Source code for ll.xist.css

# -*- coding: utf-8 -*-
# cython: language_level=3, always_allow_keywords=True

## Copyright 1999-2023 by LivingLogic AG, Bayreuth/Germany
## Copyright 1999-2023 by Walter Dörwald
##
## All Rights Reserved
##
## See ll/xist/__init__.py for the license


"""
This module contains functions related to the handling of CSS.
"""

import os, contextlib, operator

try:
	import cssutils
	from cssutils import css, codec
except ImportError:
	cssutils = None
else:
	import logging
	cssutils.log.setLevel(logging.FATAL)

from ll import misc, url
from ll.xist import xsc, xfind
from ll.xist.ns import html


__docformat__ = "reStructuredText"


def _isstyle(path):
	if path:
		node = path[-1]
		return isinstance(node, (html.style, html.link)) and ("type" not in node.attrs or str(node.attrs.type) == "text/css")
	return False


[docs] def replaceurls(stylesheet, replacer): """ Replace all URLs appearing in the :class:`CSSStyleSheet` ``stylesheet``. For each URL the function ``replacer`` will be called and the URL will be replaced with the result. """ def newreplacer(u): return str(replacer(url.URL(u))) cssutils.replaceUrls(stylesheet, newreplacer)
[docs] def geturls(stylesheet): """ Return a list of all URLs appearing in the :class:`CSSStyleSheet` ``stylesheet``. """ return [url.URL(u) for u in cssutils.getUrls(stylesheet)] # This requires cssutils 0.9.5b1
def _getmedia(stylesheet): while stylesheet is not None: if stylesheet.media is not None: return {mq.value.mediaType for mq in stylesheet.media} stylesheet = stylesheet.parentStyleSheet return None def _doimport(wantmedia, parentsheet, base): def prependbase(u): if base is not None: u = base/u return u havemedia = _getmedia(parentsheet) if wantmedia is None or not havemedia or wantmedia in havemedia: replaceurls(parentsheet, prependbase) for rule in parentsheet.cssRules: if rule.type == css.CSSRule.IMPORT_RULE: href = url.URL(rule.href) if base is not None: href = base/href havemedia = rule.media with contextlib.closing(href.open("rb")) as r: href = r.finalurl() text = r.read() sheet = css.CSSStyleSheet(href=str(href), media=havemedia, parentStyleSheet=parentsheet) sheet.cssText = text yield from _doimport(wantmedia, sheet, href) elif rule.type == css.CSSRule.MEDIA_RULE: if wantmedia in (mq.value.mediaType for mq in rule.media): yield from rule.cssRules elif rule.type == css.CSSRule.STYLE_RULE: yield rule
[docs] def iterrules(node, base=None, media=None, title=None): """ Return an iterator for all CSS rules defined in the HTML tree ``node``. This will parse the CSS defined in any :class:`html.style` or :class:`html.link` element (and recursively in those stylesheets imported via the ``@import`` rule). The rules will be returned as :class:`CSSStyleRule` objects from the :mod:`cssutils` package (so this requires :mod:`cssutils`). The ``base`` argument will be used as the base URL for parsing the stylesheet references in the tree (so :const:`None` means the URLs will be used exactly as they appear in the tree). All URLs in the style properties will be resolved. If ``media`` is given, only rules that apply to this media type will be produced. ``title`` can be used to specify which stylesheet group should be used. If ``title`` is :const:`None` only the persistent and preferred stylesheets will be used. If ``title`` is a string only the persistent stylesheets and alternate stylesheets with that style name will be used. For a description of "persistent", "preferred" and "alternate" stylesheets see <http://www.w3.org/TR/2002/WD-xhtml2-20020805/mod-styleSheet.html#sec_20.1.2.