'''
Kivy Language
=============
The Kivy language is a language dedicated to describing user interface and
interactions. You could compare this language to Qt's QML
(http://qt.nokia.com), but we included new concepts such as rule definitions
(which are somewhat akin to what you may know from CSS), templating and so on.
.. versionchanged:: 1.7.0
The Builder doesn't execute canvas expressions in realtime anymore. It will
pack all the expressions that need to be executed first and execute them
after dispatching input, just before drawing the frame. If you want to
force the execution of canvas drawing, just call
:meth:`Builder.sync <BuilderBase.sync>`.
An experimental profiling tool for the kv lang is also included. You can
activate it by setting the environment variable `KIVY_PROFILE_LANG=1`.
It will then generate an html file named `builder_stats.html`.
Overview
--------
The language consists of several constructs that you can use:
Rules
A rule is similar to a CSS rule. A rule applies to specific widgets (or
classes thereof) in your widget tree and modifies them in a
certain way.
You can use rules to specify interactive behaviour or use them to add
graphical representations of the widgets they apply to.
You can target a specific class of widgets (similar to the CSS
concept of a *class*) by using the ``cls`` attribute (e.g.
``cls=MyTestWidget``).
A Root Widget
You can use the language to create your entire user interface.
A kv file must contain only one root widget at most.
Templates
*(introduced in version 1.0.5.)*
Templates will be used to populate parts of your application, such as a
list's content. If you want to design the look of an entry in a list
(icon on the left, text on the right), you will use a template
for that.
Syntax of a kv File
-------------------
.. highlight:: kv
A Kivy language file must have ``.kv`` as filename extension.
The content of the file should always start with the Kivy header, where
`version` must be replaced with the Kivy language version you're using.
For now, use 1.0::
#:kivy `1.0`
# content here
The `content` can contain rule definitions, a root widget and templates::
# Syntax of a rule definition. Note that several Rules can share the same
# definition (as in CSS). Note the braces: they are part of the definition.
<Rule1,Rule2>:
# .. definitions ..
<Rule3>:
# .. definitions ..
# Syntax for creating a root widget
RootClassName:
# .. definitions ..
# Syntax for create a template
[TemplateName@BaseClass1,BaseClass2]:
# .. definitions ..
Regardless of whether it's a rule, root widget or template you're defining,
the definition should look like this::
# With the braces it's a rule. Without them, it's a root widget.
<ClassName>:
prop1: value1
prop2: value2
canvas:
CanvasInstruction1:
canvasprop1: value1
CanvasInstruction2:
canvasprop2: value2
AnotherClass:
prop3: value1
Here `prop1` and `prop2` are the properties of `ClassName` and `prop3` is the
property of `AnotherClass`. If the widget doesn't have a property with
the given name, an :class:`~kivy.properties.ObjectProperty` will be
automatically created and added to the instance.
`AnotherClass` will be created and added as a child of the `ClassName`
instance.
- The indentation is important and must be consistent. The spacing must be a
multiple of the number of spaces used on the first indented line. Spaces
are encouraged: mixing tabs and spaces is not recommended.
- The value of a property must be given on a single line (for now at least).
- The `canvas` property is special: you can put graphics instructions in it
to create a graphical representation of the current class.
Here is a simple example of a kv file that contains a root widget::
#:kivy 1.0
Button:
text: 'Hello world'
.. versionchanged:: 1.7.0
The indentation is not limited to 4 spaces anymore. The spacing must be a
multiple of the number of spaces used on the first indented line.
Both the :meth:`~BuilderBase.load_file` and the
:meth:`~BuilderBase.load_string` methods
return the root widget defined in your kv file/string. They will also add any
class and template definitions to the :class:`~kivy.factory.Factory` for later
usage.
Value Expressions, on_property Expressions, and Reserved Keywords
-----------------------------------------------------------------
When you specify a property's value, the value is evaluated as a Python
expression. This expression can be static or dynamic, which means that
the value can use the values of other properties using reserved keywords.
self
The keyword self references the "current widget instance"::
Button:
text: 'My state is %s' % self.state
root
This keyword is available only in rule definitions and represents the
root widget of the rule (the first instance of the rule)::
<Widget>:
custom: 'Hello world'
Button:
text: root.custom
app
This keyword always refers to your app instance. It's equivalent
to a call to :meth:`kivy.app.App.get_running_app` in Python.::
Label:
text: app.name
args
This keyword is available in on_<action> callbacks. It refers to the
arguments passed to the callback.::
TextInput:
on_focus: self.insert_text("Focus" if args[1] else "No focus")
Furthermore, if a class definition contains an id, you can use it as a
keyword::
<Widget>:
Button:
id: btn1
Button:
text: 'The state of the other button is %s' % btn1.state
Please note that the `id` will not be available in the widget instance:
it is used exclusively for external references. `id` is a weakref to the
widget, and not the widget itself. The widget itself can be accessed
with `id.__self__` (`btn1.__self__` in this case).
Valid expressons
~~~~~~~~~~~~~~~~
There are two places that accept python statments in a kv file:
after a property, which assigns to the property the result of the expression
(such as the text of a button as shown above) and after a on_property, which
executes the statement when the property is updated (such as on_state).
In the former case, the
`expression <http://docs.python.org/2/reference/expressions.html>`_ can only
span a single line, cannot be extended to multiple lines using newline
escaping, and must return a value. An example of a valid expression is
``text: self.state and ('up' if self.state == 'normal' else 'down')``.
In the latter case, multiple single line statements are valid including
multi-line statements that escape their newline, as long as they don't
add an indentation level.
Examples of valid statements are::
on_press: if self.state == 'normal': print('normal')
on_state:
if self.state == 'normal': print('normal')
else: print('down')
if self.state == 'normal': \
print('multiline normal')
for i in range(10): print(i)
print([1,2,3,4,
5,6,7])
An example of a invalid statement::
on_state:
if self.state == 'normal':
print('normal')
Relation Between Values and Properties
--------------------------------------
When you use the Kivy language, you might notice that we do some work
behind the scenes to automatically make things work properly. You should
know that :doc:`api-kivy.properties` implement the
`Observer Design Pattern <http://en.wikipedia.org/wiki/Observer_pattern>`_.
