/*
 * Copyright 2008 Google Inc.
 *
 * 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 com.google.gwt.dev.jjs.impl.gflow.unreachable;

import com.google.gwt.dev.jjs.impl.gflow.AssumptionMap;
import com.google.gwt.dev.jjs.impl.gflow.AssumptionUtil;
import com.google.gwt.dev.jjs.impl.gflow.IntegratedFlowFunction;
import com.google.gwt.dev.jjs.impl.gflow.TransformationFunction.Transformation;
import com.google.gwt.dev.jjs.impl.gflow.cfg.Cfg;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgEdge;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgNode;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgNopNode;
import com.google.gwt.dev.jjs.impl.gflow.cfg.CfgTransformer;

/**
 *
 */
public class UnreachabeIntegratedTransformationFunction implements
    IntegratedFlowFunction<CfgNode<?>, CfgEdge, CfgTransformer, Cfg,
                           UnreachableAssumptions> {
  @Override
  public Transformation<CfgTransformer, Cfg>
  interpretOrReplace(CfgNode<?> node, Cfg graph,
      AssumptionMap<CfgEdge, UnreachableAssumptions> assumptionMap) {
    UnreachableAssumptions in = AssumptionUtil.join(
        graph.getInEdges(node), assumptionMap);

    if (UnreachableAssumptions.isReachable(in)) {
      AssumptionUtil.setAssumptions(graph.getOutEdges(node), UnreachableAssumptions.REACHABLE, assumptionMap);
      return null;
    }

    if (node instanceof CfgNopNode) {
      AssumptionUtil.setAssumptions(graph.getOutEdges(node), UnreachableAssumptions.UNREACHABLE, assumptionMap);
      return null;
    }

    return new DeleteNodeTransformation(graph, node);
  }
}
