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