Implement parsing of an @viewport rule

components/style/lib.rs

@@ -50,6 +50,7 @@ pub mod media_queries;
 pub mod font_face;
 pub mod legacy;
 pub mod animation;
+pub mod viewport;
 
 macro_rules! reexport_computed_values {
     ( $( $name: ident )+ ) => {
@@ -63,4 +64,3 @@ macro_rules! reexport_computed_values {
     }
 }
 longhand_properties_idents!(reexport_computed_values);
-

components/style/parser.rs

@@ -11,6 +11,7 @@ use log;
 use stylesheets::Origin;
 
 pub struct ParserContext<'a> {
+    pub stylesheet_origin: Origin,
     pub base_url: &'a Url,
     pub selector_context: SelectorParserContext,
 }
@@ -20,6 +21,7 @@ impl<'a> ParserContext<'a> {
         let mut selector_context = SelectorParserContext::new();
         selector_context.in_user_agent_stylesheet = stylesheet_origin == Origin::UserAgent;
         ParserContext {
+            stylesheet_origin: stylesheet_origin,
             base_url: base_url,
             selector_context: selector_context,
         }

components/style/stylesheets.rs

@@ -19,6 +19,7 @@ use properties::{PropertyDeclarationBlock, parse_property_declaration_list};
 use media_queries::{Device, MediaQueryList, parse_media_query_list};
 use font_face::{FontFaceRule, parse_font_face_block};
 use util::smallvec::SmallVec2;
+use viewport::ViewportRule;
 
 
 /// Each style rule has an origin, which determines where it enters the cascade.
@@ -53,6 +54,7 @@ pub enum CSSRule {
     Style(StyleRule),
     Media(MediaRule),
     FontFace(FontFaceRule),
+    Viewport(ViewportRule),
 }
 
 #[derive(Debug, PartialEq)]
@@ -216,6 +218,7 @@ pub mod rule_filter {
     use std::marker::PhantomData;
     use super::{CSSRule, MediaRule, StyleRule};
     use super::super::font_face::FontFaceRule;
+    use super::super::viewport::ViewportRule;
 
     macro_rules! rule_filter {
         ($variant:ident -> $value:ty) => {
@@ -259,6 +262,7 @@ pub mod rule_filter {
     rule_filter!(FontFace -> FontFaceRule);
     rule_filter!(Media -> MediaRule);
     rule_filter!(Style -> StyleRule);
+    rule_filter!(Viewport -> ViewportRule);
 }
 
 /// Extension methods for `CSSRule` iterators.
@@ -271,6 +275,9 @@ pub trait CSSRuleIteratorExt<'a>: Iterator<Item=&'a CSSRule> {
 
     /// Yield only style rules.
     fn style(self) -> rule_filter::Style<'a, Self>;
+
+    /// Yield only @viewport rules.
+    fn viewport(self) -> rule_filter::Viewport<'a, Self>;
 }
 
 impl<'a, I> CSSRuleIteratorExt<'a> for I where I: Iterator<Item=&'a CSSRule> {
@@ -288,6 +295,11 @@ impl<'a, I> CSSRuleIteratorExt<'a> for I where I: Iterator<Item=&'a CSSRule> {
     fn style(self) -> rule_filter::Style<'a, I> {
         rule_filter::Style::new(self)
     }
+
+    #[inline]
+    fn viewport(self) -> rule_filter::Viewport<'a, I> {
+        rule_filter::Viewport::new(self)
+    }
 }
 
 fn parse_nested_rules(context: &ParserContext, input: &mut Parser) -> Vec<CSSRule> {
@@ -324,6 +336,7 @@ enum State {
 enum AtRulePrelude {
     FontFace,
     Media(MediaQueryList),
+    Viewport,
 }
 
