com.fitbur.bytebuddy.dynamic.MethodTransformer Maven / Gradle / Ivy
package com.fitbur.bytebuddy.dynamic;
import com.fitbur.bytebuddy.description.annotation.AnnotationList;
import com.fitbur.bytebuddy.description.method.MethodDescription;
import com.fitbur.bytebuddy.description.method.ParameterDescription;
import com.fitbur.bytebuddy.description.method.ParameterList;
import com.fitbur.bytebuddy.description.modifier.ModifierContributor;
import com.fitbur.bytebuddy.description.type.TypeDefinition;
import com.fitbur.bytebuddy.description.type.TypeDescription;
import com.fitbur.bytebuddy.description.type.TypeList;
import java.util.Arrays;
import java.util.List;
import static com.fitbur.bytebuddy.matcher.ElementMatchers.is;
/**
* A method transformer allows to transform a method prior to its definition. This way, previously defined methods
* can be substituted by a different method description. It is the responsibility of the method transformer that
* the substitute method remains compatible to the substituted method.
*/
public interface MethodTransformer {
/**
* Transforms a method. The transformed method is not validated by Byte Buddy and it is the responsibility
* of the transformer to assure the validity of the transformation.
*
* @param instrumentedType The instrumented type.
* @param methodDescription The method to be transformed.
* @return The transformed method.
*/
MethodDescription transform(TypeDescription instrumentedType, MethodDescription methodDescription);
/**
* A method transformer that returns the original method.
*/
enum NoOp implements MethodTransformer {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public MethodDescription transform(TypeDescription instrumentedType, MethodDescription methodDescription) {
return methodDescription;
}
@Override
public String toString() {
return "MethodTransformer.NoOp." + name();
}
}
/**
* A method transformer that modifies method properties by applying a {@link TokenTransformer}.
*/
class Simple implements MethodTransformer {
/**
* The transformer to be applied.
*/
private final TokenTransformer tokenTransformer;
/**
* Creates a new transforming method transformer.
*
* @param tokenTransformer The transformer to be applied.
*/
public Simple(TokenTransformer tokenTransformer) {
this.tokenTransformer = tokenTransformer;
}
/**
* Creates a transformer that enforces the supplied modifier contributors. All ranges of each contributor is first cleared and then overridden
* by the specified modifiers in the order they are supplied.
*
* @param modifierTransformer The modifier transformers in their application order.
* @return A method transformer where each method's modifiers are adapted to the given modifiers.
*/
public static MethodTransformer withModifiers(ModifierContributor.ForMethod... modifierTransformer) {
return new Simple(new TokenTransformer.ForModifierTransformation(Arrays.asList(modifierTransformer)));
}
@Override
public MethodDescription transform(TypeDescription instrumentedType, MethodDescription methodDescription) {
return new TransformedMethod(methodDescription.getDeclaringType(),
tokenTransformer.transform(methodDescription.asToken(is(instrumentedType))), methodDescription.asDefined());
}
@Override
public boolean equals(Object other) {
return this == other || !(other == null || getClass() != other.getClass())
&& tokenTransformer.equals(((Simple) other).tokenTransformer);
}
@Override
public int hashCode() {
return tokenTransformer.hashCode();
}
@Override
public String toString() {
return "MethodTransformer.Simple{" +
"tokenTransformer=" + tokenTransformer +
'}';
}
/**
* A transformer is responsible for transforming a method token into its transformed form.
*/
public interface TokenTransformer {
/**
* Transforms a method token.
*
* @param token The original method's token.
* @return The transformed method token.
*/
MethodDescription.Token transform(MethodDescription.Token token);
/**
* A transformation for a modifier transformation.
*/
class ForModifierTransformation implements TokenTransformer {
/**
* The modifier contributors to apply on each transformation.
*/
private final List modifierContributors;
/**
* Creates a new modifier transformation.
*
* @param modifierContributors The modifier contributors to apply on each transformation in their application order.
*/
public ForModifierTransformation(List modifierContributors) {
this.modifierContributors = modifierContributors;
}
@Override
public MethodDescription.Token transform(MethodDescription.Token token) {
return new MethodDescription.Token(token.getName(),
ModifierContributor.Resolver.of(modifierContributors).resolve(token.getModifiers()),
token.getTypeVariableTokens(),
token.getReturnType(),
token.getParameterTokens(),
token.getExceptionTypes(),
token.getAnnotations(),
token.getDefaultValue(),
token.getReceiverType());
}
@Override
public boolean equals(Object other) {
return this == other || !(other == null || getClass() != other.getClass())
&& modifierContributors.equals(((ForModifierTransformation) other).modifierContributors);
}
@Override
public int hashCode() {
return modifierContributors.hashCode();
}
@Override
public String toString() {
return "MethodTransformer.Simple.TokenTransformer.ForModifierTransformation{" +
"modifierContributors=" + modifierContributors +
'}';
}
}
}
/**
* The transformed method.
