315 lines
10 KiB
Python
315 lines
10 KiB
Python
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"""External interface to the BeautifulSoup HTML parser.
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"""
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__all__ = ["fromstring", "parse", "convert_tree"]
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import re
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from lxml import etree, html
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try:
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from bs4 import (
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BeautifulSoup, Tag, Comment, ProcessingInstruction, NavigableString,
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Declaration, Doctype)
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_DECLARATION_OR_DOCTYPE = (Declaration, Doctype)
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except ImportError:
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from BeautifulSoup import (
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BeautifulSoup, Tag, Comment, ProcessingInstruction, NavigableString,
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Declaration)
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_DECLARATION_OR_DOCTYPE = Declaration
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def fromstring(data, beautifulsoup=None, makeelement=None, **bsargs):
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"""Parse a string of HTML data into an Element tree using the
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BeautifulSoup parser.
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Returns the root ``<html>`` Element of the tree.
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You can pass a different BeautifulSoup parser through the
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`beautifulsoup` keyword, and a diffent Element factory function
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through the `makeelement` keyword. By default, the standard
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``BeautifulSoup`` class and the default factory of `lxml.html` are
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used.
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"""
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return _parse(data, beautifulsoup, makeelement, **bsargs)
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def parse(file, beautifulsoup=None, makeelement=None, **bsargs):
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"""Parse a file into an ElemenTree using the BeautifulSoup parser.
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You can pass a different BeautifulSoup parser through the
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`beautifulsoup` keyword, and a diffent Element factory function
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through the `makeelement` keyword. By default, the standard
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``BeautifulSoup`` class and the default factory of `lxml.html` are
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used.
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"""
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if not hasattr(file, 'read'):
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file = open(file)
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root = _parse(file, beautifulsoup, makeelement, **bsargs)
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return etree.ElementTree(root)
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def convert_tree(beautiful_soup_tree, makeelement=None):
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"""Convert a BeautifulSoup tree to a list of Element trees.
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Returns a list instead of a single root Element to support
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HTML-like soup with more than one root element.
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You can pass a different Element factory through the `makeelement`
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keyword.
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"""
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root = _convert_tree(beautiful_soup_tree, makeelement)
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children = root.getchildren()
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for child in children:
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root.remove(child)
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return children
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# helpers
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def _parse(source, beautifulsoup, makeelement, **bsargs):
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if beautifulsoup is None:
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beautifulsoup = BeautifulSoup
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if hasattr(beautifulsoup, "HTML_ENTITIES"): # bs3
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if 'convertEntities' not in bsargs:
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bsargs['convertEntities'] = 'html'
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if hasattr(beautifulsoup, "DEFAULT_BUILDER_FEATURES"): # bs4
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if 'features' not in bsargs:
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bsargs['features'] = 'html.parser' # use Python html parser
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tree = beautifulsoup(source, **bsargs)
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root = _convert_tree(tree, makeelement)
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# from ET: wrap the document in a html root element, if necessary
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if len(root) == 1 and root[0].tag == "html":
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return root[0]
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root.tag = "html"
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return root
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_parse_doctype_declaration = re.compile(
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r'(?:\s|[<!])*DOCTYPE\s*HTML'
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r'(?:\s+PUBLIC)?(?:\s+(\'[^\']*\'|"[^"]*"))?'
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r'(?:\s+(\'[^\']*\'|"[^"]*"))?',
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re.IGNORECASE).match
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class _PseudoTag:
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# Minimal imitation of BeautifulSoup.Tag
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def __init__(self, contents):
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self.name = 'html'
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self.attrs = []
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self.contents = contents
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def __iter__(self):
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return self.contents.__iter__()
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def _convert_tree(beautiful_soup_tree, makeelement):
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if makeelement is None:
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makeelement = html.html_parser.makeelement
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# Split the tree into three parts:
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# i) everything before the root element: document type
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# declaration, comments, processing instructions, whitespace
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# ii) the root(s),
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# iii) everything after the root: comments, processing
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# instructions, whitespace
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first_element_idx = last_element_idx = None
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html_root = declaration = None
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for i, e in enumerate(beautiful_soup_tree):
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if isinstance(e, Tag):
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if first_element_idx is None:
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first_element_idx = i
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last_element_idx = i
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if html_root is None and e.name and e.name.lower() == 'html':
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html_root = e
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elif declaration is None and isinstance(e, _DECLARATION_OR_DOCTYPE):
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declaration = e
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# For a nice, well-formatted document, the variable roots below is
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# a list consisting of a single <html> element. However, the document
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# may be a soup like '<meta><head><title>Hello</head><body>Hi
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# all<\p>'. In this example roots is a list containing meta, head
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# and body elements.
