package net.bytebuddy.dynamic.scaffold.subclass;
import lombok.EqualsAndHashCode;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.MethodList;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.dynamic.Transformer;
import net.bytebuddy.dynamic.scaffold.MethodRegistry;
import net.bytebuddy.implementation.SuperMethodCall;
import net.bytebuddy.implementation.attribute.MethodAttributeAppender;
import net.bytebuddy.matcher.LatentMatcher;
import org.objectweb.asm.Opcodes;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import static net.bytebuddy.matcher.ElementMatchers.*;
/**
* A constructor strategy is responsible for creating bootstrap constructors for a
* {@link SubclassDynamicTypeBuilder}.
*
* @see net.bytebuddy.dynamic.scaffold.subclass.ConstructorStrategy.Default
*/
public interface ConstructorStrategy {
/**
* Extracts constructors for a given super type. The extracted constructor signatures will then be imitated by the
* created dynamic type.
*
* @param instrumentedType The type for which the constructors should be created.
* @return A list of tokens that describe the constructors that are to be implemented.
*/
List<MethodDescription.Token> extractConstructors(TypeDescription instrumentedType);
/**
* Returns a method registry that is capable of creating byte code for the constructors that were
* provided by the
* {@link net.bytebuddy.dynamic.scaffold.subclass.ConstructorStrategy#extractConstructors(TypeDescription)}
* method of this instance.
*
* @param methodRegistry The original method registry.
* @return A method registry that is capable of providing byte code for the constructors that were added by this strategy.
*/
MethodRegistry inject(MethodRegistry methodRegistry);
/**
* Default implementations of constructor strategies. Any such strategy offers to additionally apply an {@link MethodAttributeAppender.Factory}.
*/
enum Default implements ConstructorStrategy {
/**
* This strategy is adding no constructors such that the instrumented type will by default not have any. This
* is legal by Java byte code requirements. However, if no constructor is added manually if this strategy is
* applied, the type is not constructable without using JVM non-public functionality.
*/
NO_CONSTRUCTORS {
@Override
protected List<MethodDescription.Token> doExtractConstructors(TypeDescription superClass) {
return Collections.emptyList();
}
@Override
protected MethodRegistry doInject(MethodRegistry methodRegistry, MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
return methodRegistry;
}
},
/**
* This strategy is adding a default constructor that calls it's super types default constructor. If no such
* constructor is defined by the super class, an {@link IllegalArgumentException} is thrown. Note that the default
* constructor needs to be visible to its sub type for this strategy to work. The declared default constructor of
* the created class is declared public and without annotations.
*/
DEFAULT_CONSTRUCTOR {
@Override
protected List<MethodDescription.Token> doExtractConstructors(TypeDescription instrumentedType) {
TypeDescription.Generic superClass = instrumentedType.getSuperClass();
MethodList<?> defaultConstructors = superClass == null
? new MethodList.Empty<MethodDescription.InGenericShape>()
: superClass.getDeclaredMethods().filter(isConstructor().and(takesArguments(0)).<MethodDescription>and(isVisibleTo(instrumentedType)));
if (defaultConstructors.size() == 1) {
return Collections.singletonList(new MethodDescription.Token(Opcodes.ACC_PUBLIC));
} else {
throw new IllegalArgumentException(instrumentedType.getSuperClass() + " declares no constructor that is visible to " + instrumentedType);
}
}
@Override
protected MethodRegistry doInject(MethodRegistry methodRegistry, MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
return methodRegistry.append(new LatentMatcher.Resolved<MethodDescription>(isConstructor()),
new MethodRegistry.Handler.ForImplementation(SuperMethodCall.INSTANCE),
methodAttributeAppenderFactory,
Transformer.NoOp.<MethodDescription>make());
}
},
/**
* This strategy is adding all constructors of the instrumented type's super class where each constructor is
* directly invoking its signature-equivalent super class constructor. Only constructors that are visible to the
* instrumented type are added, i.e. package-private constructors are only added if the super type is defined
* in the same package as the instrumented type and private constructors are always skipped.
*/
IMITATE_SUPER_CLASS {
@Override
protected List<MethodDescription.Token> doExtractConstructors(TypeDescription instrumentedType) {
TypeDescription.Generic superClass = instrumentedType.getSuperClass();
return (superClass == null
? new MethodList.Empty<MethodDescription.InGenericShape>()
: superClass.getDeclaredMethods().filter(isConstructor().and(isVisibleTo(instrumentedType)))).asTokenList(is(instrumentedType));
}
@Override
public MethodRegistry doInject(MethodRegistry methodRegistry, MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
return methodRegistry.append(new LatentMatcher.Resolved<MethodDescription>(isConstructor()),
new MethodRegistry.Handler.ForImplementation(SuperMethodCall.INSTANCE),
methodAttributeAppenderFactory,
Transformer.NoOp.<MethodDescription>make());
}
},
/**
* This strategy is adding all constructors of the instrumented type's super class where each constructor is
* directly invoking its signature-equivalent super class constructor. Only {@code public} constructors are
* added.
