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https://github.com/Kozea/WeasyPrint.git
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799 lines
24 KiB
Python
799 lines
24 KiB
Python
# coding: utf8
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# WeasyPrint converts web documents (HTML, CSS, ...) to PDF.
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# Copyright (C) 2011 Simon Sapin
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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"""
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Validator for all supported properties.
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See http://www.w3.org/TR/CSS21/propidx.html for allowed values.
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"""
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# TODO: unit-test these validators
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import functools
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import logging
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from .values import get_keyword, get_single_keyword, as_css
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from .properties import INITIAL_VALUES, NOT_PRINT_MEDIA
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from . import computed_values
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LOGGER = logging.getLogger('WEASYPRINT')
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# yes/no validators for non-shorthand properties
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# Maps property names to functions taking a property name and a value list,
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# returning a value or None for invalid.
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# Also transform values: keyword and URLs are returned as strings.
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# For properties that take a single value, that value is returned by itself
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# instead of a list.
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VALIDATORS = {}
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EXPANDERS = {}
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class InvalidValues(ValueError):
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"""Invalid or unsupported values for a known CSS property."""
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# Validators
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def validator(property_name=None):
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"""Decorator adding a function to the ``VALIDATORS``.
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The name of the property covered by the decorated function is set to
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``property_name`` if given, or is inferred from the function name
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(replacing underscores by hyphens).
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"""
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def decorator(function):
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"""Add ``function`` to the ``VALIDATORS``."""
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if property_name is None:
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name = function.__name__
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else:
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name = property_name.replace('-', '_')
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assert name in INITIAL_VALUES, name
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assert name not in VALIDATORS, name
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VALIDATORS[name] = function
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return function
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return decorator
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def single_keyword(function):
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"""Decorator for validators that only accept a single keyword."""
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@functools.wraps(function)
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def keyword_validator(values):
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"""Wrap a validator to call get_single_keyword on values."""
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keyword = get_single_keyword(values)
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if function(keyword):
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return keyword
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return keyword_validator
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def single_value(function):
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"""Decorator for validators that only accept a single value."""
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@functools.wraps(function)
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def single_value_validator(values):
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"""Validate a property whose value is single."""
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if len(values) == 1:
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return function(values[0])
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single_value_validator.__func__ = function
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return single_value_validator
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def is_dimension(value, negative=True):
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"""Get if ``value`` is a dimension.
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The ``negative`` argument sets wether negative values are allowed.
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"""
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type_ = value.type
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# Units may be ommited on zero lenghts.
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return (
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type_ == 'DIMENSION' and (negative or value.value >= 0) and (
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value.dimension in computed_values.LENGTHS_TO_PIXELS or
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value.dimension in ('em', 'ex'))
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) or (type_ == 'NUMBER' and value.value == 0)
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def is_dimension_or_percentage(value, negative=True):
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"""Get if ``value`` is a dimension or a percentage.
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The ``negative`` argument sets wether negative values are allowed.
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"""
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return is_dimension(value, negative) or (
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value.type == 'PERCENTAGE' and (negative or value.value >= 0))
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@validator()
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@single_keyword
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def background_attachment(keyword):
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"""``background-attachment`` property validation."""
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return keyword in ('scroll', 'fixed')
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@validator('background-color')
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@validator('border-top-color')
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@validator('border-right-color')
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@validator('border-bottom-color')
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@validator('border-left-color')
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@validator('color')
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@single_value
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def color(value):
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"""``*-color`` and ``color`` properties validation."""
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if value.type == 'COLOR_VALUE':
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return value
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if get_keyword(value) == 'currentColor':
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return 'currentColor'
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@validator('background-image')
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@validator('list-style-image')
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@single_value
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def image(value):
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"""``*-image`` properties validation."""
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if get_keyword(value) == 'none':
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return 'none'
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if value.type == 'URI':
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return value.absoluteUri
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@validator()
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def background_position(values):
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"""``background-position`` property validation.