That means that you can bind your own function to be
called when the value of a property changes (i.e. you passively
`observe` the property for potential changes).
The Kivy language detects properties in your `value` expression and will create
create callbacks to automatically update the property via your expression when
changes occur.
Here's a simple example that demonstrates this behaviour::
Button:
text: str(self.state)
In this example, the parser detects that `self.state` is a dynamic value (a
property). The :attr:`~kivy.uix.button.Button.state` property of the button
can change at any moment (when the user touches it).
We now want this button to display its own state as text, even as the state
changes. To do this, we use the state property of the Button and use it in the
value expression for the button's `text` property, which controls what text is
displayed on the button (We also convert the state to a string representation).
Now, whenever the button state changes, the text property will be updated
automatically.
Remember: The value is a python expression! That means that you can do
something more interesting like::
Button:
text: 'Plop world' if self.state == 'normal' else 'Release me!'
The Button text changes with the state of the button. By default, the button
text will be 'Plop world', but when the button is being pressed, the text will
change to 'Release me!'.
Graphical Instructions
----------------------
The graphical instructions are a special part of the Kivy language. They are
handled by the 'canvas' property definition::
Widget:
canvas:
Color:
rgb: (1, 1, 1)
Rectangle:
size: self.size
pos: self.pos
All the classes added inside the canvas property must be derived from the
:class:`~kivy.graphics.Instruction` class. You cannot put any Widget class
inside the canvas property (as that would not make sense because a
widget is not a graphics instruction).
If you want to do theming, you'll have the same question as in CSS: which rules
have been executed first? In our case, the rules are executed
in processing order (i.e. top-down).
If you want to change how Buttons are rendered, you can create your own kv file
and add something like this::
<Button>:
canvas:
Color:
rgb: (1, 0, 0)
Rectangle:
pos: self.pos
size: self.size
Rectangle:
pos: self.pos
size: self.texture_size
texture: self.texture
This will result in buttons having a red background with the label in the
bottom left, in addition to all the preceding rules.
You can clear all the previous instructions by using the `Clear` command::
<Button>:
canvas:
Clear
Color:
rgb: (1, 0, 0)
Rectangle:
pos: self.pos
size: self.size
Rectangle:
pos: self.pos
size: self.texture_size
texture: self.texture
Then, only your rules that follow the `Clear` command will be taken into
consideration.
.. _dynamic_classes:
Dynamic classes
---------------
Dynamic classes allow you to create new widgets on-the-fly, without any python
declaration in the first place. The syntax of the dynamic classes is similar to
the Rules, but you need to specify the base classes you want to
subclass.
The syntax look like:
.. code-block:: kv
# Simple inheritance
<NewWidget@Button>:
# kv code here ...
# Multiple inheritance
<NewWidget@ButtonBehavior+Label>:
# kv code here ...
The `@` character is used to seperate your class name from the classes you want
to subclass. The Python equivalent would have been:
.. code-block:: python
# Simple inheritance
class NewWidget(Button):
pass
# Multiple inheritance
class NewWidget(ButtonBehavior, Label):
pass
Any new properties, usually added in python code, should be declared first.
If the property doesn't exist in the dynamic class, it will be automatically
created as an :class:`~kivy.properties.ObjectProperty`.
.. versionchanged:: 1.8.0
If the property value is an expression that can be evaluated right away (no
external binding), then the value will be used as default value of the
property, and the type of the value will be used for the specialization of
the Property class. In other terms: if you declare `hello: "world"`, a new
:class:`~kivy.properties.StringProperty` will be instanciated, with the
default value `"world"`. List, tuples, dictionnary, strings, are supported.
Let's illustrate the usage of theses dynamic classes with an
implementation of a basic Image button. We could derive our classes from
the Button and just add a property for the image filename:
.. code-block:: kv
<ImageButton@Button>:
source: None
Image:
source: root.source
pos: root.pos
size: root.size
# let's use the new classes in another rule:
<MainUI>:
BoxLayout:
ImageButton:
source: 'hello.png'
on_press: root.do_something()
ImageButton:
source: 'world.png'
on_press: root.do_something_else()
In Python, you can create an instance of the dynamic class as follows:
.. code-block:: python
from kivy.factory import Factory
button_inst = Factory.ImageButton()
.. _template_usage:
Templates
---------
.. versionchanged:: 1.7.0
Template usage is now deprecated. Please use Dynamic classes instead.
Syntax of templates
~~~~~~~~~~~~~~~~~~~
Using a template in Kivy requires 2 things :
#. a context to pass for the context (will be ctx inside template).
#. a kv definition of the template.
Syntax of a template:
.. code-block:: kv
# With only one base class
[ClassName@BaseClass]:
# .. definitions ..
# With more than one base class
[ClassName@BaseClass1,BaseClass2]:
# .. definitions ..
For example, for a list, you'll need to create a entry with a image on
the left, and a label on the right. You can create a template for making
that definition easier to use.
So, we'll create a template that uses 2 entries in the context: an image
filename and a title:
.. code-block:: kv
[IconItem@BoxLayout]:
Image:
source: ctx.image
Label:
text: ctx.title
Then in Python, you can instanciate the template using:
.. code-block:: python
from kivy.lang import Builder
# create a template with hello world + an image
# the context values should be passed as kwargs to the Builder.template
# function
icon1 = Builder.template('IconItem', title='Hello world',
image='myimage.png')
# create a second template with other information
ctx = {'title': 'Another hello world',
'image': 'myimage2.png'}
icon2 = Builder.template('IconItem', **ctx)
# and use icon1 and icon2 as other widget.
Template example
~~~~~~~~~~~~~~~~
Most of time, when you are creating a screen in the kv lang, you use a lot of
redefinitions. In our example, we'll create a Toolbar, based on a
BoxLayout, and put in a few :class:`~kivy.uix.image.Image` widgets that
will react to the *on_touch_down* event.:
.. code-block:: kv
<MyToolbar>:
BoxLayout:
Image:
source: 'data/text.png'
size: self.texture_size
size_hint: None, None
on_touch_down: self.collide_point(*args[1].pos) and\
root.create_text()
Image:
source: 'data/image.png'
size: self.texture_size
size_hint: None, None
on_touch_down: self.collide_point(*args[1].pos) and\
root.create_image()
Image:
source: 'data/video.png'
size: self.texture_size
size_hint: None, None
on_touch_down: self.collide_point(*args[1].pos) and\
root.create_video()
We can see that the size and size_hint attribute are exactly the same.