*/
IMITATE_SUPER_CLASS_PUBLIC {
@Override
protected List<MethodDescription.Token> doExtractConstructors(TypeDescription instrumentedType) {
TypeDescription.Generic superClass = instrumentedType.getSuperClass();
return (superClass == null
? new MethodList.Empty<MethodDescription.InGenericShape>()
: superClass.getDeclaredMethods().filter(isPublic().and(isConstructor()))).asTokenList(is(instrumentedType));
}
@Override
public MethodRegistry doInject(MethodRegistry methodRegistry, MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
return methodRegistry.append(new LatentMatcher.Resolved<MethodDescription>(isConstructor()),
new MethodRegistry.Handler.ForImplementation(SuperMethodCall.INSTANCE),
methodAttributeAppenderFactory,
Transformer.NoOp.<MethodDescription>make());
}
},
/**
* This strategy is adding all constructors of the instrumented type's super class where each constructor is
* directly invoking its signature-equivalent super class constructor. A constructor is added for any constructor
* of the super class that is invokable and is declared as {@code public}.
*/
IMITATE_SUPER_CLASS_OPENING {
@Override
protected List<MethodDescription.Token> doExtractConstructors(TypeDescription instrumentedType) {
TypeDescription.Generic superClass = instrumentedType.getSuperClass();
return (superClass == null
? new MethodList.Empty<MethodDescription.InGenericShape>()
: superClass.getDeclaredMethods().filter(isConstructor().and(isVisibleTo(instrumentedType)))).asTokenList(is(instrumentedType));
}
@Override
public MethodRegistry doInject(MethodRegistry methodRegistry, MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
return methodRegistry.append(new LatentMatcher.Resolved<MethodDescription>(isConstructor()),
new MethodRegistry.Handler.ForImplementation(SuperMethodCall.INSTANCE),
methodAttributeAppenderFactory,
Transformer.NoOp.<MethodDescription>make());
}
@Override
protected int resolveModifier(int modifiers) {
return Opcodes.ACC_PUBLIC;
}
};
@Override
public List<MethodDescription.Token> extractConstructors(TypeDescription instrumentedType) {
List<MethodDescription.Token> tokens = doExtractConstructors(instrumentedType), stripped = new ArrayList<MethodDescription.Token>(tokens.size());
for (MethodDescription.Token token : tokens) {
stripped.add(new MethodDescription.Token(token.getName(),
resolveModifier(token.getModifiers()),
token.getTypeVariableTokens(),
token.getReturnType(),
token.getParameterTokens(),
token.getExceptionTypes(),
token.getAnnotations(),
token.getDefaultValue(),
TypeDescription.Generic.UNDEFINED));
}
return stripped;
}
/**
* Resolves a constructor's modifiers.
*
* @param modifiers The actual constructor's modifiers.
* @return The resolved modifiers.
*/
protected int resolveModifier(int modifiers) {
return modifiers;
}
/**
* Extracts the relevant method tokens of the instrumented type's constructors.
*
* @param instrumentedType The type for which to extract the constructors.
* @return A list of relevant method tokens.
*/
protected abstract List<MethodDescription.Token> doExtractConstructors(TypeDescription instrumentedType);
@Override
public MethodRegistry inject(MethodRegistry methodRegistry) {
return doInject(methodRegistry, MethodAttributeAppender.NoOp.INSTANCE);
}
/**
* Applies the actual injection with a method attribute appender factory supplied.
*
* @param methodRegistry The method registry into which to inject the constructors.
* @param methodAttributeAppenderFactory The method attribute appender to use.
* @return The resulting method registry.
*/
protected abstract MethodRegistry doInject(MethodRegistry methodRegistry, MethodAttributeAppender.Factory methodAttributeAppenderFactory);
/**
* Returns a constructor strategy that supplies the supplied method attribute appender factory.
*
* @param methodAttributeAppenderFactory The method attribute appender factory to use.
* @return A copy of this constructor strategy with the method attribute appender factory applied.
*/
public ConstructorStrategy with(MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
return new WithMethodAttributeAppenderFactory(this, methodAttributeAppenderFactory);
}
/**
* Applies this constructor strategy while retaining any of the base constructor's annotations.
*
* @return A copy of this constructor strategy which retains any of the base constructor's annotations.
*/
public ConstructorStrategy withInheritedAnnotations() {
return new WithMethodAttributeAppenderFactory(this, MethodAttributeAppender.ForInstrumentedMethod.EXCLUDING_RECEIVER);
}
/**
* A wrapper for a default constructor strategy which additionally applies a method attribute appender factory.
*/
@EqualsAndHashCode
protected static class WithMethodAttributeAppenderFactory implements ConstructorStrategy {
/**
* The delegate default constructor strategy.
*/
private final Default delegate;
/**
* The method attribute appender factory to apply.
*/
private final MethodAttributeAppender.Factory methodAttributeAppenderFactory;
/**
* Creates a new wrapper for a default constructor strategy.
*
* @param delegate The delegate default constructor strategy.
* @param methodAttributeAppenderFactory The method attribute appender factory to apply.
*/
protected WithMethodAttributeAppenderFactory(Default delegate, MethodAttributeAppender.Factory methodAttributeAppenderFactory) {
this.delegate = delegate;
this.methodAttributeAppenderFactory = methodAttributeAppenderFactory;
}
@Override
public List<MethodDescription.Token> extractConstructors(TypeDescription instrumentedType) {
return delegate.extractConstructors(instrumentedType);
}
@Override
public MethodRegistry inject(MethodRegistry methodRegistry) {
return delegate.doInject(methodRegistry, methodAttributeAppenderFactory);
}
}
}
}