f47611020a
- 正文抽取下钻 SDT 内容控件，目录等内容不再整段丢失 - 切片投影匹配剥离序列化插入的列表自动编号，新增行锚点兜底与游标防回退 - fixed/semantic 切分路径定位失败时保留切片，不再静默丢弃 - Word 预览按段落大纲级别识别标题，未套标题样式的小节正常渲染 - 本地嵌入模型抽为共享单例，供语义分块与质量评分共用
588 lines
21 KiB
Python
588 lines
21 KiB
Python
"""基于 Docling 与 LlamaIndex 的文档切分实现。"""
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from __future__ import annotations
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import os
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import re
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import threading
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import unicodedata
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from dataclasses import dataclass
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from functools import lru_cache
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from io import BytesIO
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from typing import Any, Literal
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import tiktoken
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from docling_core.transforms.chunker.hierarchical_chunker import ChunkingSerializerProvider
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from llama_index.core import Document
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from llama_index.core.base.embeddings.base import BaseEmbedding
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from llama_index.core.node_parser import SemanticSplitterNodeParser, SentenceSplitter
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from app.modules.data_process.algorithms import normalize_text
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from app.modules.data_process.algorithms.embedding import semantic_embedding_model
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ChunkMethod = Literal["layout_hybrid", "semantic", "fixed"]
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_PAGE_FURNITURE = re.compile(
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r"(?m)^\s*(?:第\s*\d+\s*页\s*共\s*\d+\s*页|[-—–]?\s*\d+\s*[/／]\s*\d+\s*[-—–]?)\s*$"
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)
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# Docling 的 markdown 序列化会给列表项补上自动编号，而 Word 的编号存放在
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# numbering.xml 中，python-docx 抽取的正文不含这些编号；紧凑匹配前剥掉
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# 行首编号，否则带列表的切片会整体定位失败。
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_LIST_MARKER_PREFIX = re.compile(
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r"(?m)^[ \t>]*(?:(?:\d{1,3}[.)])+|\([a-zA-Z0-9]{1,3}\)|[a-zA-Z][.)]|[-*+•·])[ \t]+"
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)
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_COMPACT_CHARACTER = re.compile(r"[\w\u3400-\u4dbf\u4e00-\u9fff]", re.UNICODE)
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_CONVERTER_LOCK = threading.Lock()
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@dataclass(frozen=True, slots=True)
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class DocumentChunk:
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"""切片正文及其在原文件中的可追溯信息。"""
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original_content: str
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contextualized_content: str
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source_start: int | None
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source_end: int | None
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source_start_line: int | None
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source_end_line: int | None
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token_count: int
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heading_path: tuple[str, ...] = ()
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source_pages: tuple[int, ...] = ()
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doc_item_refs: tuple[str, ...] = ()
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source_bboxes: tuple[dict[str, Any], ...] = ()
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def _sentence_chunks(text: str) -> list[str]:
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"""提供稳定的中英文句界，避免 LlamaIndex 默认分词器下载额外资源。"""
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boundary = re.compile(
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r".*?(?:\n\s*\n|[。！？!?；;](?:[\"'”’）】》]*)|\.(?:\s+|$)|$)",
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re.DOTALL,
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)
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return [part for part in boundary.findall(text) if part]
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@lru_cache(maxsize=1)
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def _tokenizer() -> tiktoken.Encoding:
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"""加载 cl100k_base 编码器，优先在线下载，失败时使用本地缓存以支持离线环境。"""
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import os
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import base64
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# 先设置缓存目录环境变量
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offline_cache = os.path.expanduser("~/.cache/tiktoken")
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os.environ.setdefault("TIKTOKEN_CACHE_DIR", offline_cache)
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try:
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# 尝试标准方式加载
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return tiktoken.get_encoding("cl100k_base")
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except Exception:
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# 如果失败，尝试手动从本地文件构造
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try:
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from pathlib import Path
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local_file = Path(offline_cache) / "9b5ad71b2ce5302211f9c61530b329a4922fc6a4"
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if not local_file.exists():
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# 尝试另一个可能的文件名
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local_file = Path(offline_cache) / "cl100k_base.tiktoken"
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if local_file.exists():
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# 读取 BPE 文件内容
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with open(local_file, "rb") as f:
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contents = f.read()
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# 解析 BPE 文件
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mergeable_ranks = {}
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for line in contents.splitlines():
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if line:
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token, rank = line.split()
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mergeable_ranks[base64.b64decode(token)] = int(rank)
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# 构造 Encoding 对象（模块顶部已 import tiktoken，
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# 此处不能再 import tiktoken.core，否则会把 tiktoken
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# 变成局部变量，使函数开头的 tiktoken.get_encoding 抛
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# UnboundLocalError）
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return tiktoken.core.Encoding(
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name="cl100k_base",