More than that, the callback in on_touch_down and the image are changing.
Theses can be the variable part of the template that we can put into a context.
Let's try to create a template for the Image:
.. code-block:: kv
[ToolbarButton@Image]:
# This is the same as before
size: self.texture_size
size_hint: None, None
# Now, we are using the ctx for the variable part of the template
source: 'data/%s.png' % ctx.image
on_touch_down: self.collide_point(*args[1].pos) and ctx.callback()
The template can be used directly in the MyToolbar rule:
.. code-block:: kv
<MyToolbar>:
BoxLayout:
ToolbarButton:
image: 'text'
callback: root.create_text
ToolbarButton:
image: 'image'
callback: root.create_image
ToolbarButton:
image: 'video'
callback: root.create_video
That's all :)
Template limitations
~~~~~~~~~~~~~~~~~~~~
When you are creating a context:
#. you cannot use references other than "root":
.. code-block:: kv
<MyRule>:
Widget:
id: mywidget
value: 'bleh'
Template:
ctxkey: mywidget.value # << fail, this reference mywidget id
#. not all of the dynamic parts will be understood:
.. code-block:: kv
<MyRule>:
Template:
ctxkey: 'value 1' if root.prop1 else 'value2' # << even if
# root.prop1 is a property, the context will not update the
# context
Redefining a widget's style
---------------------------
Sometimes we would like to inherit from a widget in order to use its Python
properties without also using its .kv defined style. For example, we would
like to inherit from a Label, but we would also like to define our own
canvas instructions instead of automatically using the canvas instructions
inherited from the Label. We can achieve this by prepending a dash (-) before
the class name in the .kv style definition.
In myapp.py:
.. code-block:: python
class MyWidget(Label):
pass
and in my.kv:
.. code-block:: kv
<-MyWidget>:
canvas:
Color:
rgb: 1, 1, 1
Rectangle:
size: (32, 32)
MyWidget will now have a Color and Rectangle instruction in its canvas
without any of the instructions inherited from the Label.
Lang Directives
---------------
You can use directives to add declarative commands, such as imports or constant
definitions, to the lang files. Directives are added as comments in the
following format:
.. code-block:: kv
#:<directivename> <options>
import <package>
~~~~~~~~~~~~~~~~
.. versionadded:: 1.0.5
Syntax:
.. code-block:: kv
#:import <alias> <package>
You can import a package by writing:
.. code-block:: kv
#:import os os
<Rule>:
Button:
text: os.getcwd()
Or more complex:
.. code-block:: kv
#:import ut kivy.utils
<Rule>:
canvas:
Color:
rgba: ut.get_random_color()
.. versionadded:: 1.0.7
You can directly import classes from a module:
.. code-block:: kv
#: import Animation kivy.animation.Animation
<Rule>:
on_prop: Animation(x=.5).start(self)
set <key> <expr>
~~~~~~~~~~~~~~~~
.. versionadded:: 1.0.6
Syntax:
.. code-block:: kv
#:set <key> <expr>
Set a key that will be available anywhere in the kv. For example:
.. code-block:: kv
#:set my_color (.4, .3, .4)
#:set my_color_hl (.5, .4, .5)
<Rule>:
state: 'normal'
canvas:
Color:
rgb: my_color if self.state == 'normal' else my_color_hl
'''
__all__ = ('Builder', 'BuilderBase', 'BuilderException',
'Parser', 'ParserException')
import codecs
import re
import sys
from re import sub, findall
from os import environ
from os.path import join
from copy import copy
from types import CodeType
from functools import partial
from collections import OrderedDict
from kivy.factory import Factory
from kivy.logger import Logger
from kivy.utils import QueryDict
from kivy.cache import Cache
from kivy import kivy_data_dir, require
from kivy.compat import PY2, iteritems, iterkeys
from kivy.context import register_context
from kivy.resources import resource_find
import kivy.metrics as Metrics
trace = Logger.trace
global_idmap = {}
# late import
Instruction = None
# register cache for creating new classtype (template)
Cache.register('kv.lang')
# precompile regexp expression
lang_str = re.compile('([\'"][^\'"]*[\'"])')
lang_key = re.compile('([a-zA-Z_]+)')
lang_keyvalue = re.compile('([a-zA-Z_][a-zA-Z0-9_.]*\.[a-zA-Z0-9_.]+)')
lang_tr = re.compile('(_\()')
# delayed calls are canvas expression triggered during an loop
_delayed_calls = []
# all the widget handlers, used to correctly unbind all the callbacks then the
# widget is deleted
_handlers = {}
class ProxyApp(object):
# proxy app object
# taken from http://code.activestate.com/recipes/496741-object-proxying/
__slots__ = ['_obj']
def __init__(self):
object.__init__(self)
object.__setattr__(self, '_obj', None)
def _ensure_app(self):
app = object.__getattribute__(self, '_obj')
if app is None:
from kivy.app import App
app = App.get_running_app()
object.__setattr__(self, '_obj', app)
# Clear cached application instance, when it stops
app.bind(on_stop=lambda instance:
object.__setattr__(self, '_obj', None))
return app
def __getattribute__(self, name):
object.__getattribute__(self, '_ensure_app')()
return getattr(object.__getattribute__(self, '_obj'), name)
def __delattr__(self, name):
object.__getattribute__(self, '_ensure_app')()
delattr(object.__getattribute__(self, '_obj'), name)
def __setattr__(self, name, value):
object.__getattribute__(self, '_ensure_app')()
setattr(object.__getattribute__(self, '_obj'), name, value)
def __bool__(self):
object.__getattribute__(self, '_ensure_app')()
return bool(object.__getattribute__(self, '_obj'))
def __str__(self):
object.__getattribute__(self, '_ensure_app')()
return str(object.__getattribute__(self, '_obj'))
def __repr__(self):
object.__getattribute__(self, '_ensure_app')()
return repr(object.__getattribute__(self, '_obj'))
global_idmap['app'] = ProxyApp()
global_idmap['pt'] = Metrics.pt
global_idmap['inch'] = Metrics.inch
global_idmap['cm'] = Metrics.cm
global_idmap['mm'] = Metrics.mm
global_idmap['dp'] = Metrics.dp
global_idmap['sp'] = Metrics.sp
[docs]class ParserException(Exception):
'''Exception raised when something wrong happened in a kv file.
