Add tree_merge for law parsers, significantly outperforming hierarchical_merge (#10202)

### What problem does this PR solve?
Add tree_merge for law parsers, significantly outperforming
hierarchical_merge, solved: #8637
1. Add tree_merge for law parsers, include build_tree and get_tree by
dfs.
2. add Copyright statement for helath_utils
### Type of change

- [x] Documentation Update
- [x] Performance Improvement

api/utils/health_utils.py

@@ -1,3 +1,20 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  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.
+#
+
+
 from timeit import default_timer as timer
 
 from api import settings

rag/app/laws.py

@@ -22,12 +22,15 @@ from docx import Document
 
 from api.db import ParserType
 from deepdoc.parser.utils import get_text
-from rag.nlp import bullets_category, remove_contents_table, hierarchical_merge, \
-    make_colon_as_title, tokenize_chunks, docx_question_level
-from rag.nlp import rag_tokenizer
+from rag.nlp import bullets_category, remove_contents_table, \
+    make_colon_as_title, tokenize_chunks, docx_question_level, tree_merge
+from rag.nlp import rag_tokenizer, Node
 from deepdoc.parser import PdfParser, DocxParser, PlainParser, HtmlParser
 
 
+
+
+
 class Docx(DocxParser):
     def __init__(self):
         pass
@@ -59,6 +62,7 @@ class Docx(DocxParser):
                 filename) if not binary else Document(BytesIO(binary))
             pn = 0
             lines = []
+            level_set = set()
             bull = bullets_category([p.text for p in self.doc.paragraphs])
             for p in self.doc.paragraphs:
                 if pn > to_page:
@@ -67,7 +71,7 @@ class Docx(DocxParser):
                 if not p_text.strip("\n"):
                     continue
                 lines.append((question_level, p_text))
-
+                level_set.add(question_level)
                 for run in p.runs:
                     if 'lastRenderedPageBreak' in run._element.xml:
                         pn += 1
@@ -75,29 +79,16 @@ class Docx(DocxParser):
                     if 'w:br' in run._element.xml and 'type="page"' in run._element.xml:
                         pn += 1
 
-        visit = [False for _ in range(len(lines))]
-        sections = []
-        for s in range(len(lines)):
-            e = s + 1
-            while e < len(lines):
-                if lines[e][0] <= lines[s][0]:
-                    break
-                e += 1
-            if e - s == 1 and visit[s]:
-                continue
-            sec = []
-            next_level = lines[s][0] + 1
-            while not sec and next_level < 22:
-                for i in range(s+1, e):
-                    if lines[i][0] != next_level:
-                        continue
-                    sec.append(lines[i][1])
-                    visit[i] = True
-                next_level += 1
-            sec.insert(0, lines[s][1])
+            sorted_levels = sorted(level_set)
+
+            h2_level = sorted_levels[1] if len(sorted_levels) > 1 else 1
+            h2_level = sorted_levels[-2] if h2_level == sorted_levels[-1] and len(sorted_levels) > 2 else h2_level
+
+            root = Node(level=0, depth=h2_level, texts=[])
+            root.build_tree(lines)
+
+            return [("\n").join(element) for element in root.get_tree() if element]
 
-            sections.append("\n".join(sec))
-        return [s for s in sections if s]
 
     def __str__(self) -> str:
         return f'''
@@ -172,7 +163,7 @@ def chunk(filename, binary=None, from_page=0, to_page=100000,
                                     from_page=from_page, to_page=to_page, callback=callback)[0]:
             sections.append(txt + poss)
 
-    elif re.search(r"\.txt$", filename, re.IGNORECASE):
+    elif re.search(r"\.(txt|md|markdown|mdx)$", filename, re.IGNORECASE):
         callback(0.1, "Start to parse.")
         txt = get_text(filename, binary)
         sections = txt.split("\n")
@@ -203,13 +194,16 @@ def chunk(filename, binary=None, from_page=0, to_page=100000,
 
     make_colon_as_title(sections)
     bull = bullets_category(sections)
-    chunks = hierarchical_merge(bull, sections, 5)
-    if not chunks:
+    res = tree_merge(bull, sections, 2)
+
+
+    if not res:
         callback(0.99, "No chunk parsed out.")
 
