Source code for cssvalueparser

# python 2
from __future__ import absolute_import
# plugins
from cssutils.css import Property
from xml.dom import SyntaxErr
# custom
from blowdrycss.utilities import contains_a_digit
from blowdrycss.datalibrary import property_alias_dict
from blowdrycss.colorparser import ColorParser
from blowdrycss.fontparser import FontParser
from blowdrycss.unitparser import UnitParser

__author__ = 'chad nelson'
__project__ = 'blowdrycss'


[docs]class CSSPropertyValueParser(object): """ Accepts a ``property_name`` and ``use_em`` unit conversion flag. Contains multiple parsers and methods that decodes the CSS property_value. :type property_name: str :param property_name: A CSS property name. :return: None **Attributes:** **property_name** (*str*) -- A CSS property name. Not allowed to be ``''`` or None. **color_parser** (*ColorParser*) -- Parses encoded color values. **unit_parser** (*UnitParser*) -- Parses encoded unit values, and handles unit conversion. **Important note about methods:** These methods are intended to be called in the order they are defined inside the class. """ def __init__(self, property_name=''): self.property_name = property_name self.color_parser = ColorParser(property_name=property_name) self.unit_parser = UnitParser(property_name=property_name)
[docs] def is_built_in(self, value=''): """ Checks if the encoded ``value`` identically matches a value built-in to the CSS standard. Returns True if ``value`` matches a CSS built-in valued and False if it does not. Examples include: 'bold', 'italic', 'w-resize', 'arial', etc. :type value: str :param value: Encoded CSS property value. :return: (*bool*) - Returns ``True`` if ``value`` matches a CSS built-in valued and ``False`` if it does not. - The values 'bold', 'italic', 'w-resize', 'arial' all return ``True``. - The values '-bold', 'fw-', 'color-' all return ``False``. - Invalid ``self.property_name`` also returns ``False`` (KeyError Case). **Examples:** >>> value_parser = CSSPropertyValueParser( >>> property_name='font-weight', use_em=True >>> ) >>> value_parser.is_built_in('bold') True >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.is_built_in('7-4-7-4') False >>> value_parser = CSSPropertyValueParser( >>> property_name='InvalidCSSPropertyName', use_em=True >>> ) >>> value_parser.is_built_in('italic') False """ if value.startswith('-') or value.endswith('-'): return False try: aliases = property_alias_dict[self.property_name] return True if value in aliases else False except KeyError: return False
[docs] @staticmethod def replace_dashes(value=''): """ Remove leading and trailing dashes. Replace internal dashes with spaces. Return the modified value. ``-`` becomes either ``''`` or ``' '``. :type value: str :param value: Encoded CSS property value. :return: (*str*) -- Return the value with dashes removed if necessary. >>> # Delete leading dash '-bold' --> 'bold' >>> value_parser = CSSPropertyValueParser( >>> property_name='font-weight', use_em=True >>> ) >>> value_parser.replace_dashes('-bold') 'bold' >>> # >>> # Delete trailing 'white-' --> 'white' >>> value_parser = CSSPropertyValueParser( >>> property_name='color', use_em=True >>> ) >>> value_parser.replace_dashes('white-') 'white' >>> # >>> # Replace internal '1-5-1-5' --> '1 5 1 5' >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.replace_dashes('1-5-1-5') '1 5 1 5' """ value = value[1:] if value.startswith('-') else value value = value[:-1] if value.endswith('-') else value return value.replace('-', ' ')
[docs] @staticmethod def replace_underscore_with_decimal(value=''): """ Replace underscore with decimal point. Underscores are used to encode a decimal point ``'_'`` becomes ``'.'`` :type value: str :param value: Encoded CSS property value. :return: (*str*) -- Return the value with decimal points added if necessary. **Example** >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.replace_underscore_with_decimal('1_32rem') '1.32rem' """ if contains_a_digit(string=value): value = value.replace('_', '.') return value
[docs] @staticmethod def replace_p_with_percent(value=''): """ Replace ``'p'`` suffix with ``'%'`` if found at the end of any substring containing digits. ``'p '`` becomes ``'%'`` Mind the space :type value: str :param value: Encoded CSS property value. :return: (*str*) -- Return the value with percent signs added if necessary. **Example:** >>> # Multi-value: '1p 10p 3p 1p' --> '1% 10% 3% 1%' >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.replace_p_with_percent(value='1p 10p 3p 1p') '1% 10% 3% 1%' >>> # >>> # Single value ' 1p' --> ' 1%' >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.replace_p_with_percent(value=' 1p') ' 1%' """ if contains_a_digit(string=value): value = value.replace('p ', '% ') if value.endswith('p'): value = value[:-1] + '%' # chop last character and add percentage sign return value