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See http://www.w3.org/TR/CSS21/colors.html#propdef-background-position
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"""
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if len(values) == 1:
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value = values[0]
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keyword = get_keyword(value)
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if keyword in ('left', 'right', 'top', 'bottom', 'center'):
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return keyword, 'center'
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elif is_dimension_or_percentage(value):
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return value, 'center'
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elif len(values) == 2:
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value_1, value_2 = values
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keyword_1, keyword_2 = map(get_keyword, values)
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if is_dimension_or_percentage(value_1):
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if keyword_2 in ('top', 'center', 'bottom'):
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return value_1, keyword_2
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elif is_dimension_or_percentage(value_2):
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return value_1, value_2
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elif is_dimension_or_percentage(value_2):
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if keyword_1 in ('left', 'center', 'right'):
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return keyword_1, value_2
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elif (
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keyword_1 in ('left', 'center', 'right') and
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keyword_2 in ('top', 'center', 'bottom')
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) or (
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keyword_1 in ('top', 'center', 'bottom') and
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keyword_2 in ('left', 'center', 'right')
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):
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return keyword_1, keyword_2
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#else: invalid
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@validator()
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@single_keyword
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def background_repeat(keyword):
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"""``background-repeat`` property validation."""
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return keyword in ('repeat', 'repeat-x', 'repeat-y', 'no-repeat')
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@validator('border-top-style')
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@validator('border-right-style')
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@validator('border-left-style')
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@validator('border-bottom-style')
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@single_keyword
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def border_style(keyword):
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"""``border-*-style`` properties validation."""
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return keyword in ('none', 'hidden', 'dotted', 'dashed', 'solid',
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'double', 'groove', 'ridge', 'inset', 'outset')
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@validator('border-top-width')
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@validator('border-right-width')
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@validator('border-left-width')
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@validator('border-bottom-width')
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@single_value
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def border_width(value):
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"""``border-*-width`` properties validation."""
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if is_dimension(value, negative=False):
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return value
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keyword = get_keyword(value)
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if keyword in ('thin', 'medium', 'thick'):
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return keyword
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#@validator('top')
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#@validator('right')
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#@validator('left')
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#@validator('bottom')
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@validator('margin-top')
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@validator('margin-right')
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@validator('margin-bottom')
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@validator('margin-left')
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@single_value
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def lenght_precentage_or_auto(value, negative=True):
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"""``margin-*`` properties validation."""
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if is_dimension_or_percentage(value, negative):
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return value
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if get_keyword(value) == 'auto':
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return 'auto'
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@validator('height')
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@validator('width')
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@single_value
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def positive_lenght_precentage_or_auto(value):
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return lenght_precentage_or_auto.__func__(value, negative=False)
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@validator()
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@single_keyword
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def direction(keyword):
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"""``direction`` property validation."""
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return keyword in ('ltr', 'rtl')
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@validator()
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@single_keyword
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def display(keyword):
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"""``display`` property validation."""
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if keyword in (
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'inline-block', 'table', 'inline-table',
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'table-row-group', 'table-header-group', 'table-footer-group',
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'table-row', 'table-column-group', 'table-column', 'table-cell',
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'table-caption'):
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raise InvalidValues('value not supported yet')
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return keyword in ('inline', 'block', 'list-item', 'none')
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@validator()
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def font_family(values):
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"""``font-family`` property validation."""
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# TODO: we should split on commas only.
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# " If a sequence of identifiers is given as a font family name, the
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# computed value is the name converted to a string by joining all the
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# identifiers in the sequence by single spaces. "
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# http://www.w3.org/TR/CSS21/fonts.html#font-family-prop
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# eg. `font-family: Foo bar, "baz
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if all(value.type in ('IDENT', 'STRING') for value in values):
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return [value.value for value in values]
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@validator()
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@single_value
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def font_size(value):
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"""``font-size`` property validation."""
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if is_dimension_or_percentage(value):
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return value
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font_size_keyword = get_keyword(value)
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if font_size_keyword in ('smaller', 'larger'):
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raise InvalidValues('value not supported yet')
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if (
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font_size_keyword in computed_values.FONT_SIZE_KEYWORDS #or
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#keyword in ('smaller', 'larger')
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):
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return font_size_keyword
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@validator()
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@single_keyword
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def font_style(keyword):
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"""``font-style`` property validation."""
