添加一个占位符解析器

hutool-core/src/main/java/cn/hutool/core/text/PlaceholderParser.java

@@ -0,0 +1,162 @@
+package cn.hutool.core.text;
+
+import cn.hutool.core.lang.Assert;
+
+import java.util.Objects;
+import java.util.function.UnaryOperator;
+
+/**
+ * <p>一个简单的占位符解析器。给定占位符的左右边界符号以及转义符，
+ * 将允许把一段字符串中的占位符解析并替换为指定内容，支持指定转义符对边界符号进行转义。<br>
+ * 比如：
+ * <pre>{@code
+ * String text = "select * from #[tableName] where id = #[id]";
+ * PlaceholderParser parser = new PlaceholderParser(str -> "?", "#[", "]");
+ * parser.apply(text); // = select * from ? where id = ?
+ * }</pre>
+ *
+ * @author huangchengxing
+ */
+public class PlaceholderParser implements UnaryOperator<String> {
+
+	/**
+	 * processor
+	 */
+	private final UnaryOperator<String> processor;
+
+	/**
+	 * 占位符开始符号
+	 */
+	private final String open;
+
+	/**
+	 * 结束符号长度
+	 */
+	private final int openLength;
+
+	/**
+	 * 占位符结束符号
+	 */
+	private final String close;
+
+	/**
+	 * 结束符号长度
+	 */
+	private final int closeLength;
+
+	/**
+	 * 转义符
+	 */
+	private final char escape;
+
+	/**
+	 * 创建一个占位符解析器
+	 *
+	 * @param processor 占位符处理器
+	 * @param open      占位符开始符号，不允许为空
+	 * @param close     占位符结束符号，不允许为空
+	 * @param escape    转义符
+	 */
+	public PlaceholderParser(UnaryOperator<String> processor, String open, String close, char escape) {
+		Assert.isFalse(StrChecker.isEmpty(open), "开始符号不能为空");
+		Assert.isFalse(StrChecker.isEmpty(close), "结束符号不能为空");
+		this.processor = processor;
+		this.open = open;
+		this.openLength = open.length();
+		this.close = close;
+		this.closeLength = close.length();
+		this.escape = escape;
+	}
+
+	/**
+	 * 创建一个占位符解析器，默认转义符为{@code "\"}
+	 *
+	 * @param processor 占位符处理器
+	 * @param open      占位符开始符号，不允许为空
+	 * @param close     占位符结束符号，不允许为空
+	 */
+	public PlaceholderParser(UnaryOperator<String> processor, String open, String close) {
+		this(processor, open, close, '\\');
+	}
+
+	/**
+	 * 解析并替换字符串中的占位符
+	 *
+	 * @param text      待解析的字符串
+	 * @return 处理后的字符串
+	 */
+	@Override
+	public String apply(String text) {
+		Objects.requireNonNull(processor);
+		if (StrChecker.isEmpty(text)) {
+			return StrChecker.EMPTY;
+		}
+
+		// 寻找第一个开始符号
+		int closeCursor = 0;
+		int openCursor = text.indexOf(open, closeCursor);
+		if (openCursor == -1) {
+			return text;
+		}
+
+		// 开始匹配
+		char[] src = text.toCharArray();
+		final StringBuilder result = new StringBuilder();
+		StringBuilder expression = new StringBuilder();
+		while (openCursor > -1) {
+
+			// 开始符号是否被转义，若是则跳过并寻找下一个开始符号
+			if (openCursor > 0 && src[openCursor - 1] == escape) {
+				result.append(src, closeCursor, openCursor - closeCursor - 1).append(open);
+				closeCursor = openCursor + openLength;
+				openCursor = text.indexOf(open, closeCursor);
+				continue;
+			}
+
+			// 记录当前位符的开始符号与上一占位符的结束符号间的字符串
+			result.append(src, closeCursor, openCursor - closeCursor);
+
+			// 重置结束游标至当前占位符的开始处
+			closeCursor = openCursor + openLength;
+
+			// 寻找结束符号下标
+			int end = text.indexOf(close, closeCursor);
+			while (end > -1) {
+				// 结束符号被转义，寻找下一个结束符号
+				if (end > closeCursor && src[end - 1] == escape) {
+					expression.append(src, closeCursor, end - closeCursor - 1).append(close);
+					closeCursor = end + closeLength;
+					end = text.indexOf(close, closeCursor);
+				}
+				// 找到结束符号
+				else {
+					expression.append(src, closeCursor, end - closeCursor);
+					break;
+				}
+			}
+
+			// 未能找到结束符号，说明匹配结束
+			if (end == -1) {
+				result.append(src, openCursor, src.length - openCursor);
+				closeCursor = src.length;
+			}
+			// 找到结束符号，将开始到结束符号之间的字符串替换为指定表达式
+			else {
+				result.append(processor.apply(expression.toString()));
+				expression = new StringBuilder();
+				// 完成当前占位符的处理匹配，寻找下一个
+				closeCursor = end + close.length();
+			}
+
+			// 寻找下一个开始符号
+			openCursor = text.indexOf(open, closeCursor);
+		}
+
+		// 若匹配结束后仍有未处理的字符串，则直接将其拼接到表达式上
+		if (closeCursor < src.length) {
+			result.append(src, closeCursor, src.length - closeCursor);
+		}
+		return result.toString();
+	}
+
+}

hutool-core/src/test/java/cn/hutool/core/text/PlaceholderParserTest.java

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+package cn.hutool.core.text;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * test for {@link PlaceholderParser}
+ *
+ * @author huangchengxing
+ */
+public class PlaceholderParserTest {
+
+	@Test
+	public void testParse() {
+		String text = "i {a}{m} a {jvav} programmer";
+		PlaceholderParser parser = new PlaceholderParser(str -> str, "{", "}");
+		Assert.assertEquals(
+			"i am a jvav programmer",
+			parser.apply(text)
+		);
+
+		text = "i [a][m] a [jvav] programmer";
+		parser = new PlaceholderParser(str -> str, "[", "]");
+		Assert.assertEquals(
+			"i am a jvav programmer",
+			parser.apply(text)
+		);
+
+		text = "i \\[a][[m\\]] a [jvav] programmer";
+		parser = new PlaceholderParser(str -> str, "[", "]");
+		Assert.assertEquals(
+			"i [a][m] a jvav programmer",
+			parser.apply(text)
+		);
+
+		text = "i /[a][[m/]] a [jvav] programmer";
+		parser = new PlaceholderParser(str -> str, "[", "]", '/');
+		Assert.assertEquals(
+			"i [a][m] a jvav programmer",
+			parser.apply(text)
+		);
+	}
+
+}