org.apache.wicket.util.parse.metapattern.Group.java Source code

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Here is the source code for org.apache.wicket.util.parse.metapattern.Group.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.util.parse.metapattern;

import java.util.regex.Matcher;

/**
 * A Group is a piece of a regular expression (referenced by some Java field or local variable) that
 * forms a "capturing group" within the larger regular expression. A Group is bound to a regular
 * expression MetaPattern when a matcher is retrieved for the pattern by calling one of the
 * matcher() methods. Once bound, a Group cannot be rebound.
 * 
 * @author Jonathan Locke
 */
public class Group extends MetaPattern {
    private static final long serialVersionUID = 1L;

    /** The capturing group that this Group is bound to. */
    private int group = -1;

    /**
     * Constructor.
     * 
     * @param pattern
     *            MetaPattern to capture
     */
    public Group(final MetaPattern pattern) {
        super(pattern);
    }

    /**
     * Threadsafe method to retrieve contents of this captured group.
     * 
     * @param matcher
     *            The matcher from which to retrieve this Group's group
     * @return The captured characters
     */
    public final String get(final Matcher matcher) {
        if (group == -1) {
            throw new GroupNotBoundException();
        }

        return matcher.group(group);
    }

    /**
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return "(" + super.toString() + ")";
    }

    /**
     * Binds this capture expression if not already bound.
     * 
     * @param bindTo
     *            The group to bind to
     * @throws GroupAlreadyBoundException
     *             Thrown if this Group is already bound
     */
    final void bind(final int bindTo) {
        if (group == -1) {
            group = bindTo;
        } else {
            throw new GroupAlreadyBoundException();
        }
    }
}