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if first_element_idx is None:
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pre_root = post_root = []
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roots = beautiful_soup_tree.contents
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else:
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pre_root = beautiful_soup_tree.contents[:first_element_idx]
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roots = beautiful_soup_tree.contents[first_element_idx:last_element_idx+1]
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post_root = beautiful_soup_tree.contents[last_element_idx+1:]
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# Reorganize so that there is one <html> root...
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if html_root is not None:
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# ... use existing one if possible, ...
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i = roots.index(html_root)
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html_root.contents = roots[:i] + html_root.contents + roots[i+1:]
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else:
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# ... otherwise create a new one.
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html_root = _PseudoTag(roots)
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convert_node = _init_node_converters(makeelement)
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# Process pre_root
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res_root = convert_node(html_root)
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prev = res_root
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for e in reversed(pre_root):
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converted = convert_node(e)
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if converted is not None:
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prev.addprevious(converted)
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prev = converted
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# ditto for post_root
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prev = res_root
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for e in post_root:
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converted = convert_node(e)
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if converted is not None:
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prev.addnext(converted)
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prev = converted
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if declaration is not None:
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try:
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# bs4 provides full Doctype string
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doctype_string = declaration.output_ready()
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except AttributeError:
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doctype_string = declaration.string
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match = _parse_doctype_declaration(doctype_string)
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if not match:
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# Something is wrong if we end up in here. Since soupparser should
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# tolerate errors, do not raise Exception, just let it pass.
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pass
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else:
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external_id, sys_uri = match.groups()
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docinfo = res_root.getroottree().docinfo
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# strip quotes and update DOCTYPE values (any of None, '', '...')
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docinfo.public_id = external_id and external_id[1:-1]
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docinfo.system_url = sys_uri and sys_uri[1:-1]
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return res_root
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def _init_node_converters(makeelement):
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converters = {}
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ordered_node_types = []
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def converter(*types):
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def add(handler):
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for t in types:
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converters[t] = handler
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ordered_node_types.append(t)
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return handler
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return add
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def find_best_converter(node):
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for t in ordered_node_types:
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if isinstance(node, t):
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return converters[t]
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return None
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def convert_node(bs_node, parent=None):
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# duplicated in convert_tag() below
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try:
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handler = converters[type(bs_node)]
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except KeyError:
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handler = converters[type(bs_node)] = find_best_converter(bs_node)
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if handler is None:
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return None
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return handler(bs_node, parent)
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def map_attrs(bs_attrs):
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if isinstance(bs_attrs, dict): # bs4
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attribs = {}
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for k, v in bs_attrs.items():
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if isinstance(v, list):
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v = " ".join(v)
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attribs[k] = unescape(v)
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else:
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attribs = dict((k, unescape(v)) for k, v in bs_attrs)
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return attribs
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def append_text(parent, text):
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if len(parent) == 0:
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parent.text = (parent.text or '') + text
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else:
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parent[-1].tail = (parent[-1].tail or '') + text
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# converters are tried in order of their definition
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@converter(Tag, _PseudoTag)
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def convert_tag(bs_node, parent):
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attrs = bs_node.attrs
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if parent is not None:
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attribs = map_attrs(attrs) if attrs else None
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res = etree.SubElement(parent, bs_node.name, attrib=attribs)
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else:
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attribs = map_attrs(attrs) if attrs else {}
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res = makeelement(bs_node.name, attrib=attribs)
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for child in bs_node:
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# avoid double recursion by inlining convert_node(), see above
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try:
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handler = converters[type(child)]
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except KeyError:
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pass
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else:
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if handler is not None:
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handler(child, res)
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continue
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convert_node(child, res)
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return res
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@converter(Comment)
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def convert_comment(bs_node, parent):
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res = html.HtmlComment(bs_node)
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if parent is not None:
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parent.append(res)
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return res
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@converter(ProcessingInstruction)
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def convert_pi(bs_node, parent):
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if bs_node.endswith('?'):
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# The PI is of XML style (<?as df?>) but BeautifulSoup
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# interpreted it as being SGML style (<?as df>). Fix.
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bs_node = bs_node[:-1]
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res = etree.ProcessingInstruction(*bs_node.split(' ', 1))
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if parent is not None:
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parent.append(res)
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return res
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@converter(NavigableString)
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def convert_text(bs_node, parent):
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if parent is not None:
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append_text(parent, unescape(bs_node))
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return None
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return convert_node
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# copied from ET's ElementSoup
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try:
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from html.entities import name2codepoint # Python 3
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except ImportError:
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from htmlentitydefs import name2codepoint
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handle_entities = re.compile(r"&(\w+);").sub
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try:
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unichr
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except NameError:
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# Python 3
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unichr = chr
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def unescape(string):
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if not string:
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return ''
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# work around oddities in BeautifulSoup's entity handling
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def unescape_entity(m):
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try:
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return unichr(name2codepoint[m.group(1)])
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except KeyError:
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return m.group(0) # use as is
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return handle_entities(unescape_entity, string)
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