Auto merge of #16067 - Wafflespeanut:grid, r=nox,Wafflespeanut

Stylo: Add support for grid-template-{rows,columns}

This has the implementation of grid's `<track-list>` nightmare.

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #15311

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- [x] There are tests for these changes

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components/style/build_gecko.rs

@@ -662,7 +662,8 @@ mod bindings {
             .header(add_include("mozilla/ServoBindings.h"))
             .hide_type("nsACString_internal")
             .hide_type("nsAString_internal")
-            .raw_line("pub use nsstring::{nsACString, nsAString, nsString};")
+            .raw_line("pub use nsstring::{nsACString, nsAString, nsString, nsStringRepr};")
+            .raw_line("use gecko_bindings::structs::nsTArray;")
             .raw_line("type nsACString_internal = nsACString;")
             .raw_line("type nsAString_internal = nsAString;")
             .whitelisted_function("Servo_.*")
@@ -859,7 +860,13 @@ mod bindings {
             // type with zero_size_type. If we ever introduce immutable borrow types
             // which _do_ need to be opaque, we'll need a separate mode.
         }
-        write_binding_file(builder, BINDINGS_FILE, &Vec::new());
+        let fixups = vec![
+            Fixup {     // hack for gecko-owned string
+                pat: "<nsString".into(),
+                rep: "<nsStringRepr".into()
+            },
+        ];
+        write_binding_file(builder, BINDINGS_FILE, &fixups);
     }
 
     fn generate_atoms() {

components/style/gecko/generated/bindings.rs

@@ -1,6 +1,7 @@
 /* automatically generated by rust-bindgen */
 
-pub use nsstring::{nsACString, nsAString, nsString};
+pub use nsstring::{nsACString, nsAString, nsString, nsStringRepr};
+use gecko_bindings::structs::nsTArray;
 type nsACString_internal = nsACString;
 type nsAString_internal = nsAString;
 use gecko_bindings::structs::mozilla::css::GridTemplateAreasValue;
@@ -943,6 +944,15 @@ extern "C" {
 extern "C" {
     pub fn Gecko_DropElementSnapshot(snapshot: ServoElementSnapshotOwned);
 }
+extern "C" {
+    pub fn Gecko_ResizeTArrayForStrings(array: *mut nsTArray<nsStringRepr>,
+                                        length: u32);
+}
+extern "C" {
+    pub fn Gecko_SetStyleGridTemplateArrayLengths(grid_template:
+                                                      *mut nsStyleGridTemplate,
+                                                  track_sizes: u32);
+}
 extern "C" {
     pub fn Gecko_CopyStyleGridTemplateValues(grid_template:
                                                  *mut nsStyleGridTemplate,

components/style/properties/gecko.mako.rs

@@ -1053,7 +1053,7 @@ fn static_assert() {
                   skip_longhands="${skip_position_longhands} z-index box-sizing order align-content
                                   justify-content align-self justify-self align-items
                                   justify-items grid-auto-rows grid-auto-columns grid-auto-flow
-                                  grid-template-areas">
+                                  grid-template-areas grid-template-rows grid-template-columns">
     % for side in SIDES:
     <% impl_split_style_coord("%s" % side.ident,
                               "mOffset",
@@ -1165,9 +1165,9 @@ fn static_assert() {
         let ident = v.ident.unwrap_or(String::new());
         self.gecko.${value.gecko}.mLineName.assign_utf8(&ident);
         self.gecko.${value.gecko}.mHasSpan = v.is_span;
-        self.gecko.${value.gecko}.mInteger = v.integer.map(|i| {
+        self.gecko.${value.gecko}.mInteger = v.line_num.map(|i| {
             // clamping the integer between a range
-            cmp::max(nsStyleGridLine_kMinLine, cmp::min(i, nsStyleGridLine_kMaxLine))
+            cmp::max(nsStyleGridLine_kMinLine, cmp::min(i.value(), nsStyleGridLine_kMaxLine))
         }).unwrap_or(0);
     }
 