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pat_str=r"""'(?i:[sdmt]|ll|ve|re)|[^\r\n\p{L}\p{N}]?+\p{L}+|\p{N}{1,3}| ?[^\s\p{L}\p{N}]++[\r\n]*|\s*[\r\n]|\s+(?!\S)|\s+""",
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mergeable_ranks=mergeable_ranks,
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special_tokens={
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"<|endoftext|>": 100257,
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"<|fim_prefix|>": 100258,
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"<|fim_middle|>": 100259,
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"<|fim_suffix|>": 100260,
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"<|endofprompt|>": 100276,
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},
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)
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except Exception:
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pass
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raise RuntimeError(
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f"无法加载 cl100k_base 编码器\n"
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f"请确保以下任一条件满足:\n"
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f"1. 服务器可以访问网络\n"
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f"2. 本地存在缓存文件: {offline_cache}/9b5ad71b2ce5302211f9c61530b329a4922fc6a4"
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)
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def _text_chunks(
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text: str,
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*,
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chunk_size: int,
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chunk_overlap: int,
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) -> list[DocumentChunk]:
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normalized = normalize_text(text)
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if not normalized:
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return []
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splitter = SentenceSplitter(
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chunk_size=chunk_size,
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chunk_overlap=chunk_overlap,
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tokenizer=_tokenizer().encode,
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chunking_tokenizer_fn=_sentence_chunks,
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include_metadata=False,
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include_prev_next_rel=False,
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)
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nodes = splitter.get_nodes_from_documents([Document(text=normalized)])
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return _nodes_to_chunks(nodes, normalized)
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def chunk_fixed_text(
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text: str,
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*,
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chunk_size: int,
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chunk_overlap: int,
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) -> list[DocumentChunk]:
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"""使用 LlamaIndex SentenceSplitter 按句界控制固定 Token 长度。"""
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return _text_chunks(text, chunk_size=chunk_size, chunk_overlap=chunk_overlap)
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def chunk_semantic_text(
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text: str,
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*,
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chunk_size: int,
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chunk_overlap: int,
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breakpoint_percentile_threshold: int,
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embed_model: BaseEmbedding | None = None,
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) -> list[DocumentChunk]:
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"""使用 LlamaIndex SemanticSplitter 识别主题跳变，再限制最大长度。"""
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normalized = normalize_text(text)
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if not normalized:
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return []
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splitter = SemanticSplitterNodeParser.from_defaults(
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embed_model=embed_model or semantic_embedding_model(),
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breakpoint_percentile_threshold=breakpoint_percentile_threshold,
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buffer_size=1,
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sentence_splitter=_sentence_chunks,
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include_metadata=False,
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include_prev_next_rel=False,
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)
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semantic_nodes = splitter.get_nodes_from_documents([Document(text=normalized)])
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result: list[DocumentChunk] = []
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search_from = 0
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for node in semantic_nodes:
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content = node.get_content().strip()
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if not content:
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continue
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start = _locate_text(normalized, content, search_from)
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if start is None:
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start = _locate_text(normalized, content, 0)
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if start is None:
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result.append(_unlocated_chunk(content))
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continue
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if len(_tokenizer().encode(content)) <= chunk_size:
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result.append(_make_text_chunk(normalized, start, start + len(content)))
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else:
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for child in _text_chunks(
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content,
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chunk_size=chunk_size,
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chunk_overlap=chunk_overlap,
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):
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if child.source_start is None or child.source_end is None:
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result.append(_unlocated_chunk(child.original_content))
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continue
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result.append(
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_make_text_chunk(
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normalized,
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start + child.source_start,