 
@@ -414,6 +427,9 @@ impl<'a, 'b> AtRuleParser for NestedRuleParser<'a, 'b> {
             },
             "font-face" => {
                 Ok(AtRuleType::WithBlock(AtRulePrelude::FontFace))
+            },
+            "viewport" => {
+                Ok(AtRuleType::WithBlock(AtRulePrelude::Viewport))
             }
             _ => Err(())
         }
@@ -430,6 +446,9 @@ impl<'a, 'b> AtRuleParser for NestedRuleParser<'a, 'b> {
                     rules: parse_nested_rules(self.context, input),
                 }))
             }
+            AtRulePrelude::Viewport => {
+                ViewportRule::parse(input, self.context).map(CSSRule::Viewport)
+            }
         }
     }
 }

components/style/values.rs

@@ -86,6 +86,22 @@ pub mod specified {
     use util::geometry::Au;
     use super::CSSFloat;
 
+    #[derive(Clone, Copy, Debug, PartialEq, Eq)]
+    pub enum AllowedNumericType {
+        All,
+        NonNegative
+    }
+
+    impl AllowedNumericType {
+        #[inline]
+        pub fn is_ok(&self, value: f32) -> bool {
+            match self {
+                &AllowedNumericType::All => true,
+                &AllowedNumericType::NonNegative => value >= 0.,
+            }
+        }
+    }
+
     #[derive(Clone, PartialEq, Debug)]
     pub struct CSSColor {
         pub parsed: cssparser::Color,
@@ -397,33 +413,32 @@ pub mod specified {
             }
         }
     }
+
     impl LengthOrPercentageOrAuto {
-        fn parse_internal(input: &mut Parser, negative_ok: bool)
+        fn parse_internal(input: &mut Parser, context: &AllowedNumericType)
-                     -> Result<LengthOrPercentageOrAuto, ()> {
+                          -> Result<LengthOrPercentageOrAuto, ()>
+        {
             match try!(input.next()) {
-                Token::Dimension(ref value, ref unit) if negative_ok || value.value >= 0. => {
+                Token::Dimension(ref value, ref unit) if context.is_ok(value.value) => {
                     Length::parse_dimension(value.value, unit)
-                    .map(LengthOrPercentageOrAuto::Length)
+                        .map(LengthOrPercentageOrAuto::Length)
-                }
-                Token::Percentage(ref value) if negative_ok || value.unit_value >= 0. => {
-                    Ok(LengthOrPercentageOrAuto::Percentage(value.unit_value))
-                }
-                Token::Number(ref value) if value.value == 0. => {
-                    Ok(LengthOrPercentageOrAuto::Length(Length::Absolute(Au(0))))
-                }
-                Token::Ident(ref value) if value.eq_ignore_ascii_case("auto") => {
-                    Ok(LengthOrPercentageOrAuto::Auto)
                 }
+                Token::Percentage(ref value) if context.is_ok(value.unit_value) =>
+                    Ok(LengthOrPercentageOrAuto::Percentage(value.unit_value)),
+                Token::Number(ref value) if context.is_ok(value.value) =>
+                    Ok(LengthOrPercentageOrAuto::Length(Length::Absolute(Au(0)))),
+                Token::Ident(ref value) if value.eq_ignore_ascii_case("auto") =>
+                    Ok(LengthOrPercentageOrAuto::Auto),
                 _ => Err(())
             }
         }
         #[inline]
         pub fn parse(input: &mut Parser) -> Result<LengthOrPercentageOrAuto, ()> {
-            LengthOrPercentageOrAuto::parse_internal(input, /* negative_ok = */ true)
+            LengthOrPercentageOrAuto::parse_internal(input, &AllowedNumericType::All)
         }
         #[inline]
         pub fn parse_non_negative(input: &mut Parser) -> Result<LengthOrPercentageOrAuto, ()> {
-            LengthOrPercentageOrAuto::parse_internal(input, /* negative_ok = */ false)
+            LengthOrPercentageOrAuto::parse_internal(input, &AllowedNumericType::NonNegative)
         }
     }
 

