css 0.0.22

// 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.


/// ViewportLength is a length | percentage | auto
/// See http://dev.w3.org/csswg/css-device-adapt/#min-max-width-desc
/// extend-to-zoom is explicitly not supported as it does not occur in CSS, only when converting from HTML's meta name="viewport" tag (see http://dev.w3.org/csswg/css-device-adapt/#extend-to-zoom)
#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
#[allow(missing_docs)]
pub enum ViewportLength
{
	/// Automatic length
	auto,
	
	/// invariant or calculated non-negative length or non-negative percentage
	value(CalculablePropertyValue<LengthOrPercentageUnit<CssUnsignedNumber>>),
}

impl ToCss for ViewportLength
{
	fn to_css<W: fmt::Write>(&self, dest: &mut W) -> fmt::Result
	{
		match *self
		{
			auto => dest.write_str("auto"),
			
			value(ref numeric_value) => numeric_value.to_css(dest),
		}
	}
}

impl ViewportLength
{
	pub(crate) fn parse<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i, CustomParseError<'i>>>
	{
		use self::ViewportLength::*;
		
		if input.try(|i| i.expect_ident_matching("auto")).is_ok()
		{
			return Ok(auto);
		}
		
		Ok(value(LengthOrPercentageUnit::parse_one_outside_calc_function(context, input)?))
	}
}