Files
ragflow/rag/app/manual.py
Rodger Blom d8cefcf052 feat: add native Dutch language support for BM25 tokenization (#14140)
## Summary
- Add language-aware Snowball stemmer to `RagTokenizer` supporting 16
languages (Dutch, German, French, Spanish, etc.)
- Thread the KB `language` parameter through the full tokenization
pipeline (14 parser modules + task executor)
- Add Dutch to the frontend language lists and cross-language form

## Problem
RAGFlow uses the English Porter stemmer + WordNet lemmatizer for **all**
BM25 tokenization, regardless of the knowledge base language setting.
This produces incorrect stems for non-English text. For example:

| Dutch word | Dutch stemmer | English Porter |
|---|---|---|
| documenten | document | documenten (unchanged!) |
| gebruikers | gebruiker | gebruik (over-stemmed) |
| instellingen | instell | instellingen (unchanged!) |

This degrades BM25 recall for any non-English knowledge base.

## Solution
NLTK already ships Snowball stemmers for 16 languages. This PR:

1. **`rag/nlp/rag_tokenizer.py`**: Overrides `tokenize()` with
`set_language()` and `_normalize_token()` that selects the correct NLTK
Snowball stemmer. Falls back to Porter for unmapped languages (Chinese,
Japanese, Korean, etc. — these use character-based tokenization anyway).
2. **`rag/nlp/__init__.py`** + **14 `rag/app/*.py` parsers** +
**`rag/svr/task_executor.py`**: Threads the `language` parameter through
`tokenize()`, `tokenize_chunks()`, `tokenize_table()`, and all callers.
3. **Frontend**: Adds Dutch (`Nederlands`) to `LanguageList`,
`LanguageMap`, `LanguageAbbreviationMap`, `LanguageTranslationMap`,
cross-language form field, and `en.ts` locale.

## Backward Compatibility
- Default language is `"English"`, preserving existing behavior for all
current users
- Languages without a Snowball stemmer mapping fall back to Porter (no
change)
- No new dependencies — NLTK Snowball is already bundled
2026-07-06 23:39:56 +08:00