> """ if base is not None: base = url.URL(base) def matchlink(node): if node.attrs.media.hasmedia(media): if title is None: if "title" not in node.attrs and "alternate" not in str(node.attrs.rel).split(): return True elif not node.attrs.title.isfancy() and str(node.attrs.title) == title and "alternate" in str(node.attrs.rel).split(): return True return False def matchstyle(node): if node.attrs.media.hasmedia(media): if title is None: if "title" not in node.attrs: return True elif str(node.attrs.title) == title: return True return False def doiter(node): for cssnode in node.walknodes(_isstyle): if isinstance(cssnode, html.style): href = str(base) if base is not None else None if matchstyle(cssnode): stylesheet = cssutils.parseString(str(cssnode.content), href=href, media=str(cssnode.attrs.media)) yield from _doimport(media, stylesheet, base) else: # link if "href" in cssnode.attrs: href = cssnode.attrs.href.asURL() if base is not None: href = base/href if matchlink(cssnode): stylesheet = cssutils.parseUrl(str(href), media=str(cssnode.attrs.media)) yield from _doimport(media, stylesheet, href) return misc.Iterator(doiter(node))
[docs] def applystylesheets(node, base=None, media=None, title=None): r""" :func:`applystylesheets` modifies the XIST tree ``node`` by removing all CSS (from :class:`html.link` and :class:`html.style` elements and their ``@import``\ed stylesheets) and putting the resulting style properties into the ``style`` attribute of every affected element instead. For the meaning of ``base``, ``media`` and ``title`` see :func:`iterrules`. """ def iterstyles(node, rules): yield from rules # According to CSS 2.1 (http://www.w3.org/TR/CSS21/cascade.html#specificity) # style attributes have the highest weight, so we yield it last # (CSS 3 uses the same weight) if "style" in node.attrs: style = node.attrs.style if not style.isfancy(): yield ( (1, 0, 0, 0), xfind.IsSelector(node), cssutils.parseStyle(str(style)) # parse the style out of the style attribute ) rules = [] for rule in iterrules(node, base=base, media=media, title=title): for sel in rule.selectorList: rules.append((sel.specificity, selector(sel), rule.style)) rules.sort(key=operator.itemgetter(0)) count = 0 for cursor in node.walk(xsc.Element): del cursor.node[_isstyle] # drop style sheet nodes if cursor.node.Attrs.isdeclared("style"): styles = {} for (spec, sel, style) in iterstyles(cursor.node, rules): if cursor.path in sel: for prop in style: # Properties from later rules overwrite those from earlier ones # We're storing the count so that sorting keeps the order styles[prop.name] = (count, prop.cssText) count += 1 style = " ".join(f"{value};" for (count, value) in sorted(styles.values())) if style: cursor.node.attrs.style = style
### ### Selector helper functions ### def _is_nth_node(iterator, node, index): # Return whether ``node`` is the ``index``'th node in ``iterator`` (starting at 1) # ``index`` is an int or int string or "even" or "odd" if index == "even": for (i, child) in enumerate(iterator): if child is node: return i % 2 == 1 return False elif index == "odd": for (i, child) in enumerate(iterator): if child is node: return i % 2 == 0 return False else: if not isinstance(index, int): try: index = int(index) except ValueError: raise ValueError(f"illegal argument {index!r}") else: if index < 1: return False try: return iterator[index-1] is node except IndexError: return False def _is_nth_last_node(iterator, node, index): # Return whether ``node`` is the ``index``'th last node in ``iterator`` # ``index`` is an int or int string or "even" or "odd" if index == "even": pos = None for (i, child) in enumerate(iterator): if child is node: pos = i return pos is None or (i-pos) % 2 == 1 elif index == "odd": pos = None for (i, child) in enumerate(iterator): if child is node: pos = i return pos is None or (i-pos) % 2 == 0 else: if not isinstance(index, int): try: index = int(index) except ValueError: raise ValueError(f"illegal argument {index!r}") else: if index < 1: return False try: return iterator[-index] is node except IndexError: return False def _children_of_type(node, type): for child in node: if isinstance(child, xsc.Element) and child.xmlname == type: yield child ### ### Selectors ###
[docs] class CSSWeightedSelector(xfind.Selector): """ Base class for all CSS pseudo-class selectors. """
