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"""Integration code for CSS selectors using `Soup Sieve <https://facelessuser.github.io/soupsieve/>`_ (pypi: ``soupsieve``).
Acquire a `CSS` object through the `element.Tag.css` attribute of
the starting point of your CSS selector, or (if you want to run a
selector against the entire document) of the `BeautifulSoup` object
itself.
The main advantage of doing this instead of using ``soupsieve``
functions is that you don't need to keep passing the `element.Tag` to be
selected against, since the `CSS` object is permanently scoped to that
`element.Tag`.
"""
from __future__ import annotations
from types import ModuleType
from typing import (
Any,
cast,
Iterable,
Iterator,
MutableSequence,
Optional,
TYPE_CHECKING,
)
import warnings
from bs4._typing import _NamespaceMapping
if TYPE_CHECKING:
from soupsieve import SoupSieve
from bs4 import element
from bs4.element import ResultSet, Tag
soupsieve: Optional[ModuleType]
try:
import soupsieve
except ImportError:
soupsieve = None
warnings.warn(
"The soupsieve package is not installed. CSS selectors cannot be used."
)
class CSS(object):
"""A proxy object against the ``soupsieve`` library, to simplify its
CSS selector API.
You don't need to instantiate this class yourself; instead, use
`element.Tag.css`.
:param tag: All CSS selectors run by this object will use this as
their starting point.
:param api: An optional drop-in replacement for the ``soupsieve`` module,
intended for use in unit tests.
"""
def __init__(self, tag: element.Tag, api: Optional[ModuleType] = None):
if api is None:
api = soupsieve
if api is None:
raise NotImplementedError(
"Cannot execute CSS selectors because the soupsieve package is not installed."
)
self.api = api
self.tag = tag
def escape(self, ident: str) -> str:
"""Escape a CSS identifier.
This is a simple wrapper around `soupsieve.escape() <https://facelessuser.github.io/soupsieve/api/#soupsieveescape>`_. See the
documentation for that function for more information.
"""
if soupsieve is None:
raise NotImplementedError(
"Cannot escape CSS identifiers because the soupsieve package is not installed."
)
return cast(str, self.api.escape(ident))
def _ns(
self, ns: Optional[_NamespaceMapping], select: str
) -> Optional[_NamespaceMapping]:
"""Normalize a dictionary of namespaces."""
if not isinstance(select, self.api.SoupSieve) and ns is None:
# If the selector is a precompiled pattern, it already has
# a namespace context compiled in, which cannot be
# replaced.
ns = self.tag._namespaces
return ns
def _rs(self, results: MutableSequence[Tag]) -> ResultSet[Tag]:
"""Normalize a list of results to a py:class:`ResultSet`.
A py:class:`ResultSet` is more consistent with the rest of
Beautiful Soup's API, and :py:meth:`ResultSet.__getattr__` has
a helpful error message if you try to treat a list of results
as a single result (a common mistake).
"""
# Import here to avoid circular import
from bs4 import ResultSet
return ResultSet(None, results)
def compile(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
flags: int = 0,
**kwargs: Any,
) -> SoupSieve:
"""Pre-compile a selector and return the compiled object.
:param selector: A CSS selector.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will use the prefixes it encountered while
parsing the document.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.compile() <https://facelessuser.github.io/soupsieve/api/#soupsievecompile>`_ method.
:param kwargs: Keyword arguments to be passed into Soup Sieve's
`soupsieve.compile() <https://facelessuser.github.io/soupsieve/api/#soupsievecompile>`_ method.
:return: A precompiled selector object.
:rtype: soupsieve.SoupSieve
"""
return self.api.compile(select, self._ns(namespaces, select), flags, **kwargs)
def select_one(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
flags: int = 0,
**kwargs: Any,
) -> element.Tag | None:
"""Perform a CSS selection operation on the current Tag and return the
first result, if any.
This uses the Soup Sieve library. For more information, see
that library's documentation for the `soupsieve.select_one() <https://facelessuser.github.io/soupsieve/api/#soupsieveselect_one>`_ method.
:param selector: A CSS selector.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will use the prefixes it encountered while
parsing the document.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.select_one() <https://facelessuser.github.io/soupsieve/api/#soupsieveselect_one>`_ method.
:param kwargs: Keyword arguments to be passed into Soup Sieve's
`soupsieve.select_one() <https://facelessuser.github.io/soupsieve/api/#soupsieveselect_one>`_ method.
"""
return self.api.select_one(
select, self.tag, self._ns(namespaces, select), flags, **kwargs
)
def select(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
limit: int = 0,
flags: int = 0,
**kwargs: Any,
) -> ResultSet[element.Tag]:
"""Perform a CSS selection operation on the current `element.Tag`.
