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The official Couchbase JVM Core IO Library
/*
* Copyright 2014 - Present Rafael Winterhalter
*
* 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 net.bytebuddy.build;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import net.bytebuddy.description.annotation.AnnotationDescription;
import net.bytebuddy.description.field.FieldDescription;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.MethodList;
import net.bytebuddy.description.type.TypeDefinition;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.dynamic.ClassFileLocator;
import net.bytebuddy.dynamic.DynamicType;
import net.bytebuddy.implementation.EqualsMethod;
import net.bytebuddy.implementation.HashCodeMethod;
import net.bytebuddy.implementation.attribute.AnnotationValueFilter;
import net.bytebuddy.implementation.attribute.MethodAttributeAppender;
import net.bytebuddy.matcher.ElementMatcher;
import net.bytebuddy.matcher.ElementMatchers;
import net.bytebuddy.utility.nullability.MaybeNull;
import net.bytebuddy.jar.asm.AnnotationVisitor;
import net.bytebuddy.jar.asm.MethodVisitor;
import java.lang.annotation.*;
import java.util.Comparator;
import static net.bytebuddy.matcher.ElementMatchers.*;
/**
* A build tool plugin that adds {@link Object#hashCode()} and {@link Object#equals(Object)} methods to a class if the
* {@link Enhance} annotation is present and no explicit method declaration was added. This plugin does not need to be closed.
*/
@HashCodeAndEqualsPlugin.Enhance
public class HashCodeAndEqualsPlugin implements Plugin, Plugin.Factory, MethodAttributeAppender.Factory, MethodAttributeAppender {
/**
* A description of the {@link Enhance#invokeSuper()} method.
*/
private static final MethodDescription.InDefinedShape ENHANCE_INVOKE_SUPER;
/**
* A description of the {@link Enhance#simpleComparisonsFirst()} method.
*/
private static final MethodDescription.InDefinedShape ENHANCE_SIMPLE_COMPARISON_FIRST;
/**
* A description of the {@link Enhance#includeSyntheticFields()} method.
*/
private static final MethodDescription.InDefinedShape ENHANCE_INCLUDE_SYNTHETIC_FIELDS;
/**
* A description of the {@link Enhance#permitSubclassEquality()} method.
*/
private static final MethodDescription.InDefinedShape ENHANCE_PERMIT_SUBCLASS_EQUALITY;
/**
* A description of the {@link Enhance#useTypeHashConstant()} method.
*/
private static final MethodDescription.InDefinedShape ENHANCE_USE_TYPE_HASH_CONSTANT;
/**
* A description of the {@link ValueHandling#value()} method.
*/
private static final MethodDescription.InDefinedShape VALUE_HANDLING_VALUE;
/**
* A description of the {@link Sorted#value()} method.
*/
private static final MethodDescription.InDefinedShape SORTED_VALUE;
/*
* Resolves diverse annotation properties.
*/
static {
MethodList enhanceMethods = TypeDescription.ForLoadedType.of(Enhance.class).getDeclaredMethods();
ENHANCE_INVOKE_SUPER = enhanceMethods.filter(named("invokeSuper")).getOnly();
ENHANCE_SIMPLE_COMPARISON_FIRST = enhanceMethods.filter(named("simpleComparisonsFirst")).getOnly();
ENHANCE_INCLUDE_SYNTHETIC_FIELDS = enhanceMethods.filter(named("includeSyntheticFields")).getOnly();
ENHANCE_PERMIT_SUBCLASS_EQUALITY = enhanceMethods.filter(named("permitSubclassEquality")).getOnly();
ENHANCE_USE_TYPE_HASH_CONSTANT = enhanceMethods.filter(named("useTypeHashConstant")).getOnly();
VALUE_HANDLING_VALUE = TypeDescription.ForLoadedType.of(ValueHandling.class).getDeclaredMethods().filter(named("value")).getOnly();
SORTED_VALUE = TypeDescription.ForLoadedType.of(Sorted.class).getDeclaredMethods().filter(named("value")).getOnly();
}
/**
* Defines the binary name of a runtime-visible annotation type that should be added to the parameter of the
* {@link Object#equals(Object)} method, or {@code null} if no such name should be defined.
*/
@MaybeNull
@ValueHandling(ValueHandling.Sort.REVERSE_NULLABILITY)
private final String annotationType;
/**
* Creates a new hash code equals plugin.
*/
public HashCodeAndEqualsPlugin() {
this(null);
}
/**
* Creates a new hash code equals plugin.
*
* @param annotationType Defines the binary name of a runtime-visible annotation type that should be added to the
* parameter of the {@link Object#equals(Object)} method, or {@code null} if no such name
* should be defined.
