Added SPDG

package tfm.graphs.sergio;

import com.github.javaparser.ast.body.MethodDeclaration;

import com.github.javaparser.ast.stmt.BreakStmt;

import com.github.javaparser.ast.stmt.ContinueStmt;

import com.github.javaparser.ast.stmt.ReturnStmt;

import tfm.arcs.Arc;

import tfm.graphs.augmented.ACFG;

import tfm.graphs.augmented.APDG;

import tfm.graphs.cfg.CFG;

import tfm.nodes.GraphNode;

import java.util.HashSet;

import java.util.Objects;

import java.util.Set;

public class SPDG extends APDG {

    public SPDG() {

        super();

    }

    public SPDG(ACFG acfg) {

        super(acfg);

    }

    @Override

    public void build(MethodDeclaration method) {

        super.build(method);

        Set<Arc> toBeCleared = new HashSet<>();

        for (GraphNode<?> node : vertexSet()) {

            // Is an unconditional jump

            if (isUnconditionalJump(node)) {

                // Has an unconditional jump as parent (control dependence)

                for (Arc arc : incomingEdgesOf(node)) {

                    GraphNode<?> src = getEdgeSource(arc);

                    // Both node and src lead to the same spot

                    if (isUnconditionalJump(src) && Objects.equals(dest(node, getCfg()), dest(src, getCfg()))) {

                        // All conditions are ok! Remove all incoming edges of node.

                        toBeCleared.addAll(incomingEdgesOf(node));

                    }

                }

            }

        }

        for (Arc arc : toBeCleared)

            removeEdge(arc);

    }

    /**

     * Obtains the destination of a jump statement.

     * @param jump The jump instruction.

     * @param cfg The CFG in which the jump instruction is located.

     * @return The graphnode that corresponds to the jump's destination.

     */

    private static GraphNode<?> dest(GraphNode<?> jump, CFG cfg) {

        if (cfg.outDegreeOf(jump) != 2) {

            throw new IllegalStateException("This unconditional jump should have 2 outgoing edges!");

        }

        for (Arc arc : cfg.outgoingEdgesOf(jump))

            if (arc.isExecutableControlFlowArc())

                return cfg.getEdgeTarget(arc);

        throw new IllegalStateException("Could not found an executable outgoing edge of the jump in the CFG");

    }

    private static boolean isUnconditionalJump(GraphNode<?> node) {

        return node.getAstNode() instanceof BreakStmt ||

                node.getAstNode() instanceof ContinueStmt ||

                (node.getAstNode() instanceof ReturnStmt && !((ReturnStmt) node.getAstNode()).getExpression().isPresent());

    }

}