components/style/viewport.rs

@@ -0,0 +1,302 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use cssparser::{Parser, DeclarationListParser, AtRuleParser, DeclarationParser, ToCss, parse_important};
+use parser::{ParserContext, log_css_error};
+use stylesheets::Origin;
+use values::specified::{AllowedNumericType, Length, LengthOrPercentageOrAuto};
+
+use std::ascii::AsciiExt;
+use std::collections::hash_map::{Entry, HashMap};
+use std::fmt;
+use std::intrinsics;
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum ViewportDescriptor {
+    MinWidth(LengthOrPercentageOrAuto),
+    MaxWidth(LengthOrPercentageOrAuto),
+
+    MinHeight(LengthOrPercentageOrAuto),
+    MaxHeight(LengthOrPercentageOrAuto),
+
+    Zoom(Zoom),
+    MinZoom(Zoom),
+    MaxZoom(Zoom),
+
+    UserZoom(UserZoom),
+    Orientation(Orientation)
+}
+
+/// Zoom is a number | percentage | auto
+/// See http://dev.w3.org/csswg/css-device-adapt/#descdef-viewport-zoom
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub enum Zoom {
+    Number(f32),
+    Percentage(f32),
+    Auto,
+}
+
+impl ToCss for Zoom {
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
+        where W: fmt::Write
+    {
+        match self {
+            &Zoom::Number(number) => write!(dest, "{}", number),
+            &Zoom::Percentage(percentage) => write!(dest, "{}%", percentage * 100.),
+            &Zoom::Auto => write!(dest, "auto")
+        }
+    }
+}
+
+impl Zoom {
+    pub fn parse(input: &mut Parser) -> Result<Zoom, ()> {
+        use cssparser::Token;
+
+        match try!(input.next()) {
+            Token::Percentage(ref value) if AllowedNumericType::NonNegative.is_ok(value.unit_value) =>
+                Ok(Zoom::Percentage(value.unit_value)),
+            Token::Number(ref value) if AllowedNumericType::NonNegative.is_ok(value.value) =>
+                Ok(Zoom::Number(value.value)),
+            Token::Ident(ref value) if value.eq_ignore_ascii_case("auto") =>
+                Ok(Zoom::Auto),
+            _ => Err(())
+        }
+    }
+
+    #[inline]
+    pub fn to_f32(&self) -> Option<f32> {
+        match self {
+            &Zoom::Number(number) => Some(number as f32),
+            &Zoom::Percentage(percentage) => Some(percentage as f32),
+            &Zoom::Auto => None
+        }
+    }
+}
+
+define_css_keyword_enum!(UserZoom:
+                         "zoom" => Zoom,
+                         "fixed" => Fixed);
+
+define_css_keyword_enum!(Orientation:
+                         "auto" => Auto,
+                         "portrait" => Portrait,
+                         "landscape" => Landscape);
+
+struct ViewportRuleParser<'a, 'b: 'a> {
+    context: &'a ParserContext<'b>
+}
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct ViewportDescriptorDeclaration {
+    pub origin: Origin,
+    pub descriptor: ViewportDescriptor,
+    pub important: bool
+}
+
+impl ViewportDescriptorDeclaration {
+    pub fn new(origin: Origin,
+               descriptor: ViewportDescriptor,
+               important: bool) -> ViewportDescriptorDeclaration
+    {
+        ViewportDescriptorDeclaration {
+            origin: origin,
+            descriptor: descriptor,
+            important: important
+        }
+    }
+}
+
+fn parse_shorthand(input: &mut Parser) -> Result<[LengthOrPercentageOrAuto; 2], ()> {
+    let min = try!(LengthOrPercentageOrAuto::parse_non_negative(input));
+    match input.try(|input| LengthOrPercentageOrAuto::parse_non_negative(input)) {
