package org.apache.commons.lang;

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/**
 * 文字の範囲。隣接するアルファベットの範囲、除外する文字、文字のセットの概念を表すことができます。
 * 文字のセットを扱うために CharSet にて使用されます。
 * {@primary A range of characters. Able to understand the idea of a contiguous 
 * sublist of an alphabet, a negated concept, and a set of characters.
 * Used by CharSet to handle sets of characters.}
 *
 * @author <a href="bayard@generationjava.com">Henri Yandell</a>
 * @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
 * @translator 日置 聡
 * @status firstdraft
 * @update 2003/08/05
 * @version $Id: CharRange.java,v 1.1.1.1 2004/02/13 10:02:04 hioki Exp $
 */
class CharRange {

    /**
     * char が null であることを表現するために内部で使用されます。
     * {@primary Used internally to represent null in a char.}
     */
    private static char UNSET;

    private char start;
    private char close;
    private boolean negated;

    /**
     * 単一の文字を意味する CharRange を生成します。
     * {@primary Construct a CharRange over a single character.}
     *
     * @param start この文字の範囲が表す文字
     * {@primary char over which this range is placed}
     */
    public CharRange(char start) {
        this.start = start;
    }

    /**
     * 文字のセットを意味する CharRange を生成します。
     * {@primary Construct a CharRange over a set of characters.}
     *
     * @param start  この文字範囲の開始文字(この文字も含む)。
     * {@primary char start character in this range. inclusive}
     * @param close  この文字範囲の終了文字(この文字も含む)。
     * {@primary char close character in this range. inclusive}
     */
    public CharRange(char start, char close) {
        this.start = start;
        this.close = close;
    }

    /**
     * 文字のセットを意味する CharRange を生成します。
     * {@primary Construct a CharRange over a set of characters.}
     *
     * @param start  文字列の最初の文字がこの文字範囲の開始文字となる(この文字も含む)。
     * {@primary String start first character is in this range (inclusive).}
     * @param close  文字列の最初の文字がこの文字範囲の終了文字となる(この文字も含む)。
     * {@primary String first character is close character in this range (inclusive).}
     */
    public CharRange(String start, String close) {
        this.start = start.charAt(0);
        this.close = close.charAt(0);
    }

    /**
     * 文字範囲の開始文字を返します。
     * {@primary Get the start character for this character range}
     * 
     * @return 開始文字(この文字も含む)
     * {@primary start char (inclusive)}
     */
    public char getStart() {
        return this.start;
    }

    /**
     * 文字範囲の終了文字を返します。
     * {@primary Get the end character for this character range}
     * 
     * @return 終了文字(この文字も含む)
     * {@primary end char (inclusive)}
     */
    public char getEnd() {
        return this.close;
    }

    /**
     * 文字範囲の開始文字を設定します。
     * {@primary Set the start character for this character range}
     * 
     * @param ch  開始文字(この文字も含む)
     * {@primary start char (inclusive)}
     */
    public void setStart(char ch) {
        this.start = ch;
    }

    /**
     * 文字範囲の終了文字を設定します。
     * {@primary Set the end character for this character range}
     * 
     * @param ch  終了文字(この文字も含む)
     * {@primary start char (inclusive)}
     */
    public void setEnd(char ch) {
        this.close = ch;
    }

    /**
     * この CharRange が複数の文字を表すかどうか。
     * {@primary Is this CharRange over many characters}
     *
     * @return boolean true is many characters
     * {@primary 複数の文字を表す場合 true}
     */
    public boolean isRange() {
        return this.close != UNSET;
    }

    /**
     * 指定された文字が範囲に含まれるかどうか。
     * {@primary Is the passed in character inside this range}
     *
     * @return 指定された文字が範囲内の場合 true
     * {@primary boolean true is in range}
     */
    public boolean inRange(char ch) {
        if(isRange()) {
            return ((ch >= start) && (ch <= close) );
        } else {
            return start == ch;
        }
    }

    /**
     * この CharRange が除外条件かどうかチェックします。
     * {@primary Checks if this CharRange is negated.}
     *
     * @return 除外条件の場合 true
     * {@primary boolean true is negated}
     */
    public boolean isNegated() {
        return negated;
    }

    /**
     * この文字範囲が除外条件かどうかを設定します。
     * この CharRange に設定されている範囲の全ての文字は除外されます。
     * {@primary Sets this character range to be negated or not. 
     * This implies that this CharRange is over all characters except 
     * the ones in this range.}
     * 
     * @param negated  除外条件の場合 true
     * {@primary true to negate the range}
     */
    public void setNegated(boolean negated) {
        this.negated = negated;
    }

    /**
     * この文字範囲の文字列表現を返します。
     * {@primary Output a string representation of the character range}
     * 
     * @return 文字列表現
     * {@primary string representation}
     */
    public String toString() {
        String str = "";
        if(isNegated()) {
            str += "^";
        }
        str += start;
        if(isRange()) {
            str += "-";
            str += close;
        }
        return str;
    }
    
}