<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse_ref(self, ref):
 """Analyze the ref block, and return the information needed. Parameters ref : nodes.reference Returns ------- result : tuple of (str, str, str) The returned result is tuple of (title, uri, docpath). title is the display title of the ref. uri is the html uri of to the ref after resolve. docpath is the absolute document path to the document, if the target corresponds to an internal document, this can bex None """

        title = None
        if len(ref.children) == 0:
            title = ref['name'] if 'name' in ref else None
        elif isinstance(ref.children[0], nodes.Text):
            title = ref.children[0].astext()
        uri = ref['refuri']
        if uri.find('://') != -1:
            return (title, uri, None)
        anchor = None
        arr = uri.split('#')
        if len(arr) == 2:
            anchor = arr[1]
        if len(arr) > 2 or len(arr[0]) == 0:
            return (title, uri, None)
        uri = arr[0]

        abspath = os.path.abspath(os.path.join(self.file_dir, uri))
        relpath = os.path.relpath(abspath, self.root_dir)
        suffix = abspath.rsplit('.', 1)
        if len(suffix) == 2 and suffix[1] in AutoStructify.suffix_set and (
                os.path.exists(abspath) and abspath.startswith(self.root_dir)):
            # replace the path separator if running on non-UNIX environment
            if os.path.sep != '/':
                relpath = relpath.replace(os.path.sep, '/')
            docpath = '/' + relpath.rsplit('.', 1)[0]
            # rewrite suffix to html, this is suboptimal
            uri = docpath + '.html'
            if anchor is None:
                return (title, uri, docpath)
            else:
                return (title, uri + '#' + anchor, None)
        else:
            # use url resolver
            if self.url_resolver:
                uri = self.url_resolver(relpath)
            if anchor:
                uri += '#' + anchor
            return (title, uri, None)