com.iofairy.si.StringExtractor Maven / Gradle / Ivy

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/*
 * Copyright (C) 2021 iofairy, 
 *
 * 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 com.iofairy.si;

import com.iofairy.top.S;
import com.iofairy.tuple.Tuple2;

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

import static com.iofairy.si.SIBase.*;

/**
 * Extracting expression from ${}
 *
 * @since 0.0.1
 */
public class StringExtractor {

    /**
     * Regex for extracting expression from ${}, but { or } can't be included in ${}
     */
    private final static Pattern PATTERN = Pattern.compile("\\$\\{((?![{}]).)*}", Pattern.MULTILINE);

    /**
     * Get String Tokens by ${}
     *
     * @param source 待插值的字符串
     * @return StringToken列表
     */
    public static List split(String source) {
        List sts = new ArrayList<>();
        final Matcher matcher = PATTERN.matcher(source);

        int startIndex = 0;
        while (matcher.find()) {
            String matchStr = matcher.group();
            int start = matcher.start();    // 起始字符位置
            int end = matcher.end();        // 结束字符+1 的位置

            if ($__.equals(matchStr)) {
                String strBefore$ = source.substring(startIndex, start);  // ${} 前面还未加入列表的字符串，如： abc${}，则 strBefore$ == "abc"
                sts.add(new StringToken(StringType.STRING, strBefore$ + $, strBefore$ + $__));
            } else {
                if (start != startIndex) {  // 不相等说明${}前面有一段字符串常量还未添加进列表
                    String value = source.substring(startIndex, start);
                    sts.add(new StringToken(StringType.STRING, value, value));
                }

                String strInBrace = matchStr.substring(2, matchStr.length() - 1);   // 获取${}中的内容
                Tuple2 keyDefault = S.splitOnce(strInBrace, DEFAULT_VALUE_DELIMITER);
                sts.add(new StringToken(StringType.VARIABLE, keyDefault._1, keyDefault._2 == null ? matchStr : keyDefault._2));
            }
            startIndex = end;
        }

        if (startIndex < source.length()) {
            String value = source.substring(startIndex);
            sts.add(new StringToken(StringType.STRING, value, value));
        }

        return sts;
    }

    /**
     * 嵌套字符串插值分词器
     *
     * @param source 原字符串
     * @return 分词后的列表
     * @since 0.4.0
     */
    public static List