'BEAUTIFY',
    'BODY',
    'BR',
    'BUTTON',
    'CENTER',
    'CAT',
    'CODE',
    'COL',
    'COLGROUP',
    'DIV',
    'EM',
    'EMBED',
    'FIELDSET',
    'FORM',
    'H1',
    'H2',

def URL(
    a=None,
    c=None,
    f=None,
    r=None,
    args=None,
    vars=None,
    anchor='',
    extension=None,
    env=None,
    hmac_key=None,
    hash_vars=True,
    salt=None,
    user_signature=None,
    scheme=None,
    host=None,
    port=None,
    encode_embedded_slash=False,
    ):
    """
    generate a URL

    example::

        >>> str(URL(a='a', c='c', f='f', args=['x', 'y', 'z'],

        '/a/c/f/x/y/z?p=3&p=1&q=2#1'

        >>> str(URL(a='a', c='c', f='f', anchor='1+2'))
        '/a/c/f#1%2B2'

        >>> str(URL(a='a', c='c', f='f', args=['x', 'y', 'z'],
        ...     vars={'p':(1,3), 'q':2}, anchor='1', hmac_key='key'))
        '/a/c/f/x/y/z?p=1&p=3&q=2&_signature=a32530f0d0caa80964bb92aad2bedf8a4486a31f#1'

        >>> str(URL(a='a', c='c', f='f', args=['w/x', 'y/z']))
        '/a/c/f/w/x/y/z'

        >>> str(URL(a='a', c='c', f='f', args=['w/x', 'y/z'], encode_embedded_slash=True))
        '/a/c/f/w%2Fx/y%2Fz'

    generates a url '/a/c/f' corresponding to application a, controller c
    and function f. If r=request is passed, a, c, f are set, respectively,
    to r.application, r.controller, r.function.

    The more typical usage is:

    function2 = '%s.%s' % (function,extension or 'html')

    if not (application and controller and function):
        raise SyntaxError, 'not enough information to build the url'

    if not isinstance(args, (list, tuple)):
        args = [args]

    if args:
        if encode_embedded_slash:
            other = '/' + '/'.join([urllib.quote(str(x), '') for x in args])
        else:
            other = args and urllib.quote('/' + '/'.join([str(x) for x in args]))
    else:
        other = ''

    if other.endswith('/'):
        other += '/'    # add trailing slash to make last trailing empty arg explicit

    if vars.has_key('_signature'): vars.pop('_signature')
    list_vars = []
    for (key, vals) in sorted(vars.items()):
        if not isinstance(vals, (list, tuple)):

            if hash_vars and not isinstance(hash_vars, (list, tuple)):
                hash_vars = [hash_vars]
            h_vars = [(k, v) for (k, v) in list_vars if k in hash_vars]

        # re-assembling the same way during hash authentication
        message = h_args + '?' + urllib.urlencode(sorted(h_vars))

        sig = hmac_hash(message, hmac_key, digest_alg='sha1', salt=salt)
        # add the signature into vars
        list_vars.append(('_signature', sig))

    if list_vars:
        other += '?%s' % urllib.urlencode(list_vars)
    if anchor:
        other += '#' + urllib.quote(str(anchor))

    do not call directly. Use instead:

    URL.verify(hmac_key='...')

    the key has to match the one used to generate the URL.

        >>> r = Storage()
        >>> gv = Storage(p=(1,3),q=2,_signature='a32530f0d0caa80964bb92aad2bedf8a4486a31f')
        >>> r.update(dict(application='a', controller='c', function='f', extension='html'))
        >>> r['args'] = ['x', 'y', 'z']
        >>> r['get_vars'] = gv
        >>> verifyURL(r, 'key')
        True
        >>> verifyURL(r, 'kay')
        False
        >>> r.get_vars.p = (3, 1)

        except:
            # user has removed one of our vars! Immediate fail
            return False
    # build the full message string with both args & vars
    message = h_args + '?' + urllib.urlencode(sorted(h_vars))

    # hash with the hmac_key provided
    sig = hmac_hash(message, str(hmac_key), digest_alg='sha1', salt=salt)

    # put _signature back in get_vars just in case a second call to URL.verify is performed
    # (otherwise it'll immediately return false)
    request.get_vars['_signature'] = original_sig

    # return whether or not the signature in the request matched the one we just generated
    # (I.E. was the message the same as the one we originally signed)

        kargs['first_only'] = True
        sibs = self.siblings(*args, **kargs)
        if not sibs:
            return None
        return sibs[0]

class CAT(DIV):

    tag = ''

def TAG_unpickler(data):
    return cPickle.loads(data)

def TAG_pickler(data):
    d = DIV()

class A(DIV):

    tag = 'a'