+        Err(()) => Ok([min.clone(), min]),
+        Ok(max) => Ok([min, max])
+    }
+}
+
+impl<'a, 'b> AtRuleParser for ViewportRuleParser<'a, 'b> {
+    type Prelude = ();
+    type AtRule = Vec<ViewportDescriptorDeclaration>;
+}
+
+impl<'a, 'b> DeclarationParser for ViewportRuleParser<'a, 'b> {
+    type Declaration = Vec<ViewportDescriptorDeclaration>;
+
+    fn parse_value(&self, name: &str, input: &mut Parser) -> Result<Vec<ViewportDescriptorDeclaration>, ()> {
+        macro_rules! declaration {
+            ($declaration:ident($parse:path)) => {
+                declaration!($declaration(value: try!($parse(input)),
+                                          important: input.try(parse_important).is_ok()))
+            };
+            ($declaration:ident(value: $value:expr, important: $important:expr)) => {
+                ViewportDescriptorDeclaration::new(
+                    self.context.stylesheet_origin,
+                    ViewportDescriptor::$declaration($value),
+                    $important)
+            }
+        }
+
+        macro_rules! ok {
+            ($declaration:ident($parse:path)) => {
+                Ok(vec![declaration!($declaration($parse))])
+            };
+            (shorthand -> [$min:ident, $max:ident]) => {{
+                let shorthand = try!(parse_shorthand(input));
+                let important = input.try(parse_important).is_ok();
+
+                Ok(vec![declaration!($min(value: shorthand[0], important: important)),
+                        declaration!($max(value: shorthand[1], important: important))])
+            }}
+        }
+
+        match name {
+            n if n.eq_ignore_ascii_case("min-width") =>
+                ok!(MinWidth(LengthOrPercentageOrAuto::parse_non_negative)),
+            n if n.eq_ignore_ascii_case("max-width") =>
+                ok!(MaxWidth(LengthOrPercentageOrAuto::parse_non_negative)),
+            n if n.eq_ignore_ascii_case("width") =>
+                ok!(shorthand -> [MinWidth, MaxWidth]),
+
+            n if n.eq_ignore_ascii_case("min-height") =>
+                ok!(MinHeight(LengthOrPercentageOrAuto::parse_non_negative)),
+            n if n.eq_ignore_ascii_case("max-height") =>
+                ok!(MaxHeight(LengthOrPercentageOrAuto::parse_non_negative)),
+            n if n.eq_ignore_ascii_case("height") =>
+                ok!(shorthand -> [MinHeight, MaxHeight]),
+
+            n if n.eq_ignore_ascii_case("zoom") =>
+                ok!(Zoom(Zoom::parse)),
+            n if n.eq_ignore_ascii_case("min-zoom") =>
+                ok!(MinZoom(Zoom::parse)),
+            n if n.eq_ignore_ascii_case("max-zoom") =>
+                ok!(MaxZoom(Zoom::parse)),
+
+            n if n.eq_ignore_ascii_case("user-zoom") =>
+                ok!(UserZoom(UserZoom::parse)),
+            n if n.eq_ignore_ascii_case("orientation") =>
+                ok!(Orientation(Orientation::parse)),
+
+            _ => Err(()),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq)]
+pub struct ViewportRule {
+    pub declarations: Vec<ViewportDescriptorDeclaration>
+}
+
+impl ViewportRule {
+    pub fn parse<'a>(input: &mut Parser, context: &'a ParserContext)
+                     -> Result<ViewportRule, ()>
+    {
+        let parser = ViewportRuleParser { context: context };
+
+        let mut errors = vec![];
+        let valid_declarations = DeclarationListParser::new(input, parser)
+            .filter_map(|result| {
+                match result {