'''
def __init__(self, context, line, message):
self.filename = context.filename or '<inline>'
self.line = line
sourcecode = context.sourcecode
sc_start = max(0, line - 2)
sc_stop = min(len(sourcecode), line + 3)
sc = ['...']
for x in range(sc_start, sc_stop):
if x == line:
sc += ['>> %4d:%s' % (line + 1, sourcecode[line][1])]
else:
sc += [' %4d:%s' % (x + 1, sourcecode[x][1])]
sc += ['...']
sc = '\n'.join(sc)
message = 'Parser: File "%s", line %d:\n%s\n%s' % (
self.filename, self.line + 1, sc, message)
super(ParserException, self).__init__(message)
[docs]class BuilderException(ParserException):
'''Exception raised when the Builder failed to apply a rule on a widget.
'''
pass
class ParserRuleProperty(object):
'''Represent a property inside a rule.
'''
__slots__ = ('ctx', 'line', 'name', 'value', 'co_value',
'watched_keys', 'mode', 'count')
def __init__(self, ctx, line, name, value):
super(ParserRuleProperty, self).__init__()
#: Associated parser
self.ctx = ctx
#: Line of the rule
self.line = line
#: Name of the property
self.name = name
#: Value of the property
self.value = value
#: Compiled value
self.co_value = None
#: Compilation mode
self.mode = None
#: Watched keys
self.watched_keys = None
#: Stats
self.count = 0
def precompile(self):
name = self.name
value = self.value
# first, remove all the string from the value
tmp = sub(lang_str, '', self.value)
# detecting how to handle the value according to the key name
mode = self.mode
if self.mode is None:
self.mode = mode = 'exec' if name[:3] == 'on_' else 'eval'
if mode == 'eval':
# if we don't detect any string/key in it, we can eval and give the
# result
if re.search(lang_key, tmp) is None:
self.co_value = eval(value)
return
# ok, we can compile.
value = '\n' * self.line + value
self.co_value = compile(value, self.ctx.filename or '<string>', mode)
# for exec mode, we don't need to watch any keys.
if mode == 'exec':
return
# now, detect obj.prop
# first, remove all the string from the value
tmp = sub(lang_str, '', value)
# detect key.value inside value, and split them
wk = list(set(findall(lang_keyvalue, tmp)))
if len(wk):
self.watched_keys = [x.split('.') for x in wk]
if findall(lang_tr, tmp):
if self.watched_keys:
self.watched_keys += [['_']]
else:
self.watched_keys = [['_']]
def __repr__(self):
return '<ParserRuleProperty name=%r filename=%s:%d ' \
'value=%r watched_keys=%r>' % (
self.name, self.ctx.filename, self.line + 1,
self.value, self.watched_keys)
class ParserRule(object):
'''Represents a rule, in terms of the Kivy internal language.
'''
__slots__ = ('ctx', 'line', 'name', 'children', 'id', 'properties',
'canvas_before', 'canvas_root', 'canvas_after',
'handlers', 'level', 'cache_marked', 'avoid_previous_rules')
def __init__(self, ctx, line, name, level):
super(ParserRule, self).__init__()
#: Level of the rule in the kv
self.level = level
#: Associated parser
self.ctx = ctx
#: Line of the rule
self.line = line
#: Name of the rule
self.name = name
#: List of children to create
self.children = []
#: Id given to the rule
self.id = None
#: Properties associated to the rule
self.properties = OrderedDict()
#: Canvas normal
self.canvas_root = None
#: Canvas before
self.canvas_before = None
#: Canvas after
self.canvas_after = None
#: Handlers associated to the rule
self.handlers = []
#: Properties cache list: mark which class have already been checked
self.cache_marked = []
#: Indicate if any previous rules should be avoided.
self.avoid_previous_rules = False
if level == 0:
self._detect_selectors()
else:
self._forbid_selectors()
def precompile(self):
for x in self.properties.values():
x.precompile()
for x in self.handlers:
x.precompile()
for x in self.children:
x.precompile()
if self.canvas_before:
self.canvas_before.precompile()
if self.canvas_root:
self.canvas_root.precompile()
if self.canvas_after:
self.canvas_after.precompile()
def create_missing(self, widget):
# check first if the widget class already been processed by this rule
cls = widget.__class__
if cls in self.cache_marked:
return
self.cache_marked.append(cls)
for name in self.properties:
if hasattr(widget, name):
continue
value = self.properties[name].co_value
if type(value) is CodeType:
value = None
widget.create_property(name, value)
def _forbid_selectors(self):
c = self.name[0]
if c == '<' or c == '[':
raise ParserException(
self.ctx, self.line,
'Selectors rules are allowed only at the first level')
def _detect_selectors(self):
c = self.name[0]
if c == '<':
self._build_rule()
elif c == '[':
self._build_template()
else:
if self.ctx.root is not None:
raise ParserException(
self.ctx, self.line,
'Only one root object is allowed by .kv')
self.ctx.root = self
def _build_rule(self):
name = self.name
if __debug__:
trace('Builder: build rule for %s' % name)
if name[0] != '<' or name[-1] != '>':
raise ParserException(self.ctx, self.line,
'Invalid rule (must be inside <>)')
# if the very first name start with a -, avoid previous rules
name = name[1:-1]
if name[:1] == '-':
self.avoid_previous_rules = True
name = name[1:]
rules = name.split(',')
for rule in rules:
crule = None
if not len(rule):
raise ParserException(self.ctx, self.line,
'Empty rule detected')
if '@' in rule:
