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from __future__ import annotations
import dataclasses as dc
import html
import itertools
from typing import cast, get_args, Iterable, Literal, Sequence
from markdown_it.token import Token
from .utils import Freezeable
# FragmentType is used to restrict structural include blocks.
FragmentType = Literal['preface', 'part', 'chapter', 'section', 'appendix']
# in the TOC all fragments are allowed, plus the all-encompassing book.
TocEntryType = Literal['book', 'preface', 'part', 'chapter', 'section', 'appendix', 'example', 'figure']
def is_include(token: Token) -> bool:
return token.type == "fence" and token.info.startswith("{=include=} ")
# toplevel file must contain only the title headings and includes, anything else
# would cause strange rendering.
def _check_book_structure(tokens: Sequence[Token]) -> None:
for token in tokens[6:]:
if not is_include(token):
assert token.map
raise RuntimeError(f"unexpected content in line {token.map[0] + 1}, "
"expected structural include")
# much like books, parts may not contain headings other than their title heading.
# this is a limitation of the current renderers and TOC generators that do not handle
# this case well even though it is supported in docbook (and probably supportable
# anywhere else).
def _check_part_structure(tokens: Sequence[Token]) -> None:
_check_fragment_structure(tokens)
for token in tokens[3:]:
if token.type == 'heading_open':
assert token.map
raise RuntimeError(f"unexpected heading in line {token.map[0] + 1}")
# two include blocks must either be adjacent or separated by a heading, otherwise
# we cannot generate a correct TOC (since there'd be nothing to link to between
# the two includes).
def _check_fragment_structure(tokens: Sequence[Token]) -> None:
for i, token in enumerate(tokens):
if is_include(token) \
and i + 1 < len(tokens) \
and not (is_include(tokens[i + 1]) or tokens[i + 1].type == 'heading_open'):
assert token.map
raise RuntimeError(f"unexpected content in line {token.map[0] + 1}, "
"expected heading or structural include")
def check_structure(kind: TocEntryType, tokens: Sequence[Token]) -> None:
wanted = { 'h1': 'title' }
wanted |= { 'h2': 'subtitle' } if kind == 'book' else {}
for (i, (tag, role)) in enumerate(wanted.items()):
if len(tokens) < 3 * (i + 1):
raise RuntimeError(f"missing {role} ({tag}) heading")
token = tokens[3 * i]
if token.type != 'heading_open' or token.tag != tag:
assert token.map
raise RuntimeError(f"expected {role} ({tag}) heading in line {token.map[0] + 1}", token)
for t in tokens[3 * len(wanted):]:
if t.type != 'heading_open' or not (role := wanted.get(t.tag, '')):
continue
assert t.map
raise RuntimeError(
f"only one {role} heading ({t.markup} [text...]) allowed per "
f"{kind}, but found a second in line {t.map[0] + 1}. "
"please remove all such headings except the first or demote the subsequent headings.",
t)
last_heading_level = 0
for token in tokens:
if token.type != 'heading_open':
continue
# book subtitle headings do not need an id, only book title headings do.
# every other headings needs one too. we need this to build a TOC and to
# provide stable links if the manual changes shape.
if 'id' not in token.attrs and (kind != 'book' or token.tag != 'h2'):
assert token.map
raise RuntimeError(f"heading in line {token.map[0] + 1} does not have an id")
level = int(token.tag[1:]) # because tag = h1..h6
if level > last_heading_level + 1:
assert token.map
raise RuntimeError(f"heading in line {token.map[0] + 1} skips one or more heading levels, "
"which is currently not allowed")
last_heading_level = level
if kind == 'book':
_check_book_structure(tokens)
elif kind == 'part':
_check_part_structure(tokens)
else:
_check_fragment_structure(tokens)
@dc.dataclass(frozen=True)
class XrefTarget:
id: str
"""link label for `[](#local-references)`"""
title_html: str
"""toc label"""
toc_html: str | None
"""text for `<title>` tags and `title="..."` attributes"""
title: str | None
"""path to file that contains the anchor"""
path: str
"""whether to drop the `#anchor` from links when expanding xrefs"""
drop_fragment: bool = False
"""whether to drop the `path.html` from links when expanding xrefs.
