cz.muni.stanse.reachabilitychecker.ReachabilityChecker.java Source code

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Here is the source code for cz.muni.stanse.reachabilitychecker.ReachabilityChecker.java

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/**
 * @brief ReachabilityChecker implementation
 *
 * Copyright (c) 2009 Jiri Slaby <jirislaby@gmail.com>
 *
 * Licensed under GPLv2.
 */
package cz.muni.stanse.reachabilitychecker;

import cz.muni.stanse.codestructures.CFGNode;
import cz.muni.stanse.codestructures.LazyInternalStructures;
import cz.muni.stanse.checker.CheckerError;
import cz.muni.stanse.checker.CheckerErrorReceiver;
import cz.muni.stanse.checker.CheckerProgressMonitor;
import cz.muni.stanse.checker.CheckingResult;
import cz.muni.stanse.checker.CheckingSuccess;
import cz.muni.stanse.codestructures.CFGHandle;
import cz.muni.stanse.utils.Make;

import org.dom4j.Element;

import java.util.regex.Pattern;

/**
 * @brief Static checker which is able to detect unrechable code.
 *
 * @see cz.muni.stanse.checker.Checker
 */
final class ReachabilityChecker extends cz.muni.stanse.checker.Checker {
    private static Pattern exprCompoundPattern = Pattern.compile("[eE]xpression.*\\bcompoundStatement\\b");
    private static Pattern retCompoundPattern = Pattern.compile("\\breturnStatement\\b.*\\bcompoundStatement\\b");

    // public section

    public ReachabilityChecker() {
        super();
    }

    /**
     * @brief Uniquely identifies the checker by the string identifier.
     *
     * @return String which uniquely identifies the checker.
     * @see cz.muni.stanse.checker.Checker#getName()
     */
    @Override
    public String getName() {
        return ReachabilityCheckerCreator.getNameForCheckerFactory();
    }

    /**
     * @brief Does the source code checking itself.
     *
     * Method searches through source code to find nodes (except start node)
     * with no predecessors.
     *
     * @return List of errors found in the source code.
     * @see cz.muni.stanse.checker.Checker#check(java.util.List)
     */
    @Override
    public CheckingResult check(final LazyInternalStructures internals, final CheckerErrorReceiver errReceiver,
            final CheckerProgressMonitor monitor) {
        CheckingResult result = new CheckingSuccess();
        monitor.write("Starting Reachability Checker");
        for (CFGHandle cfg : internals.getCFGHandles()) {
            CFGNode start = cfg.getStartNode();
            CFGNode end = cfg.getEndNode();
            for (CFGNode node : cfg.getAllNodesReverse()) {
                if (node.equals(start) || node.equals(end))
                    continue;
                if (!node.getPredecessors().isEmpty())
                    continue;
                if (!node.getOptPredecessors().isEmpty())
                    continue;
                Element nodeElem = node.getElement();
                String elemPath = nodeElem.getPath();

                /* we don't do CFGs of statements inside expressions ({ .. }) */
                if (exprCompoundPattern.matcher(elemPath).find())
                    continue;
                if (retCompoundPattern.matcher(elemPath).find())
                    continue;

                String elemName = nodeElem.getName();
                if (elemName.equals("intConst") && nodeElem.getText().equals("0"))
                    continue;
                int importance = 0;
                StringBuilder fullDesc = new StringBuilder("The code is " + "unreachable by any path.");
                monitor.write("An error found");
                if (elemName.equals("emptyStatement") || elemName.equals("breakStatement")
                        || elemName.equals("returnStatement")) {
                    importance += 3;
                    fullDesc.append(" Superfluous semicolon, break or return " + "statement.");
                }
                Element parentElem = nodeElem.getParent();
                if (parentElem != null && parentElem.getName().equals("forStatement")
                        && nodeElem.equals(parentElem.elements().get(2))) {
                    importance += 5;
                    fullDesc.append(" The third 'for' expression is never " + "used.");
                }
                errReceiver.receive(new CheckerError("Unreachable code", fullDesc.toString(), importance,
                        ReachabilityCheckerCreator.getNameForCheckerFactory(), Make.<CFGNode>linkedList(node, node),
                        "This node is unreachable", "", "This node is unreachable", internals));
            }
        }
        monitor.write("Reachability Checker finished");
        return result;
    }
}