# new class creation ?
# ensure the name is correctly written
rule, baseclasses = rule.split('@', 1)
if not re.match(lang_key, rule):
raise ParserException(self.ctx, self.line,
'Invalid dynamic class name')
# save the name in the dynamic classes dict.
self.ctx.dynamic_classes[rule] = baseclasses
crule = ParserSelectorName(rule)
else:
# classical selectors.
if rule[0] == '.':
crule = ParserSelectorClass(rule[1:])
elif rule[0] == '#':
crule = ParserSelectorId(rule[1:])
else:
crule = ParserSelectorName(rule)
self.ctx.rules.append((crule, self))
def _build_template(self):
name = self.name
if __debug__:
trace('Builder: build template for %s' % name)
if name[0] != '[' or name[-1] != ']':
raise ParserException(self.ctx, self.line,
'Invalid template (must be inside [])')
item_content = name[1:-1]
if not '@' in item_content:
raise ParserException(self.ctx, self.line,
'Invalid template name (missing @)')
template_name, template_root_cls = item_content.split('@')
self.ctx.templates.append((template_name, template_root_cls, self))
def __repr__(self):
return '<ParserRule name=%r>' % (self.name, )
[docs]class Parser(object):
'''Create a Parser object to parse a Kivy language file or Kivy content.
'''
PROP_ALLOWED = ('canvas.before', 'canvas.after')
CLASS_RANGE = list(range(ord('A'), ord('Z') + 1))
PROP_RANGE = (
list(range(ord('A'), ord('Z') + 1)) +
list(range(ord('a'), ord('z') + 1)) +
list(range(ord('0'), ord('9') + 1)) + [ord('_')])
__slots__ = ('rules', 'templates', 'root', 'sourcecode',
'directives', 'filename', 'dynamic_classes')
def __init__(self, **kwargs):
super(Parser, self).__init__()
self.rules = []
self.templates = []
self.root = None
self.sourcecode = []
self.directives = []
self.dynamic_classes = {}
self.filename = kwargs.get('filename', None)
content = kwargs.get('content', None)
if content is None:
raise ValueError('No content passed')
self.parse(content)
def execute_directives(self):
for ln, cmd in self.directives:
cmd = cmd.strip()
if __debug__:
trace('Parser: got directive <%s>' % cmd)
if cmd[:5] == 'kivy ':
version = cmd[5:].strip()
if len(version.split('.')) == 2:
version += '.0'
require(version)
elif cmd[:4] == 'set ':
try:
name, value = cmd[4:].strip().split(' ', 1)
except:
Logger.exception('')
raise ParserException(self, ln, 'Invalid directive syntax')
try:
value = eval(value)
except:
Logger.exception('')
raise ParserException(self, ln, 'Invalid value')
global_idmap[name] = value
elif cmd[:7] == 'import ':
package = cmd[7:].strip()
l = package.split(' ')
if len(l) != 2:
raise ParserException(self, ln, 'Invalid import syntax')
alias, package = l
try:
if package not in sys.modules:
try:
mod = __import__(package)
except ImportError:
mod = __import__('.'.join(package.split('.')[:-1]))
# resolve the whole thing
for part in package.split('.')[1:]:
mod = getattr(mod, part)
else:
mod = sys.modules[package]
global_idmap[alias] = mod
except ImportError:
Logger.exception('')
raise ParserException(self, ln,
'Unable to import package %r' %
package)
else:
raise ParserException(self, ln, 'Unknown directive')
[docs] def parse(self, content):
'''Parse the contents of a Parser file and return a list
of root objects.
'''
# Read and parse the lines of the file
lines = content.splitlines()
if not lines:
return
num_lines = len(lines)
lines = list(zip(list(range(num_lines)), lines))
self.sourcecode = lines[:]
if __debug__:
trace('Parser: parsing %d lines' % num_lines)
# Strip all comments
self.strip_comments(lines)
# Execute directives
self.execute_directives()
# Get object from the first level
objects, remaining_lines = self.parse_level(0, lines)
# Precompile rules tree
for rule in objects:
rule.precompile()
# After parsing, there should be no remaining lines
# or there's an error we did not catch earlier.
if remaining_lines:
ln, content = remaining_lines[0]
raise ParserException(self, ln, 'Invalid data (not parsed)')
[docs] def parse_level(self, level, lines, spaces=0):
'''Parse the current level (level * spaces) indentation.
'''
indent = spaces * level if spaces > 0 else 0
objects = []
current_object = None
current_property = None
current_propobject = None
i = 0
while i < len(lines):
line = lines[i]
ln, content = line
# Get the number of space
tmp = content.lstrip(' \t')
# Replace any tab with 4 spaces
tmp = content[:len(content) - len(tmp)]
tmp = tmp.replace('\t', ' ')
# first indent designates the indentation
if spaces == 0:
spaces = len(tmp)
count = len(tmp)
if spaces > 0 and count % spaces != 0:
raise ParserException(self, ln,
'Invalid indentation, '
'must be a multiple of '
'%s spaces' % spaces)
content = content.strip()
rlevel = count // spaces if spaces > 0 else 0
# Level finished
if count < indent:
return objects, lines[i - 1:]
# Current level, create an object
elif count == indent:
x = content.split(':', 1)
if not len(x[0]):
raise ParserException(self, ln, 'Identifier missing')
if len(x) == 2 and len(x[1]):
raise ParserException(self, ln,
'Invalid data after declaration')
name = x[0]
# if it's not a root rule, then we got some restriction
# aka, a valid name, without point or everything else
if count != 0:
if False in [ord(z) in Parser.PROP_RANGE for z in name]:
raise ParserException(self, ln, 'Invalid class name')
current_object = ParserRule(self, ln, x[0], rlevel)
current_property = None
objects.append(current_object)
