is forbidden), the function ensures that the result never contains

    '&', '<' and '>', thus making it safe in both those contexts (but

    not in attributes).

    """

    return literal(

        ('(' + json.dumps(value) + ')')

        # In JSON, the following can only appear in string literals.

        .replace('&', r'\x26')

        .replace('<', r'\x3c')

        .replace('>', r'\x3e')

    )

def jshtml(val):

    """HTML escapes a string value, then converts the resulting string

    to its corresponding JavaScript representation (see `js`).

    This is used when a plain-text string (possibly containing special

    HTML characters) will be used by a script in an HTML context (e.g.

    element.innerHTML or jQuery's 'html' method).

    If in doubt, err on the side of using `jshtml` over `js`, since it's

    better to escape too much than too little.

    """

    return js(escape(val))

def shorter(s, size=20, firstline=False, postfix='...'):

    """Truncate s to size, including the postfix string if truncating.

    If firstline, truncate at newline.

    """

    if firstline:

        s = s.split('\n', 1)[0].rstrip()

    if len(s) > size:

        return s[:size - len(postfix)] + postfix

    return s

def reset(name, value, id=NotGiven, **attrs):

    """Create a reset button, similar to webhelpers2.html.tags.submit ."""

    return _input("reset", name, value, id, attrs)

def select(name, selected_values, options, id=NotGiven, **attrs):

    """Convenient wrapper of webhelpers2 to let it accept options as a tuple list"""

    if isinstance(options, list):

        l = []

        for x in options:

                value, label = x

            l.append(Option(label, value))

        options = Options(l)

    return webhelpers2_select(name, selected_values, options, id=id, **attrs)

safeid = _make_safe_id_component

def FID(raw_id, path):

    """

    Creates a unique ID for filenode based on it's hash of path and revision

    it's safe to use in urls

    :param raw_id:

    :param path:

    """

    return 'C-%s-%s' % (short_id(raw_id), hashlib.md5(safe_str(path)).hexdigest()[:12])

class _FilesBreadCrumbs(object):

    def __call__(self, repo_name, rev, paths):

        if isinstance(paths, str):

            paths = safe_unicode(paths)

        url_l = [link_to(repo_name, url('files_home',

                                        repo_name=repo_name,

                                        revision=rev, f_path=''),

                         class_='ypjax-link')]

        paths_l = paths.split('/')

        for cnt, p in enumerate(paths_l):

            if p != '':

                url_l.append(link_to(p,

                                     url('files_home',

                                         repo_name=repo_name,

                                         revision=rev,

                                         f_path='/'.join(paths_l[:cnt + 1])

                                         ),

                                     class_='ypjax-link'

                                     )

                             )

        return literal('/'.join(url_l))

files_breadcrumbs = _FilesBreadCrumbs()