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from __future__ import absolute_import 

 

import copy 

import weakref 

import re 

import itertools 

import inspect 

import webob 

import uuid 

 

from . import templating 

from . import core 

from . import util 

from . import validation as vd 

from . import params as pm 

import six 

from six.moves import filter 

from markupsafe import Markup 

 

try: 

    import formencode 

except ImportError: 

    formencode = None 

 

reserved_names = ( 

    'parent', 

    'demo_for', 

    'child', 

    'submit', 

    'datasrc', 

    'newlink', 

    'edit', 

) 

_widget_seq = itertools.count(0) 

 

 

class WidgetMeta(pm.ParamMeta): 

    """ 

    This metaclass: 

 

     * Detects members that are widgets, and constructs the 

       `children` parameter based on this. 

     * Gives widgets a sequence number, so ordering works correctly. 

     * Calls post_define for the widget class and base classes. This 

       is needed as it's not possible to call super() in post_define. 

    """ 

    @classmethod 

    def _collect_base_children(meta, bases): 

        ''' Collect the children from the base classes ''' 

        children = [] 

        for b in bases: 

            bcld = getattr(b, 'children', None) 

            if bcld and not isinstance(bcld, RepeatingWidgetBunchCls): 

                children.extend(bcld) 

        return children 

 

    def __new__(meta, name, bases, dct): 

        if name != 'Widget' and 'children' not in dct: 

            new_children = [] 

            for d, v in list(dct.items()): 

                if isinstance(v, type) and \ 

                   issubclass(v, Widget) and \ 

                   d not in reserved_names: 

 

                    new_children.append((v, d)) 

                    del dct[d] 

 

            children = meta._collect_base_children(bases) 

            new_children = sorted(new_children, key=lambda t: t[0]._seq) 

            children.extend( 

                hasattr(v, 'id') and v or v(id=d) for v, d in new_children 

            ) 

            if children: 

                dct['children'] = children 

 

        widget = super(WidgetMeta, meta).__new__(meta, name, bases, dct) 

 

        widget._seq = six.advance_iterator(_widget_seq) 

        for w in reversed(widget.__mro__): 

            if 'post_define' in w.__dict__: 

                w.post_define.__func__(widget) 

        return widget 

 

 

class Widget(six.with_metaclass(WidgetMeta, pm.Parametered)): 

    """ 

    Base class for all widgets. 

    """ 

 

    id = pm.Param('Widget identifier', request_local=False) 

    key = pm.Param('Widget data key; None just uses id', 

                   default=None, request_local=False) 

    template = pm.Param( 

        'Template file for the widget, in the format ' + 

        'engine_name:template_path.  If `engine_name` is specified, this ' + 

        'is interepreted not as a path, but as an *inline template*', 

    ) 

    inline_engine_name = pm.Param( 

        'Name of an engine.  If specified, `template` is interpreted as ' + 

        'an *inline template* and not a path.', 

        default=None, 

    ) 

    validator = pm.Param( 

        'Validator for the widget.', 

        default=None, 

        request_local=False, 

    ) 

    attrs = pm.Param( 

        "Extra attributes to include in the widget's outer-most HTML tag.", 

        default={}, 

    ) 

    css_class = pm.Param( 

        'CSS class name', 

        default=None, 

        attribute=True, 

        view_name='class', 

    ) 

    value = pm.Param("The value for the widget.", default=None) 

    resources = pm.Param( 

        "Resources used by the widget. This must be an iterable, each " + \ 

        "item of which is a :class:`Resource` subclass.", 

        default=[], 

        request_local=False, 

    ) 

 

    error_msg = pm.Variable("Validation error message.") 

    parent = pm.Variable( 

        "The parent of this widget, or None if this is a root widget." 

    ) 

 

    _sub_compound = False 

    _valid_id_re = re.compile(r'^[a-zA-Z][\w\-\_\.]*$') 

 

    @classmethod 

    def req(cls, **kw): 

        """ 

        Generate an instance of the widget. 

 

        Return the validated widget for this request if one exists. 