[docs] class CSSHasAttributeSelector(CSSWeightedSelector): """ A :class:`CSSHasAttributeSelector` selector selects all element nodes that have an attribute with the specified XML name. """ def __init__(self, attributename): self.attributename = attributename def __contains__(self, path): if path: node = path[-1] if isinstance(node, xsc.Element): return node.attrs.has(self.attributename) return False def __str__(self): return f"{self.__class___.__qualname__}({self.attributename!r})"
[docs] class CSSAttributeListSelector(CSSWeightedSelector): """ A :class:`CSSAttributeListSelector` selector selects all element nodes where an attribute with the specified XML name has the specified word among the white space-separated list of words in the attribute value. """ def __init__(self, attributename, attributevalue): self.attributename = attributename self.attributevalue = attributevalue def __contains__(self, path): if path: node = path[-1] if isinstance(node, xsc.Element): attr = node.attrs.get(self.attributename) return self.attributevalue in str(attr).split() return False def __str__(self): return f"{self.__class__.__qualname__}({self.attributename!r}, {self.attributevalue!r})"
[docs] class CSSAttributeLangSelector(CSSWeightedSelector): """ A :class:`CSSAttributeLangSelector` selector selects all element nodes where an attribute with the specified XML name either is exactly the specified value or starts with the specified value followed by ``"-"``. """ def __init__(self, attributename, attributevalue): self.attributename = attributename self.attributevalue = attributevalue def __contains__(self, path): if path: node = path[-1] if isinstance(node, xsc.Element): attr = node.attrs.get(self.attributename) parts = str(attr).split("-", 1) if parts: return parts[0] == self.attributevalue return False def __str__(self): return f"{self.__class__.__qualname__}({self.attributename!r}, {self.attributevalue!r})"
[docs] class CSSFirstChildSelector(CSSWeightedSelector): """ A :class:`CSSFirstChildSelector` selector selects all element nodes that are the first child of its parent. """ def __contains__(self, path): return len(path) >= 2 and _is_nth_node(path[-2][xsc.Element], path[-1], 1) def __str__(self): return "CSSFirstChildSelector()"
[docs] class CSSLastChildSelector(CSSWeightedSelector): """ A :class:`CSSLastChildSelector` selector selects all element nodes that are the last child of its parent. """ def __contains__(self, path): return len(path) >= 2 and _is_nth_last_node(path[-2][xsc.Element], path[-1], 1) def __str__(self): return "CSSLastChildSelector()"
[docs] class CSSFirstOfTypeSelector(CSSWeightedSelector): """ A :class:`CSSLastChildSelector` selector selects all element nodes that are the first of its type among their siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] return isinstance(node, xsc.Element) and _is_nth_node(misc.Iterator(_children_of_type(path[-2], node.xmlname)), node, 1) return False def __str__(self): return "CSSFirstOfTypeSelector()"
[docs] class CSSLastOfTypeSelector(CSSWeightedSelector): """ A :class:`CSSLastChildSelector` selector selects all element nodes that are the last of its type among their siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] return isinstance(node, xsc.Element) and _is_nth_last_node(misc.Iterator(_children_of_type(path[-2], node.xmlname)), node, 1) return False def __str__(self): return "CSSLastOfTypeSelector()"
[docs] class CSSOnlyChildSelector(CSSWeightedSelector): """ A :class:`CSSOnlyChildSelector` selector selects all element nodes that are the only element among its siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] if isinstance(node, xsc.Element): for child in path[-2][xsc.Element]: if child is not node: return False return True return False def __str__(self): return "CSSOnlyChildSelector()"
