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package de.hysky.skyblocker.utils;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.reflect.Field;
import java.lang.runtime.ObjectMethods;
import java.util.Arrays;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Stream;
import org.slf4j.Logger;
import com.mojang.logging.LogUtils;
import it.unimi.dsi.fastutil.objects.ObjectOpenHashSet;
/**
* @implNote If implementing any of these onto a class, ensure that all subclasses have an implementation of the methods too.
*/
public class InstancedUtils {
private static final Logger LOGGER = LogUtils.getLogger();
private static final Map<Class<?>, MethodHandle> EQUALS_CACHE = new ConcurrentHashMap<>();
private static final Map<Class<?>, MethodHandle> HASH_CODE_CACHE = new ConcurrentHashMap<>();
private static final Map<Class<?>, MethodHandle> TO_STRING_CACHE = new ConcurrentHashMap<>();
public static MethodHandle equals(Class<?> type) {
if (EQUALS_CACHE.containsKey(type)) return EQUALS_CACHE.get(type);
try {
Field[] fields = getClassFields(type);
MethodHandle[] getters = getFieldGetters(fields);
//The field names param can be anything as equals and hashCode don't care about it.
MethodHandle equalsHandle = (MethodHandle) ObjectMethods.bootstrap(MethodHandles.lookup(), "equals", MethodHandle.class, type, "", getters);
EQUALS_CACHE.put(type, equalsHandle);
return equalsHandle;
} catch (Throwable t) {
LOGGER.error("[Skyblocked Instanced Utils] Failed to create an equals method handle.", t);
throw new RuntimeException();
}
}
public static MethodHandle hashCode(Class<?> type) {
if (HASH_CODE_CACHE.containsKey(type)) return HASH_CODE_CACHE.get(type);
try {
Field[] fields = getClassFields(type);
MethodHandle[] getters = getFieldGetters(fields);
//The field names param can be anything as equals and hashCode don't care about it.
MethodHandle hashCodeHandle = (MethodHandle) ObjectMethods.bootstrap(MethodHandles.lookup(), "hashCode", MethodHandle.class, type, "", getters);
HASH_CODE_CACHE.put(type, hashCodeHandle);
return hashCodeHandle;
} catch (Throwable t) {
LOGGER.error("[Skyblocked Instanced Utils] Failed to create a hashCode method handle.", t);
throw new RuntimeException();
}
}
public static MethodHandle toString(Class<?> type) {
if (TO_STRING_CACHE.containsKey(type)) return TO_STRING_CACHE.get(type);
try {
Field[] fields = getClassFields(type);
MethodHandle[] getters = getFieldGetters(fields);
String fieldNames = String.join(";", Arrays.stream(fields).map(Field::getName).toArray(String[]::new));
MethodHandle toStringHandle = (MethodHandle) ObjectMethods.bootstrap(MethodHandles.lookup(), "toString", MethodHandle.class, type, fieldNames, getters);
TO_STRING_CACHE.put(type, toStringHandle);
return toStringHandle;
} catch (Throwable t) {
LOGGER.error("[Skyblocked Instanced Utils] Failed to create a toString method handle.", t);
throw new RuntimeException();
}
}
private static Field[] getClassFields(Class<?> type) {
return Stream.concat(Arrays.stream(type.getDeclaredFields()), Arrays.stream(type.getFields())).distinct().toArray(Field[]::new);
}
private static MethodHandle[] getFieldGetters(Field[] fields) throws Throwable {
ObjectOpenHashSet<MethodHandle> handles = new ObjectOpenHashSet<>();
for (Field field : fields) {
field.setAccessible(true);
MethodHandle getter = MethodHandles.lookup().unreflectGetter(field);
handles.add(getter);
}
return handles.toArray(MethodHandle[]::new);
}
}
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