@@ -1179,7 +1179,7 @@ fn static_assert() {
     % endfor
 
     % for kind in ["rows", "columns"]:
-    pub fn set_grid_auto_${kind}(&mut self, v: longhands::grid_auto_rows::computed_value::T) {
+    pub fn set_grid_auto_${kind}(&mut self, v: longhands::grid_auto_${kind}::computed_value::T) {
         use values::specified::grid::TrackSize;
 
         match v {
@@ -1206,6 +1206,136 @@ fn static_assert() {
         self.gecko.mGridAuto${kind.title()}Min.copy_from(&other.gecko.mGridAuto${kind.title()}Min);
         self.gecko.mGridAuto${kind.title()}Max.copy_from(&other.gecko.mGridAuto${kind.title()}Max);
     }
+
+    pub fn set_grid_template_${kind}(&mut self, v: longhands::grid_template_${kind}::computed_value::T) {
+        <% self_grid = "self.gecko.mGridTemplate%s" % kind.title() %>
+        use gecko::values::GeckoStyleCoordConvertible;
+        use gecko_bindings::structs::{nsTArray, nsStyleGridLine_kMaxLine};
+        use nsstring::{nsCString, nsStringRepr};
+        use std::usize;
+        use values::specified::grid::TrackListType::Auto;
+        use values::specified::grid::{RepeatCount, TrackSize};
+
+        #[inline]
+        fn set_bitfield(bitfield: &mut u8, pos: u8, val: bool) {
+            let mask = 1 << (pos - 1);
+            *bitfield &= !mask;
+            *bitfield |= (val as u8) << (pos - 1);
+        }
+
+        #[inline]
+        fn set_line_names(servo_names: &[String], gecko_names: &mut nsTArray<nsStringRepr>) {
+            unsafe {
+                bindings::Gecko_ResizeTArrayForStrings(gecko_names, servo_names.len() as u32);
+            }
+
+            for (servo_name, gecko_name) in servo_names.iter().zip(gecko_names.iter_mut()) {
+                gecko_name.assign_utf8(&nsCString::from(&*servo_name));
+            }
+        }
+
+        fn set_track_size<G, T>(value: TrackSize<T>, gecko_min: &mut G, gecko_max: &mut G)
+            where G: CoordDataMut, T: GeckoStyleCoordConvertible
+        {
+            match value {
+                TrackSize::FitContent(lop) => {
+                    gecko_min.set_value(CoordDataValue::None);
+                    lop.to_gecko_style_coord(gecko_max);
+                },
+                TrackSize::Breadth(breadth) => {
+                    breadth.to_gecko_style_coord(gecko_min);
+                    breadth.to_gecko_style_coord(gecko_max);
+                },
+                TrackSize::MinMax(min, max) => {
+                    min.to_gecko_style_coord(gecko_min);
+                    max.to_gecko_style_coord(gecko_max);
+                },
+            }
+        }
+
+        // Set defaults
+        ${self_grid}.mRepeatAutoIndex = -1;
+        set_bitfield(&mut ${self_grid}._bitfield_1, 1, false);   // mIsAutoFill
+        set_bitfield(&mut ${self_grid}._bitfield_1, 2, false);   // mIsSubgrid
+        // FIXME: mIsSubgrid is false only for <none>, but we don't support subgrid name lists at the moment.
+
+        match v {
+            Either::First(track) => {
+                let mut auto_idx = usize::MAX;
+                let mut auto_track_size = None;
+                if let Auto(idx) = track.list_type {
+                    auto_idx = idx as usize;
+                    let auto_repeat = track.auto_repeat.as_ref().expect("expected <auto-track-repeat> value");
+
+                    if auto_repeat.count == RepeatCount::AutoFill {
+                        set_bitfield(&mut ${self_grid}._bitfield_1, 1, true);
+                    }
+
+                    ${self_grid}.mRepeatAutoIndex = idx as i16;
+                    // NOTE: Gecko supports only one set of values in <auto-repeat>
+                    // i.e., it can only take repeat(auto-fill, [a] 10px [b]), and no more.
+                    set_line_names(&auto_repeat.line_names[0], &mut ${self_grid}.mRepeatAutoLineNameListBefore);
+                    set_line_names(&auto_repeat.line_names[1], &mut ${self_grid}.mRepeatAutoLineNameListAfter);
+                    auto_track_size = Some(auto_repeat.track_sizes.get(0).unwrap().clone());
+                } else {
+                    unsafe {
+                        bindings::Gecko_ResizeTArrayForStrings(
+                            &mut ${self_grid}.mRepeatAutoLineNameListBefore, 0);
+                        bindings::Gecko_ResizeTArrayForStrings(
+                            &mut ${self_grid}.mRepeatAutoLineNameListAfter, 0);
+                    }
+                }
+
+                let mut num_values = track.values.len();
+                if auto_track_size.is_some() {
+                    num_values += 1;
+                }
+
+                let max_lines = nsStyleGridLine_kMaxLine as usize - 1;      // for accounting the final <line-names>
+                num_values = cmp::min(num_values, max_lines);
+                unsafe {
+                    bindings::Gecko_SetStyleGridTemplateArrayLengths(&mut ${self_grid}, num_values as u32);
+                }
+
+                let mut line_names = track.line_names.into_iter();
+                let mut values_iter = track.values.into_iter();
+                let min_max_iter = ${self_grid}.mMinTrackSizingFunctions.iter_mut()
+                                               .zip(${self_grid}.mMaxTrackSizingFunctions.iter_mut());
+
+                for (i, (gecko_min, gecko_max)) in min_max_iter.enumerate().take(max_lines) {
+                    let name_list = line_names.next().expect("expected line-names");
+                    set_line_names(&name_list, &mut ${self_grid}.mLineNameLists[i]);
+                    if i == auto_idx {
+                        set_track_size(auto_track_size.take().expect("expected <track-size> for <auto-track-repeat>"),
+                                       gecko_min, gecko_max);
+                        continue
+                    }
+
+                    let track_size = values_iter.next().expect("expected <track-size> value");
+                    set_track_size(track_size, gecko_min, gecko_max);
+                }
+
+                let final_names = line_names.next().unwrap();
+                set_line_names(&final_names, ${self_grid}.mLineNameLists.last_mut().unwrap());
+            },
+            Either::Second(_none) => {
+                unsafe {
+                    bindings::Gecko_SetStyleGridTemplateArrayLengths(&mut ${self_grid}, 0);
+                    bindings::Gecko_ResizeTArrayForStrings(
+                        &mut ${self_grid}.mRepeatAutoLineNameListBefore, 0);
+                    bindings::Gecko_ResizeTArrayForStrings(
+                        &mut ${self_grid}.mRepeatAutoLineNameListAfter, 0);
+                }
+            },
+        }
+    }
+
+    pub fn copy_grid_template_${kind}_from(&mut self, other: &Self) {
+        unsafe {
+            bindings::Gecko_CopyStyleGridTemplateValues(&mut ${self_grid},
+                                                        &other.gecko.mGridTemplate${kind.title()});
+        }
+    }
     % endfor
 
