Method _parseHeader

markdown/extensions/codehilite.py:194–247

Determines language of a code block from shebang line and whether the said line should be removed or left in place. If the shebang line contains a path (even a single /) then it is assumed to be a real shebang line and left alone. However, if no path is given

(self)

            )

    def _parseHeader(self) -> None:
        """
        Determines language of a code block from shebang line and whether the
        said line should be removed or left in place. If the shebang line
        contains a path (even a single /) then it is assumed to be a real
        shebang line and left alone. However, if no path is given
        (e.i.: `#!python` or `:::python`) then it is assumed to be a mock shebang
        for language identification of a code fragment and removed from the
        code block prior to processing for code highlighting. When a mock
        shebang (e.i: `#!python`) is found, line numbering is turned on. When
        colons are found in place of a shebang (e.i.: `:::python`), line
        numbering is left in the current state - off by default.

        Also parses optional list of highlight lines, like:

            :::python hl_lines="1 3"
        """

        import re

        # split text into lines
        lines = self.src.split("\n")
        # pull first line to examine
        fl = lines.pop(0)

        c = re.compile(r'''
            (?:(?:^::+)|(?P<shebang>^[#]!)) # Shebang or 2 or more colons
            (?P<path>(?:/\w+)*[/ ])?        # Zero or 1 path
            (?P<lang>[\w#.+-]*)             # The language
            \s*                             # Arbitrary whitespace
            # Optional highlight lines, single- or double-quote-delimited
            (hl_lines=(?P<quot>"|&#x27;)(?P<hl_lines>.*?)(?P=quot))?
            ''&#x27;,  re.VERBOSE)
        # search first line for shebang
        m = c.search(fl)
        if m:
            # we have a match
            try:
                self.lang = m.group('lang').lower()
            except IndexError:  # pragma: no cover
                self.lang = None
            if m.group('path'):
                # path exists - restore first line
                lines.insert(0, fl)
            if self.options['linenos'] is None and m.group('shebang'):
                # Overridable and Shebang exists - use line numbers
                self.options['linenos'] = True

            self.options['hl_lines'] = parse_hl_lines(m.group('hl_lines'))
        else:
            # No match
            lines.insert(0, fl)

        self.src = "\n".join(lines).strip("\n")


# ------------------ The Markdown Extension -------------------------------