        """ 

 

        ins = None 

 

        # Create an instance.  First check for the validated widget. 

        vw = vw_class = core.request_local().get('validated_widget') 

        if vw: 

            # Pull out actual class instances to compare to see if this 

            # is really the widget that was actually validated 

            if not getattr(vw_class, '__bases__', None): 

                vw_class = vw.__class__ 

 

            if vw_class is not cls: 

                vw = None 

 

            if vw: 

                ins = vw 

                for key, value in kw.items(): 

                    setattr(ins, key, value) 

 

        if ins is None: 

            # We weren't the validated widget (or there wasn't one), so 

            # create a new instance 

            ins = object.__new__(cls) 

            ins.__init__(**kw) 

 

        return ins 

 

    def __new__(cls, id=None, **kw): 

        """ 

        New is overloaded to return a subclass of the widget, rather than an 

        instance. 

        """ 

 

        # Support backwards compatibility with tw1-style calling 

        if id and 'id' not in kw: 

            kw['id'] = id 

 

        newname = calc_name(cls, kw) 

        return type(cls.__name__ + '_s', (cls, ), kw) 

 

    def __init__(self, **kw): 

        for k, v in six.iteritems(kw): 

            setattr(self, k, v) 

        self._js_calls = [] 

 

    @classmethod 

    def post_define(cls): 

        """ 

        This is a class method, that is called when a subclass of this Widget 

        is created. Process static configuration here. Use it like this:: 

 

            class MyWidget(LeafWidget): 

                @classmethod 

                def post_define(cls): 

                    id = getattr(cls,  'id', None) 

                    if id and not id.startswith('my'): 

                        raise pm.ParameterError("id must start with 'my'") 

 

        post_define should always cope with missing data - the class may be an 

        abstract class. There is no need to call super(), the metaclass will do 

        this automatically. 

        """ 

 

        if getattr(cls, 'id', None): 

            if not cls._valid_id_re.match(cls.id): 

                # http://www.w3schools.com/tags/att_standard_id.asp 

                raise pm.ParameterError( 

                    "Not a valid W3C id: '%s'" % cls.id) 

 

        if hasattr(cls, 'id') and not getattr(cls, 'key', None): 

            cls.key = cls.id 

 

        cls.compound_id = cls._gen_compound_id(for_url=False) 

        if cls.compound_id: 

            cls.attrs = cls.attrs.copy() 

            cls.attrs['id'] = cls.compound_id 

 

        cls.compound_key = cls._gen_compound_key() 

 

        if hasattr(cls, 'request') and getattr(cls, 'id', None): 

            from . import middleware 

            path = cls._gen_compound_id(for_url=True) 

            middleware.register_controller(cls, path) 

 

        if cls.validator: 

            if cls.validator is pm.Required: 

                vld = cls.__mro__[1].validator 

                cls.validator = vld and vld.clone(required=True) or \ 

                        vd.Validator(required=True) 

 

            if isinstance(cls.validator, type) and \ 

               issubclass(cls.validator, vd.Validator): 

                cls.validator = cls.validator() 

 

            if formencode and isinstance(cls.validator, type) and \ 

               issubclass(cls.validator, formencode.Validator): 

                cls.validator = cls.validator() 

 

            if not isinstance(cls.validator, vd.Validator) and \ 

               not (formencode and 

                    isinstance(cls.validator, formencode.Validator)): 

                raise pm.ParameterError( 

                    "Validator must be either a tw2 or FormEncode validator" 

                ) 

 

        cls.resources = [r(parent=cls) for r in cls.resources] 

        cls._deferred = [k for k, v in inspect.getmembers(cls) 

                         if isinstance(v, pm.Deferred)] 

        cls._attr = [p.name for p in cls._params.values() if p.attribute] 

 

        if cls.parent: 

            for p in cls.parent._all_params.values(): 

                if p.child_param and \ 

                   not hasattr(cls, p.name) and \ 

                   p.default is not pm.Required: 

 

                    setattr(cls, p.name, p.default) 

 

    @classmethod 

    def _gen_compound_name(cls, attr, for_url): 

        ancestors = [] 

        cur = cls 

        while cur: 

            if cur in ancestors: 

                raise core.WidgetError('Parent loop') 

            ancestors.append(cur) 

            cur = cur.parent 

        elems = reversed(list(filter(None, [ 

            a._compound_name_elem(attr, for_url) for a in ancestors 

        ]))) 

        if getattr(cls, attr, None) or \ 

           (cls.parent and issubclass(cls.parent, RepeatingWidget)): 

            return ':'.join(elems) 

        else: 

            return None 

 

