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