[docs] class CSSOnlyOfTypeSelector(CSSWeightedSelector): """ A :class:`CSSOnlyOfTypeSelector` selector selects all element nodes that are the only element of its type among its siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] if isinstance(node, xsc.Element): for child in _children_of_type(path[-2], node.xmlname): if child is not node: return False return True return False def __str__(self): return "CSSOnlyOfTypeSelector()"
[docs] class CSSEmptySelector(CSSWeightedSelector): """ A :class:`CSSEmptySelector` selector selects all element nodes that are empty (i.e. they contain no elements or non-whitespace text). """ def __contains__(self, path): if path: node = path[-1] if isinstance(node, xsc.Element): for child in path[-1].content: if isinstance(child, xsc.Element) or (isinstance(child, xsc.Text) and child): return False return True return False def __str__(self): return "CSSEmptySelector()"
[docs] class CSSRootSelector(CSSWeightedSelector): """ A :class:`CSSRootSelector` selector selects the root element. """ def __contains__(self, path): return len(path) == 1 and isinstance(path[-1], xsc.Element) def __str__(self): return "CSSRootSelector()"
[docs] class CSSLinkSelector(CSSWeightedSelector): """ A :class:`CSSLinkSelector` selector selects all HTML links. """ def __contains__(self, path): if path: node = path[-1] return isinstance(node, xsc.Element) and node.xmlns=="http://www.w3.org/1999/xhtml" and node.xmlname=="a" and "href" in node.attrs return False def __str__(self): return f"{self.__class__.__qualname__}()"
class CSSInvalidPseudoSelector(CSSWeightedSelector): def __contains__(self, path): return False def __str__(self): return f"{self.__class__.__qualname__}()" class CSSHoverSelector(CSSInvalidPseudoSelector): pass class CSSActiveSelector(CSSInvalidPseudoSelector): pass class CSSVisitedSelector(CSSInvalidPseudoSelector): pass class CSSFocusSelector(CSSInvalidPseudoSelector): pass class CSSAfterSelector(CSSInvalidPseudoSelector): pass class CSSBeforeSelector(CSSInvalidPseudoSelector): pass class CSSValidSelector(CSSInvalidPseudoSelector): pass class CSSInvalidSelector(CSSInvalidPseudoSelector): pass
[docs] class CSSFunctionSelector(CSSWeightedSelector): """ Base class of all CSS selectors that require an argument. """ def __init__(self, value=None): self.value = value def __str__(self): return f"{self.__class__.__qualname__}({self.value!r})"
[docs] class CSSNthChildSelector(CSSFunctionSelector): """ A :class:`CSSNthChildSelector` selector selects all element nodes that are the n-th element among their siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] if isinstance(node, xsc.Element): return _is_nth_node(path[-2][xsc.Element], node, self.value) return False
[docs] class CSSNthLastChildSelector(CSSFunctionSelector): """ A :class:`CSSNthLastChildSelector` selector selects all element nodes that are the n-th last element among their siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] if isinstance(node, xsc.Element): return _is_nth_last_node(path[-2][xsc.Element], node, self.value) return False
[docs] class CSSNthOfTypeSelector(CSSFunctionSelector): """ A :class:`CSSNthOfTypeSelector` selector selects all element nodes that are the n-th of its type among their siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] if isinstance(node, xsc.Element): return _is_nth_node(misc.Iterator(_children_of_type(path[-2], node.xmlname)), node, self.value) return False
[docs] class CSSNthLastOfTypeSelector(CSSFunctionSelector): """ A :class:`CSSNthOfTypeSelector` selector selects all element nodes that are the n-th last of its type among their siblings. """ def __contains__(self, path): if len(path) >= 2: node = path[-1] if isinstance(node, xsc.Element): return _is_nth_last_node(misc.Iterator(_children_of_type(path[-2], node.xmlname)), node, self.value) return False