# Next level, is it a property or an object ?
elif count == indent + spaces:
x = content.split(':', 1)
if not len(x[0]):
raise ParserException(self, ln, 'Identifier missing')
# It's a class, add to the current object as a children
current_property = None
name = x[0]
if ord(name[0]) in Parser.CLASS_RANGE or name[0] == '+':
_objects, _lines = self.parse_level(
level + 1, lines[i:], spaces)
current_object.children = _objects
lines = _lines
i = 0
# It's a property
else:
if name not in Parser.PROP_ALLOWED:
if not all(ord(z) in Parser.PROP_RANGE for z in name):
raise ParserException(self, ln,
'Invalid property name')
if len(x) == 1:
raise ParserException(self, ln, 'Syntax error')
value = x[1].strip()
if name == 'id':
if len(value) <= 0:
raise ParserException(self, ln, 'Empty id')
if value in ('self', 'root'):
raise ParserException(
self, ln,
'Invalid id, cannot be "self" or "root"')
current_object.id = value
elif len(value):
rule = ParserRuleProperty(self, ln, name, value)
if name[:3] == 'on_':
current_object.handlers.append(rule)
else:
current_object.properties[name] = rule
else:
current_property = name
current_propobject = None
# Two more levels?
elif count == indent + 2 * spaces:
if current_property in (
'canvas', 'canvas.after', 'canvas.before'):
_objects, _lines = self.parse_level(
level + 2, lines[i:], spaces)
rl = ParserRule(self, ln, current_property, rlevel)
rl.children = _objects
if current_property == 'canvas':
current_object.canvas_root = rl
elif current_property == 'canvas.before':
current_object.canvas_before = rl
else:
current_object.canvas_after = rl
current_property = None
lines = _lines
i = 0
else:
if current_propobject is None:
current_propobject = ParserRuleProperty(
self, ln, current_property, content)
if current_property[:3] == 'on_':
current_object.handlers.append(current_propobject)
else:
current_object.properties[current_property] = \
current_propobject
else:
current_propobject.value += '\n' + content
# Too much indentation, invalid
else:
raise ParserException(self, ln,
'Invalid indentation (too many levels)')
# Check the next line
i += 1
return objects, []
def get_proxy(widget):
try:
return widget.proxy_ref
except AttributeError:
return widget
def custom_callback(__kvlang__, idmap, *largs, **kwargs):
idmap['args'] = largs
exec(__kvlang__.co_value, idmap)
def create_handler(iself, element, key, value, rule, idmap, delayed=False):
locals()['__kvlang__'] = rule
# create an handler
uid = iself.uid
if uid not in _handlers:
_handlers[uid] = []
idmap = copy(idmap)
idmap.update(global_idmap)
idmap['self'] = iself.proxy_ref
def call_fn(*args):
if __debug__:
trace('Builder: call_fn %s, key=%s, value=%r, %r' % (
element, key, value, rule.value))
rule.count += 1
e_value = eval(value, idmap)
if __debug__:
trace('Builder: call_fn => value=%r' % (e_value, ))
setattr(element, key, e_value)
def delayed_call_fn(*args):
_delayed_calls.append(call_fn)
fn = delayed_call_fn if delayed else call_fn
# bind every key.value
if rule.watched_keys is not None:
for k in rule.watched_keys:
try:
f = idmap[k[0]]
for x in k[1:-1]:
f = getattr(f, x)
if hasattr(f, 'bind'):
f.bind(**{k[-1]: fn})
# make sure _handlers doesn't keep widgets alive
_handlers[uid].append([get_proxy(f), k[-1], fn])
except KeyError:
continue
except AttributeError:
continue
try:
return eval(value, idmap)
except Exception as e:
raise BuilderException(rule.ctx, rule.line,
'{}: {}'.format(e.__class__.__name__, e))
class ParserSelector(object):
def __init__(self, key):
self.key = key.lower()
def match(self, widget):
raise NotImplemented()
def __repr__(self):
return '<%s key=%s>' % (self.__class__.__name__, self.key)
class ParserSelectorId(ParserSelector):
def match(self, widget):
if widget.id:
return widget.id.lower() == self.key
class ParserSelectorClass(ParserSelector):
def match(self, widget):
return self.key in widget.cls
class ParserSelectorName(ParserSelector):
parents = {}
def get_bases(self, cls):
for base in cls.__bases__:
if base.__name__ == 'object':
break
yield base
if base.__name__ == 'Widget':
break
for cbase in self.get_bases(base):
yield cbase
def match(self, widget):
parents = ParserSelectorName.parents
cls = widget.__class__
if not cls in parents:
classes = [x.__name__.lower() for x in
[cls] + list(self.get_bases(cls))]
parents[cls] = classes
return self.key in parents[cls]
[docs]class BuilderBase(object):
'''The Builder is responsible for creating a :class:`Parser` for parsing a
kv file, merging the results into its internal rules, templates, etc.
By default, :class:`Builder` is a global Kivy instance used in widgets
that you can use to load other kv files in addition to the default ones.
'''
_cache_match = {}
def __init__(self):
super(BuilderBase, self).__init__()
self.files = []
self.dynamic_classes = {}
self.templates = {}
self.rules = []
self.rulectx = {}
[docs] def load_file(self, filename, **kwargs):
'''Insert a file into the language builder and return the root widget
(if defined) of the kv file.
:parameters:
`rulesonly`: bool, defaults to False
If True, the Builder will raise an exception if you have a root
widget inside the definition.
'''
filename = resource_find(filename) or filename
if __debug__:
trace('Builder: load file %s' % filename)
with open(filename, 'r') as fd:
kwargs['filename'] = filename
data = fd.read()
# remove bom ?
if PY2:
if data.startswith((codecs.BOM_UTF16_LE, codecs.BOM_UTF16_BE)):
raise ValueError('Unsupported UTF16 for kv files.')
if data.startswith((codecs.BOM_UTF32_LE, codecs.BOM_UTF32_BE)):
raise ValueError('Unsupported UTF32 for kv files.')
if data.startswith(codecs.BOM_UTF8):
data = data[len(codecs.BOM_UTF8):]
return self.load_string(data, **kwargs)
[docs] def unload_file(self, filename):
'''Unload all rules associated with a previously imported file.
