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An unofficial backport of the JDK Classfile API to Java 17
/*
* Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package io.github.dmlloyd.classfile;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.function.Supplier;
import io.github.dmlloyd.classfile.attribute.CodeAttribute;
import io.github.dmlloyd.classfile.impl.TransformImpl;
import io.github.dmlloyd.classfile.extras.PreviewFeature;
/**
* A transformation on streams of {@link ClassElement}.
*
* @see ClassFileTransform
*
* @since 22
*/
@PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
@FunctionalInterface
public non-sealed interface ClassTransform
extends ClassFileTransform {
/**
* A class transform that sends all elements to the builder.
*/
static final ClassTransform ACCEPT_ALL = new ClassTransform() {
@Override
public void accept(ClassBuilder builder, ClassElement element) {
builder.with(element);
}
};
/**
* Create a stateful class transform from a {@link Supplier}. The supplier
* will be invoked for each transformation.
*
* @param supplier a {@link Supplier} that produces a fresh transform object
* for each traversal
* @return the stateful class transform
*/
static ClassTransform ofStateful(Supplier supplier) {
return new TransformImpl.SupplierClassTransform(supplier);
}
/**
* Create a class transform that passes each element through to the builder,
* and calls the specified function when transformation is complete.
*
* @param finisher the function to call when transformation is complete
* @return the class transform
*/
static ClassTransform endHandler(Consumer finisher) {
return new ClassTransform() {
@Override
public void accept(ClassBuilder builder, ClassElement element) {
builder.with(element);
}
@Override
public void atEnd(ClassBuilder builder) {
finisher.accept(builder);
}
};
}
/**
* Create a class transform that passes each element through to the builder,
* except for those that the supplied {@link Predicate} is true for.
*
* @param filter the predicate that determines which elements to drop
* @return the class transform
*/
static ClassTransform dropping(Predicate filter) {
return (b, e) -> {
if (!filter.test(e))
b.with(e);
};
}
/**
* Create a class transform that transforms {@link MethodModel} elements
* with the supplied method transform.
*
* @param filter a predicate that determines which methods to transform
* @param xform the method transform
* @return the class transform
*/
static ClassTransform transformingMethods(Predicate filter,
MethodTransform xform) {
return new TransformImpl.ClassMethodTransform(xform, filter);
}
/**
* Create a class transform that transforms {@link MethodModel} elements
* with the supplied method transform.
*
* @param xform the method transform
* @return the class transform
*/
static ClassTransform transformingMethods(MethodTransform xform) {
return transformingMethods(mm -> true, xform);
}
/**
* Create a class transform that transforms the {@link CodeAttribute} (method body)
* of {@link MethodModel} elements with the supplied code transform.
*
* @param filter a predicate that determines which methods to transform
* @param xform the code transform
* @return the class transform
*/
static ClassTransform transformingMethodBodies(Predicate filter,
CodeTransform xform) {
return transformingMethods(filter, MethodTransform.transformingCode(xform));
}
/**
* Create a class transform that transforms the {@link CodeAttribute} (method body)
* of {@link MethodModel} elements with the supplied code transform.
*
* @param xform the code transform
* @return the class transform
*/
static ClassTransform transformingMethodBodies(CodeTransform xform) {
return transformingMethods(MethodTransform.transformingCode(xform));
}
/**
* Create a class transform that transforms {@link FieldModel} elements
* with the supplied field transform.
*
* @param xform the field transform
* @return the class transform
*/
static ClassTransform transformingFields(FieldTransform xform) {
return new TransformImpl.ClassFieldTransform(xform, f -> true);
}
/**
* @implSpec
* The default implementation returns this class transform chained with another
* class transform from the argument. Chaining of two transforms requires to
* involve a chained builder serving as a target builder for this transform
* and also as a source of elements for the downstream transform.
*/
@Override
default ClassTransform andThen(ClassTransform t) {
return new TransformImpl.ChainedClassTransform(this, t);
}
}