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1"""
2Module containing a preprocessor that removes cells if they match
3one or more regular expression.
4"""
6# Copyright (c) IPython Development Team.
7# Distributed under the terms of the Modified BSD License.
8from __future__ import annotations
10import re
12from traitlets import List, Unicode
14from .base import Preprocessor
17class RegexRemovePreprocessor(Preprocessor):
18 """
19 Removes cells from a notebook that match one or more regular expression.
21 For each cell, the preprocessor checks whether its contents match
22 the regular expressions in the ``patterns`` traitlet which is a list
23 of unicode strings. If the contents match any of the patterns, the cell
24 is removed from the notebook.
26 To modify the list of matched patterns,
27 modify the patterns traitlet. For example, execute the following command
28 to convert a notebook to html and remove cells containing only whitespace::
30 jupyter nbconvert --RegexRemovePreprocessor.patterns="['\\s*\\Z']" mynotebook.ipynb
32 The command line argument
33 sets the list of patterns to ``'\\s*\\Z'`` which matches an arbitrary number
34 of whitespace characters followed by the end of the string.
36 See https://regex101.com/ for an interactive guide to regular expressions
37 (make sure to select the python flavor). See
38 https://docs.python.org/library/re.html for the official regular expression
39 documentation in python.
40 """
42 patterns = List(Unicode()).tag(config=True)
44 def check_conditions(self, cell):
45 """
46 Checks that a cell matches the pattern.
48 Returns: Boolean.
49 True means cell should *not* be removed.
50 """
52 # Compile all the patterns into one: each pattern is first wrapped
53 # by a non-capturing group to ensure the correct order of precedence
54 # and the patterns are joined with a logical or
55 pattern = re.compile("|".join("(?:%s)" % pattern for pattern in self.patterns))
57 # Filter out cells that meet the pattern and have no outputs
58 return not pattern.match(cell.source)
60 def preprocess(self, nb, resources):
61 """
62 Preprocessing to apply to each notebook. See base.py for details.
63 """
64 # Skip preprocessing if the list of patterns is empty
65 if not self.patterns:
66 return nb, resources
68 # Filter out cells that meet the conditions
69 nb.cells = [cell for cell in nb.cells if self.check_conditions(cell)]
71 return nb, resources