.. versionadded:: 1.0.8
.. warning::
This will not remove rules or templates already applied/used on
current widgets. It will only effect the next widgets creation or
template invocation.
'''
# remove rules and templates
self.rules = [x for x in self.rules if x[1].ctx.filename != filename]
self._clear_matchcache()
templates = {}
for x, y in self.templates.items():
if y[2] != filename:
templates[x] = y
self.templates = templates
if filename in self.files:
self.files.remove(filename)
# unregister all the dynamic classes
Factory.unregister_from_filename(filename)
[docs] def load_string(self, string, **kwargs):
'''Insert a string into the Language Builder and return the root widget
(if defined) of the kv string.
:Parameters:
`rulesonly`: bool, defaults to False
If True, the Builder will raise an exception if you have a root
widget inside the definition.
'''
kwargs.setdefault('rulesonly', False)
self._current_filename = fn = kwargs.get('filename', None)
# put a warning if a file is loaded multiple times
if fn in self.files:
Logger.warning(
'Lang: The file {} is loaded multiples times, '
'you might have unwanted behaviors.'.format(fn))
try:
# parse the string
parser = Parser(content=string, filename=fn)
# merge rules with our rules
self.rules.extend(parser.rules)
self._clear_matchcache()
# add the template found by the parser into ours
for name, cls, template in parser.templates:
self.templates[name] = (cls, template, fn)
Factory.register(name,
cls=partial(self.template, name),
is_template=True)
# register all the dynamic classes
for name, baseclasses in iteritems(parser.dynamic_classes):
Factory.register(name, baseclasses=baseclasses, filename=fn)
# create root object is exist
if kwargs['rulesonly'] and parser.root:
filename = kwargs.get('rulesonly', '<string>')
raise Exception('The file <%s> contain also non-rules '
'directives' % filename)
# save the loaded files only if there is a root without
# template/dynamic classes
if fn and (parser.templates or
parser.dynamic_classes or parser.rules):
self.files.append(fn)
if parser.root:
widget = Factory.get(parser.root.name)()
self._apply_rule(widget, parser.root, parser.root)
return widget
finally:
self._current_filename = None
[docs] def template(self, *args, **ctx):
'''Create a specialized template using a specific context.
.. versionadded:: 1.0.5
With templates, you can construct custom widgets from a kv lang
definition by giving them a context. Check :ref:`Template usage
<template_usage>`.
'''
# Prevent naming clash with whatever the user might be putting into the
# ctx as key.
name = args[0]
if name not in self.templates:
raise Exception('Unknown <%s> template name' % name)
baseclasses, rule, fn = self.templates[name]
key = '%s|%s' % (name, baseclasses)
cls = Cache.get('kv.lang', key)
if cls is None:
rootwidgets = []
for basecls in baseclasses.split('+'):
rootwidgets.append(Factory.get(basecls))
cls = type(name, tuple(rootwidgets), {})
Cache.append('kv.lang', key, cls)
widget = cls()
# in previous versions, ``ctx`` is passed as is as ``template_ctx``
# preventing widgets in it from be collected by the GC. This was
# especially relevant to AccordionItem's title_template.
proxy_ctx = {k: get_proxy(v) for k, v in ctx.items()}
self._apply_rule(widget, rule, rule, template_ctx=proxy_ctx)
return widget
[docs] def apply(self, widget):
'''Search all the rules that match the widget and apply them.
'''
rules = self.match(widget)
if __debug__:
trace('Builder: Found %d rules for %s' % (len(rules), widget))
if not rules:
return
for rule in rules:
self._apply_rule(widget, rule, rule)
def _clear_matchcache(self):
BuilderBase._match_cache = {}
def _apply_rule(self, widget, rule, rootrule, template_ctx=None):
# widget: the current instanciated widget
# rule: the current rule
# rootrule: the current root rule (for children of a rule)
# will collect reference to all the id in children
assert(rule not in self.rulectx)
self.rulectx[rule] = rctx = {
'ids': {'root': widget.proxy_ref},
'set': [], 'hdl': []}
# extract the context of the rootrule (not rule!)
assert(rootrule in self.rulectx)
rctx = self.rulectx[rootrule]
# if a template context is passed, put it as "ctx"
if template_ctx is not None:
rctx['ids']['ctx'] = QueryDict(template_ctx)
# if we got an id, put it in the root rule for a later global usage
if rule.id:
# use only the first word as `id` discard the rest.
rule.id = rule.id.split('#', 1)[0].strip()
rctx['ids'][rule.id] = widget.proxy_ref
# set id name as a attribute for root widget so one can in python
# code simply access root_widget.id_name
_ids = dict(rctx['ids'])
_root = _ids.pop('root')
_new_ids = _root.ids
for _key in iterkeys(_ids):
if _ids[_key] == _root:
# skip on self
continue
_new_ids[_key] = _ids[_key]
_root.ids = _new_ids
# first, ensure that the widget have all the properties used in
# the rule if not, they will be created as ObjectProperty.
rule.create_missing(widget)
# build the widget canvas
if rule.canvas_before:
with widget.canvas.before:
self._build_canvas(widget.canvas.before, widget,
rule.canvas_before, rootrule)
if rule.canvas_root:
with widget.canvas:
self._build_canvas(widget.canvas, widget,
rule.canvas_root, rootrule)
if rule.canvas_after:
with widget.canvas.after:
self._build_canvas(widget.canvas.after, widget,
rule.canvas_after, rootrule)
# create children tree
Factory_get = Factory.get
Factory_is_template = Factory.is_template
for crule in rule.children:
cname = crule.name
# depending if the child rule is a template or not, we are not
# having the same approach
cls = Factory_get(cname)
if Factory_is_template(cname):