class CSSTypeSelector(xfind.Selector): def __init__(self, type=None, xmlns=None, *selectors): self.type = type self.xmlns = xsc.nsname(xmlns) self.selectors = [] # id, class, attribute etc. selectors for this node def __contains__(self, path): if path: node = path[-1] if self.type is None or node.xmlname == self.type: if self.xmlns is None or node.xmlns == self.xmlns: for selector in self.selectors: if path not in selector: return False return True return False def __str__(self): v = [self.__class__.__name__, "("] if self.type is not None or self.xmlns is not None or self.selectors: v.append(repr(self.type)) if self.xmlns is not None or self.selectors: v.append(", ") v.append(repr(self.xmlns)) for selector in self.selectors: v.append(", ") v.append(str(selector)) v.append(")") return "".join(v)
[docs] class CSSAdjacentSiblingCombinator(xfind.BinaryCombinator): """ A :class:`CSSAdjacentSiblingCombinator` works similar to an :class:`~ll.xist.xfind.AdjacentSiblingCombinator` except that only preceding *elements* are considered. """ def __contains__(self, path): if len(path) >= 2 and path in self.right: # Find sibling node = path[-1] sibling = None for child in path[-2][xsc.Element]: if child is node: break sibling = child if sibling is not None: return path[:-1]+[sibling] in self.left return False def __str__(self): return f"{self.__class__.__qualname__}({self.left}, {self.right})"
[docs] class CSSGeneralSiblingCombinator(xfind.BinaryCombinator): """ A :class:`CSSGeneralSiblingCombinator` works similar to an :class:`xfind.GeneralSiblingCombinator` except that only preceding *elements* are considered. """ def __contains__(self, path): if len(path) >= 2 and path in self.right: node = path[-1] for child in path[-2][xsc.Element]: if child is node: # no previous element siblings return False if path[:-1]+[child] in self.left: return True return False def __str__(self): return f"{self.__class__.__qualname__}({self.left}, {self.right})"
_pseudoname2class = { "first-child": CSSFirstChildSelector, "last-child": CSSLastChildSelector, "first-of-type": CSSFirstOfTypeSelector, "last-of-type": CSSLastOfTypeSelector, "only-child": CSSOnlyChildSelector, "only-of-type": CSSOnlyOfTypeSelector, "empty": CSSEmptySelector, "root": CSSRootSelector, "hover": CSSHoverSelector, "focus": CSSFocusSelector, "link": CSSLinkSelector, "visited": CSSVisitedSelector, "active": CSSActiveSelector, "after": CSSAfterSelector, "before": CSSBeforeSelector, "valid": CSSValidSelector, "invalid": CSSInvalidSelector, } _function2class = { "nth-child": CSSNthChildSelector, "nth-last-child": CSSNthLastChildSelector, "nth-of-type": CSSNthOfTypeSelector, "nth-last-of-type": CSSNthLastOfTypeSelector, }
[docs] def selector(selectors, prefixes=None): """ Create a :class:`xfind.Selector` object that matches all nodes that match the specified CSS selector expression. ``selectors`` can be a string or a :class:`cssutils.css.selector.Selector` object. ``prefixes`` may be a mapping mapping namespace prefixes to namespace names. """ if isinstance(selectors, str): if prefixes is not None: prefixes = dict((key, xsc.nsname(value)) for (key, value) in prefixes.items()) namespaces = "\n".join(f"@namespace {key if key is not None else ''} {value!r};" for (key, value) in prefixes.items()) selectors = f"{namespaces}\n{selectors}{{}}" else: selectors = f"{selectors}{{}}" for rule in cssutils.CSSParser().parseString(selectors).cssRules: if isinstance(rule, css.CSSStyleRule): selectors = rule.selectorList.seq break else: raise ValueError("can't happen") elif isinstance(selectors, css.CSSStyleRule): selectors = selectors.selectorList.seq elif isinstance(selectors, css.Selector): selectors = [selectors] else: raise TypeError(f"can't handle {type(selectors)!r}") orcombinators = [] for selector in selectors: rule = root = CSSTypeSelector() attributename = None attributevalue = None combinator = None for item in selector.seq: t = item.type v = item.value if t == "type-selector": rule.xmlns = v[0] if v[0] != -1 else None rule.type = v[1] elif t == "universal": rule.xmlns = v[0] if v[0] != -1 else None rule.type = None elif t == "id": rule.selectors.append(xfind.hasid(v.lstrip("#"))) elif t == "class": rule.selectors.append(xfind.hasclass(v.lstrip("."))) elif t == "attribute-start": combinator = None elif t == "attribute-end": if combinator is None: rule.selectors.append(CSSHasAttributeSelector(attributename)) else: rule.selectors.append(combinator(attributename, attributevalue)) elif t == "attribute-selector": attributename = v elif t == "equals": combinator = xfind.attrhasvalue elif t == "includes": combinator = CSSAttributeListSelector elif t == "dashmatch": combinator = CSSAttributeLangSelector elif t == "prefixmatch": combinator = xfind.attrstartswith elif t == "suffixmatch": combinator = xfind.attrendswith elif t == "substringmatch": combinator = xfind.attrcontains elif t == "pseudo-class": if v.endswith("("): try: rule.selectors.append(_function2class[v.lstrip(":").rstrip("(")]()) except KeyError: raise ValueError(f"unknown function {v}") rule.function = v else: try: rule.selectors.append(_pseudoname2class[v.lstrip(":")]()) except KeyError: raise ValueError(f"unknown pseudo-class {v}") elif t == "NUMBER" or t == "IDENT": # can only appear in a function => set the function value rule.selectors[-1].value = v elif t == "STRING": # can only appear in a attribute selector => set the attribute value attributevalue = v elif t == "child": rule = CSSTypeSelector() root = xfind.ChildCombinator(root, rule) elif t == "descendant": rule = CSSTypeSelector() root = xfind.DescendantCombinator(root, rule) elif t == "adjacent-sibling": rule = CSSTypeSelector() root = CSSAdjacentSiblingCombinator(root, rule) elif t == "following-sibling": rule = CSSTypeSelector() root = CSSGeneralSiblingCombinator(root, rule) orcombinators.append(root) return orcombinators[0] if len(orcombinators) == 1 else xfind.OrCombinator(*orcombinators)
[docs] def parsestring(data, base=None, encoding=None): """ Parse the string ``data`` into a :mod:`cssutils` stylesheet. ``base`` is the base URL for the parsing process, ``encoding`` can be used to force the parser to use the specified encoding. """ if encoding is None: encoding = "css" if base is not None: base = url.URL(base) href = str(base) else: href = None stylesheet = cssutils.parseString(data.decode(encoding), href=href) if base is not None: def prependbase(u): return base/u replaceurls(stylesheet, prependbase) return stylesheet
[docs] def parsestream(stream, base=None, encoding=None): """ Parse a :mod:`cssutils` stylesheet from the stream ``stream``. ``base`` is the base URL for the parsing process, ``encoding`` can be used to force the parser to use the specified encoding. """ return parsestring(stream.read(), base=base, encoding=None)
[docs] def parsefile(filename, base=None, encoding=None): """ Parse a :mod:`cssutils` stylesheet from the file named ``filename``. ``base`` is the base URL for the parsing process (defaulting to the filename itself), ``encoding`` can be used to force the parser to use the specified encoding. """ filename = os.path.expanduser(filename) if base is None: base = filename with contextlib.closing(open(filename, "rb")) as stream: return parsestream(stream, base=base, encoding=encoding)
[docs] def parseurl(name, base=None, encoding=None, *args, **kwargs): """ Parse a :mod:`cssutils` stylesheet from the URL ``name``. ``base`` is the base URL for the parsing process (defaulting to the final URL of the response, i.e. including redirects), ``encoding`` can be used to force the parser to use the specified encoding. ``arg`` and ``kwargs`` are passed on to :meth:`URL.openread`, so you can pass POST data and request headers. """ with contextlib.closing(url.URL(name).openread(*args, **kwargs)) as stream: if base is None: base = stream.finalurl() return parsestream(stream, base=base, encoding=encoding)
def write(stylesheet, stream, base=None, encoding=None): if base is not None: def reltobase(u): return u.relative(base) replaceurls(stylesheet, reltobase) if encoding is not None: stylesheet.encoding = encoding stream.write(stylesheet.cssText)