114 lines
4.2 KiB
Python
114 lines
4.2 KiB
Python
"""CSS4 selectors for Python.
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cssselect2 is a straightforward implementation of CSS4 Selectors for markup
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documents (HTML, XML, etc.) that can be read by ElementTree-like parsers
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(including cElementTree, lxml, html5lib, etc.)
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"""
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from webencodings import ascii_lower
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# Classes are imported here to expose them at the top level of the module
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from .compiler import compile_selector_list # noqa
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from .parser import SelectorError # noqa
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from .tree import ElementWrapper # noqa
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VERSION = __version__ = '0.8.0'
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class Matcher:
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"""A CSS selectors storage that can match against HTML elements."""
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def __init__(self):
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self.id_selectors = {}
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self.class_selectors = {}
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self.lower_local_name_selectors = {}
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self.namespace_selectors = {}
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self.lang_attr_selectors = []
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self.other_selectors = []
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self.order = 0
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def add_selector(self, selector, payload):
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"""Add a selector and its payload to the matcher.
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:param selector:
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A :class:`compiler.CompiledSelector` object.
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:param payload:
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Some data associated to the selector,
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such as :class:`declarations <tinycss2.ast.Declaration>`
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parsed from the :attr:`tinycss2.ast.QualifiedRule.content`
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of a style rule.
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It can be any Python object,
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and will be returned as-is by :meth:`match`.
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"""
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self.order += 1
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if selector.never_matches:
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return
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entry = (
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selector.test, selector.specificity, self.order, selector.pseudo_element,
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payload)
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if selector.id is not None:
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self.id_selectors.setdefault(selector.id, []).append(entry)
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elif selector.class_name is not None:
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self.class_selectors.setdefault(selector.class_name, []).append(entry)
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elif selector.local_name is not None:
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self.lower_local_name_selectors.setdefault(
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selector.lower_local_name, []).append(entry)
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elif selector.namespace is not None:
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self.namespace_selectors.setdefault(selector.namespace, []).append(entry)
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elif selector.requires_lang_attr:
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self.lang_attr_selectors.append(entry)
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else:
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self.other_selectors.append(entry)
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def match(self, element):
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"""Match selectors against the given element.
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:param element:
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An :class:`ElementWrapper`.
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:returns:
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A list of the payload objects associated to selectors that match
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element, in order of lowest to highest
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:attr:`compiler.CompiledSelector` specificity and in order of
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addition with :meth:`add_selector` among selectors of equal
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specificity.
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"""
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relevant_selectors = []
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if element.id is not None and element.id in self.id_selectors:
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self.add_relevant_selectors(
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element, self.id_selectors[element.id], relevant_selectors)
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for class_name in element.classes:
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if class_name in self.class_selectors:
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self.add_relevant_selectors(
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element, self.class_selectors[class_name], relevant_selectors)
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lower_name = ascii_lower(element.local_name)
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if lower_name in self.lower_local_name_selectors:
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self.add_relevant_selectors(
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element, self.lower_local_name_selectors[lower_name],
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relevant_selectors)
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if element.namespace_url in self.namespace_selectors:
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self.add_relevant_selectors(
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element, self.namespace_selectors[element.namespace_url],
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relevant_selectors)
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if 'lang' in element.etree_element.attrib:
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self.add_relevant_selectors(
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element, self.lang_attr_selectors, relevant_selectors)
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self.add_relevant_selectors(element, self.other_selectors, relevant_selectors)
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relevant_selectors.sort()
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return relevant_selectors
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@staticmethod
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def add_relevant_selectors(element, selectors, relevant_selectors):
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for test, specificity, order, pseudo, payload in selectors:
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if test(element):
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relevant_selectors.append((specificity, order, pseudo, payload))
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