     pub fn set_grid_auto_flow(&mut self, v: longhands::grid_auto_flow::computed_value::T) {

components/style/properties/longhand/position.mako.rs

@@ -319,6 +319,17 @@ ${helpers.predefined_type("object-position",
                               spec="https://drafts.csswg.org/css-grid/#propdef-grid-auto-%ss" % kind,
                               products="gecko",
                               boxed=True)}
+
+    // NOTE: The spec lists only `none | <track-list> | <auto-track-list>`, but gecko seems to support
+    // `subgrid <line-name-list>?` in addition to this (probably old spec). We should support it soon.
+    ${helpers.predefined_type("grid-template-%ss" % kind,
+                              "TrackListOrNone",
+                              "Either::Second(None_)",
+                              products="gecko",
+                              spec="https://drafts.csswg.org/css-grid/#propdef-grid-template-%ss" % kind,
+                              boxed=True,
+                              animation_value_type="none")}
+
 % endfor
 
 <%helpers:longhand name="grid-auto-flow"

components/style/properties/shorthand/position.mako.rs

@@ -154,7 +154,7 @@
             GridLine::parse(context, input)?
         } else {
             let mut line = GridLine::default();
-            if start.integer.is_none() && !start.is_span {
+            if start.line_num.is_none() && !start.is_span {
                 line.ident = start.ident.clone();       // ident from start value should be taken
             }
 
@@ -188,7 +188,7 @@
     pub fn parse_value(context: &ParserContext, input: &mut Parser) -> Result<Longhands, ()> {
         fn line_with_ident_from(other: &GridLine) -> GridLine {
             let mut this = GridLine::default();
-            if other.integer.is_none() && !other.is_span {
+            if other.line_num.is_none() && !other.is_span {
                 this.ident = other.ident.clone();
             }
 

components/style/values/computed/mod.rs

@@ -19,6 +19,7 @@ use super::{CSSFloat, CSSInteger, RGBA};
 use super::generics::BorderRadiusSize as GenericBorderRadiusSize;
 use super::specified;
 use super::specified::grid::{TrackBreadth as GenericTrackBreadth, TrackSize as GenericTrackSize};
+use super::specified::grid::TrackList as GenericTrackList;
 
 pub use app_units::Au;
 pub use cssparser::Color as CSSColor;
@@ -595,6 +596,13 @@ pub type TrackBreadth = GenericTrackBreadth<LengthOrPercentage>;
 /// The computed value of a grid `<track-size>`
 pub type TrackSize = GenericTrackSize<LengthOrPercentage>;
 
