/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * 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 org.jboss.vfs.util;

import static org.jboss.vfs.VFSMessages.MESSAGES;

import java.util.regex.Pattern;

import org.jboss.vfs.VirtualFile;
import org.jboss.vfs.VirtualFileFilter;

/**
 * Regexp patter filter.
 *
 * @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a>
 */
public abstract class AbstractPatternVirtualFileFilter implements VirtualFileFilter {
    private Pattern pattern;

    public AbstractPatternVirtualFileFilter(String regexp) {
        if (regexp == null) {
            throw MESSAGES.nullArgument("regexp");
        }

        pattern = Pattern.compile(regexp);
    }

    /**
     * Extract match string from file.
     *
     * @param file the file
     * @return extracted match string
     */
    protected abstract String getMatchString(VirtualFile file);

    /**
     * Should we match the pattern.
     *
     * @return the match flag
     */
    protected abstract boolean doMatch();

    public boolean accepts(VirtualFile file) {
        String string = getMatchString(file);
        return pattern.matcher(string).matches() == doMatch();
    }
}