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#
# 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.
#
import logging
import copy
import re
from common.constants import ParserType, MAXIMUM_PAGE_NUMBER
from io import BytesIO
from deepdoc.parser.utils import extract_pdf_outlines
from rag.nlp import rag_tokenizer, tokenize, tokenize_table, bullets_category, title_frequency, tokenize_chunks, docx_question_level, attach_media_context, concat_img
from common.token_utils import num_tokens_from_string
from deepdoc.parser import PdfParser, DocxParser
from deepdoc.parser.figure_parser import vision_figure_parser_pdf_wrapper, vision_figure_parser_docx_wrapper
from docx import Document
from rag.app.naive import by_plaintext, PARSERS
from common.parser_config_utils import normalize_layout_recognizer
class Pdf(PdfParser):
def __init__(self):
self.model_species = ParserType.MANUAL.value
super().__init__()
def __call__(self, filename, binary=None, from_page=0, to_page=MAXIMUM_PAGE_NUMBER, zoomin=3, callback=None):
from timeit import default_timer as timer
start = timer()
callback(msg="OCR started")
self.__images__(filename if not binary else binary, zoomin, from_page, to_page, callback)
callback(msg="OCR finished ({:.2f}s)".format(timer() - start))
logging.debug("OCR: {}".format(timer() - start))
start = timer()
self._layouts_rec(zoomin)
callback(0.65, "Layout analysis ({:.2f}s)".format(timer() - start))
logging.debug("layouts: {}".format(timer() - start))
start = timer()
self._table_transformer_job(zoomin)
callback(0.67, "Table analysis ({:.2f}s)".format(timer() - start))
start = timer()
self._text_merge()
tbls = self._extract_table_figure(True, zoomin, True, True)
self._concat_downward()
self._filter_forpages()
callback(0.68, "Text merged ({:.2f}s)".format(timer() - start))
# clean mess
for b in self.boxes:
b["text"] = re.sub(r"([\t  ]|\u3000){2,}", " ", b["text"].strip())
return [(b["text"], b.get("layoutno", ""), self.get_position(b, zoomin)) for i, b in enumerate(self.boxes)], tbls
class Docx(DocxParser):
def __init__(self):
pass
def __call__(self, filename, binary=None, from_page=0, to_page=MAXIMUM_PAGE_NUMBER, callback=None):
self.doc = Document(filename) if not binary else Document(BytesIO(binary))
pn = 0
last_answer, last_image = "", None
question_stack, level_stack = [], []
ti_list = []
for p in self.doc.paragraphs:
if pn > to_page:
break
question_level, p_text = 0, ""
if from_page <= pn < to_page and p.text.strip():
question_level, p_text = docx_question_level(p)
if not question_level or question_level > 6: # not a question
last_answer = f"{last_answer}\n{p_text}"
current_image = self.get_picture(self.doc, p)
last_image = concat_img(last_image, current_image)
else: # is a question
if last_answer or last_image:
sum_question = "\n".join(question_stack)
if sum_question:
ti_list.append((f"{sum_question}\n{last_answer}", last_image))
last_answer, last_image = "", None
i = question_level
while question_stack and i <= level_stack[-1]:
question_stack.pop()
level_stack.pop()
question_stack.append(p_text)
level_stack.append(question_level)
for run in p.runs:
if "lastRenderedPageBreak" in run._element.xml:
pn += 1
continue
if "w:br" in run._element.xml and 'type="page"' in run._element.xml:
pn += 1
if last_answer:
sum_question = "\n".join(question_stack)
if sum_question:
ti_list.append((f"{sum_question}\n{last_answer}", last_image))
tbls = []
for tb in self.doc.tables:
html = "<table>"
for r in tb.rows:
html += "<tr>"
i = 0
while i < len(r.cells):
span = 1
c = r.cells[i]
for j in range(i + 1, len(r.cells)):
if c.text == r.cells[j].text:
span += 1
i = j
else:
break
i += 1
html += f"<td>{c.text}</td>" if span == 1 else f"<td colspan='{span}'>{c.text}</td>"
html += "</tr>"
html += "</table>"
tbls.append(((None, html), ""))
return ti_list, tbls
def chunk(filename, binary=None, from_page=0, to_page=MAXIMUM_PAGE_NUMBER, lang="Chinese", callback=None, **kwargs):
"""
Only pdf is supported.
"""
parser_config = kwargs.get("parser_config", {"chunk_token_num": 512, "delimiter": "\n!?。;!?", "layout_recognize": "DeepDOC"})
pdf_parser = None
doc = {"docnm_kwd": filename}
doc["title_tks"] = rag_tokenizer.tokenize(re.sub(r"\.[a-zA-Z]+$", "", doc["docnm_kwd"]))
doc["title_sm_tks"] = rag_tokenizer.fine_grained_tokenize(doc["title_tks"])
# is it English
eng = lang.lower() == "english" # pdf_parser.is_english
if re.search(r"\.pdf$", filename, re.IGNORECASE):
layout_recognizer, parser_model_name = normalize_layout_recognizer(parser_config.get("layout_recognize", "DeepDOC"))
if isinstance(layout_recognizer, bool):
layout_recognizer = "DeepDOC" if layout_recognizer else "Plain Text"