    def xml(self):
        if self['delete']:
            d = "jQuery(this).closest('%s').remove();" % self['delete']
        else:
            d = ''
        if self['component']:
            self['_onclick']="web2py_component('%s','%s');%sreturn false;" % \
                (self['component'],self['target'] or '',d)
            self['_href'] = self['_href'] or '#null'
        elif self['callback']:
            if d:
                self['_onclick']="if(confirm(w2p_ajax_confirm_message||'Are you sure you want o delete this object?')){ajax('%s',[],'%s');%s};return false;" % (self['callback'],self['target'] or '',d)
            else:
                self['_onclick']="ajax('%s',[],'%s');%sreturn false;" % \
                    (self['callback'],self['target'] or '',d)
            self['_href'] = self['_href'] or '#null'
        elif self['cid']:
            self['_onclick']='web2py_component("%s","%s");return false;' % \
                (self['_href'],self['cid'])
        return DIV.xml(self)


class BUTTON(DIV):

    tag = 'button'


class EM(DIV):

    tag = 'em'

                self['value'] = self['_value'] == value
        requires = self['requires']
        if requires:
            if not isinstance(requires, (list, tuple)):
                requires = [requires]
            for validator in requires:
                (value, errors) = validator(value)
                if not errors is None:
                    self.vars[name] = value
                    self.errors[name] = errors
                    break
        if not name in self.errors:
            self.vars[name] = value
            return True
        return False

    def _postprocessing(self):
        t = self['_type']
        if not t:
            t = self['_type'] = 'text'
        t = t.lower()
        value = self['value']
        if self['_value'] is None:
            _value = None
        else:
            _value = str(self['_value'])
        if t == 'checkbox' and not '_checked' in self.attributes:
            if not _value:
                _value = self['_value'] = 'on'
            if not value:
                value = []
            elif value is True:
                value = [_value]
            elif not isinstance(value,(list,tuple)):
                value = str(value).split('|')
            self['_checked'] = _value in value and 'checked' or None
        elif t == 'radio' and not '_checked' in self.attributes:
            if str(value) == str(_value):
                self['_checked'] = 'checked'
            else:
                self['_checked'] = None
        elif t == 'text' or t == 'hidden':
            if value is None:
                self['value'] = _value
            else:
                self['_value'] = value

    def xml(self):
        name = self.attributes.get('_name', None)
        if name and hasattr(self, 'errors') \
                and self.errors.get(name, None) \
                and self['hideerror'] != True:
            return DIV.xml(self) + DIV(self.errors[name], _class='error',

    tag = 'textarea'

    def _postprocessing(self):
        if not '_rows' in self.attributes:
            self['_rows'] = 10
        if not '_cols' in self.attributes:
            self['_cols'] = 40
        if not self['value'] is None:
            self.components = [self['value']]
        elif self.components:
            self['value'] = self.components[0]


class OPTION(DIV):

            if isinstance(c, OPTGROUP):
                component_list.append(c.components)
            else:
                component_list.append([c])
        options = itertools.chain(*component_list)

        value = self['value']
        if not value is None:
            if not self['_multiple']:
                for c in options: # my patch
                    if value and str(c['_value'])==str(value):
                        c['_selected'] = 'selected'
                    else:
                        c['_selected'] = None
            else:

    tag = 'form'

    def __init__(self, *components, **attributes):
        DIV.__init__(self, *components,  **attributes)
        self.vars = Storage()
        self.errors = Storage()
        self.latest = Storage()
        self.accepted = None # none for not submitted

    def accepts(
        self,
        request_vars,
        session=None,
        formname='default',
        keepvalues=False,
        onvalidation=None,
        hideerror=False,
        **kwargs
        ):
        """
        kwargs is not used but allows to specify the same interface for FROM and SQLFORM
        """
        if request_vars.__class__.__name__ == 'Request':
            request_vars=request_vars.post_vars
        self.errors.clear()
        self.request_vars = Storage()
        self.request_vars.update(request_vars)
        self.session = session
        self.formname = formname
        self.keepvalues = keepvalues

        # if this tag is a form and we are in accepting mode (status=True)
        # check formname and formkey

        status = self._traverse(status,hideerror)
        if onvalidation:
            if isinstance(onvalidation, dict):
                onsuccess = onvalidation.get('onsuccess', None)
                onfailure = onvalidation.get('onfailure', None)
                if onsuccess and status:
                    onsuccess(self)
                if onfailure and request_vars and not status:
                    onfailure(self)
                    status = len(self.errors) == 0
            elif status:
                if isinstance(onvalidation, (list, tuple)):
                    [f(self) for f in onvalidation]
                else:
                    onvalidation(self)
        if self.errors:
            status = False
        if not session is None:
            if hasattr(self,'record_hash'):
                formkey = self.record_hash
            else:
                formkey = web2py_uuid()
            self.formkey = session['_formkey[%s]' % formname] = formkey
        if status and not keepvalues:
            self._traverse(False,hideerror)
        self.accepted = status
        return status

    def _postprocessing(self):
        if not '_action' in self.attributes:
            self['_action'] = ''
        if not '_method' in self.attributes:
            self['_method'] = 'post'

    def xml(self):
        newform = FORM(*self.components, **self.attributes)
        hidden_fields = self.hidden_fields()
        if hidden_fields.components:
            newform.append(hidden_fields)
        return DIV.xml(newform)

    def validate(self,**kwargs):











        """
        This function validates the form,
        you can use it instead of directly form.accepts.

