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from __future__ import unicode_literals
import re
class _WriterOutput(object):
def __init__(self, start, end, anchor_position=None):
self.start = start
self.end = end
self.anchor_position = anchor_position
def _symmetric_wrapped(end):
return _Wrapped(end, end)
class _Wrapped(object):
def __init__(self, start, end):
self._start = start
self._end = end
def __call__(self, attributes):
return _WriterOutput(self._start, self._end)
def _hyperlink(attributes):
href = attributes.get("href", "")
if href:
return _WriterOutput(
"[", "]({0})".format(href),
anchor_position="before",
)
else:
return _default_output
def _image(attributes):
src = attributes.get("src", "")
alt_text = attributes.get("alt", "")
return _WriterOutput("".format(alt_text, src), "")
def _init_writers():
writers = {
"p": _Wrapped("", "\n\n"),
"br": _Wrapped("", " \n"),
"strong": _symmetric_wrapped("__"),
"em": _symmetric_wrapped("*"),
"a": _hyperlink,
"img": _image,
}
for level in range(1, 7):
writers["h{0}".format(level)] = _Wrapped("#" * level + " ", "\n\n")
return writers
_writers = _init_writers()
_default_output = _WriterOutput("", "")
_default_writer = lambda attributes: _default_output
class MarkdownWriter(object):
def __init__(self):
self._fragments = []
self._element_stack = []
def text(self, text):
self._fragments.append(_escape_markdown(text))
def start(self, name, attributes=None):
if attributes is None:
attributes = {}
output = _writers.get(name, _default_writer)(attributes)
anchor_before_start = output.anchor_position == "before"
if anchor_before_start:
self._write_anchor(attributes)
self._fragments.append(output.start)
if not anchor_before_start:
self._write_anchor(attributes)
self._element_stack.append(output.end)
def end(self, name):
end = self._element_stack.pop()
self._fragments.append(end)
def self_closing(self, name, attributes=None):
self.start(name, attributes)
self.end(name)
def append(self, other):
self._fragments.append(other)
def as_string(self):
return "".join(self._fragments)
def _write_anchor(self, attributes):
html_id = attributes.get("id")
if html_id:
self._fragments.append('<a id="{0}"></a>'.format(html_id))
def _escape_markdown(value):
return re.sub(r"([\`\*_\{\}\[\]\(\)\#\+\-\.\!])", r"\\\1", re.sub("\\\\", "\\\\\\\\", value))
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