member :
ElementFilter.methodsIn(annotationElement.getEnclosedElements())) {
String name = member.getSimpleName().toString();
AnnotationValue defaultValue = member.getDefaultValue();
if (defaultValue != null) {
defaultValues.put(name, defaultValue);
}
}
return defaultValues.build();
}
private Set<TypeMirror> getMemberTypes(Collection<ExecutableElement> memberMethods) {
Set<TypeMirror> types = new TypeMirrorSet();
for (ExecutableElement memberMethod : memberMethods) {
types.add(memberMethod.getReturnType());
}
return types;
}
private ImmutableMap<String, Parameter> getParameters(
TypeElement annotationElement,
ExecutableElement method,
Map<String, Member> members,
TypeSimplifier typeSimplifier) {
ImmutableMap.Builder<String, Parameter> parameters = ImmutableMap.builder();
boolean error = false;
for (VariableElement parameter : method.getParameters()) {
String name = parameter.getSimpleName().toString();
Member member = members.get(name);
if (member == null) {
reportError(parameter,
"@AutoAnnotation method parameter '%s' must have the same name as a member of %s",
name, annotationElement);
error = true;
} else {
TypeMirror parameterType = parameter.asType();
TypeMirror memberType = member.getTypeMirror();
if (compatibleTypes(parameterType, memberType)) {
parameters.put(name, new Parameter(parameterType, typeSimplifier));
} else {
reportError(parameter,
"@AutoAnnotation method parameter '%s' has type %s but %s.%s has type %s",
name, parameterType, annotationElement, name, memberType);
error = true;
}
}
}
if (error) {
throw new AbortProcessingException();
}
return parameters.build();
}
private void validateParameters(
TypeElement annotationElement,
ExecutableElement method,
ImmutableMap<String, Member> members,
ImmutableMap<String, Parameter> parameters,
ImmutableMap<String, AnnotationValue> defaultValues) {
boolean error = false;
for (String memberName : members.keySet()) {
if (!parameters.containsKey(memberName) && !defaultValues.containsKey(memberName)) {
reportError(method,
"@AutoAnnotation method needs a parameter with name '%s' and type %s"
+ " corresponding to %s.%s, which has no default value",
memberName, members.get(memberName).getType(), annotationElement, memberName);
error = true;
}
}
if (error) {
throw new AbortProcessingException();
}
}
/**
* Returns true if {@code parameterType} can be used to provide the value of an annotation member
* of type {@code memberType}. They must either be the same type, or the member type must be an
* array and the parameter type must be a collection of a compatible type.
*/
private boolean compatibleTypes(TypeMirror parameterType, TypeMirror memberType) {
if (typeUtils.isAssignable(parameterType, memberType)) {
// parameterType assignable to memberType, which in the restricted world of annotations
// means they are the same type, or maybe memberType is an annotation type and parameterType
// is a subtype of that annotation interface (why would you do that?).
return true;
}
// They're not the same, but we could still consider them compatible if for example
// parameterType is List<Integer> and memberType is int[]. We accept any type that is assignable
// to Collection<Integer> (in this example).
if (memberType.getKind() != TypeKind.ARRAY) {
return false;
}
TypeMirror arrayElementType = ((ArrayType) memberType).getComponentType();
TypeMirror wrappedArrayElementType = arrayElementType.getKind().isPrimitive()
? typeUtils.boxedClass((PrimitiveType) arrayElementType).asType()
: arrayElementType;
TypeElement javaUtilCollection =
processingEnv.getElementUtils().getTypeElement(Collection.class.getCanonicalName());
DeclaredType collectionOfElement =
typeUtils.getDeclaredType(javaUtilCollection, wrappedArrayElementType);
return typeUtils.isAssignable(parameterType, collectionOfElement);
}
/**
* Returns the wrapper types ({@code Integer.class} etc) that are used in collection parameters
* like {@code List<Integer>}. This is needed because we will emit a helper method for each such
* type, for example to convert {@code Collection<Integer>} into {@code int[]}.