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return keyword in ('normal', 'italic', 'oblique')
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@validator()
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@single_keyword
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def font_variant(keyword):
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"""``font-variant`` property validation."""
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return keyword in ('normal', 'small-caps')
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@validator()
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@single_value
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def font_weight(value):
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"""``font-weight`` property validation."""
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keyword = get_keyword(value)
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if keyword in ('normal', 'bold', 'bolder', 'lighter'):
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return keyword
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if value.type == 'NUMBER':
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value = value.value
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if value in [100, 200, 300, 400, 500, 600, 700, 800, 900]:
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return value
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#@validator() XXX not supported yet
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@single_value
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def letter_spacing(value):
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"""``letter-spacing`` property validation."""
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if get_keyword(value) == 'normal':
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return 'normal'
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if is_dimension(value):
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return value
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@validator()
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@single_value
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def line_height(value):
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"""``line-height`` property validation."""
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if get_keyword(value) == 'normal':
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return 'normal'
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if (value.type in ('NUMBER', 'DIMENSION', 'PERCENTAGE') and
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value.value >= 0):
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return value
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@validator()
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@single_keyword
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def list_style_position(keyword):
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"""``list-style-position`` property validation."""
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return keyword in ('inside', 'outside')
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@validator()
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@single_keyword
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def list_style_type(keyword):
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"""``list-style-type`` property validation."""
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if keyword in ('decimal', 'decimal-leading-zero',
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'lower-roman', 'upper-roman', 'lower-greek', 'lower-latin',
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'upper-latin', 'armenian', 'georgian', 'lower-alpha',
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'upper-alpha'):
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raise InvalidValues('value not supported yet')
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return keyword in ('disc', 'circle', 'square', 'none')
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@validator('padding-top')
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@validator('padding-right')
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@validator('padding-bottom')
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@validator('padding-left')
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@single_value
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def length_or_precentage(value):
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"""``padding-*`` properties validation."""
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if is_dimension_or_percentage(value, negative=False):
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return value
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@validator()
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@single_keyword
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def position(keyword):
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"""``position`` property validation."""
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if keyword in ('relative', 'absolute', 'fixed'):
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raise InvalidValues('value not supported yet')
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return keyword in ('static',)
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@validator()
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@single_keyword
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def text_align(keyword):
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"""``text-align`` property validation."""
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if keyword in ('justify',):
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raise InvalidValues('value not supported yet')
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return keyword in ('left', 'right', 'center')
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@validator()
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def text_decoration(values):
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"""``text-decoration`` property validation."""
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keywords = map(get_keyword, values)
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if keywords == ['none']:
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return 'none'
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if all(keyword in ('underline', 'overline', 'line-through', 'blink')
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for keyword in keywords):
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unique = frozenset(keywords)
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if len(unique) == len(keywords):
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# No duplicate
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return unique
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@validator()
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@single_keyword
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def text_transform(keyword):
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"""``text-align`` property validation."""
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return keyword in ('none', 'uppercase', 'lowercase', 'capitalize')
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@validator()
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@single_value
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def vertical_align(value):
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if is_dimension_or_percentage(value, negative=True):
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return value
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keyword = get_keyword(value)
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if keyword in ('middle', 'sub', 'sup', 'text-top', 'text-bottom',
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'top', 'bottom'):
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raise InvalidValues('value not supported yet')
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if keyword in ('baseline',):
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return keyword
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@validator()
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@single_keyword
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def visibility(keyword):
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"""``white-space`` property validation."""
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return keyword in ('visible', 'hidden', 'collapse')
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@validator()
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@single_keyword
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def white_space(keyword):
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"""``white-space`` property validation."""
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return keyword in ('normal', 'pre', 'nowrap', 'pre-wrap', 'pre-line')
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@validator()
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def size(values):
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"""``size`` property validation.
