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138 lines
4.3 KiB
138 lines
4.3 KiB
"""Utility for calling pandoc"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import print_function, absolute_import
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import subprocess
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import warnings
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import re
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from io import TextIOWrapper, BytesIO
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from nbconvert.utils.version import check_version
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import shutil
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from .exceptions import ConversionException
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_minimal_version = "1.12.1"
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_maximal_version = "3.0.0"
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def pandoc(source, fmt, to, extra_args=None, encoding='utf-8'):
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"""Convert an input string using pandoc.
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Pandoc converts an input string `from` a format `to` a target format.
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Parameters
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----------
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source : string
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Input string, assumed to be valid format `from`.
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fmt : string
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The name of the input format (markdown, etc.)
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to : string
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The name of the output format (html, etc.)
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Returns
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-------
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out : unicode
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Output as returned by pandoc.
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Raises
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------
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PandocMissing
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If pandoc is not installed.
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Any error messages generated by pandoc are printed to stderr.
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"""
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cmd = ['pandoc', '-f', fmt, '-t', to]
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if extra_args:
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cmd.extend(extra_args)
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# this will raise an exception that will pop us out of here
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check_pandoc_version()
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# we can safely continue
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p = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
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out, _ = p.communicate(source.encode())
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out = TextIOWrapper(BytesIO(out), encoding, 'replace').read()
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return out.rstrip('\n')
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def get_pandoc_version():
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"""Gets the Pandoc version if Pandoc is installed.
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If the minimal version is not met, it will probe Pandoc for its version, cache it and return that value.
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If the minimal version is met, it will return the cached version and stop probing Pandoc
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(unless `clean_cache()` is called).
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Raises
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------
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PandocMissing
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If pandoc is unavailable.
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"""
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global __version
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if __version is None:
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if not shutil.which('pandoc'):
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raise PandocMissing()
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out = subprocess.check_output(['pandoc', '-v'])
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out_lines = out.splitlines()
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version_pattern = re.compile(r"^\d+(\.\d+){1,}$")
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for tok in out_lines[0].decode('ascii', 'replace').split():
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if version_pattern.match(tok):
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__version = tok
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break
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return __version
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def check_pandoc_version():
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"""Returns True if pandoc's version meets at least minimal version.
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Raises
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------
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PandocMissing
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If pandoc is unavailable.
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"""
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if check_pandoc_version._cached is not None:
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return check_pandoc_version._cached
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v = get_pandoc_version()
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if v is None:
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warnings.warn("Sorry, we cannot determine the version of pandoc.\n"
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"Please consider reporting this issue and include the"
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"output of pandoc --version.\nContinuing...",
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RuntimeWarning, stacklevel=2)
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return False
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ok = check_version(v, _minimal_version, max_v=_maximal_version)
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check_pandoc_version._cached = ok
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if not ok:
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warnings.warn( "You are using an unsupported version of pandoc (%s).\n" % v +
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"Your version must be at least (%s) " % _minimal_version +
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"but less than (%s).\n" % _maximal_version +
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"Refer to https://pandoc.org/installing.html.\nContinuing with doubts...",
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RuntimeWarning, stacklevel=2)
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return ok
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check_pandoc_version._cached = None
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#-----------------------------------------------------------------------------
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# Exception handling
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#-----------------------------------------------------------------------------
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class PandocMissing(ConversionException):
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"""Exception raised when Pandoc is missing."""
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def __init__(self, *args, **kwargs):
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super().__init__( "Pandoc wasn't found.\n" +
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"Please check that pandoc is installed:\n" +
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"https://pandoc.org/installing.html" )
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#-----------------------------------------------------------------------------
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# Internal state management
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#-----------------------------------------------------------------------------
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def clean_cache():
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global __version
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__version = None
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__version = None
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