package net.bytebuddy.dynamic.scaffold;
import lombok.EqualsAndHashCode;
import net.bytebuddy.description.field.FieldDescription;
import net.bytebuddy.description.field.FieldList;
import net.bytebuddy.description.type.TypeDefinition;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.matcher.ElementMatcher;
import static net.bytebuddy.matcher.ElementMatchers.*;
/**
* A field locator offers an interface for locating a field that is declared by a specified type.
*/
public interface FieldLocator {
/**
* Locates a field with the given name and throws an exception if no such type exists.
*
* @param name The name of the field to locate.
* @return A resolution for a field lookup.
*/
Resolution locate(String name);
/**
* Locates a field with the given name and type and throws an exception if no such type exists.
*
* @param name The name of the field to locate.
* @param type The type fo the field to locate.
* @return A resolution for a field lookup.
*/
Resolution locate(String name, TypeDescription type);
/**
* A resolution for a field lookup.
*/
interface Resolution {
/**
* Returns {@code true} if a field was located.
*
* @return {@code true} if a field was located.
*/
boolean isResolved();
/**
* Returns the field description if a field was located. This method must only be called if
* this resolution was actually resolved.
*
* @return The located field.
*/
FieldDescription getField();
/**
* An illegal resolution.
*/
enum Illegal implements Resolution {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public boolean isResolved() {
return false;
}
@Override
public FieldDescription getField() {
throw new IllegalStateException("Could not locate field");
}
}
/**
* A simple implementation for a field resolution.
*/
@EqualsAndHashCode
class Simple implements Resolution {
/**
* A description of the located field.
*/
private final FieldDescription fieldDescription;
/**
* Creates a new simple resolution for a field.
*
* @param fieldDescription A description of the located field.
*/
protected Simple(FieldDescription fieldDescription) {
this.fieldDescription = fieldDescription;
}
@Override
public boolean isResolved() {
return true;
}
@Override
public FieldDescription getField() {
return fieldDescription;
}
}
}
/**
* A factory for creating a {@link FieldLocator}.
*/
interface Factory {
/**
* Creates a field locator for a given type.
*
* @param typeDescription The type for which to create a field locator.
* @return A suitable field locator.
*/
FieldLocator make(TypeDescription typeDescription);
}
/**
* A field locator that never discovers a field.
*/
enum NoOp implements FieldLocator, Factory {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public FieldLocator make(TypeDescription typeDescription) {
return this;
}
@Override
public Resolution locate(String name) {
return Resolution.Illegal.INSTANCE;
}
@Override
public Resolution locate(String name, TypeDescription type) {
return Resolution.Illegal.INSTANCE;
}
}
/**
* An abstract base implementation of a field locator.
*/
@EqualsAndHashCode
abstract class AbstractBase implements FieldLocator {
/**
* The type accessing the field.
*/
protected final TypeDescription accessingType;
/**
* Creates a new field locator.
*
* @param accessingType The type accessing the field.
*/
protected AbstractBase(TypeDescription accessingType) {
this.accessingType = accessingType;
}
@Override
public Resolution locate(String name) {
FieldList<?> candidates = locate(named(name).and(isVisibleTo(accessingType)));
return candidates.size() == 1
? new Resolution.Simple(candidates.getOnly())
: Resolution.Illegal.INSTANCE;
}
@Override
public Resolution locate(String name, TypeDescription type) {
FieldList<?> candidates = locate(named(name).and(fieldType(type)).and(isVisibleTo(accessingType)));
return candidates.size() == 1
? new Resolution.Simple(candidates.getOnly())
: Resolution.Illegal.INSTANCE;
}
/**
* Locates fields that match the given matcher.
*
* @param matcher The matcher that identifies fields of interest.
* @return A list of fields that match the specified matcher.
*/
protected abstract FieldList<?> locate(ElementMatcher<? super FieldDescription> matcher);
}
/**
* A field locator that only looks up fields that are declared by a specific type.
*/
@EqualsAndHashCode(callSuper = true)
class ForExactType extends AbstractBase {
/**
* The type for which to look up fields.
*/
private final TypeDescription typeDescription;
/**
* Creates a new field locator for locating fields from a declared type.
*
* @param typeDescription The type for which to look up fields that is also providing the accessing type.
*/
public ForExactType(TypeDescription typeDescription) {
this(typeDescription, typeDescription);
}
/**
* Creates a new field locator for locating fields from a declared type.
*
* @param typeDescription The type for which to look up fields.
* @param accessingType The accessing type.
*/
public ForExactType(TypeDescription typeDescription, TypeDescription accessingType) {
super(accessingType);
this.typeDescription = typeDescription;
}
@Override
protected FieldList<?> locate(ElementMatcher<? super FieldDescription> matcher) {
return typeDescription.getDeclaredFields().filter(matcher);
}
/**
* A factory for creating a {@link ForExactType}.
*/
@EqualsAndHashCode
public static class Factory implements FieldLocator.Factory {
/**
* The type for which to locate a field.
*/
private final TypeDescription typeDescription;
/**
* Creates a new factory for a field locator that locates a field for an exact type.
*
* @param typeDescription The type for which to locate a field.
*/
public Factory(TypeDescription typeDescription) {
this.typeDescription = typeDescription;
}
@Override
public FieldLocator make(TypeDescription typeDescription) {
return new ForExactType(this.typeDescription, typeDescription);
}
}
}
/**
* A field locator that looks up fields that are declared within a class's class hierarchy.
*/
@EqualsAndHashCode(callSuper = true)
class ForClassHierarchy extends AbstractBase {
/**
* The type for which to look up a field within its class hierarchy.
*/
private final TypeDescription typeDescription;
/**
* Creates a field locator that looks up fields that are declared within a class's class hierarchy.
*
* @param typeDescription The type for which to look up a field within its class hierarchy which is also the accessing type.
*/
public ForClassHierarchy(TypeDescription typeDescription) {
this(typeDescription, typeDescription);
}
/**
* Creates a field locator that looks up fields that are declared within a class's class hierarchy.
*
* @param typeDescription The type for which to look up a field within its class hierarchy.
* @param accessingType The accessing type.
*/
public ForClassHierarchy(TypeDescription typeDescription, TypeDescription accessingType) {
super(accessingType);
this.typeDescription = typeDescription;
}
@Override
protected FieldList<?> locate(ElementMatcher<? super FieldDescription> matcher) {
for (TypeDefinition typeDefinition : typeDescription) {
FieldList<?> candidates = typeDefinition.getDeclaredFields().filter(matcher);
if (!candidates.isEmpty()) {
return candidates;
}
}
return new FieldList.Empty<FieldDescription>();
}
/**
* A factory for creating a {@link ForClassHierarchy}.
*/
public enum Factory implements FieldLocator.Factory {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public FieldLocator make(TypeDescription typeDescription) {
return new ForClassHierarchy(typeDescription);
}
}
}
/**
* A field locator that only locates fields in the top-level type.
*/
class ForTopLevelType extends AbstractBase {
/**
* Creates a new type locator for a top-level type.
*
* @param typeDescription The type to access.
*/
protected ForTopLevelType(TypeDescription typeDescription) {
super(typeDescription);
}
@Override
protected FieldList<?> locate(ElementMatcher<? super FieldDescription> matcher) {
return accessingType.getDeclaredFields().filter(matcher);
}
/**
* A factory for locating a field in a top-level type.
*/
public enum Factory implements FieldLocator.Factory {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public FieldLocator make(TypeDescription typeDescription) {
return new ForTopLevelType(typeDescription);
}
}
}
}