*/
public HashCodeAndEqualsPlugin(@MaybeNull String annotationType) {
this.annotationType = annotationType;
}
/**
* {@inheritDoc}
*/
public Plugin make() {
return this;
}
/**
* {@inheritDoc}
*/
public boolean matches(@MaybeNull TypeDescription target) {
return target != null && target.getDeclaredAnnotations().isAnnotationPresent(Enhance.class);
}
/**
* {@inheritDoc}
*/
@SuppressFBWarnings(value = "NP_NULL_ON_SOME_PATH_FROM_RETURN_VALUE", justification = "Annotation presence is required by matcher.")
public DynamicType.Builder apply(DynamicType.Builder builder, TypeDescription typeDescription, ClassFileLocator classFileLocator) {
AnnotationDescription.Loadable enhance = typeDescription.getDeclaredAnnotations().ofType(Enhance.class);
if (typeDescription.getDeclaredMethods().filter(isHashCode()).isEmpty()) {
builder = builder.method(isHashCode()).intercept(enhance.getValue(ENHANCE_INVOKE_SUPER).load(Enhance.class.getClassLoader()).resolve(Enhance.InvokeSuper.class)
.hashCodeMethod(typeDescription,
enhance.getValue(ENHANCE_USE_TYPE_HASH_CONSTANT).resolve(Boolean.class),
enhance.getValue(ENHANCE_PERMIT_SUBCLASS_EQUALITY).resolve(Boolean.class))
.withIgnoredFields(enhance.getValue(ENHANCE_INCLUDE_SYNTHETIC_FIELDS).resolve(Boolean.class)
? ElementMatchers.none()
: ElementMatchers.isSynthetic())
.withIgnoredFields(new ValueMatcher(ValueHandling.Sort.IGNORE))
.withNonNullableFields(nonNullable(new ValueMatcher(ValueHandling.Sort.REVERSE_NULLABILITY))));
}
if (typeDescription.getDeclaredMethods().filter(isEquals()).isEmpty()) {
EqualsMethod equalsMethod = enhance.getValue(ENHANCE_INVOKE_SUPER).load(Enhance.class.getClassLoader()).resolve(Enhance.InvokeSuper.class)
.equalsMethod(typeDescription)
.withIgnoredFields(enhance.getValue(ENHANCE_INCLUDE_SYNTHETIC_FIELDS).resolve(Boolean.class)
? ElementMatchers.none()
: ElementMatchers.isSynthetic())
.withIgnoredFields(new ValueMatcher(ValueHandling.Sort.IGNORE))
.withNonNullableFields(nonNullable(new ValueMatcher(ValueHandling.Sort.REVERSE_NULLABILITY)))
.withFieldOrder(AnnotationOrderComparator.INSTANCE);
if (enhance.getValue(ENHANCE_SIMPLE_COMPARISON_FIRST).resolve(Boolean.class)) {
equalsMethod = equalsMethod
.withPrimitiveTypedFieldsFirst()
.withEnumerationTypedFieldsFirst()
.withPrimitiveWrapperTypedFieldsFirst()
.withStringTypedFieldsFirst();
}
builder = builder.method(isEquals()).intercept(enhance.getValue(ENHANCE_PERMIT_SUBCLASS_EQUALITY).resolve(Boolean.class)
? equalsMethod.withSubclassEquality()
: equalsMethod).attribute(this);
}
return builder;
}
/**
* Resolves the matcher to identify non-nullable fields.
*
* @param matcher The matcher that identifies fields that are either nullable or non-nullable.
* @return The actual matcher to identify non-nullable fields.
*/
protected ElementMatcher nonNullable(ElementMatcher matcher) {
return matcher;
}
/**
* {@inheritDoc}
*/
public void close() {
/* do nothing */
}
/**
* {@inheritDoc}
*/
public MethodAttributeAppender make(TypeDescription typeDescription) {
return this;
}
/**
* {@inheritDoc}
*/
public void apply(MethodVisitor methodVisitor, MethodDescription methodDescription, AnnotationValueFilter annotationValueFilter) {
if (annotationType != null) {
AnnotationVisitor annotationVisitor = methodVisitor.visitParameterAnnotation(0,
"L" + annotationType.replace('.', '/') + ";",
true);
if (annotationVisitor != null) {
annotationVisitor.visitEnd();
}
}
}
/**
* A version of the {@link HashCodeAndEqualsPlugin} that assumes that all fields are non-nullable unless they are explicitly marked.
*/
@HashCodeAndEqualsPlugin.Enhance
public static class WithNonNullableFields extends HashCodeAndEqualsPlugin {
/**
* Creates a new hash code equals plugin where fields are assumed nullable by default.
*/
public WithNonNullableFields() {
this(null);
}
/**
* Creates a new hash code equals plugin where fields are assumed nullable by default.