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See http://www.w3.org/TR/css3-page/#page-size-prop
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"""
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if len(values) == 1:
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if is_dimension(values[0]):
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return values
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keyword = get_single_keyword(values)
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if (keyword in ('auto', 'portrait', 'landscape') or
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keyword in computed_values.PAGE_SIZES):
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return values
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if len(values) == 2:
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if all(is_dimension(value) for value in values):
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return values
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keywords = map(get_keyword, values)
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if (
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keywords[0] in ('portrait', 'landscape') and
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keywords[1] in computed_values.PAGE_SIZES
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) or (
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keywords[0] in computed_values.PAGE_SIZES and
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keywords[1] in ('portrait', 'landscape')
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):
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return values
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# Expanders
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# Let's be consistent, always use ``name`` as an argument even
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# when it is useless.
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# pylint: disable=W0613
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def expander(property_name):
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"""Decorator adding a function to the ``EXPANDERS``."""
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property_name = property_name.replace('-', '_')
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def expander_decorator(function):
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"""Add ``function`` to the ``EXPANDERS``."""
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assert property_name not in EXPANDERS, property_name
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EXPANDERS[property_name] = function
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return function
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return expander_decorator
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|
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@expander('border-color')
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@expander('border-style')
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@expander('border-width')
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@expander('margin')
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@expander('padding')
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def expand_four_sides(name, values):
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"""Expand properties setting a value for the four sides of a box."""
|
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# Make sure we have 4 values
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if len(values) == 1:
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values *= 4
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elif len(values) == 2:
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values *= 2 # (bottom, left) defaults to (top, right)
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elif len(values) == 3:
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values.append(values[1]) # left defaults to right
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elif len(values) != 4:
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raise InvalidValues(
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'Expected 1 to 4 value components got %i' % len(values))
|
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for suffix, value in zip(('_top', '_right', '_bottom', '_left'), values):
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i = name.rfind('_')
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if i == -1:
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new_name = name + suffix
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else:
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# eg. border-color becomes border-*-color, not border-color-*
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||
new_name = name[:i] + suffix + name[i:]
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|
||
# validate_non_shorthand returns [(name, value)], we want
|
||
# to yield (name, value)
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||
result, = validate_non_shorthand(new_name, [value], required=True)
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||
yield result
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||
|
||
|
||
def generic_expander(*expanded_names):
|
||
"""Decorator helping expanders to handle ``inherit`` and ``initial``.
|
||
|
||
Wrap an expander so that it does not have to handle the 'inherit' and
|
||
'initial' cases, and can just yield name suffixes. Missing suffixes
|
||
get the initial value.
|
||
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||
"""
|
||
expanded_names = [name.replace('-', '_') for name in expanded_names]
|
||
def generic_expander_decorator(wrapped):
|
||
"""Decorate the ``wrapped`` expander."""
|
||
@functools.wraps(wrapped)
|
||
def generic_expander_wrapper(name, values):
|
||
"""Wrap the expander."""
|
||
keyword = get_single_keyword(values)
|
||
if keyword in ('inherit', 'initial'):
|
||
results = dict.fromkeys(expanded_names, keyword)
|
||
skip_validation = True
|
||
else:
|
||
skip_validation = False
|
||
results = {}
|
||
for new_name, new_values in wrapped(name, values):
|
||
assert new_name in expanded_names, new_name
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||
assert new_name not in results, new_name
|
||
results[new_name] = new_values
|
||
|
||
for new_name in expanded_names:
|
||
if new_name.startswith('_'):
|
||
# new_name is a suffix
|
||
actual_new_name = name + new_name
|
||
else:
|
||
actual_new_name = new_name
|
||
|
||
if new_name in results:
|
||
values = results[new_name]
|
||
if not skip_validation:
|
||
# validate_non_shorthand returns [(name, value)]
|
||
(actual_new_name, values), = validate_non_shorthand(
|
||
actual_new_name, values, required=True)
|
||
else:
|
||
values = INITIAL_VALUES[actual_new_name]
|
||
|
||
yield actual_new_name, values
|
||
return generic_expander_wrapper
|
||
return generic_expander_decorator
|
||
|
||
|
||
@expander('list-style')
|
||
@generic_expander('-type', '-position', '-image')
|
||
def expand_list_style(name, values):
|
||
"""Expand the ``list-style`` shorthand property.