This uses the Soup Sieve library. For more information, see
that library's documentation for the `soupsieve.select() <https://facelessuser.github.io/soupsieve/api/#soupsieveselect>`_ method.
:param selector: A CSS selector.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will pass in the prefixes it encountered while
parsing the document.
:param limit: After finding this number of results, stop looking.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.select() <https://facelessuser.github.io/soupsieve/api/#soupsieveselect>`_ method.
:param kwargs: Keyword arguments to be passed into Soup Sieve's
`soupsieve.select() <https://facelessuser.github.io/soupsieve/api/#soupsieveselect>`_ method.
"""
if limit is None:
limit = 0
return self._rs(
self.api.select(
select, self.tag, self._ns(namespaces, select), limit, flags, **kwargs
)
)
def iselect(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
limit: int = 0,
flags: int = 0,
**kwargs: Any,
) -> Iterator[element.Tag]:
"""Perform a CSS selection operation on the current `element.Tag`.
This uses the Soup Sieve library. For more information, see
that library's documentation for the `soupsieve.iselect()
<https://facelessuser.github.io/soupsieve/api/#soupsieveiselect>`_
method. It is the same as select(), but it returns a generator
instead of a list.
:param selector: A string containing a CSS selector.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will pass in the prefixes it encountered while
parsing the document.
:param limit: After finding this number of results, stop looking.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.iselect() <https://facelessuser.github.io/soupsieve/api/#soupsieveiselect>`_ method.
:param kwargs: Keyword arguments to be passed into Soup Sieve's
`soupsieve.iselect() <https://facelessuser.github.io/soupsieve/api/#soupsieveiselect>`_ method.
"""
return self.api.iselect(
select, self.tag, self._ns(namespaces, select), limit, flags, **kwargs
)
def closest(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
flags: int = 0,
**kwargs: Any,
) -> Optional[element.Tag]:
"""Find the `element.Tag` closest to this one that matches the given selector.
This uses the Soup Sieve library. For more information, see
that library's documentation for the `soupsieve.closest()
<https://facelessuser.github.io/soupsieve/api/#soupsieveclosest>`_
method.
:param selector: A string containing a CSS selector.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will pass in the prefixes it encountered while
parsing the document.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.closest() <https://facelessuser.github.io/soupsieve/api/#soupsieveclosest>`_ method.
:param kwargs: Keyword arguments to be passed into Soup Sieve's
`soupsieve.closest() <https://facelessuser.github.io/soupsieve/api/#soupsieveclosest>`_ method.
"""
return self.api.closest(
select, self.tag, self._ns(namespaces, select), flags, **kwargs
)
def match(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
flags: int = 0,
**kwargs: Any,
) -> bool:
"""Check whether or not this `element.Tag` matches the given CSS selector.
This uses the Soup Sieve library. For more information, see
that library's documentation for the `soupsieve.match()
<https://facelessuser.github.io/soupsieve/api/#soupsievematch>`_
method.
:param: a CSS selector.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will pass in the prefixes it encountered while
parsing the document.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.match()
<https://facelessuser.github.io/soupsieve/api/#soupsievematch>`_
method.
:param kwargs: Keyword arguments to be passed into SoupSieve's
`soupsieve.match()
<https://facelessuser.github.io/soupsieve/api/#soupsievematch>`_
method.
"""
return cast(
bool,
self.api.match(
select, self.tag, self._ns(namespaces, select), flags, **kwargs
),
)
def filter(
self,
select: str,
namespaces: Optional[_NamespaceMapping] = None,
flags: int = 0,
**kwargs: Any,
) -> ResultSet[element.Tag]:
"""Filter this `element.Tag`'s direct children based on the given CSS selector.
This uses the Soup Sieve library. It works the same way as
passing a `element.Tag` into that library's `soupsieve.filter()
<https://facelessuser.github.io/soupsieve/api/#soupsievefilter>`_
method. For more information, see the documentation for
`soupsieve.filter()
<https://facelessuser.github.io/soupsieve/api/#soupsievefilter>`_.
:param namespaces: A dictionary mapping namespace prefixes
used in the CSS selector to namespace URIs. By default,
Beautiful Soup will pass in the prefixes it encountered while
parsing the document.
:param flags: Flags to be passed into Soup Sieve's
`soupsieve.filter()
<https://facelessuser.github.io/soupsieve/api/#soupsievefilter>`_
method.
:param kwargs: Keyword arguments to be passed into SoupSieve's
`soupsieve.filter()
<https://facelessuser.github.io/soupsieve/api/#soupsievefilter>`_
method.
"""
return self._rs(
self.api.filter(
select, self.tag, self._ns(namespaces, select), flags, **kwargs
)
)
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