repo_description: An extremely fast CSS parser, transformer, bundler, and minifier written in Rust.
repo_topics: build-tool compiler css minifier parser rust
code: //! The `@nest` rule.
  
  use smallvec::SmallVec;
  
  use super::style::StyleRule;
  use super::Location;
  use super::MinifyContext;
  use crate::context::DeclarationContext;
  use crate::declaration::DeclarationBlock;
  use crate::error::{MinifyError, PrinterError};
  use crate::parser::DefaultAtRule;
  use crate::printer::Printer;
  use crate::targets::should_compile;
  use crate::traits::ToCss;
  #[cfg(feature = "visitor")]
  use crate::visitor::Visit;
  
  /// A [@nest](https://www.w3.org/TR/css-nesting-1/#at-nest) rule.
  #[derive(Debug, PartialEq, Clone)]
  #[cfg_attr(feature = "visitor", derive(Visit))]
  #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
  #[cfg_attr(feature = "jsonschema", derive(schemars::JsonSchema))]
  #[cfg_attr(feature = "into_owned", derive(static_self::IntoOwned))]
  pub struct NestingRule<'i, R = DefaultAtRule> {
    /// The style rule that defines the selector and declarations for the `@nest` rule.
    #[cfg_attr(feature = "serde", serde(borrow))]
    pub style: StyleRule<'i, R>,
    /// The location of the rule in the source file.
    #[cfg_attr(feature = "visitor", skip_visit)]
    pub loc: Location,
  }
  
  impl<'i, T: Clone> NestingRule<'i, T> {
    pub(crate) fn minify(
      &mut self,
      context: &mut MinifyContext<'_, 'i>,
      parent_is_unused: bool,
    ) -> Result<bool, MinifyError> {
      self.style.minify(context, parent_is_unused)
    }
  }
  
  impl<'a, 'i, T: ToCss> ToCss for NestingRule<'i, T> {
    fn to_css<W>(&self, dest: &mut Printer<W>) -> Result<(), PrinterError>
    where
      W: std::fmt::Write,
    {
      #[cfg(feature = "sourcemap")]
      dest.add_mapping(self.loc);
      if dest.context().is_none() {
        dest.write_str("@nest ")?;
      }
      self.style.to_css(dest)
    }
  }
  
  /// A [nested declarations](https://drafts.csswg.org/css-nesting/#nested-declarations-rule) rule.
  #[derive(Debug, PartialEq, Clone)]
  #[cfg_attr(feature = "visitor", derive(Visit))]
  #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
  #[cfg_attr(feature = "jsonschema", derive(schemars::JsonSchema))]
  #[cfg_attr(feature = "into_owned", derive(static_self::IntoOwned))]
  pub struct NestedDeclarationsRule<'i> {
    /// The style rule that defines the selector and declarations for the `@nest` rule.
    #[cfg_attr(feature = "serde", serde(borrow))]
    pub declarations: DeclarationBlock<'i>,
    /// The location of the rule in the source file.
    #[cfg_attr(feature = "visitor", skip_visit)]
    pub loc: Location,
  }
  
  impl<'i> NestedDeclarationsRule<'i> {
    pub(crate) fn minify(&mut self, context: &mut MinifyContext<'_, 'i>, parent_is_unused: bool) -> bool {
      if parent_is_unused {
        return true;
      }
  
      context.handler_context.context = DeclarationContext::StyleRule;
      self
        .declarations
        .minify(context.handler, context.important_handler, &mut context.handler_context);
      context.handler_context.context = DeclarationContext::None;
      return false;
    }
  }
  
  impl<'i> ToCss for NestedDeclarationsRule<'i> {
    fn to_css<W>(&self, dest: &mut Printer<W>) -> Result<(), PrinterError>
    where
      W: std::fmt::Write,
    {
      #[cfg(feature = "sourcemap")]
      dest.add_mapping(self.loc);
  
      if should_compile!(dest.targets.current, Nesting) {
        if let Some(context) = dest.context() {
          let has_printable_declarations = self.declarations.has_printable_declarations();
          if has_printable_declarations {
            dest.with_parent_context(|dest| context.selectors.to_css(dest))?;
            dest.whitespace()?;
            dest.write_char('{')?;
            dest.indent();
            dest.newline()?;
          }
  
          self
            .declarations
            .to_css_declarations(dest, false, &context.selectors, self.loc.source_index)?;
  
          if has_printable_declarations {
            dest.dedent();
            dest.newline()?;
            dest.write_char('}')?;
          }
          return Ok(());
        }
      }
  
      self
        .declarations
        .to_css_declarations(dest, false, &parcel_selectors::SelectorList(SmallVec::new()), 0)
    }
  }
  