*
* @param annotationType Defines the binary name of a runtime-visible annotation type that should be added to the
* parameter of the {@link Object#equals(Object)} method, or {@code null} if no such name
* should be defined.
*/
public WithNonNullableFields(@MaybeNull String annotationType) {
super(annotationType);
}
/**
* {@inheritDoc}
*/
protected ElementMatcher nonNullable(ElementMatcher matcher) {
return not(matcher);
}
}
/**
* Instructs the {@link HashCodeAndEqualsPlugin} to generate {@link Object#hashCode()} and {@link Object#equals(Object)} for the annotated
* class unless these methods are already declared explicitly.
*/
@Documented
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface Enhance {
/**
* Determines the base value of any added method, i.e. if hash code or equality is based on the super type or not.
*
* @return A strategy for determining the base value.
*/
InvokeSuper invokeSuper() default InvokeSuper.IF_DECLARED;
/**
* Determines if fields with primitive types, then enumeration types, then primtive wrapper types and then {@link String} types
* should be compared for equality before fields with other types. Before determining such a field order,
* the {@link Sorted} property is always considered first if it is defined.
*
* @return {@code true} if fields with simple comparison methods should be compared first.
*/
boolean simpleComparisonsFirst() default true;
/**
* Determines if synthetic fields should be included in the hash code and equality contract.
*
* @return {@code true} if synthetic fields should be included.
*/
boolean includeSyntheticFields() default false;
/**
* Determines if instances subclasses of the instrumented type are accepted upon an equality check.
*
* @return {@code true} if instances subclasses of the instrumented type are accepted upon an equality check.
*/
boolean permitSubclassEquality() default false;
/**
* Determines if the hash code constant should be derived of the instrumented type. If {@link Enhance#permitSubclassEquality()}
* is set to {@code true}, this constant is derived of the declared class, otherwise the type hash is computed of the active instance.
*
* @return {@code true} if the hash code constant should be derived of the instrumented type.
*/
boolean useTypeHashConstant() default true;
/**
* A strategy for determining the base value of a hash code or equality contract.
*/
enum InvokeSuper {
/**
* Only invokes the super method's hash code and equality methods if any super class that is not {@link Object} explicitly defines such a method.
*/
IF_DECLARED {
@Override
protected HashCodeMethod hashCodeMethod(TypeDescription instrumentedType, boolean typeHash, boolean subclassEquality) {
TypeDefinition typeDefinition = instrumentedType.getSuperClass();
while (typeDefinition != null && !typeDefinition.represents(Object.class)) {
if (typeDefinition.asErasure().getDeclaredAnnotations().isAnnotationPresent(Enhance.class)) {
return HashCodeMethod.usingSuperClassOffset();
}
MethodList hashCode = typeDefinition.getDeclaredMethods().filter(isHashCode());
if (!hashCode.isEmpty()) {
return hashCode.getOnly().isAbstract()
? (typeHash ? HashCodeMethod.usingTypeHashOffset(!subclassEquality) : HashCodeMethod.usingDefaultOffset())
: HashCodeMethod.usingSuperClassOffset();
}
typeDefinition = typeDefinition.getSuperClass();
}
return typeHash ? HashCodeMethod.usingTypeHashOffset(!subclassEquality) : HashCodeMethod.usingDefaultOffset();
}
@Override
protected EqualsMethod equalsMethod(TypeDescription instrumentedType) {
TypeDefinition typeDefinition = instrumentedType.getSuperClass();
while (typeDefinition != null && !typeDefinition.represents(Object.class)) {
if (typeDefinition.asErasure().getDeclaredAnnotations().isAnnotationPresent(Enhance.class)) {
return EqualsMethod.requiringSuperClassEquality();
}
MethodList hashCode = typeDefinition.getDeclaredMethods().filter(isHashCode());
if (!hashCode.isEmpty()) {
return hashCode.getOnly().isAbstract()
? EqualsMethod.isolated()
: EqualsMethod.requiringSuperClassEquality();
}
typeDefinition = typeDefinition.getSuperClass();
}
return EqualsMethod.isolated();
}
},
/**
* Only invokes the super method's hash code and equality methods if the super class is also annotated with {@link Enhance}.
*/
IF_ANNOTATED {
@Override
protected HashCodeMethod hashCodeMethod(TypeDescription instrumentedType, boolean typeHash, boolean subclassEquality) {
TypeDefinition superClass = instrumentedType.getSuperClass();
return superClass != null && superClass.asErasure().getDeclaredAnnotations().isAnnotationPresent(Enhance.class)
? HashCodeMethod.usingSuperClassOffset()
: (typeHash ? HashCodeMethod.usingTypeHashOffset(!subclassEquality) : HashCodeMethod.usingDefaultOffset());
}
@Override
protected EqualsMethod equalsMethod(TypeDescription instrumentedType) {
TypeDefinition superClass = instrumentedType.getSuperClass();
return superClass != null && superClass.asErasure().getDeclaredAnnotations().isAnnotationPresent(Enhance.class)
? EqualsMethod.requiringSuperClassEquality()
: EqualsMethod.isolated();
}
},
/**
* Always invokes the super class's hash code and equality methods.
