Method _parse_example

Lib/doctest.py:722–764

Given a regular expression match from `_EXAMPLE_RE` (`m`), return a pair `(source, want)`, where `source` is the matched example's source code (with prompts and indentation stripped); and `want` is the example's expected output (with indentation stripped).

(self, m, name, lineno)

                if isinstance(x, Example)]

    def _parse_example(self, m, name, lineno):
        """
        Given a regular expression match from `_EXAMPLE_RE` (`m`),
        return a pair `(source, want)`, where `source` is the matched
        example's source code (with prompts and indentation stripped);
        and `want` is the example's expected output (with indentation
        stripped).

        `name` is the string's name, and `lineno` is the line number
        where the example starts; both are used for error messages.
        """
        # Get the example's indentation level.
        indent = len(m.group('indent'))

        # Divide source into lines; check that they're properly
        # indented; and then strip their indentation & prompts.
        source_lines = m.group('source').split('\n')
        self._check_prompt_blank(source_lines, indent, name, lineno)
        self._check_prefix(source_lines[1:], ' '*indent + '.', name, lineno)
        source = '\n'.join([sl[indent+4:] for sl in source_lines])

        # Divide want into lines; check that it's properly indented; and
        # then strip the indentation.  Spaces before the last newline should
        # be preserved, so plain rstrip() isn't good enough.
        want = m.group('want')
        want_lines = want.split('\n')
        if len(want_lines) > 1 and re.match(r' *$', want_lines[-1]):
            del want_lines[-1]  # forget final newline & spaces after it
        self._check_prefix(want_lines, ' '*indent, name,
                           lineno + len(source_lines))
        want = '\n'.join([wl[indent:] for wl in want_lines])

        # If `want` contains a traceback message, then extract it.
        m = self._EXCEPTION_RE.match(want)
        if m:
            exc_msg = m.group('msg')
        else:
            exc_msg = None

        # Extract options from the source.
        options = self._find_options(source, name, lineno)

        return source, options, want, exc_msg

    # This regular expression looks for option directives in the
    # source code of an example.  Option directives are comments