*/
protected static class TransformedMethod extends MethodDescription.AbstractBase {
/**
* The method's declaring type.
*/
private final TypeDefinition declaringType;
/**
* The method representing the transformed method.
*/
private final MethodDescription.Token token;
/**
* The defined shape of the transformed method.
*/
private final MethodDescription.InDefinedShape methodDescription;
/**
* Creates a new transformed method.
*
* @param declaringType The method's declaring type.
* @param token The method representing the transformed method.
* @param methodDescription The defined shape of the transformed method.
*/
protected TransformedMethod(TypeDefinition declaringType,
MethodDescription.Token token,
MethodDescription.InDefinedShape methodDescription) {
this.declaringType = declaringType;
this.token = token;
this.methodDescription = methodDescription;
}
@Override
public TypeList.Generic getTypeVariables() {
return TypeList.Generic.ForDetachedTypes.attachVariables(this, token.getTypeVariableTokens());
}
@Override
public TypeDescription.Generic getReturnType() {
return token.getReturnType().accept(TypeDescription.Generic.Visitor.Substitutor.ForAttachment.of(this));
}
@Override
public ParameterList getParameters() {
return new TransformedParameterList();
}
@Override
public TypeList.Generic getExceptionTypes() {
return TypeList.Generic.ForDetachedTypes.attach(this, token.getExceptionTypes());
}
@Override
public AnnotationList getDeclaredAnnotations() {
return token.getAnnotations();
}
@Override
public String getInternalName() {
return token.getName();
}
@Override
public TypeDefinition getDeclaringType() {
return declaringType;
}
@Override
public int getModifiers() {
return token.getModifiers();
}
@Override
public Object getDefaultValue() {
return token.getDefaultValue();
}
@Override
public InDefinedShape asDefined() {
return methodDescription;
}
@Override
public TypeDescription.Generic getReceiverType() {
return methodDescription.getReceiverType();
}
/**
* A parameter list representing the transformed method's parameters.
*/
protected class TransformedParameterList extends ParameterList.AbstractBase {
@Override
public ParameterDescription get(int index) {
return new TransformedParameter(index, token.getParameterTokens().get(index));
}
@Override
public int size() {
return token.getParameterTokens().size();
}
}
/**
* A transformed method's parameter.
*/
protected class TransformedParameter extends ParameterDescription.AbstractBase {
/**
* The index of the transformed method.
*/
private final int index;
/**
* The token representing the transformed method parameter's properties.
*/
private final ParameterDescription.Token parameterToken;
/**
* Creates a transformed parameter.
*
* @param index The index of the transformed method.
* @param parameterToken The token representing the transformed method parameter's properties.
*/
protected TransformedParameter(int index, ParameterDescription.Token parameterToken) {
this.index = index;
this.parameterToken = parameterToken;
}
@Override
public TypeDescription.Generic getType() {
return parameterToken.getType().accept(TypeDescription.Generic.Visitor.Substitutor.ForAttachment.of(this));
}
@Override
public MethodDescription getDeclaringMethod() {
return TransformedMethod.this;
}
@Override
public int getIndex() {
return index;
}
@Override
public boolean isNamed() {
return parameterToken.getName() != null;
}
@Override
public boolean hasModifiers() {
return parameterToken.getModifiers() != null;
}
@Override
public String getName() {
return isNamed()
? parameterToken.getName()
: super.getName();
}
@Override
public int getModifiers() {
return hasModifiers()
? parameterToken.getModifiers()
: super.getModifiers();
}
@Override
public AnnotationList getDeclaredAnnotations() {
return parameterToken.getAnnotations();
}
@Override
public InDefinedShape asDefined() {
return methodDescription.getParameters().get(index);
}
}
}
}
/**
* A method transformer that applies several method transformers in a row.
*/
class Compound implements MethodTransformer {
/**
* The method transformers in their application order.
*/
private final List methodTransformers;
/**
* Creates a new compound method transformer.
*
* @param methodTransformer The method transformers in their application order.
*/
public Compound(MethodTransformer... methodTransformer) {
this(Arrays.asList(methodTransformer));
}
/**
* Creates a new compound method transformer.
*
* @param methodTransformers The method transformers in their application order.
*/
public Compound(List methodTransformers) {
this.methodTransformers = methodTransformers;
}
@Override
public MethodDescription transform(TypeDescription instrumentedType, MethodDescription methodDescription) {
MethodDescription transformed = methodDescription;
for (MethodTransformer methodTransformer : methodTransformers) {
transformed = methodTransformer.transform(instrumentedType, transformed);
}
return transformed;
}
@Override
public boolean equals(Object other) {
return this == other || other != null && getClass() == other.getClass()
&& methodTransformers.equals(((Compound) other).methodTransformers);
}
@Override
public int hashCode() {
return methodTransformers.hashCode();
}
@Override
public String toString() {
return "MethodTransformer.Compound{" +
"methodTransformers=" + methodTransformers +
'}';
}
}
}