*/
ALWAYS {
@Override
protected HashCodeMethod hashCodeMethod(TypeDescription instrumentedType, boolean typeHash, boolean subclassEquality) {
return HashCodeMethod.usingSuperClassOffset();
}
@Override
protected EqualsMethod equalsMethod(TypeDescription instrumentedType) {
return EqualsMethod.requiringSuperClassEquality();
}
},
/**
* Never invokes the super class's hash code and equality methods.
*/
NEVER {
@Override
protected HashCodeMethod hashCodeMethod(TypeDescription instrumentedType, boolean typeHash, boolean subclassEquality) {
return typeHash ? HashCodeMethod.usingTypeHashOffset(!subclassEquality) : HashCodeMethod.usingDefaultOffset();
}
@Override
protected EqualsMethod equalsMethod(TypeDescription instrumentedType) {
return EqualsMethod.isolated();
}
};
/**
* Resolves the hash code method to use.
*
* @param instrumentedType The instrumented type.
* @param typeHash {@code true} if the base hash should be based on the instrumented class's type.
* @param subclassEquality {@code true} if subclasses can be equal to their base classes.
* @return The hash code method to use.
*/
protected abstract HashCodeMethod hashCodeMethod(TypeDescription instrumentedType, boolean typeHash, boolean subclassEquality);
/**
* Resolves the equals method to use.
*
* @param instrumentedType The instrumented type.
* @return The equals method to use.
*/
protected abstract EqualsMethod equalsMethod(TypeDescription instrumentedType);
}
}
/**
* Determines how a field should be used within generated hash code and equality methods.
*/
@Documented
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ValueHandling {
/**
* Determines the handling of the annotated field.
*
* @return The handling of the annotated field.
*/
Sort value();
/**
* Determines how a field should be handled.
*/
enum Sort {
/**
* Excludes the field from hash code and equality methods.
*/
IGNORE,
/**
* Reverses the nullability of the field, i.e. assumes this field to be non-null or {@code null} if {@link WithNonNullableFields} is used.
*/
REVERSE_NULLABILITY
}
}
/**
* Determines the sort order of fields for the equality check when implementing the {@link Object#equals(Object)} method. Any field
* that is not annotated is considered with a value of {@link Sorted#DEFAULT} where fields with a higher value are checked for equality
* first. This sort order is applied first after which the type order is considered if {@link Enhance#simpleComparisonsFirst()} is considered
* as additional sort criteria.
*/
@Documented
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Sorted {
/**
* The default sort weight.
*/
int DEFAULT = 0;
/**
* The value for the sort order where fields with higher values are checked for equality first.
*
* @return The value for the sort order where fields with higher values are checked for equality first.
*/
int value();
}
/**
* A comparator that arranges fields in the order of {@link Sorted}.
*/
protected enum AnnotationOrderComparator implements Comparator {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public int compare(FieldDescription.InDefinedShape left, FieldDescription.InDefinedShape right) {
AnnotationDescription.Loadable leftAnnotation = left.getDeclaredAnnotations().ofType(Sorted.class);
AnnotationDescription.Loadable rightAnnotation = right.getDeclaredAnnotations().ofType(Sorted.class);
int leftValue = leftAnnotation == null ? Sorted.DEFAULT : leftAnnotation.getValue(SORTED_VALUE).resolve(Integer.class);
int rightValue = rightAnnotation == null ? Sorted.DEFAULT : rightAnnotation.getValue(SORTED_VALUE).resolve(Integer.class);
if (leftValue > rightValue) {
return -1;
} else if (leftValue < rightValue) {
return 1;
} else {
return 0;
}
}
}
/**
* An element matcher for a {@link ValueHandling} annotation.
*/
@HashCodeAndEqualsPlugin.Enhance
protected static class ValueMatcher extends ElementMatcher.Junction.ForNonNullValues {
/**
* The matched value.
*/
private final ValueHandling.Sort sort;
/**
* Creates a new value matcher.
*
* @param sort The matched value.
*/
protected ValueMatcher(ValueHandling.Sort sort) {
this.sort = sort;
}
/**
* {@inheritDoc}
*/
protected boolean doMatch(FieldDescription target) {
AnnotationDescription.Loadable annotation = target.getDeclaredAnnotations().ofType(ValueHandling.class);
return annotation != null && annotation.getValue(VALUE_HANDLING_VALUE).load(ValueHandling.class.getClassLoader()).resolve(ValueHandling.Sort.class) == sort;
}
}
}
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