+                    Ok(declarations) => Some(declarations),
+                    Err(range) => {
+                        errors.push(range);
+                        None
+                    }
+                }
+            })
+            .flat_map(|declarations| declarations.into_iter())
+            .collect::<Vec<_>>();
+
+        for range in errors {
+            let pos = range.start;
+            let message = format!("Unsupported @viewport descriptor declaration: '{}'",
+                                  input.slice(range));
+            log_css_error(input, pos, &*message);
+        }
+
+        Ok(ViewportRule { declarations: valid_declarations.iter().cascade() })
+    }
+}
+
+pub trait ViewportRuleCascade: Iterator + Sized {
+    fn cascade(self) -> ViewportRule;
+}
+
+impl<'a, I> ViewportRuleCascade for I
+    where I: Iterator<Item=&'a ViewportRule>
+{
+    #[inline]
+    fn cascade(self) -> ViewportRule {
+        ViewportRule {
+            declarations: self.flat_map(|r| r.declarations.iter()).cascade()
+        }
+    }
+}
+
+trait ViewportDescriptorDeclarationCascade: Iterator + Sized {
+    fn cascade(self) -> Vec<ViewportDescriptorDeclaration>;
+}
+
+/// Computes the cascade precedence as according to
+/// http://dev.w3.org/csswg/css-cascade/#cascade-origin
+fn cascade_precendence(origin: Origin, important: bool) -> u8 {
+    match (origin, important) {
+        (Origin::UserAgent, true) => 1,
+        (Origin::User, true) => 2,
+        (Origin::Author, true) => 3,
+        (Origin::Author, false) => 4,
+        (Origin::User, false) => 5,
+        (Origin::UserAgent, false) => 6,
+    }
+}
+
+impl ViewportDescriptorDeclaration {
+    fn higher_or_equal_precendence(&self, other: &ViewportDescriptorDeclaration) -> bool {
+        let self_precedence = cascade_precendence(self.origin, self.important);
+        let other_precedence = cascade_precendence(other.origin, other.important);
+
+        self_precedence <= other_precedence
+    }
+}
+
+fn cascade<'a, I>(iter: I) -> Vec<ViewportDescriptorDeclaration>
+    where I: Iterator<Item=&'a ViewportDescriptorDeclaration>
+{
+    let mut declarations: HashMap<u64, (usize, &'a ViewportDescriptorDeclaration)> = HashMap::new();
+
+    // index is used to reconstruct order of appearance after all declarations
+    // have been added to the map
+    let mut index = 0;
+    for declaration in iter {
+        let descriptor = unsafe {
+            intrinsics::discriminant_value(&declaration.descriptor)
+        };
+
+        match declarations.entry(descriptor) {
+            Entry::Occupied(mut entry) => {
+                if declaration.higher_or_equal_precendence(entry.get().1) {
+                    entry.insert((index, declaration));
+                    index += 1;
+                }
+            }
+            Entry::Vacant(entry) => {
+                entry.insert((index, declaration));
+                index += 1;
+            }
+        }
+    }
+
+    // convert to a list and sort the descriptors by order of appearance
+    let mut declarations: Vec<_> = declarations.into_iter().map(|kv| kv.1).collect();
+    declarations.sort_by(|a, b| a.0.cmp(&b.0));
+    declarations.into_iter().map(|id| *id.1).collect::<Vec<_>>()
+}
+
+impl<'a, I> ViewportDescriptorDeclarationCascade for I
+    where I: Iterator<Item=&'a ViewportDescriptorDeclaration>
+{
+    #[inline]
+    fn cascade(self) -> Vec<ViewportDescriptorDeclaration> {
+        cascade(self)
+    }
+}