*/
private Set<Class<?>> wrapperTypesUsedInCollections(ExecutableElement method) {
TypeElement javaUtilCollection =
processingEnv.getElementUtils().getTypeElement(Collection.class.getName());
ImmutableSet.Builder<Class<?>> usedInCollections = ImmutableSet.builder();
for (Class<?> wrapper : Primitives.allWrapperTypes()) {
DeclaredType collectionOfWrapper =
typeUtils.getDeclaredType(javaUtilCollection, getTypeMirror(wrapper));
for (VariableElement parameter : method.getParameters()) {
if (typeUtils.isAssignable(parameter.asType(), collectionOfWrapper)) {
usedInCollections.add(wrapper);
break;
}
}
}
return usedInCollections.build();
}
private Set<TypeMirror> getReferencedTypes(
TypeMirror annotation,
ExecutableElement method,
Set<TypeMirror> memberTypes,
Set<Class<?>> wrapperTypesUsedInCollections) {
Set<TypeMirror> types = new TypeMirrorSet();
types.add(annotation);
types.add(getTypeMirror(Generated.class));
for (VariableElement parameter : method.getParameters()) {
// Method parameter types are usually the same as annotation member types, but in the case of
// List<Integer> for int[] we are referencing List.
types.add(parameter.asType());
}
types.addAll(memberTypes);
if (containsArrayType(types)) {
// If there are array properties then we will be referencing java.util.Arrays.
types.add(getTypeMirror(Arrays.class));
}
if (!wrapperTypesUsedInCollections.isEmpty()) {
// If there is at least one parameter whose type is a collection of a primitive wrapper type
// (for example List<Integer>) then we will be referencing java util.Collection.
types.add(getTypeMirror(Collection.class));
}
return types;
}
private TypeMirror getTypeMirror(Class<?> c) {
return processingEnv.getElementUtils().getTypeElement(c.getName()).asType();
}
private static boolean containsArrayType(Set<TypeMirror> types) {
for (TypeMirror type : types) {
if (type.getKind() == TypeKind.ARRAY) {
return true;
}
}
return false;
}
private void writeSourceFile(String className, String text, TypeElement originatingType) {
try {
JavaFileObject sourceFile =
processingEnv.getFiler().createSourceFile(className, originatingType);
Writer writer = sourceFile.openWriter();
try {
writer.write(text);
} finally {
writer.close();
}
} catch (IOException e) {
processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR,
"Could not write generated class " + className + ": " + e);
}
}
public static class Member {
private final ExecutableElement method;
private final TypeSimplifier typeSimplifier;
private final AnnotationDefaults annotationDefaults;
Member(
ExecutableElement method,
TypeSimplifier typeSimplifier,
AnnotationDefaults annotationDefaults) {
this.method = method;
this.typeSimplifier = typeSimplifier;
this.annotationDefaults = annotationDefaults;
}
@Override
public String toString() {
return method.getSimpleName().toString();
}
public String getType() {
return typeSimplifier.simplify(getTypeMirror());
}
public String getComponentType() {
Preconditions.checkState(getTypeMirror().getKind() == TypeKind.ARRAY);
ArrayType arrayType = (ArrayType) getTypeMirror();
return typeSimplifier.simplify(arrayType.getComponentType());
}
public TypeMirror getTypeMirror() {
return method.getReturnType();
}
public TypeKind getKind() {
return getTypeMirror().getKind();
}
public String getDefaultValue() {
AnnotationValue defaultValue = method.getDefaultValue();
if (defaultValue == null) {
return null;
} else {
return annotationDefaults.sourceForm(method);
}
}
}
public static class Parameter {
private final String typeName;
private final TypeKind kind;
Parameter(TypeMirror type, TypeSimplifier typeSimplifier) {
this.typeName = typeSimplifier.simplify(type);
this.kind = type.getKind();
}
public String getType() {
return typeName;
}
public TypeKind getKind() {
return kind;
}
}
}