# we got a template, so extract all the properties and
# handlers, and push them in a "ctx" dictionary.
ctx = {}
idmap = copy(global_idmap)
idmap.update({'root': rctx['ids']['root']})
if 'ctx' in rctx['ids']:
idmap.update({'ctx': rctx['ids']['ctx']})
try:
for prule in crule.properties.values():
value = prule.co_value
if type(value) is CodeType:
value = eval(value, idmap)
ctx[prule.name] = value
for prule in crule.handlers:
value = eval(prule.value, idmap)
ctx[prule.name] = value
except Exception as e:
raise BuilderException(
prule.ctx, prule.line,
'{}: {}'.format(e.__class__.__name__, e))
# create the template with an explicit ctx
child = cls(**ctx)
widget.add_widget(child)
# reference it on our root rule context
if crule.id:
rctx['ids'][crule.id] = child
else:
# we got a "normal" rule, construct it manually
# we can't construct it without __no_builder=True, because the
# previous implementation was doing the add_widget() before
# apply(), and so, we could use "self.parent".
child = cls(__no_builder=True)
widget.add_widget(child)
self.apply(child)
self._apply_rule(child, crule, rootrule)
# append the properties and handlers to our final resolution task
if rule.properties:
rctx['set'].append((widget.proxy_ref,
list(rule.properties.values())))
if rule.handlers:
rctx['hdl'].append((widget.proxy_ref, rule.handlers))
# if we are applying another rule that the root one, then it's done for
# us!
if rootrule is not rule:
del self.rulectx[rule]
return
# normally, we can apply a list of properties with a proper context
try:
rule = None
for widget_set, rules in reversed(rctx['set']):
for rule in rules:
assert(isinstance(rule, ParserRuleProperty))
key = rule.name
value = rule.co_value
if type(value) is CodeType:
value = create_handler(widget_set, widget_set, key,
value, rule, rctx['ids'])
setattr(widget_set, key, value)
except Exception as e:
if rule is not None:
raise BuilderException(rule.ctx, rule.line,
'{}: {}'.format(e.__class__.__name__,
e))
raise e
# build handlers
try:
crule = None
for widget_set, rules in rctx['hdl']:
for crule in rules:
assert(isinstance(crule, ParserRuleProperty))
assert(crule.name.startswith('on_'))
key = crule.name
if not widget_set.is_event_type(key):
key = key[3:]
idmap = copy(global_idmap)
idmap.update(rctx['ids'])
idmap['self'] = widget_set.proxy_ref
widget_set.bind(**{key: partial(custom_callback,
crule, idmap)})
#hack for on_parent
if crule.name == 'on_parent':
Factory.Widget.parent.dispatch(widget_set.__self__)
except Exception as e:
if crule is not None:
raise BuilderException(
crule.ctx, crule.line,
'{}: {}'.format(e.__class__.__name__, e))
raise e
# rule finished, forget it
del self.rulectx[rootrule]
[docs] def match(self, widget):
'''Return a list of :class:`ParserRule` objects matching the widget.
'''
cache = BuilderBase._match_cache
k = (widget.__class__, widget.id, tuple(widget.cls))
if k in cache:
return cache[k]
rules = []
for selector, rule in self.rules:
if selector.match(widget):
if rule.avoid_previous_rules:
del rules[:]
rules.append(rule)
cache[k] = rules
return rules
[docs] def sync(self):
'''Execute all the waiting operations, such as the execution of all the
expressions related to the canvas.
.. versionadded:: 1.7.0
'''
l = set(_delayed_calls)
del _delayed_calls[:]
for func in l:
try:
func(None, None)
except ReferenceError:
continue
def _build_canvas(self, canvas, widget, rule, rootrule):
global Instruction
if Instruction is None:
Instruction = Factory.get('Instruction')
idmap = copy(self.rulectx[rootrule]['ids'])
for crule in rule.children:
name = crule.name
if name == 'Clear':
canvas.clear()
continue
instr = Factory.get(name)()
if not isinstance(instr, Instruction):
raise BuilderException(
crule.ctx, crule.line,
'You can add only graphics Instruction in canvas.')
try:
for prule in crule.properties.values():
key = prule.name
value = prule.co_value
if type(value) is CodeType:
value = create_handler(
widget, instr.proxy_ref,
key, value, prule, idmap, True)
setattr(instr, key, value)
except Exception as e:
raise BuilderException(
prule.ctx, prule.line,
'{}: {}'.format(e.__class__.__name__, e))
#: Main instance of a :class:`BuilderBase`.
Builder = register_context('Builder', BuilderBase)
Builder.load_file(join(kivy_data_dir, 'style.kv'), rulesonly=True)
if 'KIVY_PROFILE_LANG' in environ:
import atexit
import cgi
def match_rule(fn, index, rule):
if rule.ctx.filename != fn:
return
for prop, prp in iteritems(rule.properties):
if prp.line != index:
continue
yield prp
for child in rule.children:
for r in match_rule(fn, index, child):
yield r
if rule.canvas_root:
for r in match_rule(fn, index, rule.canvas_root):
yield r
if rule.canvas_before:
for r in match_rule(fn, index, rule.canvas_before):
yield r
if rule.canvas_after:
for r in match_rule(fn, index, rule.canvas_after):
yield r
def dump_builder_stats():
html = [
'<!doctype html>'
'<html><body>',
'<style type="text/css">\n',
'pre { margin: 0; }\n',
'</style>']
files = set([x[1].ctx.filename for x in Builder.rules])
for fn in files:
lines = open(fn).readlines()
html += ['<h2>', fn, '</h2>', '<table>']
count = 0
for index, line in enumerate(lines):
line = line.rstrip()
line = cgi.escape(line)
matched_prp = []
for psn, rule in Builder.rules:
matched_prp += list(match_rule(fn, index, rule))
count = sum(set([x.count for x in matched_prp]))
color = (255, 155, 155) if count else (255, 255, 255)
html += ['<tr style="background-color: rgb{}">'.format(color),
'<td>', str(index + 1), '</td>',
'<td>', str(count), '</td>',
'<td><pre>', line, '</pre></td>',
'</tr>']
html += ['</table>']
html += ['</body></html>']
with open('builder_stats.html', 'w') as fd:
fd.write(''.join(html))
print('Profiling written at builder_stats.html')
atexit.register(dump_builder_stats)