153 lines
5.5 KiB
Python
153 lines
5.5 KiB
Python
from bs4.dammit import EntitySubstitution
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class Formatter(EntitySubstitution):
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"""Describes a strategy to use when outputting a parse tree to a string.
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Some parts of this strategy come from the distinction between
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HTML4, HTML5, and XML. Others are configurable by the user.
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Formatters are passed in as the `formatter` argument to methods
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like `PageElement.encode`. Most people won't need to think about
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formatters, and most people who need to think about them can pass
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in one of these predefined strings as `formatter` rather than
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making a new Formatter object:
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For HTML documents:
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* 'html' - HTML entity substitution for generic HTML documents. (default)
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* 'html5' - HTML entity substitution for HTML5 documents.
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* 'minimal' - Only make the substitutions necessary to guarantee
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valid HTML.
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* None - Do not perform any substitution. This will be faster
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but may result in invalid markup.
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For XML documents:
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* 'html' - Entity substitution for XHTML documents.
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* 'minimal' - Only make the substitutions necessary to guarantee
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valid XML. (default)
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* None - Do not perform any substitution. This will be faster
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but may result in invalid markup.
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"""
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# Registries of XML and HTML formatters.
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XML_FORMATTERS = {}
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HTML_FORMATTERS = {}
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HTML = 'html'
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XML = 'xml'
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HTML_DEFAULTS = dict(
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cdata_containing_tags=set(["script", "style"]),
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)
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def _default(self, language, value, kwarg):
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if value is not None:
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return value
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if language == self.XML:
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return set()
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return self.HTML_DEFAULTS[kwarg]
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def __init__(
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self, language=None, entity_substitution=None,
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void_element_close_prefix='/', cdata_containing_tags=None,
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):
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"""Constructor.
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:param language: This should be Formatter.XML if you are formatting
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XML markup and Formatter.HTML if you are formatting HTML markup.
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:param entity_substitution: A function to call to replace special
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characters with XML/HTML entities. For examples, see
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bs4.dammit.EntitySubstitution.substitute_html and substitute_xml.
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:param void_element_close_prefix: By default, void elements
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are represented as <tag/> (XML rules) rather than <tag>
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(HTML rules). To get <tag>, pass in the empty string.
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:param cdata_containing_tags: The list of tags that are defined
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as containing CDATA in this dialect. For example, in HTML,
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<script> and <style> tags are defined as containing CDATA,
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and their contents should not be formatted.
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"""
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self.language = language
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self.entity_substitution = entity_substitution
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self.void_element_close_prefix = void_element_close_prefix
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self.cdata_containing_tags = self._default(
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language, cdata_containing_tags, 'cdata_containing_tags'
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)
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def substitute(self, ns):
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"""Process a string that needs to undergo entity substitution.
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This may be a string encountered in an attribute value or as
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text.
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:param ns: A string.
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:return: A string with certain characters replaced by named
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or numeric entities.
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"""
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if not self.entity_substitution:
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return ns
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from .element import NavigableString
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if (isinstance(ns, NavigableString)
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and ns.parent is not None
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and ns.parent.name in self.cdata_containing_tags):
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# Do nothing.
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return ns
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# Substitute.
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return self.entity_substitution(ns)
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def attribute_value(self, value):
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"""Process the value of an attribute.
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:param ns: A string.
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:return: A string with certain characters replaced by named
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or numeric entities.
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"""
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return self.substitute(value)
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def attributes(self, tag):
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"""Reorder a tag's attributes however you want.
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By default, attributes are sorted alphabetically. This makes
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behavior consistent between Python 2 and Python 3, and preserves
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backwards compatibility with older versions of Beautiful Soup.
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"""
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if tag.attrs is None:
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return []
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return sorted(tag.attrs.items())
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class HTMLFormatter(Formatter):
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"""A generic Formatter for HTML."""
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REGISTRY = {}
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def __init__(self, *args, **kwargs):
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return super(HTMLFormatter, self).__init__(self.HTML, *args, **kwargs)
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class XMLFormatter(Formatter):
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"""A generic Formatter for XML."""
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REGISTRY = {}
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def __init__(self, *args, **kwargs):
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return super(XMLFormatter, self).__init__(self.XML, *args, **kwargs)
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# Set up aliases for the default formatters.
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HTMLFormatter.REGISTRY['html'] = HTMLFormatter(
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entity_substitution=EntitySubstitution.substitute_html
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)
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HTMLFormatter.REGISTRY["html5"] = HTMLFormatter(
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entity_substitution=EntitySubstitution.substitute_html,
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void_element_close_prefix = None
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)
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HTMLFormatter.REGISTRY["minimal"] = HTMLFormatter(
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entity_substitution=EntitySubstitution.substitute_xml
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)
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HTMLFormatter.REGISTRY[None] = HTMLFormatter(
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entity_substitution=None
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)
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XMLFormatter.REGISTRY["html"] = XMLFormatter(
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entity_substitution=EntitySubstitution.substitute_html
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)
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XMLFormatter.REGISTRY["minimal"] = XMLFormatter(
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entity_substitution=EntitySubstitution.substitute_xml
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)
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XMLFormatter.REGISTRY[None] = Formatter(
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Formatter(Formatter.XML, entity_substitution=None)
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)
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