    @classmethod 

    def _compound_name_elem(cls, attr, for_url): 

        if cls.parent and issubclass(cls.parent, RepeatingWidget): 

            if for_url: 

                return None 

            else: 

                return str(getattr(cls, 'repetition', None)) 

        else: 

            return getattr(cls, attr, None) 

 

    @classmethod 

    def _compound_id_elem(cls, for_url): 

        return cls._compound_name_elem('id', for_url) 

 

    @classmethod 

    def _gen_compound_id(cls, for_url): 

        return cls._gen_compound_name('id', for_url) 

 

    @classmethod 

    def _gen_compound_key(cls): 

        return cls._gen_compound_name('key', False) 

 

    @classmethod 

    def get_link(cls): 

        """ 

        Get the URL to the controller . This is called at run time, not startup 

        time, so we know the middleware if configured with the controller path. 

        Note: this function is a temporary measure, a cleaner API for this is 

        planned. 

        """ 

        if not hasattr(cls, 'request') or not getattr(cls, 'id', None): 

            raise core.WidgetError('Not a controller widget') 

        mw = core.request_local()['middleware'] 

        return mw.config.controller_prefix + cls._gen_compound_id(for_url=True) 

 

    def prepare(self): 

        """ 

        This is an instance method, that is called just before the Widget is 

        displayed. Process request-local configuration here. For 

        efficiency, widgets should do as little work as possible here. 

        Use it like this:: 

 

            class MyWidget(Widget): 

                def prepare(self): 

                    super(MyWidget, self).prepare() 

                    self.value = 'My: ' + str(self.value) 

        """ 

 

        # First, if we don't already have an id, then pick a random one. 

        if not hasattr(self, 'id'): 

            self.id = 'id_' + str(uuid.uuid4()).replace('-', '') 

 

        # Then, enforce any params marked with twc.Required. 

        for k, v in self._params.items(): 

            if v.default is pm.Required and not hasattr(self, k): 

                raise ValueError( 

                    "%r is a required Parameter for %r" % (k, self)) 

 

        for a in self._deferred: 

            dfr = getattr(self, a) 

            if isinstance(dfr, pm.Deferred): 

                setattr(self, a, dfr.fn()) 

 

        if self.validator and not hasattr(self, '_validated'): 

            value = self.value 

 

            # Handles the case where FE expects dict-like object, but 

            # you have None at your disposal. 

            if formencode and \ 

               isinstance(self.validator, formencode.Validator) and \ 

               self.value is None: 

                value = {} 

 

            try: 

                value = self.validator.from_python(value) 

            except vd.catch as e: 

                value = str(value) 

                self.error_msg = e.msg 

 

            if formencode and value == {} and self.value is None: 

                value = None 

 

            self.value = value 

 

        if self._attr or 'attrs' in self.__dict__: 

            self.attrs = self.attrs.copy() 

            if self.compound_id: 

                self.attrs['id'] = self.compound_id 

 

            for a in self._attr: 

                view_name = self._params[a].view_name 

                if self.attrs.get(view_name): 

                    raise pm.ParameterError( 

                        "Attr param clashes with user-supplied attr: '%s'" % a 

                    ) 

                self.attrs[view_name] = getattr(self, a) 

 

    def iteritems(self): 

        """ 

        An iterator which will provide the params of the widget in 

        key, value pairs. 

        """ 

        for param in self._params.keys(): 

            value = getattr(self, param) 

            yield param, value 

 

    @util.class_or_instance 

    def controller_path(self, cls): 

        """ Return the URL path against which this widget's controller is 

        mounted or None if it is not registered with the ControllerApp. 

        """ 

 

        mw = core.request_local().get('middleware') 

        return mw.controllers.controller_path(cls) 

 

    @util.class_or_instance 

    def add_call(self, extra_arg, call, location="bodybottom"): 

        """ 

        Not sure what the "extra_arg" needed is for, but it is needed, as is 

        the decorator, or an infinite loop ensues. 

