css 0.0.22

A crate that uses the cssparser and selectors crates to provide a domain model for CSS Stylesheets. Intended to allow effective minification of CSS and CSS transformations such as autoprefixing and removal by other crates
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// This file is part of css. It is subject to the license terms in the COPYRIGHT file found in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/css/master/COPYRIGHT. No part of predicator, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the COPYRIGHT file.
// Copyright © 2017 The developers of css. See the COPYRIGHT file in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/css/master/COPYRIGHT.


#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct AttrExpression
{
	pub attribute_lower_case_name: String,
	
	pub type_or_unit: TypeOrUnit,

	pub default_value_css: Option<String>,
	
	pub is_not_in_page_rule: bool,
}

impl ToCss for AttrExpression
{
	fn to_css<W: fmt::Write>(&self, dest: &mut W) -> fmt::Result
	{
		serialize_identifier(&self.attribute_lower_case_name, dest)?;
		
		if self.type_or_unit != TypeOrUnit::string
		{
			dest.write_char(' ')?;
			self.type_or_unit.to_css(dest)?;
		}
		
		if let Some(ref default_value_css) = self.default_value_css
		{
			dest.write_char(',')?;
			dest.write_str(default_value_css)?;
		}
		
		Ok(())
	}
}

impl<U: Unit> Expression<U> for AttrExpression
{
	/// Division by zero is handled by returning the maximum possible f32 value
	/// Subtractions for UnsignedCssNumber that are negative are handled by returning 0.0
	#[inline(always)]
	fn evaluate<Conversion: FontRelativeLengthConversion<U::Number> + ViewportPercentageLengthConversion<U::Number> + PercentageConversion<U::Number> + AttributeConversion<U> + CssVariableConversion>(&self, conversion: &Conversion) -> Option<U::Number>
	{
		self.to_unit(conversion).map(|unit| unit.to_CssNumber())
	}
}

impl AttrExpression
{
	pub fn to_unit<U: Unit, Conversion: AttributeConversion<U>>(&self, conversion: &Conversion) -> Option<U>
	{
		let (possibleValue, propertyDefaultOrIfNoPropertyDefaultTheUnitDefault) = conversion.attributeValue(&self.attribute_lower_case_name);
		if let Some(value) = possibleValue
		{
			if let Some(ref value_css) = self.type_or_unit.value_to_css(value).ok()
			{
				U::from_raw_css_for_var_expression_evaluation(value_css, self.is_not_in_page_rule)
			}
			else if let Some(ref value_css) = self.default_value_css
			{
				U::from_raw_css_for_var_expression_evaluation(value_css, self.is_not_in_page_rule)
			}
			else
			{
				Some(propertyDefaultOrIfNoPropertyDefaultTheUnitDefault)
			}
		}
		else if let Some(ref value_css) = self.default_value_css
		{
			U::from_raw_css_for_var_expression_evaluation(value_css, self.is_not_in_page_rule)
		}
		else
		{
			Some(propertyDefaultOrIfNoPropertyDefaultTheUnitDefault)
		}
	}
	
	#[inline(always)]
	pub(crate) fn parse<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i, CustomParseError<'i>>>
	{
		input.parse_nested_block(|input|
		{
			let attribute_lower_case_name =
			{
				let attribute = input.expect_ident()?;
				attribute.to_ascii_lowercase()
			};
			
			input.skip_whitespace();
			
			if input.is_exhausted()
			{
				Ok
				(
					Self
					{
						attribute_lower_case_name,
						type_or_unit: TypeOrUnit::default(),
						default_value_css: None,
						is_not_in_page_rule: context.isNotInPageRule(),
					}
				)
			}
			else
			{
				let type_or_unit = if let Some(type_or_unit) = input.try(|input| TypeOrUnit::parse(input)).ok()
				{
					type_or_unit
				}
				else
				{
					TypeOrUnit::default()
				};
				
				let result = input.try(|input|
				{
					input.skip_whitespace();
					input.expect_comma()?;
					input.skip_whitespace();
					
					let startPosition = input.position();
					let result: Result<_, ParseError<CustomParseError>> = input.parse_entirely(|input| Ok(input.slice_from(startPosition).to_owned()));
					result
				});
				
				let default_value_css = if let Ok(default_value_css) = result
				{
					if default_value_css.is_empty()
					{
						None
					}
					else
					{
						Some(default_value_css)
					}
				}
				else
				{
					None
				};
				
				Ok
				(
					Self
					{
						attribute_lower_case_name,
						type_or_unit,
						default_value_css,
						is_not_in_page_rule: context.isNotInPageRule(),
					}
				)
			}
		})
	}
}