只保留LLM提取模式，修改提取逻辑

main.py

@@ -2,7 +2,6 @@
 # -*- coding: utf-8 -*-
 """
 SRS 解析工具 - 主程序入口
-LLM 增强版 - 默认阿里云千问大模型
 """
 
 import argparse
@@ -16,6 +15,7 @@ sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
 
 from src.utils import load_config, setup_logging, validate_file_path, ensure_directory_exists, get_env_or_config
 from src.document_parser import create_parser
+from src.document_parser import Section
 from src.requirement_extractor import RequirementExtractor
 from src.json_generator import JSONGenerator
 
@@ -34,10 +34,9 @@ def create_llm(config: dict):
     """
     llm_config = config.get('llm', {})
     
-    # 检查是否启用LLM
+    # 当前版本仅支持LLM模式
     if not llm_config.get('enabled', True):
-        logger.info("LLM已禁用，使用纯规则提取模式")
-        return None
+        raise ValueError("当前版本仅支持LLM模式，请将配置 llm.enabled 设为 true")
     
     provider = llm_config.get('provider', 'qwen')
     
@@ -45,9 +44,7 @@ def create_llm(config: dict):
     api_key = get_env_or_config('DASHSCOPE_API_KEY', llm_config.get('api_key'))
     
     if not api_key:
-        logger.warning("未配置API密钥，请使用纯规则提取模式")
-        logger.warning("请设置环境变量 DASHSCOPE_API_KEY 或在 config.yaml 中配置 llm.api_key")
-        return None
+        raise ValueError("未配置API密钥：请设置环境变量 DASHSCOPE_API_KEY 或在 config.yaml 中配置 llm.api_key")
     
     try:
         from src.llm_interface import QwenLLM
@@ -67,12 +64,80 @@ def create_llm(config: dict):
         return llm
         
     except ImportError as e:
-        logger.warning(f"无法导入LLM模块: {e}")
-        logger.warning("请运行: pip install dashscope")
-        return None
+        raise RuntimeError(f"无法导入LLM模块: {e}。请安装依赖：pip install dashscope") from e
     except Exception as e:
-        logger.warning(f"创建LLM实例失败: {e}")
-        return None
+        raise RuntimeError(f"创建LLM实例失败: {e}") from e
+
+
+def parse_chapter_selector(selector: str) -> list:
+    """解析章节筛选参数。"""
+    if not selector:
+        return []
+    chapters = [x.strip() for x in selector.split(',') if x.strip()]
+    valid = []
+    for chapter in chapters:
+        if not chapter or not all(p.isdigit() for p in chapter.split('.')):
+            raise ValueError(f"无效章节编号: {chapter}，仅支持如 3 或 3.1 的格式")
+        valid.append(chapter)
+    return valid
+
+
+def _clone_section_with_children(section: Section) -> Section:
+    copied = Section(
+        level=section.level,
+        title=section.title,
+        number=section.number,
+        content=section.content,
+        uid=section.uid,
+    )
+    copied.tables = list(section.tables)
+    copied.blocks = list(section.blocks)
+    for child in section.children:
+        copied.add_child(_clone_section_with_children(child))
+    return copied
+
+
+def filter_sections_by_chapters(sections: list, chapters: list) -> list:
+    """按章节前缀过滤章节树（如3匹配3及3.x）。"""
+    if not chapters:
+        return sections
+
+    def matched(number: str) -> bool:
+        number = (number or "").strip()
+        if not number:
+            return False
+        for chapter in chapters:
+            if number == chapter or number.startswith(f"{chapter}."):
+                return True
+        return False
+
+    def recurse(section: Section) -> Section:
+        if matched(section.number):
+            return _clone_section_with_children(section)
+
+        copied = Section(
+            level=section.level,
+            title=section.title,
+            number=section.number,
+            content=section.content,
+            uid=section.uid,
+        )
+        copied.tables = list(section.tables)
+        copied.blocks = list(section.blocks)
+
+        for child in section.children:
+            filtered_child = recurse(child)
+            if filtered_child:
+                copied.add_child(filtered_child)
+
+        return copied if copied.children else None
+
+    filtered = []
+    for s in sections:
+        fs = recurse(s)
+        if fs:
+            filtered.append(fs)
+    return filtered
 
 
 def main():
@@ -86,7 +151,7 @@ def main():
 示例用法：
   python main.py --input sample.pdf --output output.json
   python main.py -i requirements.docx -o output.json --verbose
-  python main.py -i DC-SRS.pdf -o output.json --no-llm  # 禁用LLM
+    python main.py -i DC-SRS.pdf -o output.json
         """
     )
     
@@ -116,11 +181,12 @@ def main():
         action='store_true',
         help='输出详细日志'
     )
-    
+
     parser.add_argument(
-        '--no-llm',
-        action='store_true',
-        help='禁用LLM，使用纯规则提取'
+        '--chapters',
+        type=str,
+        default=None,
+        help='按章节提取（如: 3 或 3,4.1）；输入3表示提取第3章及其子章节'
     )
     
     # 解析命令行参数
@@ -129,10 +195,6 @@ def main():
     # 加载配置
     config = load_config(args.config)
     
-    # 命令行参数覆盖配置
-    if args.no_llm:
-        config.setdefault('llm', {})['enabled'] = False
-    
     # 设置日志
     if args.verbose:
         config.setdefault('logging', {})['level'] = 'DEBUG'
@@ -158,12 +220,9 @@ def main():
         
         logger.info(f"输出文件: {args.output}")
         
-        # 创建LLM实例
+        # 创建LLM实例（必需）
         llm = create_llm(config)
-        if llm:
-            logger.info("LLM增强模式已启用")
-        else:
-            logger.info("使用纯规则提取模式")
+        logger.info("LLM增强模式已启用")
         
         # 步骤1：解析文档
         logger.info("\n" + "=" * 60)
@@ -176,6 +235,13 @@ def main():
         
         sections = doc_parser.parse()
         document_title = doc_parser.get_document_title()
+
+        selected_chapters = parse_chapter_selector(args.chapters) if args.chapters else []
+        if selected_chapters:
+            sections = filter_sections_by_chapters(sections, selected_chapters)
+            if not sections:
+                raise ValueError(f"未匹配到指定章节: {', '.join(selected_chapters)}")
+            logger.info(f"章节筛选已启用: {', '.join(selected_chapters)}")
         
         logger.info(f"成功解析文档，提取{len(sections)}个顶级章节")
         
@@ -192,10 +258,7 @@ def main():
         
         # 步骤2：提取需求
         logger.info("\n" + "=" * 60)
-        if llm:
-            logger.info("步骤2：提取需求（LLM增强模式）")
-        else:
-            logger.info("步骤2：提取需求（规则匹配模式）")
+        logger.info("步骤2：提取需求（LLM增强模式）")
         logger.info("=" * 60)
         
         extractor = RequirementExtractor(config, llm=llm)