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package org.wltea.analyzer.core;

/**
 * 字符集识别工具类
 */
class CharacterUtil {

	public static final int CHAR_USELESS = 0;

	public static final int CHAR_ARABIC = 0X00000001;

	public static final int CHAR_ENGLISH = 0X00000002;

	public static final int CHAR_CHINESE = 0X00000004;

	public static final int CHAR_OTHER_CJK = 0X00000008;

	/**
	 * 识别字符类型
	 *
	 * @param input input
	 * @return int CharacterUtil定义的字符类型常量
	 */
	static int identifyCharType(char input) {
		if (input >= '0' && input <= '9') {
			return CHAR_ARABIC;

		} else if ((input >= 'a' && input <= 'z')
				|| (input >= 'A' && input <= 'Z')) {
			return CHAR_ENGLISH;

		} else {
			Character.UnicodeBlock ub = Character.UnicodeBlock.of(input);

			if (ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS
					|| ub == Character.UnicodeBlock.CJK_COMPATIBILITY_IDEOGRAPHS
					|| ub == Character.UnicodeBlock.CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A) {
				//目前已知的中文字符UTF-8集合
				return CHAR_CHINESE;

			} else if (ub == Character.UnicodeBlock.HALFWIDTH_AND_FULLWIDTH_FORMS //全角数字字符和日韩字符
					//韩文字符集
					|| ub == Character.UnicodeBlock.HANGUL_SYLLABLES
					|| ub == Character.UnicodeBlock.HANGUL_JAMO
					|| ub == Character.UnicodeBlock.HANGUL_COMPATIBILITY_JAMO
					//日文字符集
					|| ub == Character.UnicodeBlock.HIRAGANA //平假名
					|| ub == Character.UnicodeBlock.KATAKANA //片假名
					|| ub == Character.UnicodeBlock.KATAKANA_PHONETIC_EXTENSIONS) {
				return CHAR_OTHER_CJK;

			}
		}
		//其他的不做处理的字符
		return CHAR_USELESS;
	}

	/**
	 * 进行字符规格化（全角转半角，大写转小写处理）
	 *
	 * @param input input
	 * @return char
	 */
	static char regularize(char input) {
		if (input == 12288) {
			input = (char) 32;

		} else if (input > 65280 && input < 65375) {
			input = (char) (input - 65248);

		} else if (input >= 'A' && input <= 'Z') {
			input += 32;
		}

		return input;
	}
}