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The ZEL language, a simple language with concurency facilities, mathematical operations...
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/*
 * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Additionally licensed with:
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.spf4j.zel.instr;

import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import org.apache.avro.generic.GenericRecord;
import org.spf4j.reflect.CachingTypeMapWrapper;
import org.spf4j.reflect.GraphTypeMap;
import org.spf4j.zel.vm.ExecutionContext;
import org.spf4j.zel.vm.SuspendedException;

public final class DEREF extends Instruction {

  private static final long serialVersionUID = 1L;

  public static final Instruction INSTANCE = new DEREF();

  private static final CachingTypeMapWrapper TYPE_HANDLER
          = new CachingTypeMapWrapper<>(new GraphTypeMap());

  static {
    TYPE_HANDLER.safePut(Map.class,
            (Object relativeTo, Object ref, ExecutionContext context)
            -> context.push(((Map) relativeTo).get(ref)))
            .safePut(GenericRecord.class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> context.push(((GenericRecord) relativeTo).get(ref.toString())))
            .safePut(Object.class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> context.push(context.newJavaCall(relativeTo, (String) ref)))
            .safePut(Object[].class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((Object[]) relativeTo).length);
              } else {
                context.push(((Object[]) relativeTo)[((Number) ref).intValue()]);
              }
            })
            .safePut(int[].class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((int[]) relativeTo).length);
              } else {
                context.push(((int[]) relativeTo)[((Number) ref).intValue()]);
              }
            })
            .safePut(byte[].class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((byte[]) relativeTo).length);
              } else {
                context.push(((byte[]) relativeTo)[((Number) ref).intValue()]);
              }
            })
            .safePut(char[].class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((char[]) relativeTo).length);
              } else {
                context.push(((char[]) relativeTo)[((Number) ref).intValue()]);
              }
            })
            .safePut(long[].class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((long[]) relativeTo).length);
              } else {
                context.push(((long[]) relativeTo)[((Number) ref).intValue()]);
              }
            })
            .safePut(short[].class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((short[]) relativeTo).length);
              } else {
                context.push(((short[]) relativeTo)[((Number) ref).intValue()]);
              }
            })
            .safePut(List.class,
                    (Object relativeTo, Object ref, ExecutionContext context)
                    -> {
              if ("length".equals(ref)) {
                context.push(((List) relativeTo).size());
              } else {
                context.push(((List) relativeTo).get(((Number) ref).intValue()));
              }
            });
  }

  interface ReferenceHandler {

    void pushDeref(Object relativeTo, Object ref, ExecutionContext context);
  }

  private DEREF() {
  }

  public static void registerTypeDerefHandler(final Type type, final ReferenceHandler refHandler) {
    TYPE_HANDLER.safePut(type, refHandler);
  }

  public static synchronized void replaceTypeDerefHandler(final Type type, final ReferenceHandler refHandler) {
    TYPE_HANDLER.replace(type, (x) -> refHandler);
  }

  @Override
  public int execute(final ExecutionContext context)
          throws ExecutionException, SuspendedException {
    final Object[] vals = context.tuple();
    context.popSyncStackVals(vals);
    pushDeref(vals[0], vals[1], context);
    return 1;
  }

  static void pushDeref(final Object relativeTo, final Object ref, final ExecutionContext context) {
    ReferenceHandler rh = TYPE_HANDLER.get(relativeTo.getClass());
    rh.pushDeref(relativeTo, ref, context);
  }

  @Override
  public Object[] getParameters() {
    return org.spf4j.base.Arrays.EMPTY_OBJ_ARRAY;
  }
}