lxml.html.soupparser — lxml documentation

# Source code for lxml.html.soupparser

    """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 = {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)