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'Databene Formats' is an open source software library for supporting data file and other formats like CSV, fixed width files, XLS, Properties and Regex. It is designed for multithreaded use and high performance.

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/*
 * Copyright (C) 2011-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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.databene.formats.regex;

import java.util.List;
import java.util.Arrays;

/**
 * Represents an alternative expression part of a regular expression, e.g. '(yes|no)'.
 * 
 * Created: 17.09.2006 16:14:14
 */
public class Choice implements RegexPart {
	
    /** The alternatives */
    private RegexPart[] alternatives;
    
    
    // constructors ----------------------------------------------------------------------------------------------------
    
    /** Constructor that takes a list of alternative patterns 
     * @param alternatives the alternatives */
    public Choice(List alternatives) {
    	RegexPart[] ra = new RegexPart[alternatives.size()];
        this.alternatives = alternatives.toArray(ra);
    }
    
    /** Constructor that takes an array of alternative patterns 
     * @param alternatives the alternatives */
    public Choice(RegexPart... alternatives) {
        this.alternatives = alternatives;
    }
    
    
    // properties ------------------------------------------------------------------------------------------------------
    
    /** Returns the alternative patterns 
     * @return the alternatives */
    public RegexPart[] getAlternatives() {
        return alternatives;
    }
    
    
    // RegexPart interface implementation ------------------------------------------------------------------------------
    
	@Override
	public int minLength() {
		if (this.alternatives.length == 0)
			return 0;
		int min = alternatives[0].minLength();
		for (int i = alternatives.length - 1; i >= 1; i--)
			min = Math.min(min, alternatives[i].minLength());
		return min;
	}

	@Override
	public Integer maxLength() {
		if (this.alternatives.length == 0)
			return 0;
		int max = 0;
		for (RegexPart candidate : alternatives) {
			Integer partMaxLength = candidate.maxLength();
			if (partMaxLength == null)
				return null; // if any option is unlimited, then the whole choice is unlimited
			if (partMaxLength > max)
				max = partMaxLength;
		}
		return max;
	}
	
	
    // java.lang.Object overrides --------------------------------------------------------------------------------------
    
    /** @see java.lang.Object#equals(Object) */
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass())
            return false;
        return Arrays.equals(alternatives, ((Choice)o).alternatives);
    }
    
    /** @see java.lang.Object#hashCode() */
    @Override
    public int hashCode() {
        return Arrays.hashCode(alternatives);
    }
    
    /** @see java.lang.Object#toString() */
    @Override
    public String toString() {
        StringBuilder buffer = new StringBuilder("(");
        for (int i = 0; i < alternatives.length; i++) {
            if (i > 0)
                buffer.append('|');
            buffer.append(alternatives[i]);
        }
        buffer.append(')');
        return buffer.toString();
    }
    
}