 

        Adds a :func:`tw.api.js_function` call that will be made when the 

        widget is rendered. 

        """ 

        #log.debug("Adding call <%s> for %r statically.", call, self) 

        self._js_calls.append([call, location]) 

 

    @util.class_or_instance 

    def display(self, cls, value=None, displays_on=None, **kw): 

        """Display the widget - render the template. In the template, the 

        widget instance is available as the variable ``$w``. 

 

        If display is called on a class, it automatically creates an instance. 

 

        `displays_on` 

            The name of the template engine this widget is being displayed 

            inside. If not specified, this is determined automatically, from 

            the parent's template engine, or the default, if there is no 

            parent. Set this to ``string`` to get raw string output. 

        """ 

 

        # Support backwards compatibility with tw1-style calling 

        if value is not None and 'value' not in kw: 

            kw['value'] = value 

 

        # Support arguments to .display on either instance or class 

        # https://github.com/toscawidgets/tw2.core/issues/41 

        if self: 

            for key, value in kw.items(): 

                setattr(self, key, value) 

        else: 

            self = cls.req(**kw) 

 

        # Register any deferred params that are handed to us late in the game 

        # (after post_define).  The .prepare method handles processing them 

        # later. 

        self._deferred += [k for k, v in kw.items() if isinstance(v, pm.Deferred)] 

 

        if not self.parent: 

            self.prepare() 

 

        if self._js_calls: 

            self.safe_modify('resources') 

            #avoids circular reference 

            from . import resources as rs 

            for item in self._js_calls: 

                if 'JSFuncCall' in repr(item[0]): 

                    self.resources.append(item[0]) 

                else: 

                    self.resources.append(rs._JSFuncCall( 

                        src=str(item[0]), 

                        location=item[1], 

                    )) 

 

        if self.resources: 

            self.resources = WidgetBunch([r.req() for r in self.resources]) 

            for r in self.resources: 

                r.prepare() 

 

        return self.generate_output(displays_on) 

 

    def generate_output(self, displays_on): 

        """ 

        Generate the actual output text for this widget. 

 

        By default this renders the widget's template. Subclasses can override 

        this method for purely programmatic output. 

 

        `displays_on` 

            The name of the template engine this widget is being displayed 

            inside. 

 

        Use it like this:: 

 

            class MyWidget(LeafWidget): 

                def generate_output(self, displays_on): 

                    return "<span {0}>{1}</span>".format(self.attrs, self.text) 

        """ 

 

        mw = core.request_local().get('middleware') 

 

        if not displays_on: 

            displays_on = self._get_default_displays_on(mw) 

 

        # Build the arguments used while rendering the template 

        kwargs = {'w': self} 

        if mw and mw.config.params_as_vars: 

            for p in self._params: 

                if hasattr(self, p): 

                    kwargs[p] = getattr(self, p) 

 

        if self.template is None: 

            raise ValueError("A template must be provided.") 

 

        return templating.render( 

            self.template, 

            displays_on, 

            kwargs, 

            self.inline_engine_name, 

            mw, 

        ) 

 

    def _get_default_displays_on(self, mw): 

        if not self.parent: 

            if mw: 

                return mw.config.default_engine 

            return 'string' 

        else: 

            return templating.get_engine_name(self.parent.template, mw) 

 

    @classmethod 

    def validate(cls, params, state=None): 

        """ 

        Validate form input. This should always be called on a class. It 

        either returns the validated data, or raises a 

        :class:`ValidationError` exception. 

        """ 

        if cls.parent: 

            raise core.WidgetError('Only call validate on root widgets') 

        value = vd.unflatten_params(params) 

        if hasattr(cls, 'id') and cls.id: 

            value = value.get(cls.id, {}) 

        ins = cls.req() 

 

        # Key the validated widget by class id 

        core.request_local()['validated_widget'] = ins 

        return ins._validate(value, state) 

 

    @vd.catch_errors 

    def _validate(self, value, state=None): 

        """ 

        Inner validation method; this is called by validate and should not be 

        called directly. Overriding this method in widgets is discouraged; a 

        custom validator should be coded instead. However, in some 

        circumstances overriding is necessary. 