[docs] @staticmethod def replace_n_with_minus(value=''): """ If a space plus the letter ``' n'`` is immediately followed by a digit replace it with ``' -'``. If ``n`` is the first letter of the string and followed by digits replace it with ``-``. The letter ``n`` is an encoding for a negative sign. Leaves other ``n's`` unmodified. | ``' n2'`` becomes ``' -2'`` Mind the space. | ``'n5'`` becomes ``'-5'`` :type value: str :param value: Encoded CSS property value. :return: (*str*) -- Return the value with minus signs added if necessary. **Example:** >>> # Multi-value: 'n5cm n6cm' --> '-5cm -6cm' >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.replace_n_with_minus('n5cm n6cm') '-5cm -6cm' >>> # >>> # 'n9in' --> '-9in' (note that the 'n' at the end is not touched) >>> value_parser.replace_n_with_minus('n9in') '-9in' """ if contains_a_digit(string=value): value = value.replace(' n', ' -') if value.startswith('n'): value = '-' + value[1:] # add minus sign and chop first character return value
# Put everything together.
[docs] def decode_property_value(self, value=''): """ Decode the encoded property ``value`` input e.g. 'bold', '1-5-1-5', '1_32rem', '1p-10p-3p-1p', 'n12px', 'n5_25cm-n6_1cm'. Returns parsed, but non-validated CSS property value. :type value: str :param value: An encoded CSS property value. :return: (*str*) -- Returns the decoded, but non-validated CSS property value. **Examples:** >>> value_parser = CSSPropertyValueParser( >>> property_name='padding', use_em=True >>> ) >>> value_parser.decode_property_value(value='1-5-1-5') '0.0625em 0.3125em 0.0625em 0.3125em' >>> value_parser.unit_parser.use_em = False >>> value_parser.decode_property_value(value='1-5-1-5') '1px 5px 1px 5px' """ # Skip values that are built-in to the CSS standard, and represent the literal property value. if not self.is_built_in(value=value): # Apply to all non-built-in values. value = self.replace_dashes(value=value) # These only apply if value contains a digit. value = self.replace_underscore_with_decimal(value=value) value = self.replace_p_with_percent(value=value) value = self.replace_n_with_minus(value=value) # Parse color and units value = self.color_parser.replace_h_with_hash(value=value) value = self.color_parser.add_color_parenthetical(value=value) value = self.unit_parser.add_units(property_value=value) else: # Generate web safe font-family fallback strings. if self.property_name == 'font-family': font_parser = FontParser(font_value=value) value = font_parser.generate_fallback_fonts() return value
[docs] @staticmethod def property_is_valid(name='', value='', priority=''): """ Detects if a given property name, value, and priority combination is valid. Returns True if the combination is valid, and false otherwise. Validation occurs after the property value is decoded. :param name: CSS property name :param value: Decoded CSS property value :param priority: CSS priority designator :return: (*bool*) -- Returns True if the CSS property name, value, and priority combination is valid, and false otherwise. **Examples:** >>> value_parser = CSSPropertyValueParser() >>> value_parser.property_is_valid( >>> name='padding', value='1px', priority='' >>> ) True >>> value_parser.property_is_valid( >>> name='padding', value='invalid', priority='' >>> ) False """ try: css_property = Property(name=name, value=value, priority=priority) is_valid = css_property.valid return is_valid except SyntaxErr: return False
# TODO: Are URIs ridiculous? or should we implement syntax. For now YES they are ridiculous # background-image-url-image.png --> background-image: url("image.png") # background-image-url-_home_images_sample_image.png --> background-image: url("/home/images/sample/image.png") # IN THE LAST CASE images with underscores would not work could use a double underscore to represent final directory # but this is getting ridiculous example double underscore signifies final directory # allowing underscore in file name: # background-image-url-_home_images_sample__image_1.png --> background-image: url("/home/images/sample/image_1.png")