from beautifulsoup.element import Entities

__all__ = [
    'HTMLTreeBuilder',
    'SAXTreeBuilder',
    'TreeBuilder',
    ]

class TreeBuilder(Entities):
    """Turn a document into a Beautiful Soup object tree."""

    assume_html = False
    smart_quotes_to = Entities.XML_ENTITIES

    def __init__(self):
        self.soup = None
        self.self_closing_tags = set()
        self.preserve_whitespace_tags = set()

    def isSelfClosingTag(self, name):
        return name in self.self_closing_tags

    def reset(self):
        pass

    def feed(self, markup):
        raise NotImplementedError()


class SAXTreeBuilder(TreeBuilder):
    """A Beautiful Soup treebuilder that listens for SAX events."""

    def feed(self, markup):
        raise NotImplementedError()

    def close(self):
        pass

    def startElement(self, name, attrs):
        attrs = dict((key[1], value) for key, value in attrs.items())
        #print "Start %s, %r" % (name, attrs)
        self.soup.handle_starttag(name, attrs)

    def endElement(self, name):
        #print "End %s" % name
        self.soup.handle_endtag(name)

    def startElementNS(self, nsTuple, nodeName, attrs):
        # Throw away (ns, nodeName) for now.
        self.startElement(nodeName, attrs)

    def endElementNS(self, nsTuple, nodeName):
        # Throw away (ns, nodeName) for now.
        self.endElement(nodeName)
        #handler.endElementNS((ns, node.nodeName), node.nodeName)

    def startPrefixMapping(self, prefix, nodeValue):
        # Ignore the prefix for now.
        pass

    def endPrefixMapping(self, prefix):
        # Ignore the prefix for now.
        # handler.endPrefixMapping(prefix)
        pass

    def characters(self, content):
        self.soup.handle_data(content)

    def startDocument(self):
        pass

    def endDocument(self):
        pass


class HTMLTreeBuilder(TreeBuilder):
    """This TreeBuilder knows facts about HTML.

    Such as which tags are self-closing tags.
    """

    assume_html = True
    smart_quotes_to = Entities.HTML_ENTITIES

    preserve_whitespace_tags = set(['pre', 'textarea'])
    self_closing_tags = set(['br' , 'hr', 'input', 'img', 'meta',
                            'spacer', 'link', 'frame', 'base'])