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start + child.source_end,
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)
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)
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search_from = start + len(content)
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return result
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def _nodes_to_chunks(nodes: list[Any], source_text: str) -> list[DocumentChunk]:
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chunks: list[DocumentChunk] = []
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search_from = 0
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for node in nodes:
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content = node.get_content().strip()
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if not content:
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continue
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raw_start = getattr(node, "start_char_idx", None)
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raw_end = getattr(node, "end_char_idx", None)
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if (
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isinstance(raw_start, int)
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and isinstance(raw_end, int)
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and source_text[raw_start:raw_end].strip() == content
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):
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start = raw_start + len(source_text[raw_start:raw_end]) - len(source_text[raw_start:raw_end].lstrip())
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else:
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start = _locate_text(source_text, content, search_from)
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if start is None:
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start = _locate_text(source_text, content, 0)
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if start is None:
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chunks.append(_unlocated_chunk(content))
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continue
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end = start + len(content)
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chunks.append(_make_text_chunk(source_text, start, end))
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search_from = max(search_from, end)
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return chunks
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def _locate_text(source: str, content: str, start: int) -> int | None:
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position = source.find(content, start)
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return position if position >= 0 else None
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def _unlocated_chunk(content: str) -> DocumentChunk:
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"""正文在源文本中定位失败时保底保留切片，只放弃行号信息。"""
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return DocumentChunk(
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original_content=content,
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contextualized_content=content,
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source_start=None,
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source_end=None,
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source_start_line=None,
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source_end_line=None,
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token_count=len(_tokenizer().encode(content)),
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)
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def _make_text_chunk(source: str, start: int, end: int) -> DocumentChunk:
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content = source[start:end]
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return DocumentChunk(
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original_content=content,
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contextualized_content=content,
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source_start=start,
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source_end=end,
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source_start_line=source.count("\n", 0, start) + 1,
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source_end_line=source.count("\n", 0, max(start, end - 1)) + 1,
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token_count=len(_tokenizer().encode(content)),
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)
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@lru_cache(maxsize=1)
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def _document_converter():
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from docling.datamodel.base_models import InputFormat
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from docling.datamodel.pipeline_options import PdfPipelineOptions
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from docling.document_converter import DocumentConverter, PdfFormatOption
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pipeline_options = PdfPipelineOptions()
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pipeline_options.do_ocr = False
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return DocumentConverter(
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format_options={
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InputFormat.PDF: PdfFormatOption(pipeline_options=pipeline_options),
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}
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)
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class _MarkdownSerializerProvider(ChunkingSerializerProvider):
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def get_serializer(self, doc: Any):
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from docling_core.transforms.chunker.hierarchical_chunker import ChunkingDocSerializer
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from docling_core.transforms.serializer.markdown import (
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MarkdownParams,
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MarkdownTableSerializer,
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)
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from docling_core.types.doc import DocItemLabel
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excluded = {
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DocItemLabel.DOCUMENT_INDEX,
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DocItemLabel.PAGE_HEADER,
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DocItemLabel.PAGE_FOOTER,
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}
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return ChunkingDocSerializer(
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doc=doc,
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table_serializer=MarkdownTableSerializer(),
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params=MarkdownParams(
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labels=set(DocItemLabel) - excluded,
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compact_tables=True,
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image_placeholder="",
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escape_html=False,
