Guarantee that each file is read just once

import es.upv.mist.slicing.slicing.FileLineSlicingCriterion;

import es.upv.mist.slicing.slicing.Slice;

import es.upv.mist.slicing.slicing.SlicingCriterion;

import es.upv.mist.slicing.utils.NodeHashSet;

import es.upv.mist.slicing.utils.StaticTypeSolver;

import org.apache.commons.cli.*;

        StaticJavaParser.getConfiguration().setAttributeComments(false);

        // Build the SDG

        NodeList<CompilationUnit> units = new NodeList<>();

        Set<CompilationUnit> units = new NodeHashSet<>();

        try {

            for (File file : dirIncludeSet) {

                if (file.isDirectory())

                else

                    units.add(StaticJavaParser.parse(file));

            }

            CompilationUnit scUnit = StaticJavaParser.parse(scFile);

            if (!units.contains(scUnit))

                units.add(scUnit);

            units.add(StaticJavaParser.parse(scFile));

        } catch (FileNotFoundException e) {

            throw new ParseException(e.getMessage());

        }

            default:

                throw new IllegalArgumentException("Unknown type of graph. Available graphs are SDG, ASDG, PSDG, ESSDG");

        }

        sdg.build(units);

        sdg.build(new NodeList<>(units));

        // Slice the SDG

        SlicingCriterion sc = new FileLineSlicingCriterion(scFile, scLine);