io.github.dmlloyd.classfile.components.CodeRelabeler Maven / Gradle / Ivy
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package io.github.dmlloyd.classfile.components;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.function.BiFunction;
import io.github.dmlloyd.classfile.instruction.LabelTarget;
import io.github.dmlloyd.classfile.CodeBuilder;
import io.github.dmlloyd.classfile.CodeTransform;
import io.github.dmlloyd.classfile.Label;
import io.github.dmlloyd.classfile.impl.CodeRelabelerImpl;
import io.github.dmlloyd.classfile.extras.PreviewFeature;
/**
* A code relabeler is a {@link CodeTransform} replacing all occurrences
* of {@link Label} in the transformed code with new instances.
* All {@link LabelTarget} instructions are adjusted accordingly.
* Relabeled code graph is identical to the original.
*
* Primary purpose of CodeRelabeler is for repeated injections of the same code blocks.
* Repeated injection of the same code block must be relabeled, so each instance of
* {@link Label} is bound in the target bytecode exactly once.
*
* @since 22
*/
@PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
public sealed interface CodeRelabeler extends CodeTransform permits CodeRelabelerImpl {
/**
* Creates a new instance of CodeRelabeler.
* @return a new instance of CodeRelabeler
*/
static CodeRelabeler of() {
return of(new IdentityHashMap<>());
}
/**
* Creates a new instance of CodeRelabeler storing the label mapping into the provided map.
* @param map label map actively used for relabeling
* @return a new instance of CodeRelabeler
*/
static CodeRelabeler of(Map map) {
return of((l, cob) -> map.computeIfAbsent(l, ll -> cob.newLabel()));
}
/**
* Creates a new instance of CodeRelabeler using provided {@link BiFunction}
* to re-label the code.
* @param mapFunction function for remapping labels in the source code model
* @return a new instance of CodeRelabeler
*/
static CodeRelabeler of(BiFunction mapFunction) {
return new CodeRelabelerImpl(mapFunction);
}
}