|
||
|
||
See http://www.w3.org/TR/CSS21/generate.html#propdef-list-style
|
||
|
||
"""
|
||
type_specified = image_specified = False
|
||
none_count = 0
|
||
for value in values:
|
||
if get_keyword(value) == 'none':
|
||
# Can be either -style or -image, see at the end which is not
|
||
# otherwise specified.
|
||
none_count += 1
|
||
none_value = value
|
||
continue
|
||
|
||
if list_style_type([value]) is not None:
|
||
suffix = '_type'
|
||
type_specified = True
|
||
elif list_style_position([value]) is not None:
|
||
suffix = '_position'
|
||
elif image([value]) is not None:
|
||
suffix = '_image'
|
||
image_specified = True
|
||
else:
|
||
raise InvalidValues
|
||
yield suffix, [value]
|
||
|
||
if not type_specified and none_count:
|
||
yield '_type', [none_value]
|
||
none_count -= 1
|
||
|
||
if not image_specified and none_count:
|
||
yield '_image', [none_value]
|
||
none_count -= 1
|
||
|
||
if none_count:
|
||
# Too many none values.
|
||
raise InvalidValues
|
||
|
||
|
||
@expander('border')
|
||
def expand_border(name, values):
|
||
"""Expand the ``border`` shorthand property.
|
||
|
||
See http://www.w3.org/TR/CSS21/box.html#propdef-border
|
||
|
||
"""
|
||
for suffix in ('_top', '_right', '_bottom', '_left'):
|
||
for new_prop in expand_border_side(name + suffix, values):
|
||
yield new_prop
|
||
|
||
|
||
@expander('border-top')
|
||
@expander('border-right')
|
||
@expander('border-bottom')
|
||
@expander('border-left')
|
||
@generic_expander('-width', '-color', '-style')
|
||
def expand_border_side(name, values):
|
||
"""Expand the ``border-*`` shorthand properties.
|
||
|
||
See http://www.w3.org/TR/CSS21/box.html#propdef-border-top
|
||
|
||
"""
|
||
for value in values:
|
||
if color([value]) is not None:
|
||
suffix = '_color'
|
||
elif border_width([value]) is not None:
|
||
suffix = '_width'
|
||
elif border_style([value]) is not None:
|
||
suffix = '_style'
|
||
else:
|
||
raise InvalidValues
|
||
yield suffix, [value]
|
||
|
||
|
||
def is_valid_background_positition(value):
|
||
"""Tell whether the value is valid for ``background-position``."""
|
||
return (
|
||
value.type in ('DIMENSION', 'PERCENTAGE') or
|
||
(value.type == 'NUMBER' and value.value == 0) or
|
||
get_keyword(value) in ('left', 'right', 'top', 'bottom', 'center'))
|
||
|
||
|
||
@expander('background')
|
||
@generic_expander('-color', '-image', '-repeat', '-attachment', '-position')
|
||
def expand_background(name, values):
|
||
"""Expand the ``background`` shorthand property.
|
||
|
||
See http://www.w3.org/TR/CSS21/colors.html#propdef-background
|
||
|
||
"""
|
||
# Make `values` a stack
|
||
values = list(reversed(values))
|
||
while values:
|
||
value = values.pop()
|
||
if color([value]) is not None:
|
||
suffix = '_color'
|
||
elif image([value]) is not None:
|
||
suffix = '_image'
|
||
elif background_repeat([value]) is not None:
|
||
suffix = '_repeat'
|
||
elif background_attachment([value]) is not None:
|
||
suffix = '_attachment'
|
||
elif background_position([value]):
|
||
if values:
|
||
next_value = values.pop()
|
||
if background_position([value, next_value]):
|
||
# Two consecutive '-position' values, yield them together
|
||
yield '_position', [value, next_value]
|
||
continue
|
||
else:
|
||
# The next value is not a '-position', put it back
|
||
# for the next loop iteration
|
||
values.append(next_value)
|
||
# A single '-position' value
|
||
suffix = '_position'
|
||
else:
|
||
raise InvalidValues
|
||
yield suffix, [value]
|
||
|
||
|
||
@expander('font')
|
||
@generic_expander('-style', '-variant', '-weight', '-size',
|
||
'line-height', '-family') # line-height is not a suffix
|
||
def expand_font(name, values):
|
||
"""Expand the ``font`` shorthand property.