        """ 

        self._validated = True 

        self.value = value 

        if self.validator: 

            value = self.validator.to_python(value, state) 

        return value 

 

    def safe_modify(self, attr): 

        if (attr not in self.__dict__ and 

                isinstance(getattr(self, attr, None), (dict, list))): 

            setattr(self, attr, copy.copy(getattr(self, attr))) 

 

    @classmethod 

    def children_deep(cls): 

        yield cls 

 

 

class LeafWidget(Widget): 

    """ 

    A widget that has no children; this is the most common kind, e.g. form 

    fields. 

    """ 

 

 

class WidgetBunch(list): 

    def __getattr__(self, id): 

        for w in self: 

            if w.id == id: 

                return w 

        raise AttributeError("Widget has no child named '%s'" % id) 

 

 

class CompoundWidget(Widget): 

    """ 

    A widget that has an arbitrary number of children, this is common for 

    layout components, such as :class:`tw2.forms.TableLayout`. 

    """ 

    children = pm.Param( 

        'Children for this widget. This must be an iterable, ' + 

        'each item of which is a Widget' 

    ) 

    c = pm.Variable( 

        "Alias for children", 

        default=property(lambda s: s.children), 

    ) 

    children_deep = pm.Variable( 

        "Children, including any children from child " + 

        "CompoundWidgets that have no id", 

    ) 

    template = 'tw2.core.templates.display_children' 

    separator = pm.Param('HTML snippet which will be inserted ' 

                         'between each repeated child', default=None) 

 

    @classmethod 

    def post_define(cls): 

        """ 

        Check children are valid; update them to have a link to the parent. 

        """ 

        cls._sub_compound = not getattr(cls, 'id', None) 

        if not hasattr(cls, 'children'): 

            return 

        joined_cld = [] 

 

        for c in cls.children: 

            if not isinstance(c, type) or not issubclass(c, Widget): 

                raise pm.ParameterError("All children must be widgets") 

            joined_cld.append(c(parent=cls)) 

 

        ids = set() 

        for c in cls.children_deep(): 

            if getattr(c, 'id', None): 

                if c.id in ids: 

                    raise core.WidgetError("Duplicate id '%s'" % c.id) 

                ids.add(c.id) 

        cls.children = WidgetBunch(joined_cld) 

        cls.keyed_children = [ 

            c.id for c in joined_cld 

            if hasattr(c, 'key') and hasattr(c, 'id') and c.key != c.id 

        ] 

 

    def __init__(self, **kw): 

        super(CompoundWidget, self).__init__(**kw) 

        self.children = WidgetBunch( 

            c.req(parent=weakref.proxy(self)) 

            for c in self.children 

        ) 

 

    def prepare(self): 

        """ 

        Propagate the value for this widget to the children, based on their id. 

        """ 

        super(CompoundWidget, self).prepare() 

        if self.separator: 

            self.separator = Markup(self.separator) 

        v = self.value or {} 

        if not hasattr(self, '_validated'): 

            if hasattr(v, '__getitem__'): 

                for c in self.children: 

                    if c._sub_compound: 

                        c.value = v 

                    elif c.key in v: 

                        c.value = v[c.key] 

            else: 

                for c in self.children: 

                    if c._sub_compound: 

                        c.value = self.value 

                    else: 

                        c.value = getattr(self.value, c.key or '', None) 

        for c in self.children: 

            c.prepare() 

 

    def get_child_error_message(self, name): 

        if isinstance(self.error_msg, six.string_types): 

            if self.error_msg.startswith(name + ':'): 

                return self.error_msg.split(':')[1] 

 

    @vd.catch_errors 

    def _validate(self, value, state=None): 

        """ 

        The value must be a dict, or None. Each item in the dict is passed to 

        the corresponding child widget for validation, with special 

        consideration for _sub_compound widgets. If a child returns 

        vd.EmptyField, that value is not included in the resulting dict at all, 

        which is different to including None. Child widgets with a key are 

        passed the validated value from the field the key references. The 

        resulting dict is validated by this widget's validator. If any child 

        widgets produce an errors, this results in a "childerror" failure. 

