"""A tree representation of a linear markdown-it token stream.
This module is not part of upstream JavaScript markdown-it.
"""
from __future__ import annotations
from collections.abc import Generator, Sequence
import textwrap
from typing import Any, NamedTuple, TypeVar, overload
from .token import Token
class _NesterTokens(NamedTuple):
opening: Token
closing: Token
_NodeType = TypeVar("_NodeType", bound="SyntaxTreeNode")
[docs]class SyntaxTreeNode:
"""A Markdown syntax tree node.
A class that can be used to construct a tree representation of a linear
`markdown-it-py` token stream.
Each node in the tree represents either:
- root of the Markdown document
- a single unnested `Token`
- a `Token` "_open" and "_close" token pair, and the tokens nested in
between
"""
def __init__(
self, tokens: Sequence[Token] = (), *, create_root: bool = True
) -> None:
"""Initialize a `SyntaxTreeNode` from a token stream.
If `create_root` is True, create a root node for the document.
"""
# Only nodes representing an unnested token have self.token
self.token: Token | None = None
# Only containers have nester tokens
self.nester_tokens: _NesterTokens | None = None
# Root node does not have self.parent
self._parent: Any = None
# Empty list unless a non-empty container, or unnested token that has
# children (i.e. inline or img)
self._children: list[Any] = []
if create_root:
self._set_children_from_tokens(tokens)
return
if not tokens:
raise ValueError(
"Can only create root from empty token sequence."
" Set `create_root=True`."
)
elif len(tokens) == 1:
inline_token = tokens[0]
if inline_token.nesting:
raise ValueError(
"Unequal nesting level at the start and end of token stream."
)
self.token = inline_token
if inline_token.children:
self._set_children_from_tokens(inline_token.children)
else:
self.nester_tokens = _NesterTokens(tokens[0], tokens[-1])
self._set_children_from_tokens(tokens[1:-1])
def __repr__(self) -> str:
return f"{type(self).__name__}({self.type})"
@overload
def __getitem__(self: _NodeType, item: int) -> _NodeType:
...
@overload
def __getitem__(self: _NodeType, item: slice) -> list[_NodeType]:
...
def __getitem__(self: _NodeType, item: int | slice) -> _NodeType | list[_NodeType]:
return self.children[item]
[docs] def to_tokens(self: _NodeType) -> list[Token]:
"""Recover the linear token stream."""
def recursive_collect_tokens(node: _NodeType, token_list: list[Token]) -> None:
if node.type == "root":
for child in node.children:
recursive_collect_tokens(child, token_list)
elif node.token:
token_list.append(node.token)
else:
assert node.nester_tokens
token_list.append(node.nester_tokens.opening)
for child in node.children:
recursive_collect_tokens(child, token_list)
token_list.append(node.nester_tokens.closing)
tokens: list[Token] = []
recursive_collect_tokens(self, tokens)
return tokens
@property
def children(self: _NodeType) -> list[_NodeType]:
return self._children
@children.setter
def children(self: _NodeType, value: list[_NodeType]) -> None:
self._children = value
@property
def parent(self: _NodeType) -> _NodeType | None:
return self._parent # type: ignore
@parent.setter
def parent(self: _NodeType, value: _NodeType | None) -> None:
self._parent = value
@property
def is_root(self) -> bool:
"""Is the node a special root node?"""
return not (self.token or self.nester_tokens)
@property
def is_nested(self) -> bool:
"""Is this node nested?.
Returns `True` if the node represents a `Token` pair and tokens in the
sequence between them, where `Token.nesting` of the first `Token` in
the pair is 1 and nesting of the other `Token` is -1.
"""
return bool(self.nester_tokens)
@property
def siblings(self: _NodeType) -> Sequence[_NodeType]:
"""Get siblings of the node.
Gets the whole group of siblings, including self.
"""
if not self.parent:
return [self]
return self.parent.children
@property
def type(self) -> str:
"""Get a string type of the represented syntax.
- "root" for root nodes
- `Token.type` if the node represents an unnested token
- `Token.type` of the opening token, with "_open" suffix stripped, if
the node represents a nester token pair
"""
if self.is_root:
return "root"
if self.token:
return self.token.type
assert self.nester_tokens
return _removesuffix(self.nester_tokens.opening.type, "_open")
@property
def next_sibling(self: _NodeType) -> _NodeType | None:
"""Get the next node in the sequence of siblings.
Returns `None` if this is the last sibling.
"""
self_index = self.siblings.index(self)
if self_index + 1 < len(self.siblings):
return self.siblings[self_index + 1]
return None
@property
def previous_sibling(self: _NodeType) -> _NodeType | None:
"""Get the previous node in the sequence of siblings.
