189 lines
5.1 KiB
Python
189 lines
5.1 KiB
Python
"""
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文件解析工具
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支持PDF、Markdown、TXT文件的文本提取
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"""
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import os
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from pathlib import Path
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from typing import List, Optional
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def _read_text_with_fallback(file_path: str) -> str:
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"""
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读取文本文件，UTF-8失败时自动探测编码。
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采用多级回退策略：
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1. 首先尝试 UTF-8 解码
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2. 使用 charset_normalizer 检测编码
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3. 回退到 chardet 检测编码
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4. 最终使用 UTF-8 + errors='replace' 兜底
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Args:
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file_path: 文件路径
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Returns:
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解码后的文本内容
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"""
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data = Path(file_path).read_bytes()
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# 首先尝试 UTF-8
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try:
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return data.decode('utf-8')
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except UnicodeDecodeError:
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pass
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# 尝试使用 charset_normalizer 检测编码
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encoding = None
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try:
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from charset_normalizer import from_bytes
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best = from_bytes(data).best()
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if best and best.encoding:
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encoding = best.encoding
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except Exception:
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pass
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# 回退到 chardet
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if not encoding:
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try:
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import chardet
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result = chardet.detect(data)
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encoding = result.get('encoding') if result else None
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except Exception:
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pass
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# 最终兜底：使用 UTF-8 + replace
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if not encoding:
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encoding = 'utf-8'
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return data.decode(encoding, errors='replace')
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class FileParser:
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"""文件解析器"""
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SUPPORTED_EXTENSIONS = {'.pdf', '.md', '.markdown', '.txt'}
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@classmethod
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def extract_text(cls, file_path: str) -> str:
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"""
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从文件中提取文本
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Args:
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file_path: 文件路径
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Returns:
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提取的文本内容
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"""
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path = Path(file_path)
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if not path.exists():
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raise FileNotFoundError(f"文件不存在: {file_path}")
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suffix = path.suffix.lower()
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if suffix not in cls.SUPPORTED_EXTENSIONS:
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raise ValueError(f"不支持的文件格式: {suffix}")
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if suffix == '.pdf':
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return cls._extract_from_pdf(file_path)
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elif suffix in {'.md', '.markdown'}:
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return cls._extract_from_md(file_path)
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elif suffix == '.txt':
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return cls._extract_from_txt(file_path)
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raise ValueError(f"无法处理的文件格式: {suffix}")
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@staticmethod
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def _extract_from_pdf(file_path: str) -> str:
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"""从PDF提取文本"""
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try:
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import fitz # PyMuPDF
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except ImportError:
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raise ImportError("需要安装PyMuPDF: pip install PyMuPDF")
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text_parts = []
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with fitz.open(file_path) as doc:
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for page in doc:
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text = page.get_text()
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if text.strip():
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text_parts.append(text)
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return "\n\n".join(text_parts)
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@staticmethod
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def _extract_from_md(file_path: str) -> str:
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"""从Markdown提取文本，支持自动编码检测"""
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return _read_text_with_fallback(file_path)
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@staticmethod
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def _extract_from_txt(file_path: str) -> str:
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"""从TXT提取文本，支持自动编码检测"""
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return _read_text_with_fallback(file_path)
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@classmethod
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def extract_from_multiple(cls, file_paths: List[str]) -> str:
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"""
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从多个文件提取文本并合并
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Args:
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file_paths: 文件路径列表
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Returns:
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合并后的文本
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"""
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all_texts = []
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for i, file_path in enumerate(file_paths, 1):
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try:
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text = cls.extract_text(file_path)
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filename = Path(file_path).name
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all_texts.append(f"=== 文档 {i}: {filename} ===\n{text}")
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except Exception as e:
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all_texts.append(f"=== 文档 {i}: {file_path} (提取失败: {str(e)}) ===")
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return "\n\n".join(all_texts)
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def split_text_into_chunks(
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text: str,
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chunk_size: int = 500,
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overlap: int = 50
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) -> List[str]:
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"""
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将文本分割成小块
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Args:
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text: 原始文本
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chunk_size: 每块的字符数
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overlap: 重叠字符数
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Returns:
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文本块列表
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"""
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if len(text) <= chunk_size:
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return [text] if text.strip() else []
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chunks = []
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start = 0
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while start < len(text):
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end = start + chunk_size
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# 尝试在句子边界处分割
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if end < len(text):
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# 查找最近的句子结束符
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for sep in ['。', '！', '？', '.\n', '!\n', '?\n', '\n\n', '. ', '! ', '? ']:
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last_sep = text[start:end].rfind(sep)
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if last_sep != -1 and last_sep > chunk_size * 0.3:
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end = start + last_sep + len(sep)
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break
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chunk = text[start:end].strip()
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if chunk:
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chunks.append(chunk)
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# 下一个块从重叠位置开始
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start = end - overlap if end < len(text) else len(text)
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return chunks
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