tests/unit/style/lib.rs

@@ -16,6 +16,7 @@ extern crate util;
 
 #[cfg(test)] mod stylesheets;
 #[cfg(test)] mod media_queries;
+#[cfg(test)] mod viewport;
 
 #[cfg(test)] mod writing_modes {
     use util::logical_geometry::WritingMode;

tests/unit/style/viewport.rs

@@ -0,0 +1,202 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use cssparser::Parser;
+use geom::size::TypedSize2D;
+use geom::scale_factor::ScaleFactor;
+use style::media_queries::{Device, MediaType};
+use style::parser::ParserContext;
+use style::stylesheets::{Origin, Stylesheet, CSSRuleIteratorExt};
+use style::values::specified::{Length, LengthOrPercentageOrAuto};
+use style::viewport::*;
+use url::Url;
+
+macro_rules! stylesheet {
+    ($css:expr, $origin:ident) => {
+        Stylesheet::from_str($css,
+                             Url::parse("http://localhost").unwrap(),
+                             Origin::$origin);
+    }
+}
+
+fn test_viewport_rule<F>(css: &str,
+                         device: &Device,
+                         callback: F)
+    where F: Fn(&Vec<ViewportDescriptorDeclaration>, &str)
+{
+    let stylesheet = stylesheet!(css, Author);
+    let mut rule_count = 0;
+    for rule in stylesheet.effective_rules(&device).viewport() {
+        rule_count += 1;
+        callback(&rule.declarations, css);
+    }
+    assert!(rule_count > 0);
+}
+
+macro_rules! assert_declarations_len {
+    ($declarations:ident == 1) => {
+        assert!($declarations.len() == 1,
+                "expected 1 declaration; have {}: {:?})",
+                $declarations.len(), $declarations)
+    };
+    ($declarations:ident == $len:expr) => {
+        assert!($declarations.len() == $len,
+                "expected {} declarations; have {}: {:?})",
+                $len, $declarations.len(), $declarations)
+    }
+}
+
+#[test]
+fn empty_viewport_rule() {
+    let device = Device::new(MediaType::Screen, TypedSize2D(800., 600.));
+
+    test_viewport_rule("@viewport {}", &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 0);
+    });
+}
+
+macro_rules! assert_declaration_eq {
+    ($d:expr, $origin:ident, $expected:ident: $value:expr) => {{
+        assert_eq!($d.origin, Origin::$origin);
+        assert_eq!($d.descriptor, ViewportDescriptor::$expected($value));
+        assert!($d.important == false, "descriptor should not be !important");
+    }};
+    ($d:expr, $origin:ident, $expected:ident: $value:expr, !important) => {{
+        assert_eq!($d.origin, Origin::$origin);
+        assert_eq!($d.descriptor, ViewportDescriptor::$expected($value));
+        assert!($d.important == true, "descriptor should be !important");
+    }};
+}
+
+#[test]
+fn simple_viewport_rules() {
+    let device = Device::new(MediaType::Screen, TypedSize2D(800., 600.));
+
+    test_viewport_rule("@viewport { width: auto; height: auto;\
+                                    zoom: auto; min-zoom: 0; max-zoom: 200%;\
+                                    user-zoom: zoom; orientation: auto; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 9);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[1], Author, MaxWidth: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[2], Author, MinHeight: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[3], Author, MaxHeight: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[4], Author, Zoom: Zoom::Auto);
+        assert_declaration_eq!(&declarations[5], Author, MinZoom: Zoom::Number(0.));
+        assert_declaration_eq!(&declarations[6], Author, MaxZoom: Zoom::Percentage(2.));
+        assert_declaration_eq!(&declarations[7], Author, UserZoom: UserZoom::Zoom);
+        assert_declaration_eq!(&declarations[8], Author, Orientation: Orientation::Auto);
+    });
+
+    test_viewport_rule("@viewport { min-width: 200px; max-width: auto;\
+                                    min-height: 200px; max-height: auto; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 4);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Length(Length::from_px(200.)));
+        assert_declaration_eq!(&declarations[1], Author, MaxWidth: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[2], Author, MinHeight: LengthOrPercentageOrAuto::Length(Length::from_px(200.)));
+        assert_declaration_eq!(&declarations[3], Author, MaxHeight: LengthOrPercentageOrAuto::Auto);
+    });