        Usage:
        In controller

        def action():
            form=FORM(INPUT(_name=\"test\", requires=IS_NOT_EMPTY()))
            form.validate() #you can pass some args here - see below
            return dict(form=form)

        This can receive a bunch of arguments

        onsuccess = 'flash' - will show message_onsuccess in response.flash
                    None - will do nothing
                    can be a function (lambda form: pass)
        onfailure = 'flash' - will show message_onfailure in response.flash
                    None - will do nothing
                    can be a function (lambda form: pass)


        message_onsuccess
        message_onfailure
        next      = where to redirect in case of success
        any other kwargs will be passed for form.accepts(...)
        """
        from gluon import current, redirect

        kwargs['request_vars'] = kwargs.get('request_vars',current.request.post_vars)
        kwargs['session'] = kwargs.get('session',current.session)
        kwargs['dbio'] = kwargs.get('dbio',False) # necessary for SQLHTML forms

        onsuccess = kwargs.get('onsuccess','flash')
        onfailure = kwargs.get('onfailure','flash')
        message_onsuccess = kwargs.get('message_onsuccess',
                                       current.T("Success!"))
        message_onfailure = kwargs.get('message_onfailure',
                                       current.T("Errors in form, please check it out."))
        next = kwargs.get('next',None)
        for key in ('message_onsuccess','message_onfailure','onsuccess',
                    'onfailure','next'):
            if key in kwargs:
                del kwargs[key]

        if self.accepts(**kwargs):
            if onsuccess == 'flash':
                if next:
                    current.session.flash = message_onsuccess
                else:
                    current.response.flash = message_onsuccess
            elif callable(onsuccess):
                onsuccess(self)
            if next:
                if self.vars.id:
                    next = next.replace('[id]',str(self.vars.id))
                    next = next % self.vars
                    if not next.startswith('/'):
                        next = URL(next)
                redirect(next)
            return True
        elif self.errors:
            if onfailure == 'flash':
                current.response.flash = message_onfailure
            elif callable(onfailure):
                onfailure(self)
            return False

    def process(self, **kwargs):
        """
        Perform the .validate() method but returns the form

        Usage in controllers:
        # directly on return
        def action():
            #some code here

        def my_callback(status, msg):
           response.flash = "Success! "+msg if status else "Errors occured"

        # after argument can be 'flash' to response.flash messages
        # or a function name to use as callback or None to do nothing.
        def action():
            return dict(form=SQLFORM(db.table).process(onsuccess=my_callback)
        """
        kwargs['dbio'] = kwargs.get('dbio',True) # necessary for SQLHTML forms
        self.validate(**kwargs)
        return self


class BEAUTIFY(DIV):

    """
    example::

            try:
                parent_tagname=self.parent.tag
                self.parent = self.parent.parent
            except:
                raise RuntimeError, "unable to balance tag %s" % tagname
            if parent_tagname[:len(tagname)]==tagname: break

def markdown_serializer(text,tag=None,attr=None):
    attr = attr or {}
    if tag is None: return re.sub('\s+',' ',text)
    if tag=='br': return '\n\n'
    if tag=='h1': return '#'+text+'\n\n'
    if tag=='h2': return '#'*2+text+'\n\n'
    if tag=='h3': return '#'*3+text+'\n\n'
    if tag=='h4': return '#'*4+text+'\n\n'
    if tag=='p': return text+'\n\n'
    if tag=='b' or tag=='strong': return '**%s**' % text
    if tag=='em' or tag=='i': return '*%s*' % text
    if tag=='tt' or tag=='code': return '`%s`' % text
    if tag=='a': return '[%s](%s)' % (text,attr.get('_href',''))
    if tag=='img': return '![%s](%s)' % (attr.get('_alt',''),attr.get('_src',''))
    return text

def markmin_serializer(text,tag=None,attr=None):
    attr = attr or {}
    # if tag is None: return re.sub('\s+',' ',text)
    if tag=='br': return '\n\n'
    if tag=='h1': return '# '+text+'\n\n'
    if tag=='h2': return '#'*2+' '+text+'\n\n'
    if tag=='h3': return '#'*3+' '+text+'\n\n'
    if tag=='h4': return '#'*4+' '+text+'\n\n'
    if tag=='p': return text+'\n\n'

    return text


class MARKMIN(XmlComponent):
    """
    For documentation: http://web2py.com/examples/static/markmin.html
    """
    def __init__(self, text, extra=None, allowed=None, sep='p'):
        self.text = text
        self.extra = extra or {}
        self.allowed = allowed or {}
        self.sep = sep

    def xml(self):
        """
        calls the gluon.contrib.markmin render function to convert the wiki syntax
        """
        return render(self.text,extra=self.extra,allowed=self.allowed,sep=self.sep)

        """
        return [self.text]


if __name__ == '__main__':
    import doctest
    doctest.testmod()