        """ 

        self._validated = True 

        value = value or {} 

        if not isinstance(value, dict): 

            raise vd.ValidationError('corrupt', self.validator) 

        self.value = value 

        any_errors = False 

        data = {} 

 

        state = util.clone_object(state, full_dict=value, validated_values=data) 

 

        # Validate compound children 

        for c in (child for child in self.children if child._sub_compound): 

            try: 

                data.update(c._validate(value, state)) 

            except vd.catch as e: 

                if hasattr(e, 'msg'): 

                    c.error_msg = e.msg 

                any_errors = True 

 

        # Validate non compound children 

        for c in (child for child in self.children if not child._sub_compound): 

            d = value.get(c.key, '') 

            try: 

                val = c._validate(d, state) 

                if val is not vd.EmptyField: 

                    data[c.key] = val 

            except vd.catch as e: 

                if hasattr(e, 'msg'): 

                    c.error_msg = e.msg 

                data[c.key] = vd.Invalid 

                any_errors = True 

 

        # Validate self, usually a CompoundValidator or a FormEncode form-level 

        # validator. 

        exception_validator = self.validator 

        if self.validator: 

            try: 

                data = self.validator.to_python(data, state) 

            except vd.catch as e: 

                # If it failed to validate, check if the error_dict has any 

                # messages pertaining specifically to this widget's children. 

                error_dict = getattr(e, 'error_dict', {}) 

                if not error_dict: 

                    raise 

 

                for c in self.children: 

                    if getattr(c, 'key', None) in error_dict: 

                        c.error_msg = error_dict[c.key] 

                        data[c.key] = vd.Invalid 

                        exception_validator = None 

                        any_errors = True 

 

                # Only re-raise this top-level exception if the validation 

                # error doesn't pertain to any of our children. 

                if exception_validator: 

                    raise 

 

        if any_errors: 

            raise vd.ValidationError('childerror', exception_validator) 

 

        return data 

 

    @classmethod 

    def children_deep(cls): 

        if getattr(cls, 'id', None): 

            yield cls 

        else: 

            for c in getattr(cls, 'children', []): 

                for cc in c.children_deep(): 

                    yield cc 

 

 

class RepeatingWidgetBunchCls(object): 

 

    def __init__(self, parent): 

        self.parent = parent 

        self._repetition_cache = {} 

 

    def __getitem__(self, item): 

        if not isinstance(item, int): 

            raise KeyError("Must specify an integer") 

        try: 

            rep = self._repetition_cache[item] 

        except KeyError: 

            rep = self.parent.child(parent=self.parent, repetition=item) 

            self._repetition_cache[item] = rep 

        return rep 

 

 

class RepeatingWidgetBunch(object): 

    def __init__(self, parent, rwbc): 

        self.parent = parent 

        self.rwbc = rwbc 

        self._repetition_cache = {} 

 

    def __len__(self): 

        return self.parent.repetitions 

 

    def __iter__(self): 

        for i in range(len(self)): 

            yield self[i] 

 

    def __getitem__(self, item): 

        if not isinstance(item, int): 

            raise KeyError("Must specify an integer") 

        try: 

            rep = self._repetition_cache[item] 

        except KeyError: 

            rep = self.rwbc[item].req(parent=weakref.proxy(self.parent)) 

            self._repetition_cache[item] = rep 

        return rep 

 

 

class RepeatingWidget(Widget): 

    """ 

    A widget that has a single child, which is repeated an arbitrary number 

    of times, such as :class:`tw2.forms.GridLayout`. 

    """ 

    child = pm.Param('Child for this widget. The child must have no id.') 

    repetitions = pm.Param( 

        'Fixed number of repetitions. If this is None, it dynamically ' + 

        'determined, based on the length of the value list.', 

        default=None, 

    ) 

    min_reps = pm.Param('Minimum number of repetitions', default=None) 

    max_reps = pm.Param('Maximum number of repetitions', default=None) 

    extra_reps = pm.Param( 

        'Number of extra repeitions, beyond the length of the value list.', 

        default=0, 

    ) 

    children = pm.Param( 

        'Children specified for this widget will be passed to the child.  ' + 

        'In the template, children gets the list of repeated childen.', 

        default=[], 

    ) 

 

    repetition = pm.ChildVariable('The repetition of a child widget.') 

