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package com.star.regex;

import java.util.Collection;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.star.collection.ArrayUtil;
import com.star.lang.Assert;

/**
 * 正则工具类
 * 
 * @author starhq
 *
 */
public final class RegexUtil {

	/** 正则中需要被转义的关键字 */
	public final static Character[] CHARS = { '$', '(', ')', '*', '+', '.', '[', ']', '?', '\\', '^', '{', '}', '|' };


	private RegexUtil() {

	}

	/**
	 * 
	 * 获得匹配的字符串
	 * 
	 */
	public static String get(final Pattern pattern, final String content, final int groupIndex) {
		Assert.notNull(content, "regex extract content failue,the string  is null");
		Assert.notNull(pattern, "regex extract content failue,the  pattern is null");
		final Matcher matcher = pattern.matcher(content);
		return matcher.find() ? matcher.group(groupIndex) : "";
	}

	/**
	 * 
	 * 删除正则匹配到的内容之前的字符 如果没有找到，则返回原文
	 * 
	 */
	public static String delPre(final Pattern pattern, final String content) {
		Assert.notNull(content, "delete content before regex maths the content failure,the string  is null");
		Assert.notNull(pattern, "delete content before regex maths the content failue,the  pattern is null");
		final Matcher matcher = pattern.matcher(content);
		return matcher.find() ? content.substring(matcher.end(), content.length()) : content;
	}

	/**
	 * 给定内容是否匹配正则
	 */
	public static boolean isMatch(final Pattern pattern, final String content) {
		Assert.notNull(content, "Determine where the content is math the pattern failue,the string  is null");
		Assert.notNull(pattern, "Determine where the content is math the pattern failuet,the  pattern is null");
		return pattern.matcher(content).matches();
	}

	/**
	 * 表达式中提取信息到集合中
	 */
	public static > T findAll(final Pattern pattern, final String content, final int group,
			final T collections) {
		Assert.notNull(content, "extract content by patter into collection failue,the string  is null");
		Assert.notNull(pattern, "extract content by patter into collection failue,the  pattern is null");
		final Matcher matcher = pattern.matcher(content);
		while (matcher.find()) {
			collections.add(matcher.group(group));
		}
		return collections;
	}

	/**
	 * 
	 * 转义字符串，将正则的关键字转义
	 * 
	 */
	public static String escape(final String content) {
		Assert.notNull(content, "escape string failue,the input string is null");
		final StringBuilder builder = new StringBuilder();
		char current;
		for (int i = 0; i < content.length(); i++) {
			current = content.charAt(i);
			if (ArrayUtil.contains(CHARS, current)) {
				builder.append('\\');
			}
			builder.append(current);
		}
		return builder.toString();
	}

	
}