From bf0977445a4abf906306800f10b2f7f4f021eacc Mon Sep 17 00:00:00 2001
From: VampireAchao <achao@hutool.cn>
Date: Sun, 14 Jan 2024 13:07:43 +0800
Subject: [PATCH] =?UTF-8?q?[feature]=20=E6=B7=BB=E5=8A=A0=E9=80=92?=
 =?UTF-8?q?=E5=BD=92=E6=89=81=E5=B9=B3=E5=8C=96WordTree=E6=96=B9=E6=B3=95?=
 =?UTF-8?q?=EF=BC=8C=E8=83=BD=E9=80=9A=E8=BF=87WordTree=E8=BF=98=E5=8E=9F?=
 =?UTF-8?q?=E6=88=90=E5=8E=9F=E6=9D=A5=E7=9A=84=E5=85=83=E7=B4=A0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../hutool/core/text/dfa/WordTree.java        | 38 +++++++++++++++++++
 .../dromara/hutool/core/text/dfa/DfaTest.java | 12 ++++++
 2 files changed, 50 insertions(+)

diff --git a/hutool-core/src/main/java/org/dromara/hutool/core/text/dfa/WordTree.java b/hutool-core/src/main/java/org/dromara/hutool/core/text/dfa/WordTree.java
index 6ed5423fa..e7e405e3d 100644
--- a/hutool-core/src/main/java/org/dromara/hutool/core/text/dfa/WordTree.java
+++ b/hutool-core/src/main/java/org/dromara/hutool/core/text/dfa/WordTree.java
@@ -15,6 +15,7 @@ package org.dromara.hutool.core.text.dfa;
 import org.dromara.hutool.core.collection.CollUtil;
 import org.dromara.hutool.core.collection.set.SetUtil;
 import org.dromara.hutool.core.map.MapUtil;
+import org.dromara.hutool.core.stream.EasyStream;
 import org.dromara.hutool.core.text.StrUtil;
 
 import java.util.*;
@@ -324,8 +325,45 @@ public class WordTree extends HashMap<Character, WordTree> {
 		}
 		return foundWords;
 	}
+
+	/**
+	 * 扁平化WordTree
+	 * 例如：红领巾，红河 构建树后为：
+	 * <pre>
+	 *            红
+	 *            /\
+	 *          领  河
+	 *         /
+	 *       巾
+	 * </pre>
+	 * 扁平化后得到
+	 * <pre>
+	 *     红河
+	 *     红领巾
+	 * </pre>
+	 *
+	 * @return 扁平化后的结果，不保证顺序
+	 */
+	public List<String> flatten() {
+		return EasyStream.of(this.entrySet()).flat(this::innerFlatten).toList();
+	}
+
 	//--------------------------------------------------------------------------------------- Private method start
 
+	/**
+	 * 递归扁平化WordTree每个entry节点
+	 *
+	 * @param entry WordTree每个entry节点
+	 * @return 递归扁平化后的结果
+	 */
+	private Iterable<String> innerFlatten(Entry<Character, WordTree> entry) {
+		List<String> list = EasyStream.of(entry.getValue().entrySet()).flat(this::innerFlatten).map(v -> entry.getKey() + v).toList();
+		if (list.isEmpty()) {
+			return EasyStream.of(entry.getKey().toString());
+		}
+		return list;
+	}
+
 	/**
 	 * 是否末尾
 	 *
diff --git a/hutool-core/src/test/java/org/dromara/hutool/core/text/dfa/DfaTest.java b/hutool-core/src/test/java/org/dromara/hutool/core/text/dfa/DfaTest.java
index ff1c1f30b..bf58e0a07 100644
--- a/hutool-core/src/test/java/org/dromara/hutool/core/text/dfa/DfaTest.java
+++ b/hutool-core/src/test/java/org/dromara/hutool/core/text/dfa/DfaTest.java
@@ -16,6 +16,8 @@ import org.dromara.hutool.core.collection.ListUtil;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 
 /**
@@ -209,4 +211,14 @@ public class DfaTest {
 		strings = wordTree.matchAll("abab", -1, true, true);
 		Assertions.assertEquals("[ab, b, ab, b]", strings.toString());
 	}
+
+	@Test
+	void flattenTest() {
+		final WordTree wordTree = new WordTree();
+		final List<String> list = Arrays.asList("阿帕奇", "阿超", "HuTool", "HuTao");
+		wordTree.addWords(list);
+		final List<String> flattened = wordTree.flatten();
+		flattened.sort(Comparator.comparingInt(list::indexOf));
+		Assertions.assertEquals(list, flattened);
+	}
 }