/*
 * Copyright 2003-2011 JetBrains s.r.o.
 *
 * 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 jetbrains.mps.lang.dataFlow.framework.analyzers;

import jetbrains.mps.lang.dataFlow.framework.DataFlowAnalyzer;
import jetbrains.mps.lang.dataFlow.framework.AnalysisDirection;
import jetbrains.mps.lang.dataFlow.framework.Program;
import jetbrains.mps.lang.dataFlow.framework.ProgramState;

import java.util.List;

public class ReachabilityAnalyzer implements DataFlowAnalyzer<Boolean> {
  @Override
  public Boolean initial(Program p) {
    return false;
  }

  @Override
  public Boolean merge(Program p, List<Boolean> input) {
    for (Boolean value : input) {
      if (value) {
        return true;
      }
    }
    return false;
  }

  @Override
  public Boolean fun(Boolean input, ProgramState s) {
    if (s.isStart()) {
      return true;
    }
    return input;
  }

  @Override
  public AnalysisDirection getDirection() {
    return AnalysisDirection.FORWARD;
  }
}