|
||
|
||
http://www.w3.org/TR/CSS21/fonts.html#font-shorthand
|
||
"""
|
||
expand_font_keyword = get_single_keyword(values)
|
||
if expand_font_keyword in ('caption', 'icon', 'menu', 'message-box',
|
||
'small-caption', 'status-bar'):
|
||
LOGGER.warn(
|
||
'System fonts are not supported, `font: %s` ignored.',
|
||
expand_font_keyword)
|
||
return
|
||
|
||
# Make `values` a stack
|
||
values = list(reversed(values))
|
||
# Values for font-style font-variant and font-weight can come in any
|
||
# order and are all optional.
|
||
while values:
|
||
value = values.pop()
|
||
if get_keyword(value) == 'normal':
|
||
# Just ignore 'normal' keywords. Unspecified properties will get
|
||
# their initial value, which is 'normal' for all three here.
|
||
continue
|
||
|
||
if font_style([value]) is not None:
|
||
suffix = '_style'
|
||
elif font_variant([value]) is not None:
|
||
suffix = '_variant'
|
||
elif font_weight([value]) is not None:
|
||
suffix = '_weight'
|
||
else:
|
||
# We’re done with these three, continue with font-size
|
||
break
|
||
yield suffix, [value]
|
||
|
||
# Then font-size is mandatory
|
||
# Latest `value` from the loop.
|
||
if font_size([value]) is None:
|
||
raise InvalidValues
|
||
yield '_size', [value]
|
||
|
||
# Then line-height is optional, but font-family is not so the list
|
||
# must not be empty yet
|
||
if not values:
|
||
raise InvalidValues
|
||
|
||
value = values.pop()
|
||
if line_height([value]) is not None:
|
||
yield 'line_height', [value]
|
||
else:
|
||
# We pop()ed a font-family, add it back
|
||
values.append(value)
|
||
|
||
# Reverse the stack to get normal list
|
||
values.reverse()
|
||
if font_family(values) is None:
|
||
raise InvalidValues
|
||
yield '_family', values
|
||
|
||
|
||
def validate_non_shorthand(name, values, required=False):
|
||
"""Default validator for non-shorthand properties."""
|
||
if not required and name not in INITIAL_VALUES:
|
||
raise InvalidValues('unknown property')
|
||
|
||
if not required and name not in VALIDATORS:
|
||
raise InvalidValues('property not supported yet')
|
||
|
||
keyword = get_single_keyword(values)
|
||
if keyword in ('initial', 'inherit'):
|
||
value = keyword
|
||
else:
|
||
value = VALIDATORS[name](values)
|
||
if value is None:
|
||
raise InvalidValues
|
||
return [(name, value)]
|
||
|
||
|
||
def validate_and_expand(name, values):
|
||
"""Expand and validate shorthand properties.
|
||
|
||
The invalid or unsupported declarations are ignored and logged.
|
||
|
||
Return a iterable of ``(name, values)`` tuples.
|
||
|
||
"""
|
||
# Defaults
|
||
level = 'warn'
|
||
reason = 'invalid value'
|
||
|
||
if name in NOT_PRINT_MEDIA:
|
||
level = 'info'
|
||
reason = 'the property does not apply for the print media'
|
||
else:
|
||
expander_ = EXPANDERS.get(name, validate_non_shorthand)
|
||
try:
|
||
results = expander_(name, values)
|
||
# Use list() to consume any generator now,
|
||
# so that InvalidValues is caught.
|
||
return list(results)
|
||
except InvalidValues, exc:
|
||
if exc.args and exc.args[0]:
|
||
reason = exc.args[0]
|
||
getattr(LOGGER, level)('The declaration `%s: %s` was ignored: %s.',
|
||
name, as_css(values), reason)
|
||
return []
|