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package com.fitbur.bytebuddy.dynamic;
import com.fitbur.bytebuddy.description.annotation.AnnotationList;
import com.fitbur.bytebuddy.description.field.FieldDescription;
import com.fitbur.bytebuddy.description.modifier.ModifierContributor;
import com.fitbur.bytebuddy.description.type.TypeDefinition;
import com.fitbur.bytebuddy.description.type.TypeDescription;
import java.util.Arrays;
import java.util.List;
import static com.fitbur.bytebuddy.matcher.ElementMatchers.is;
/**
* A field transformer allows to transform a field prior to its definition. This way, previously defined fields
* can be substituted by a different field description. It is the responsibility of the field transformer that
* the substitute field remains compatible to the substituted field.
*/
public interface FieldTransformer {
/**
* Transforms a field. The transformed field 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 fieldDescription The field to be transformed.
* @return The transformed field.
*/
FieldDescription transform(TypeDescription instrumentedType, FieldDescription fieldDescription);
/**
* A field transformer that returns the original field.
*/
enum NoOp implements FieldTransformer {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public FieldDescription transform(TypeDescription instrumentedType, FieldDescription fieldDescription) {
return fieldDescription;
}
@Override
public String toString() {
return "FieldTransformer.NoOp." + name();
}
}
/**
* A simple implementation of a field transformer.
*/
class Simple implements FieldTransformer {
/**
* The token transformer to apply to a transformed field.
*/
private final TokenTransformer tokenTransformer;
/**
* Creates a new simple field transformer.
*
* @param tokenTransformer The token transformer to apply to a transformed field.
*/
public Simple(TokenTransformer tokenTransformer) {
this.tokenTransformer = tokenTransformer;
}
/**
* Creates a field transformer that patches the transformed field by the givien modifier contributors.
*
* @param modifierContributor The modifier contributors to apply.
* @return A suitable field transformer.
*/
public static FieldTransformer withModifiers(ModifierContributor.ForField... modifierContributor) {
return new Simple(new TokenTransformer.ForModifierTransformation(Arrays.asList(modifierContributor)));
}
@Override
public FieldDescription transform(TypeDescription instrumentedType, FieldDescription fieldDescription) {
return new TransformedField(fieldDescription.getDeclaringType(),
tokenTransformer.transform(fieldDescription.asToken(is(instrumentedType))), fieldDescription.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 "FieldTransformer.Simple{" +
"tokenTransformer=" + tokenTransformer +
'}';
}
/**
* A transformer for a field token where the resulting token is used to represent the transformed field.
*/
public interface TokenTransformer {
/**
* Transforms a field token.
*
* @param token The original token that is being transformed.
* @return The transformed field token.
*/
FieldDescription.Token transform(FieldDescription.Token token);
/**
* A token transformer that transforms a field's modifier.
*/
class ForModifierTransformation implements TokenTransformer {
/**
* The list of modifier contributors to apply onto the transformed field token.
*/
private final List modifierContributors;
/**
* Creates a new field token modifier for transforming a field's modifiers.
*
* @param modifierContributors The list of modifier contributors to apply onto the transformed field token.
*/
public ForModifierTransformation(List modifierContributors) {
this.modifierContributors = modifierContributors;
}
@Override
public FieldDescription.Token transform(FieldDescription.Token token) {
return new FieldDescription.Token(token.getName(),
ModifierContributor.Resolver.of(modifierContributors).resolve(token.getModifiers()),
token.getType(),
token.getAnnotations());
}
@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 "FieldTransformer.Simple.TokenTransformer.ForModifierTransformation{" +
"modifierContributors=" + modifierContributors +
'}';
}
}
}
/**
* An implementation of a transformed field.
*/
protected static class TransformedField extends FieldDescription.AbstractBase {
/**
* The field's declaring type.
*/
private final TypeDefinition declaringType;
/**
* A field token representing the transformed field.
*/
private final FieldDescription.Token token;
/**
* The field's defined shape.
*/
private final FieldDescription.InDefinedShape fieldDescription;
/**
* Creates a new transformed field.
*
* @param declaringType The field's declaring type.
* @param token A field token representing the transformed field.
* @param fieldDescription The field's defined shape.
*/
protected TransformedField(TypeDefinition declaringType,
FieldDescription.Token token,
FieldDescription.InDefinedShape fieldDescription) {
this.declaringType = declaringType;
this.token = token;
this.fieldDescription = fieldDescription;
}
@Override
public TypeDescription.Generic getType() {
return token.getType().accept(TypeDescription.Generic.Visitor.Substitutor.ForAttachment.of(this));
}
@Override
public AnnotationList getDeclaredAnnotations() {
return token.getAnnotations();
}
@Override
public TypeDefinition getDeclaringType() {
return declaringType;
}
@Override
public int getModifiers() {
return token.getModifiers();
}
@Override
public InDefinedShape asDefined() {
return fieldDescription;
}
@Override
public String getName() {
return token.getName();
}
}
}
/**
* A compound field transformer that applies a list of given transformers in the given order.
*/
class Compound implements FieldTransformer {
/**
* The field transformers represented by this compound transformer in their application order.
*/
private final List fieldTransformers;
/**
* Creates a new compound transformer.
*
* @param fieldTransformer The field transformers represented by this compound transformer in their application order.
*/
public Compound(FieldTransformer... fieldTransformer) {
this(Arrays.asList(fieldTransformer));
}
/**
* Creates a new compound transformer.
*
* @param fieldTransformers The field transformers represented by this compound transformer in their application order.
*/
public Compound(List fieldTransformers) {
this.fieldTransformers = fieldTransformers;
}
@Override
public FieldDescription transform(TypeDescription instrumentedType, FieldDescription fieldDescription) {
FieldDescription transformed = fieldDescription;
for (FieldTransformer fieldTransformer : fieldTransformers) {
transformed = fieldTransformer.transform(instrumentedType, transformed);
}
return transformed;
}
@Override
public boolean equals(Object other) {
return this == other || other != null && getClass() == other.getClass()
&& fieldTransformers.equals(((Compound) other).fieldTransformers);
}
@Override
public int hashCode() {
return fieldTransformers.hashCode();
}
@Override
public String toString() {
return "FieldTransformer.Compound{" +
"fieldTransformers=" + fieldTransformers +
'}';
}
}
}
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