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Bebop/bebop/gemtext.py

122 lines
2.9 KiB
Python

"""Gemtext parser.
To allow a flexible rendering of the content, the parser produces a list of
"elements", each being an instance of one of the dataclasses defined in this
module. A renderer can then completely abstract the original document.
"""
import re
from collections import namedtuple
from dataclasses import dataclass
from typing import List
from bebop.links import Links
@dataclass
class Paragraph:
text: str
@dataclass
class Title:
level: int
text: str
RE = re.compile(r"(#{1,3})\s+(.+)")
@dataclass
class Link:
url: str
text: str
ident: int = 0
RE = re.compile(r"=>\s*(?P<url>\S+)(\s+(?P<text>.+))?")
@dataclass
class Preformatted:
lines: List[str]
FENCE = "```"
@dataclass
class Blockquote:
text: str
RE = re.compile(r">\s*(.*)")
@dataclass
class ListItem:
text: str
RE = re.compile(r"\*\s(.*)")
ParsedGemtext = namedtuple("ParsedGemtext", ("elements", "links", "title"))
def parse_gemtext(text: str, dumb=False) -> ParsedGemtext:
"""Parse a string of Gemtext into a list of elements."""
elements = []
links = Links()
last_link_id = 0
title = ""
preformatted = None
for line in text.splitlines():
line = line.rstrip()
# Empty lines:
# - in standard mode, discard them, except for preformatted blocks.
# - in dumb mode, keep them.
if not line and not (dumb or preformatted):
continue
if line.startswith(Preformatted.FENCE):
if preformatted:
elements.append(preformatted)
preformatted = None
else:
preformatted = Preformatted([])
continue
if preformatted:
preformatted.lines.append(line)
continue
match = Title.RE.match(line)
if match:
hashtags, text = match.groups()
level = hashtags.count("#")
elements.append(Title(level, text))
if not title and level == 1:
title = text
continue
match = Link.RE.match(line)
if match:
match_dict = match.groupdict()
url, text = match_dict["url"], match_dict.get("text", "")
last_link_id += 1
links[last_link_id] = url
elements.append(Link(url, text, last_link_id))
continue
match = Blockquote.RE.match(line)
if match:
text = match.groups()[0]
elements.append(Blockquote(text))
continue
match = ListItem.RE.match(line)
if match:
text = match.groups()[0]
elements.append(ListItem(text))
continue
elements.append(Paragraph(line))
# If a preformatted block is not closed before the file ends, consider it
# closed anyway; the spec does not seem to talk about that case.
if preformatted:
elements.append(preformatted)
return ParsedGemtext(elements, links, title)