mostly useful for docbook compatibility"""
drop_target: bool = False
def href(self) -> str:
path = "" if self.drop_target else html.escape(self.path, True)
return path if self.drop_fragment else f"{path}#{html.escape(self.id, True)}"
@dc.dataclass
class TocEntry(Freezeable):
kind: TocEntryType
target: XrefTarget
parent: TocEntry | None = None
prev: TocEntry | None = None
next: TocEntry | None = None
children: list[TocEntry] = dc.field(default_factory=list)
starts_new_chunk: bool = False
examples: list[TocEntry] = dc.field(default_factory=list)
figures: list[TocEntry] = dc.field(default_factory=list)
@property
def root(self) -> TocEntry:
return self.parent.root if self.parent else self
@classmethod
def of(cls, token: Token) -> TocEntry:
entry = token.meta.get('TocEntry')
if not isinstance(entry, TocEntry):
raise RuntimeError('requested toc entry, none found', token)
return entry
@classmethod
def collect_and_link(cls, xrefs: dict[str, XrefTarget], tokens: Sequence[Token]) -> TocEntry:
entries, examples, figures = cls._collect_entries(xrefs, tokens, 'book')
def flatten_with_parent(this: TocEntry, parent: TocEntry | None) -> Iterable[TocEntry]:
this.parent = parent
return itertools.chain([this], *[ flatten_with_parent(c, this) for c in this.children ])
flat = list(flatten_with_parent(entries, None))
prev = flat[0]
prev.starts_new_chunk = True
paths_seen = set([prev.target.path])
for c in flat[1:]:
if prev.target.path != c.target.path and c.target.path not in paths_seen:
c.starts_new_chunk = True
c.prev, prev.next = prev, c
prev = c
paths_seen.add(c.target.path)
flat[0].examples = examples
flat[0].figures = figures
for c in flat:
c.freeze()
return entries
@classmethod
def _collect_entries(cls, xrefs: dict[str, XrefTarget], tokens: Sequence[Token],
kind: TocEntryType) -> tuple[TocEntry, list[TocEntry], list[TocEntry]]:
# we assume that check_structure has been run recursively over the entire input.
# list contains (tag, entry) pairs that will collapse to a single entry for
# the full sequence.
entries: list[tuple[str, TocEntry]] = []
examples: list[TocEntry] = []
figures: list[TocEntry] = []
for token in tokens:
if token.type.startswith('included_') and (included := token.meta.get('included')):
fragment_type_str = token.type[9:].removesuffix('s')
assert fragment_type_str in get_args(TocEntryType)
fragment_type = cast(TocEntryType, fragment_type_str)
for fragment, _path in included:
subentries, subexamples, subfigures = cls._collect_entries(xrefs, fragment, fragment_type)
entries[-1][1].children.append(subentries)
examples += subexamples
figures += subfigures
elif token.type == 'heading_open' and (id := cast(str, token.attrs.get('id', ''))):
while len(entries) > 1 and entries[-1][0] >= token.tag:
entries[-2][1].children.append(entries.pop()[1])
entries.append((token.tag,
TocEntry(kind if token.tag == 'h1' else 'section', xrefs[id])))
token.meta['TocEntry'] = entries[-1][1]
elif token.type == 'example_open' and (id := cast(str, token.attrs.get('id', ''))):
examples.append(TocEntry('example', xrefs[id]))
elif token.type == 'figure_open' and (id := cast(str, token.attrs.get('id', ''))):
figures.append(TocEntry('figure', xrefs[id]))
while len(entries) > 1:
entries[-2][1].children.append(entries.pop()[1])
return (entries[0][1], examples, figures)
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