 

    template = 'tw2.core.templates.display_children' 

    separator = pm.Param('HTML snippet which will be inserted ' 

                         'between each repeated child', default=None) 

 

    @classmethod 

    def post_define(cls): 

        """ 

        Check child is valid; update with link to parent. 

        """ 

        if not hasattr(cls, 'child'): 

            return 

 

        if getattr(cls, 'children', None): 

            cls.child = cls.child(children=cls.children) 

            cls.children = [] 

 

        if not isinstance(cls.child, type) or \ 

           not issubclass(cls.child, Widget): 

            raise pm.ParameterError("Child must be a Widget") 

 

        if getattr(cls.child, 'id', None): 

            raise pm.ParameterError("Child must have no id") 

 

        cls.child = cls.child(parent=cls) 

        cls.rwbc = RepeatingWidgetBunchCls(parent=cls) 

 

    def __init__(self, **kw): 

        super(RepeatingWidget, self).__init__(**kw) 

        self.children = RepeatingWidgetBunch(self, self.rwbc) 

 

    def prepare(self): 

        """ 

        Propagate the value for this widget to the children, based on their 

        index. 

        """ 

        super(RepeatingWidget, self).prepare() 

        if self.separator: 

            self.separator = Markup(self.separator) 

        value = self.value or [] 

        if self.repetitions is None: 

            reps = len(value) + self.extra_reps 

            if self.max_reps is not None and reps > self.max_reps: 

                reps = self.max_reps 

            if self.min_reps is not None and reps < self.min_reps: 

                reps = self.min_reps 

            self.repetitions = reps 

 

        for i, v in enumerate(value): 

            self.children[i].value = v 

        for c in self.children: 

            c.prepare() 

        if not self.repetitions: 

            self.children[0].prepare() 

 

    @vd.catch_errors 

    def _validate(self, value, state=None): 

        """ 

        The value must either be a list or None. Each item in the list is 

        passed to the corresponding child widget for validation. The resulting 

        list is passed to this widget's validator. If any of the child widgets 

        produces a validation error, this widget generates a "childerror" 

        failure. 

        """ 

        self._validated = True 

        value = value or [] 

        if not isinstance(value, list): 

            raise vd.ValidationError('corrupt', self.validator, self) 

        self.value = value 

        any_errors = False 

        data = [] 

 

        state = util.clone_object(state, full_dict=value, validated_values=data) 

 

        for i, v in enumerate(value): 

            try: 

                data.append(self.children[i]._validate(v, state)) 

            except vd.catch: 

                data.append(vd.Invalid) 

                any_errors = True 

        if self.validator: 

            data = self.validator.to_python(data, state) 

        if any_errors: 

            raise vd.ValidationError('childerror', self.validator, self) 

        return data 

 

 

class DisplayOnlyWidgetMeta(WidgetMeta): 

    @classmethod 

    def _collect_base_children(meta, bases): 

        children = [] 

        for b in bases: 

            bchild = getattr(b, 'child', None) 

            if bchild: 

                b = b.child 

            bcld = getattr(b, 'children', None) 

            if bcld and not isinstance(bcld, RepeatingWidgetBunchCls): 

                children.extend(bcld) 

        return children 

 

 

def calc_name(cls, kw, char='s'): 

    if 'parent' in kw: 

        newname = kw['parent'].__name__ + '__' + cls.__name__ 

    else: 

        newname = cls.__name__ + '_%s' % char 

    return newname 

 

 

class DisplayOnlyWidget(six.with_metaclass(DisplayOnlyWidgetMeta, Widget)): 

    """ 

    A widget that has a single child. The parent widget is only used for 

    display purposes; it does not affect value propagation or validation. 

    This is used by widgets like :class:`tw2.forms.FieldSet`. 

