/*
* 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.instructions.WriteInstruction;
import jetbrains.mps.lang.dataFlow.framework.instructions.Instruction;
import jetbrains.mps.lang.dataFlow.framework.*;
import java.util.List;
public class InitializedVariablesAnalyzer implements DataFlowAnalyzer<VarSet> {
public InitializedVariablesAnalyzer() {
}
@Override
public VarSet initial(Program p) {
return new VarSet(p, true);
}
@Override
public VarSet merge(Program p, List<VarSet> input) {
if (input.isEmpty()) {
return initial(p);
}
VarSet result = new VarSet(p, true);
for (VarSet anInput : input) {
result.retainAll(anInput);
}
return result;
}
@Override
public VarSet fun(VarSet input, ProgramState s) {
Instruction instruction = s.getInstruction();
VarSet result = input;
if (s.isStart()) {
result.clear();
}
if (instruction instanceof WriteInstruction) {
WriteInstruction write = (WriteInstruction) instruction;
result.add(write.getVariableIndex());
}
return result;
}
@Override
public AnalysisDirection getDirection() {
return AnalysisDirection.FORWARD;
}
}