org.marid.runtime.model.ModelObjectFactoryFriend Maven / Gradle / Ivy

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package org.marid.runtime.model;

import org.w3c.dom.Element;

import java.lang.invoke.MethodHandleProxies;
import java.lang.invoke.MethodHandles;
import java.util.HashMap;
import java.util.WeakHashMap;
import java.util.function.Supplier;
import java.util.stream.IntStream;
import java.util.stream.Stream;

class ModelObjectFactoryFriend {

  private static final WeakHashMap>> MAP = new WeakHashMap<>();

  static Entity newEntity(ModelObjectFactory factory, String tag) {
    synchronized (MAP) {
      return (Entity) MAP.computeIfAbsent(
        factory,
        f -> {
          final var map = new HashMap>();
          try {
            for (final var m : ModelObjectFactory.class.getMethods()) {
              if (m.getParameterCount() == 0 && Entity.class.isAssignableFrom(m.getReturnType())) {
                final var instance = (Entity) m.invoke(factory);
                final var handle = MethodHandles.publicLookup().unreflect(m).bindTo(factory);
                final var supplier = MethodHandleProxies.asInterfaceInstance(Supplier.class, handle);
                map.put(instance.tag(), supplier);
              }
            }
            return map;
          } catch (ReflectiveOperationException e) {
            throw new IllegalStateException(e);
          }
        }
      ).get(tag).get();
    }
  }

  static Stream children(Element element) {
    final var list = element.getChildNodes();
    return IntStream.range(0, list.getLength())
      .mapToObj(list::item)
      .filter(Element.class::isInstance)
      .map(Element.class::cast);
  }
}