CALLREF.java

/*
 * 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.util.Arrays;
import java.util.concurrent.ExecutionException;
import org.spf4j.zel.vm.AssignableValue;
import org.spf4j.zel.vm.ExecutionContext;
import org.spf4j.zel.vm.Method;
import org.spf4j.zel.vm.Program;
import org.spf4j.zel.vm.SuspendedException;
import org.spf4j.zel.vm.ZExecutionException;

public final class CALLREF extends Instruction {

  private static final long serialVersionUID = 1L;

  private final int nrParameters;

  public CALLREF(final int nrParameters) {
    this.nrParameters = nrParameters;
  }

  @Override
  public int execute(final ExecutionContext context)
          throws ExecutionException, InterruptedException, SuspendedException {
    final Object[] parameters = context.popSyncStackVals(nrParameters);
    final Object function = ((AssignableValue) context.pop()).get();

    context.push(new FunctionDeref(context, function, parameters));

    return 1;
  }

  @Override
  public Object[] getParameters() {
    return new Object[]{nrParameters};
  }

  private static final class FunctionDeref implements AssignableValue {

    private final ExecutionContext context;
    private final Object function;
    private final Object[] parameters;

    FunctionDeref(final ExecutionContext context, final Object function, final Object[] parameters) {
      this.context = context;
      this.function = function;
      this.parameters = parameters;
    }

    @Override
    public void assign(final Object object) throws ExecutionException {
      if (function instanceof Program && ((Program) function).getType() == Program.Type.DETERMINISTIC) {
        context.getResultCache().putPermanentResult((Program) function,
                Arrays.asList(parameters), object);
      } else {
        throw new ZExecutionException("Function " + function + " must be deterministic to memorize value ");
      }
    }

    @Override
    public Object get() throws ExecutionException, InterruptedException {

      if (function instanceof Program) {
        final Program p = (Program) function;
        final ExecutionContext nctx;
        Object obj;
        switch (p.getType()) {
          case DETERMINISTIC:
            nctx = context.getSyncSubProgramContext(p, parameters);
            obj = context.getResultCache().getResult(p, Arrays.asList(parameters),
                    nctx::call);

            break;
          case NONDETERMINISTIC:
            nctx = context.getSyncSubProgramContext(p, parameters);
            try {
              obj = nctx.call();
            } catch (SuspendedException ex) {
              throw new ZExecutionException("Suspension not supported for " + p, ex);
            }
            break;
          default:
            throw new UnsupportedOperationException(p.getType().toString());
        }
        return obj;
      } else if (function instanceof Method) {
        try {
          return ((Method) function).invoke(context, parameters);
        } catch (Exception ex) {
          throw new ZExecutionException("cannot invoke " + function, ex);
        }
      } else {
        throw new ZExecutionException("cannot invoke " + function);
      }

    }
  }
}