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escape_underscores=False,
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),
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)
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def _clean_layout_text(value: str) -> str:
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return normalize_text(_PAGE_FURNITURE.sub("", value)).strip()
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def _compact_with_offsets(value: str) -> tuple[str, list[int]]:
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compact: list[str] = []
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offsets: list[int] = []
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for index, character in enumerate(unicodedata.normalize("NFKC", value)):
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if _COMPACT_CHARACTER.fullmatch(character):
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compact.append(character.casefold())
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offsets.append(index)
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return "".join(compact), offsets
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def _expand_to_line_boundaries(source_text: str, start: int, end: int) -> tuple[int, int]:
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while start > 0 and source_text[start - 1] not in "\r\n":
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start -= 1
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while end < len(source_text) and source_text[end] not in "\r\n":
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end += 1
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return start, end
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def _project_layout_span(
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source_text: str,
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content: str,
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*,
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compact_source: str,
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source_offsets: list[int],
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compact_start: int,
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) -> tuple[int | None, int | None, int]:
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for candidate in (content, _LIST_MARKER_PREFIX.sub("", content)):
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compact_content, _ = _compact_with_offsets(candidate)
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if len(compact_content) < 4:
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continue
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position = compact_source.find(compact_content, compact_start)
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if position < 0:
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position = compact_source.find(compact_content)
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if position < 0:
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continue
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start, end = _expand_to_line_boundaries(
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source_text,
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source_offsets[position],
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source_offsets[position + len(compact_content) - 1] + 1,
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)
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# 重复内容回退匹配可能命中已消费的更早位置，游标只进不退，
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# 避免后续切片跟着错位。
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return start, end, max(compact_start, position + len(compact_content))
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return _project_layout_span_by_anchors(
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source_text,
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content,
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compact_source=compact_source,
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source_offsets=source_offsets,
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compact_start=compact_start,
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)
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def _project_layout_span_by_anchors(
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source_text: str,
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content: str,
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*,
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compact_source: str,
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source_offsets: list[int],
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compact_start: int,
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) -> tuple[int | None, int | None, int]:
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"""按行锚点顺序匹配，容忍切片里插入的重复表头等非连续内容。"""
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segments = [
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compact
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for compact in (
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_compact_with_offsets(line)[0]
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for line in _LIST_MARKER_PREFIX.sub("", content).split("\n")
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)
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if len(compact) >= 6
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]
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if not segments:
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return None, None, compact_start
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total = sum(len(segment) for segment in segments)
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def match_from(cursor: int) -> tuple[list[tuple[int, int]], int]:
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matched: list[tuple[int, int]] = []
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position = cursor
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for segment in segments:
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found = compact_source.find(segment, position)
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if found < 0:
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continue
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matched.append((found, found + len(segment)))
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position = found + len(segment)
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return matched, sum(end - start for start, end in matched)
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matched, covered = match_from(compact_start)
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if covered * 2 < total:
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retried, retry_covered = match_from(0)
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if retry_covered > covered:
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matched, covered = retried, retry_covered
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# 覆盖不足一半时宁可不定位，也不能给出错误的行号。
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if not matched or covered * 2 < total:
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return None, None, compact_start
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start, end = _expand_to_line_boundaries(
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source_text,