+}
+
+#[test]
+fn cascading_within_viewport_rule() {
+    let device = Device::new(MediaType::Screen, TypedSize2D(800., 600.));
+
+    // normal order of appearance
+    test_viewport_rule("@viewport { min-width: 200px; min-width: auto; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 1);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto);
+    });
+
+    // !important order of appearance
+    test_viewport_rule("@viewport { min-width: 200px !important; min-width: auto !important; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 1);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto, !important);
+    });
+
+    // !important vs normal
+    test_viewport_rule("@viewport { min-width: auto !important; min-width: 200px; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 1);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto, !important);
+    });
+
+    // normal longhands vs normal shorthand
+    test_viewport_rule("@viewport { min-width: 200px; max-width: 200px; width: auto; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 2);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[1], Author, MaxWidth: LengthOrPercentageOrAuto::Auto);
+    });
+
+    // normal shorthand vs normal longhands
+    test_viewport_rule("@viewport { width: 200px; min-width: auto; max-width: auto; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 2);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto);
+        assert_declaration_eq!(&declarations[1], Author, MaxWidth: LengthOrPercentageOrAuto::Auto);
+    });
+
+    // one !important longhand vs normal shorthand
+    test_viewport_rule("@viewport { min-width: auto !important; width: 200px; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 2);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto, !important);
+        assert_declaration_eq!(&declarations[1], Author, MaxWidth: LengthOrPercentageOrAuto::Length(Length::from_px(200.)));
+    });
+
+    // both !important longhands vs normal shorthand
+    test_viewport_rule("@viewport { min-width: auto !important; max-width: auto !important; width: 200px; }",
+                       &device, |declarations, css| {
+        println!("{}", css);
+        assert_declarations_len!(declarations == 2);
+        assert_declaration_eq!(&declarations[0], Author, MinWidth: LengthOrPercentageOrAuto::Auto, !important);
+        assert_declaration_eq!(&declarations[1], Author, MaxWidth: LengthOrPercentageOrAuto::Auto, !important);
+    });
+}
+
+#[test]
+fn multiple_stylesheets_cascading() {
+    let device = Device::new(MediaType::Screen, TypedSize2D(800., 600.));
+
+    let stylesheets = vec![
+        stylesheet!("@viewport { min-width: 100px; min-height: 100px; zoom: 1; }", UserAgent),
+        stylesheet!("@viewport { min-width: 200px; min-height: 200px; }", User),
+        stylesheet!("@viewport { min-width: 300px; }", Author)];
+
+    let declarations = stylesheets.iter()
+        .flat_map(|s| s.effective_rules(&device).viewport())
+        .cascade()
+        .declarations;
+    assert_declarations_len!(declarations == 3);
+    assert_declaration_eq!(&declarations[0], UserAgent, Zoom: Zoom::Number(1.));
+    assert_declaration_eq!(&declarations[1], User, MinHeight: LengthOrPercentageOrAuto::Length(Length::from_px(200.)));
+    assert_declaration_eq!(&declarations[2], Author, MinWidth: LengthOrPercentageOrAuto::Length(Length::from_px(300.)));
+
+    let stylesheets = vec![
+        stylesheet!("@viewport { min-width: 100px !important; }", UserAgent),
+        stylesheet!("@viewport { min-width: 200px !important; min-height: 200px !important; }", User),
+        stylesheet!("@viewport { min-width: 300px !important; min-height: 300px !important; zoom: 3 !important; }", Author)];
+
+    let declarations = stylesheets.iter()
+        .flat_map(|s| s.effective_rules(&device).viewport())
+        .cascade()
+        .declarations;
+    assert_declarations_len!(declarations == 3);
+    assert_declaration_eq!(&declarations[0], UserAgent, MinWidth: LengthOrPercentageOrAuto::Length(Length::from_px(100.)), !important);
+    assert_declaration_eq!(&declarations[1], User, MinHeight: LengthOrPercentageOrAuto::Length(Length::from_px(200.)), !important);
+    assert_declaration_eq!(&declarations[2], Author, Zoom: Zoom::Number(3.), !important);
+}