-    return tokenize_chunks(["\n".join(ck)
-                           for ck in chunks], doc, eng, pdf_parser)
+    return tokenize_chunks(res, doc, eng, pdf_parser)
 
+    # chunks = hierarchical_merge(bull, sections, 5)
+    #     return tokenize_chunks(["\n".join(ck)for ck in chunks], doc, eng, pdf_parser)
 
 if __name__ == "__main__":
     import sys

rag/nlp/__init__.py

@@ -189,6 +189,13 @@ BULLET_PATTERN = [[
     r"Chapter (I+V?|VI*|XI|IX|X)",
     r"Section [0-9]+",
     r"Article [0-9]+"
+], [
+    r"^#[^#]",
+    r"^##[^#]",
+    r"^###.*",
+    r"^####.*",
+    r"^#####.*",
+    r"^######.*",
 ]
 ]
 
@@ -427,8 +434,58 @@ def not_title(txt):
         return True
     return re.search(r"[,;，。；！!]", txt)
 
+def tree_merge(bull, sections, depth):
+    
+    if not sections or bull < 0:
+        return sections
+    if isinstance(sections[0], type("")):
+        sections = [(s, "") for s in sections]
+    
+    # filter out position information in pdf sections
+    sections = [(t, o) for t, o in sections if
+                t and len(t.split("@")[0].strip()) > 1 and not re.match(r"[0-9]+$", t.split("@")[0].strip())]
+    
+    def get_level(bull, section):
+        text, layout = section
+        text = re.sub(r"\u3000", " ",   text).strip()
+
+        for i, title in enumerate(BULLET_PATTERN[bull]):
+            if re.match(title, text.strip()):
+                return i+1, text
+        else:
+            if re.search(r"(title|head)", layout) and not not_title(text):
+                return len(BULLET_PATTERN[bull])+1, text
+            else:
+                return len(BULLET_PATTERN[bull])+2, text
+    
+    level_set = set()
+    lines = []
+    for section in sections:
+        level, text = get_level(bull, section)
+
+        if not text.strip("\n"):
+            continue
+            
+        lines.append((level, text))
+        level_set.add(level)
+
+    sorted_levels = sorted(list(level_set))
+
+    if depth <= len(sorted_levels):
+        target_level = sorted_levels[depth - 1]
+    else:
+        target_level = sorted_levels[-1]
+
+    if target_level == len(BULLET_PATTERN[bull]) + 2:
+        target_level = sorted_levels[-2] if len(sorted_levels) > 1 else sorted_levels[0]
+
+    root = Node(level=0, depth=target_level, texts=[])
+    root.build_tree(lines)
+
+    return [("\n").join(element) for element in root.get_tree() if element]
 
 def hierarchical_merge(bull, sections, depth):
+
     if not sections or bull < 0:
         return []
     if isinstance(sections[0], type("")):
@@ -628,7 +685,7 @@ def docx_question_level(p, bull=-1):
         for j, title in enumerate(BULLET_PATTERN[bull]):
             if re.match(title, txt):
                 return j + 1, txt
-    return len(BULLET_PATTERN[bull]), txt
+    return len(BULLET_PATTERN[bull])+1, txt
 
 
 def concat_img(img1, img2):
@@ -731,3 +788,68 @@ def get_delimiters(delimiters: str):
     dels_pattern = "|".join(dels)
 
     return dels_pattern
+
+class Node:
+    def __init__(self, level, depth=-1, texts=None):
+        self.level = level
+        self.depth = depth
+        self.texts = texts if texts is not None else []  # 存放内容
+        self.children = []  # 子节点
+
+    def add_child(self, child_node):
+        self.children.append(child_node)
+
+    def get_children(self):
+        return self.children
+
+    def get_level(self):
+        return self.level
+
+    def get_texts(self):
+        return self.texts
+
+    def set_texts(self, texts):
+        self.texts = texts
+
+    def add_text(self, text):
+        self.texts.append(text)
+
+    def clear_text(self):
+        self.texts = []
+
+    def __repr__(self):
+        return f"Node(level={self.level}, texts={self.texts}, children={len(self.children)})"
+
+    def build_tree(self, lines):
+        stack = [self]  
+        for line in lines:
+            level, text = line
+            node = Node(level=level, texts=[text])
+
+            if level <= self.depth or self.depth == -1:
+                while stack and level <= stack[-1].get_level():
+                    stack.pop()
+
+                stack[-1].add_child(node)
+                stack.append(node)
+            else:
+                stack[-1].add_text(text)
+        return self  
+
+    def get_tree(self):
+        tree_list = []  
+        self._dfs(self, tree_list, 0, [])
+        return tree_list
+
+    def _dfs(self, node, tree_list, current_depth, titles):
+
+        if node.get_texts():
+            if 0 < node.get_level() < self.depth:
+                titles.extend(node.get_texts())
+            else:
+                combined_text = ["\n".join(titles + node.get_texts())]
+                tree_list.append(combined_text)
+
+
+        for child in node.get_children():
+            self._dfs(child, tree_list, current_depth + 1, titles.copy())