src/main/java/com/puppycrawl/tools/checkstyle/checks/coding/NestedIfDepthCheck.java

////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2017 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
////////////////////////////////////////////////////////////////////////////////

package com.puppycrawl.tools.checkstyle.checks.coding;

import com.puppycrawl.tools.checkstyle.FileStatefulCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CheckUtils;

/**
 * Restricts nested if-else blocks to a specified depth (default = 1).
 *
 * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
 */
@FileStatefulCheck
public final class NestedIfDepthCheck extends AbstractCheck {

    /**
     * A key is pointing to the warning message text in "messages.properties"
     * file.
     */
    public static final String MSG_KEY = "nested.if.depth";

    /** Maximum allowed nesting depth. */
    private int max = 1;
    /** Current nesting depth. */
    private int depth;

    /**
     * Setter for maximum allowed nesting depth.
     * @param max maximum allowed nesting depth.
     */
    public void setMax(int max) {
        this.max = max;
    }

    @Override
    public int[] getDefaultTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getAcceptableTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return new int[] {TokenTypes.LITERAL_IF};
    }

    @Override
    public void beginTree(DetailAST rootAST) {
        depth = 0;
    }

    @Override
    public void visitToken(DetailAST literalIf) {
        if (!CheckUtils.isElseIf(literalIf)) {
            if (depth > max) {
                log(literalIf, MSG_KEY, depth, max);
            }
            ++depth;
        }
    }

    @Override
    public void leaveToken(DetailAST literalIf) {
        if (!CheckUtils.isElseIf(literalIf)) {
            --depth;
        }
    }

}