Returns `None` if this is the first sibling.
"""
self_index = self.siblings.index(self)
if self_index - 1 >= 0:
return self.siblings[self_index - 1]
return None
def _add_child(
self,
tokens: Sequence[Token],
) -> None:
"""Make a child node for `self`."""
child = type(self)(tokens, create_root=False)
child.parent = self
self.children.append(child)
def _set_children_from_tokens(self, tokens: Sequence[Token]) -> None:
"""Convert the token stream to a tree structure and set the resulting
nodes as children of `self`."""
reversed_tokens = list(reversed(tokens))
while reversed_tokens:
token = reversed_tokens.pop()
if not token.nesting:
self._add_child([token])
continue
if token.nesting != 1:
raise ValueError("Invalid token nesting")
nested_tokens = [token]
nesting = 1
while reversed_tokens and nesting:
token = reversed_tokens.pop()
nested_tokens.append(token)
nesting += token.nesting
if nesting:
raise ValueError(f"unclosed tokens starting {nested_tokens[0]}")
self._add_child(nested_tokens)
[docs] def pretty(
self, *, indent: int = 2, show_text: bool = False, _current: int = 0
) -> str:
"""Create an XML style string of the tree."""
prefix = " " * _current
text = prefix + f"<{self.type}"
if not self.is_root and self.attrs:
text += " " + " ".join(f"{k}={v!r}" for k, v in self.attrs.items())
text += ">"
if (
show_text
and not self.is_root
and self.type in ("text", "text_special")
and self.content
):
text += "\n" + textwrap.indent(self.content, prefix + " " * indent)
for child in self.children:
text += "\n" + child.pretty(
indent=indent, show_text=show_text, _current=_current + indent
)
return text
[docs] def walk(
self: _NodeType, *, include_self: bool = True
) -> Generator[_NodeType, None, None]:
"""Recursively yield all descendant nodes in the tree starting at self.
The order mimics the order of the underlying linear token
stream (i.e. depth first).
"""
if include_self:
yield self
for child in self.children:
yield from child.walk(include_self=True)
# NOTE:
# The values of the properties defined below directly map to properties
# of the underlying `Token`s. A root node does not translate to a `Token`
# object, so calling these property getters on a root node will raise an
# `AttributeError`.
#
# There is no mapping for `Token.nesting` because the `is_nested` property
# provides that data, and can be called on any node type, including root.
def _attribute_token(self) -> Token:
"""Return the `Token` that is used as the data source for the
properties defined below."""
if self.token:
return self.token
if self.nester_tokens:
return self.nester_tokens.opening
raise AttributeError("Root node does not have the accessed attribute")
@property
def tag(self) -> str:
"""html tag name, e.g. \"p\" """
return self._attribute_token().tag
@property
def attrs(self) -> dict[str, str | int | float]:
"""Html attributes."""
return self._attribute_token().attrs
[docs] def attrGet(self, name: str) -> None | str | int | float:
"""Get the value of attribute `name`, or null if it does not exist."""
return self._attribute_token().attrGet(name)
@property
def map(self) -> tuple[int, int] | None:
"""Source map info. Format: `tuple[ line_begin, line_end ]`"""
map_ = self._attribute_token().map
if map_:
# Type ignore because `Token`s attribute types are not perfect
return tuple(map_) # type: ignore
return None
@property
def level(self) -> int:
"""nesting level, the same as `state.level`"""
return self._attribute_token().level
@property
def content(self) -> str:
"""In a case of self-closing tag (code, html, fence, etc.), it
has contents of this tag."""
return self._attribute_token().content
@property
def markup(self) -> str:
"""'*' or '_' for emphasis, fence string for fence, etc."""
return self._attribute_token().markup
@property
def info(self) -> str:
"""fence infostring"""
return self._attribute_token().info
@property
def meta(self) -> dict[Any, Any]:
"""A place for plugins to store an arbitrary data."""
return self._attribute_token().meta
@property
def block(self) -> bool:
"""True for block-level tokens, false for inline tokens."""
return self._attribute_token().block
@property
def hidden(self) -> bool:
"""If it's true, ignore this element when rendering.
Used for tight lists to hide paragraphs."""
return self._attribute_token().hidden
def _removesuffix(string: str, suffix: str) -> str:
"""Remove a suffix from a string.
Replace this with str.removesuffix() from stdlib when minimum Python
version is 3.9.
"""
if suffix and string.endswith(suffix):
return string[: -len(suffix)]
return string