name = layout_recognizer.strip().lower()
pdf_parser = PARSERS.get(name, by_plaintext)
callback(0.1, "Start to parse.")
kwargs.pop("parse_method", None)
kwargs.pop("mineru_llm_name", None)
sections, tbls, pdf_parser = pdf_parser(
filename=filename,
binary=binary,
from_page=from_page,
to_page=to_page,
lang=lang,
callback=callback,
pdf_cls=Pdf,
layout_recognizer=layout_recognizer,
mineru_llm_name=parser_model_name,
paddleocr_llm_name=parser_model_name,
parse_method="manual",
**kwargs,
)
def _normalize_section(section):
# pad section to length 3: (txt, sec_id, poss)
if len(section) == 1:
section = (section[0], "", [])
elif len(section) == 2:
section = (section[0], "", section[1])
elif len(section) != 3:
raise ValueError(f"Unexpected section length: {len(section)} (value={section!r})")
txt, layoutno, poss = section
if isinstance(poss, str):
poss = getattr(pdf_parser, "extract_positions", lambda _: [])(poss) or [[0, 0, 0, 0, 0]]
if poss:
first = poss[0] # tuple: ([pn], x1, x2, y1, y2)
pn = first[0]
if isinstance(pn, list) and pn:
pn = pn[0] # [pn] -> pn
poss[0] = (pn, *first[1:])
return (txt, layoutno, poss)
sections = [_normalize_section(sec) for sec in sections]
if not sections and not tbls:
return []
if name in ["tcadp", "docling", "mineru", "paddleocr"]:
parser_config["chunk_token_num"] = 0
callback(0.8, "Finish parsing.")
outlines = extract_pdf_outlines(binary if binary is not None else filename)
if len(sections) > 0 and len(outlines) / len(sections) > 0.03:
max_lvl = max([lvl for _, lvl, _ in outlines])
most_level = max(0, max_lvl - 1)
levels = []
for txt, _, _ in sections:
for t, lvl, _ in outlines:
tks = set([t[i] + t[i + 1] for i in range(len(t) - 1)])
tks_ = set([txt[i] + txt[i + 1] for i in range(min(len(t), len(txt) - 1))])
if len(set(tks & tks_)) / max([len(tks), len(tks_), 1]) > 0.8:
levels.append(lvl)
break
else:
levels.append(max_lvl + 1)
else:
bull = bullets_category([txt for txt, _, _ in sections])
most_level, levels = title_frequency(bull, [(txt, lvl) for txt, lvl, _ in sections])
assert len(sections) == len(levels)
sec_ids = []
sid = 0
for i, lvl in enumerate(levels):
if lvl <= most_level and i > 0 and lvl != levels[i - 1]:
sid += 1
sec_ids.append(sid)
sections = [(txt, sec_ids[i], poss) for i, (txt, _, poss) in enumerate(sections)]
for (img, rows), poss in tbls:
if not rows:
continue
sections.append((rows if isinstance(rows, str) else rows[0], -1, [(p[0] + 1 - from_page, p[1], p[2], p[3], p[4]) for p in poss]))
def tag(pn, left, right, top, bottom):
if pn + left + right + top + bottom == 0:
return ""
return "@@{}\t{:.1f}\t{:.1f}\t{:.1f}\t{:.1f}##".format(pn, left, right, top, bottom)
chunks = []
last_sid = -2
tk_cnt = 0
for txt, sec_id, poss in sorted(sections, key=lambda x: (x[-1][0][0], x[-1][0][3], x[-1][0][1])):
poss = "\t".join([tag(*pos) for pos in poss])
if tk_cnt < 32 or (tk_cnt < 1024 and (sec_id == last_sid or sec_id == -1)):
if chunks:
chunks[-1] += "\n" + txt + poss
tk_cnt += num_tokens_from_string(txt)
continue
chunks.append(txt + poss)
tk_cnt = num_tokens_from_string(txt)
if sec_id > -1:
last_sid = sec_id
tbls = vision_figure_parser_pdf_wrapper(
tbls=tbls,
sections=sections,
callback=callback,
**kwargs,
)
res = tokenize_table(tbls, doc, eng, language=lang)
res.extend(tokenize_chunks(chunks, doc, eng, pdf_parser, language=lang))
table_ctx = max(0, int(parser_config.get("table_context_size", 0) or 0))
image_ctx = max(0, int(parser_config.get("image_context_size", 0) or 0))
if table_ctx or image_ctx:
attach_media_context(res, table_ctx, image_ctx)
if res and pdf_parser and getattr(pdf_parser, "outlines", None):
res[0]["__outline__"] = [{"title": title, "depth": depth} for title, depth, *_ in pdf_parser.outlines]
return res
elif re.search(r"\.docx?$", filename, re.IGNORECASE):
docx_parser = Docx()
ti_list, tbls = docx_parser(filename, binary, from_page=0, to_page=MAXIMUM_PAGE_NUMBER, callback=callback)
tbls = vision_figure_parser_docx_wrapper(sections=ti_list, tbls=tbls, callback=callback, **kwargs)
res = tokenize_table(tbls, doc, eng, language=lang)
for text, image in ti_list:
d = copy.deepcopy(doc)
if image:
d["image"] = image
d["doc_type_kwd"] = "image"
tokenize(d, text, eng, language=lang)
res.append(d)
table_ctx = max(0, int(parser_config.get("table_context_size", 0) or 0))
image_ctx = max(0, int(parser_config.get("image_context_size", 0) or 0))
if table_ctx or image_ctx:
attach_media_context(res, table_ctx, image_ctx)
return res
else:
raise NotImplementedError("file type not supported yet(pdf and docx supported)")
if __name__ == "__main__":
import sys
def dummy(prog=None, msg=""):
pass
chunk(sys.argv[1], callback=dummy)