lewp-css 0.2.0

Domain model for CSS Stylesheets. Allowing effective minification and transformations such as autoprefixing and removal by other crates. Updated and maintained version for lewp.
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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.

use {
    super::Expression,
    crate::{
        domain::units::{conversions::*, Unit},
        parsers::ParserContext,
        CustomParseError,
    },
    cssparser::{serialize_identifier, ParseError, Parser, ToCss},
    std::fmt,
};

#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct VarExpression {
    pub custom_property_lower_case_name_without_double_dash: String,

    pub default_value_css: Option<String>,

    pub is_not_in_page_rule: bool,
}

impl ToCss for VarExpression {
    fn to_css<W: fmt::Write>(&self, dest: &mut W) -> fmt::Result {
        dest.write_str("--")?;
        serialize_identifier(
            &self.custom_property_lower_case_name_without_double_dash,
            dest,
        )?;

        if let Some(ref default_value) = self.default_value_css {
            dest.write_char(',')?;
            dest.write_str(default_value)?;
        }

        Ok(())
    }
}

impl<U: Unit> Expression<U> for VarExpression {
    /// 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> {
        match conversion.cssVariableValue(
            &self.custom_property_lower_case_name_without_double_dash,
        ) {
            Some(value_css) => U::from_raw_css_for_var_expression_evaluation(
                value_css,
                self.is_not_in_page_rule,
            )
            .map(|unit| unit.to_CssNumber()),
            None => {
                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,
                    )
                    .map(|unit| unit.to_CssNumber())
                } else {
                    None
                }
            }
        }
    }
}

impl VarExpression {
    #[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 custom_property_lower_case_name_without_double_dash = {
                let identifier = input.expect_ident()?;
                if !identifier.starts_with("--") {
                    return Err(ParseError::from(
                        CustomParseError::CssVariablesInVarExpressionsMustStartWithTwoDashes(
                            identifier.clone(),
                        ),
                    ));
                }
                let mut custom_property_lower_case_name_without_double_dash =
                    (&identifier[2..]).to_owned();
                custom_property_lower_case_name_without_double_dash.make_ascii_lowercase();
                custom_property_lower_case_name_without_double_dash
            };

            let startPosition = input.position();

            let result = input.r#try(|input| {
                input.expect_comma()?;
                input.skip_whitespace();

                if input.is_exhausted() {
                    Ok(None)
                } else {
                    let result: Result<_, ParseError<CustomParseError>> =
                        input.parse_entirely(|input| {
                            Ok(Some(input.slice_from(startPosition).to_owned()))
                        });
                    result
                }
            });

            let default_value_css = if let Ok(Some(default_value_css)) = result {
                if default_value_css.is_empty() {
                    None
                } else {
                    Some(default_value_css)
                }
            } else {
                None
            };

            Ok(Self {
                custom_property_lower_case_name_without_double_dash,
                default_value_css,
                is_not_in_page_rule: context.isNotInPageRule(),
            })
        })
    }
}