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source_offsets[matched[0][0]],
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source_offsets[matched[-1][1] - 1] + 1,
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)
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return start, end, max(compact_start, matched[-1][1])
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def chunk_layout_document(
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raw: bytes,
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*,
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filename: str,
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source_text: str,
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chunk_size: int,
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) -> list[DocumentChunk]:
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"""使用 Docling HybridChunker 按版面层级、列表与表格边界切分。"""
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from docling.chunking import HybridChunker
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from docling.datamodel.base_models import DocumentStream
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from docling.exceptions import BaseError as DoclingError
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from docling_core.transforms.chunker.tokenizer.openai import OpenAITokenizer
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from docling_core.types.doc import DocItemLabel
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try:
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with _CONVERTER_LOCK:
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conversion = _document_converter().convert(
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DocumentStream(name=filename, stream=BytesIO(raw))
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)
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except DoclingError as exc:
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raise ValueError(f"文档版面解析失败: {exc}") from exc
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chunker = HybridChunker(
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tokenizer=OpenAITokenizer(tokenizer=_tokenizer(), max_tokens=chunk_size),
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serializer_provider=_MarkdownSerializerProvider(),
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merge_peers=True,
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repeat_table_header=True,
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)
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compact_source, source_offsets = _compact_with_offsets(source_text)
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compact_start = 0
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result: list[DocumentChunk] = []
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excluded = {
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DocItemLabel.DOCUMENT_INDEX,
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DocItemLabel.PAGE_HEADER,
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DocItemLabel.PAGE_FOOTER,
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}
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for raw_chunk in chunker.chunk(conversion.document):
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doc_items = tuple(raw_chunk.meta.doc_items or ())
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if doc_items and all(item.label in excluded for item in doc_items):
|
||
continue
|
||
content = _clean_layout_text(raw_chunk.text)
|
||
if not content:
|
||
continue
|
||
contextualized = _clean_layout_text(chunker.contextualize(raw_chunk)) or content
|
||
start, end, compact_start = _project_layout_span(
|
||
source_text,
|
||
content,
|
||
compact_source=compact_source,
|
||
source_offsets=source_offsets,
|
||
compact_start=compact_start,
|
||
)
|
||
original = source_text[start:end] if start is not None and end is not None else content
|
||
pages: set[int] = set()
|
||
refs: list[str] = []
|
||
bboxes: list[dict[str, Any]] = []
|
||
for item in doc_items:
|
||
refs.append(str(item.self_ref))
|
||
for provenance in item.prov or ():
|
||
pages.add(int(provenance.page_no))
|
||
bbox = provenance.bbox
|
||
bboxes.append(
|
||
{
|
||
"page": int(provenance.page_no),
|
||
"left": float(bbox.l),
|
||
"top": float(bbox.t),
|
||
"right": float(bbox.r),
|
||
"bottom": float(bbox.b),
|
||
"origin": str(bbox.coord_origin.value),
|
||
}
|
||
)
|
||
result.append(
|
||
DocumentChunk(
|
||
original_content=original,
|
||
contextualized_content=contextualized,
|
||
source_start=start,
|
||
source_end=end,
|
||
source_start_line=(source_text.count("\n", 0, start) + 1 if start is not None else None),
|
||
source_end_line=(
|
||
source_text.count("\n", 0, max(start or 0, (end or 1) - 1)) + 1
|
||
if end is not None
|
||
else None
|
||
),
|
||
token_count=len(_tokenizer().encode(contextualized)),
|
||
heading_path=tuple(str(item) for item in (raw_chunk.meta.headings or ())),
|
||
source_pages=tuple(sorted(pages)),
|
||
doc_item_refs=tuple(refs),
|
||
source_bboxes=tuple(bboxes),
|
||
)
|
||
)
|
||
return result
|
||
|
||
|
||
def merge_short_chunks(
|
||
chunks: list[DocumentChunk],
|
||
*,
|
||
source_text: str,
|
||
min_token_count: int,
|
||
max_token_count: int,
|
||
) -> list[DocumentChunk]:
|
||
"""在不突破长度上限的前提下，把过短块并入相邻内容。"""
|
||
|
||
result: list[DocumentChunk] = []
|
||
index = 0
|
||
while index < len(chunks):
|
||
current = chunks[index]
|
||
if current.token_count >= min_token_count:
|
||
result.append(current)
|
||
index += 1
|
||
continue
|
||
if index + 1 < len(chunks):
|
||
combined = _combine_chunks(current, chunks[index + 1], source_text)
|
||
if combined.token_count <= max_token_count:
|
||
result.append(combined)
|
||
index += 2
|
||
continue
|
||
if result:
|
||
combined = _combine_chunks(result[-1], current, source_text)
|
||
if combined.token_count <= max_token_count:
|
||
result[-1] = combined
|
||
index += 1
|
||
continue
|
||
result.append(current)
|
||
index += 1
|
||
return result
|
||
|
||
|
||
def _combine_chunks(
|
||
left: DocumentChunk,
|
||
right: DocumentChunk,
|
||
source_text: str,
|
||
) -> DocumentChunk:
|
||
contextualized = "\n\n".join(
|
||
part for part in (left.contextualized_content, right.contextualized_content) if part
|
||
)
|
||
start = left.source_start
|
||
end = right.source_end
|
||
has_contiguous_source = (
|
||
start is not None
|
||
and left.source_end is not None
|
||
and right.source_start is not None
|
||
and end is not None
|
||
and left.source_end <= right.source_start
|
||
)
|
||
original = (
|
||
source_text[start:end]
|
||
if has_contiguous_source and start is not None and end is not None
|
||
else "\n\n".join(
|
||
part for part in (left.original_content, right.original_content) if part
|
||
)
|
||
)
|
||
if not has_contiguous_source:
|
||
start = None
|
||
end = None
|
||
return DocumentChunk(
|
||
original_content=original,
|
||
contextualized_content=contextualized,
|
||
source_start=start,
|
||
source_end=end,
|
||
source_start_line=left.source_start_line if start is not None else None,
|
||
source_end_line=right.source_end_line if end is not None else None,
|
||
token_count=len(_tokenizer().encode(contextualized)),
|
||
heading_path=left.heading_path or right.heading_path,
|
||
source_pages=tuple(sorted(set(left.source_pages) | set(right.source_pages))),
|
||
doc_item_refs=left.doc_item_refs + right.doc_item_refs,
|
||
source_bboxes=left.source_bboxes + right.source_bboxes,
|
||
)
|