    """ 

    child = pm.Param('Child for this widget.') 

    children = pm.Param( 

        'Children specified for this widget will be passed to the child', 

        default=[], 

    ) 

    id_suffix = pm.Variable('Suffix to append to compound IDs', default=None) 

 

    def __new__(cls, **kw): 

        newname = calc_name(cls, kw, 'd') 

        return type(newname, (cls,), kw) 

 

    @classmethod 

    def post_define(cls): 

        if not getattr(cls, 'child', None): 

            return 

 

        if getattr(cls, 'children', None): 

            cls.child = cls.child(children=cls.children) 

            cls.children = [] 

 

        if getattr(cls, 'validator', None): 

            cls.child.validator = cls.validator 

            cls.validator = None 

 

        if not isinstance(cls.child, type) or \ 

           not issubclass(cls.child, Widget): 

            raise pm.ParameterError("Child must be a widget") 

 

        cls.compound_key = None 

        cls._sub_compound = cls.child._sub_compound 

        cls_id = getattr(cls, 'id', None) 

        child_id = getattr(cls.child, 'id', None) 

        if cls_id and child_id and cls_id != child_id: 

            raise pm.ParameterError( 

                "Can only specify id on either a DisplayOnlyWidget, or " + 

                "its child, not both: '%s' '%s'" % (cls_id, child_id) 

            ) 

        if not cls_id and child_id: 

            cls.id = child_id 

            DisplayOnlyWidget.post_define.__func__(cls) 

            Widget.post_define.__func__(cls) 

            cls.child = cls.child(parent=cls, key=cls.key) 

        else: 

            cls.child = cls.child(id=cls_id, key=cls.key, parent=cls) 

 

    @classmethod 

    def _gen_compound_name(cls, attr, for_url): 

        elems = [ 

            Widget._gen_compound_name.__func__(cls, attr, for_url), 

            getattr(cls, attr, None) 

        ] 

        elems = list(filter(None, elems)) 

        if not elems: 

            return None 

        if not for_url and attr=='id' and getattr(cls, 'id_suffix', None): 

            elems.append(cls.id_suffix) 

        return ':'.join(elems) 

 

    @classmethod 

    def _compound_name_elem(cls, attr, for_url): 

        if cls.parent and issubclass(cls.parent, RepeatingWidget): 

            Widget._compound_name_elem.__func__(cls, attr, for_url) 

        else: 

            return None 

 

    def __init__(self, **kw): 

        super(DisplayOnlyWidget, self).__init__(**kw) 

        if hasattr(self, 'child'): 

            self.child = self.child.req(parent=weakref.proxy(self)) 

        else: 

            self.child = None 

 

    def prepare(self): 

        super(DisplayOnlyWidget, self).prepare() 

        if self.child: 

            if not hasattr(self, '_validated'): 

                self.child.value = self.value 

            self.child.prepare() 

 

    @vd.catch_errors 

    def _validate(self, value, state=None): 

        self._validated = True 

        try: 

            return self.child._validate(value, state) 

        except vd.ValidationError: 

            raise vd.ValidationError('childerror', self.validator, self) 

 

    @classmethod 

    def children_deep(cls): 

        for c in cls.child.children_deep(): 

            yield c 

 

 

def default_content_type(): 

    "default_content_type" 

    return "text/html; charset=%s" % ( 

        core.request_local()['middleware'].config.encoding 

    ) 

 

 

class Page(DisplayOnlyWidget): 

    """ 

    An HTML page. This widget includes a :meth:`request` method that serves 

    the page. 

    """ 

    title = pm.Param('Title for the page', default=None) 

    content_type = pm.Param( 

        'Content type header', 

        default=pm.Deferred(default_content_type), 

        request_local=False, 

    ) 

    template = "tw2.core.templates.page" 

    id_suffix = 'page' 

    _no_autoid = True 

 

    @classmethod 

    def post_define(cls): 

        if not getattr(cls, 'id', None) and '_no_autoid' not in cls.__dict__: 

            cls.id = cls.__name__.lower() 

            DisplayOnlyWidget.post_define.__func__(cls) 

            Widget.post_define.__func__(cls) 

 

    @classmethod 

    def request(cls, req): 

        ct = cls.content_type 

        if isinstance(ct, pm.Deferred): 

            ct = ct.fn() 

        resp = webob.Response(request=req, content_type=ct) 

        ins = cls.req() 

        ins.fetch_data(req) 

        resp.body = ins.display().encode( 

            core.request_local()['middleware'].config.encoding 

        ) 

        return resp 

 

    def fetch_data(self, req): 

        pass