+/// The computed value of a grid `<track-list>`
+/// (could also be `<auto-track-list>` or `<explicit-track-list>`)
+pub type TrackList = GenericTrackList<TrackSize>;
+
+/// `<track-list> | none`
+pub type TrackListOrNone = Either<TrackList, None_>;
+
 impl ClipRectOrAuto {
     /// Return an auto (default for clip-rect and image-region) value
     pub fn auto() -> Self {

components/style/values/specified/grid.rs

@@ -4,21 +4,20 @@
 
 //! Necessary types for [grid](https://drafts.csswg.org/css-grid/).
 
-use cssparser::{Parser, Token};
+use cssparser::{Parser, Token, serialize_identifier};
 use parser::{Parse, ParserContext};
+use std::{fmt, mem, usize};
 use std::ascii::AsciiExt;
-use std::fmt;
 use style_traits::ToCss;
-use values::{CSSFloat, HasViewportPercentage};
+use values::{CSSFloat, CustomIdent, Either, HasViewportPercentage};
-use values::computed::{ComputedValueAsSpecified, Context, ToComputedValue};
+use values::computed::{self, ComputedValueAsSpecified, Context, ToComputedValue};
-use values::specified::LengthOrPercentage;
+use values::specified::{Integer, LengthOrPercentage};
 
 #[derive(PartialEq, Clone, Debug)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 /// A `<grid-line>` type.
 ///
 /// https://drafts.csswg.org/css-grid/#typedef-grid-row-start-grid-line
-#[allow(missing_docs)]
 pub struct GridLine {
     /// Flag to check whether it's a `span` keyword.
     pub is_span: bool,
@@ -27,7 +26,14 @@ pub struct GridLine {
     /// https://drafts.csswg.org/css-grid/#grid-placement-slot
     pub ident: Option<String>,
     /// Denotes the nth grid line from grid item's placement.
-    pub integer: Option<i32>,
+    pub line_num: Option<Integer>,
+}
+
+impl GridLine {
+    /// Check whether this `<grid-line>` represents an `auto` value.
+    pub fn is_auto(&self) -> bool {
+        self.ident.is_none() && self.line_num.is_none() && !self.is_span
+    }
 }
 
 impl Default for GridLine {
@@ -35,27 +41,28 @@ impl Default for GridLine {
         GridLine {
             is_span: false,
             ident: None,
-            integer: None,
+            line_num: None,
         }
     }
 }
 
 impl ToCss for GridLine {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
-        if !self.is_span && self.ident.is_none() && self.integer.is_none() {
+        if self.is_auto() {
             return dest.write_str("auto")
         }
 
         if self.is_span {
-            try!(dest.write_str("span"));
+            dest.write_str("span")?;
         }
 
-        if let Some(i) = self.integer {
+        if let Some(i) = self.line_num {
-            try!(write!(dest, " {}", i));
+            write!(dest, " {}", i.value)?;
         }
 
         if let Some(ref s) = self.ident {
-            try!(write!(dest, " {}", s));
+            dest.write_str(" ")?;
+            serialize_identifier(s, dest)?;
         }
 
         Ok(())
@@ -63,7 +70,7 @@ impl ToCss for GridLine {
 }
 
 impl Parse for GridLine {
-    fn parse(_context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+    fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
         let mut grid_line = Default::default();
         if input.try(|i| i.expect_ident_matching("auto")).is_ok() {
             return Ok(grid_line)
@@ -71,17 +78,17 @@ impl Parse for GridLine {
 
         for _ in 0..3 {     // Maximum possible entities for <grid-line>
             if input.try(|i| i.expect_ident_matching("span")).is_ok() {
-                if grid_line.is_span {
+                if grid_line.is_span || grid_line.line_num.is_some() || grid_line.ident.is_some() {
+                    return Err(())      // span (if specified) should be first
+                }
+                grid_line.is_span = true;       // span (if specified) should be first
+            } else if let Ok(i) = input.try(|i| Integer::parse(context, i)) {
+                if i.value == 0 || grid_line.line_num.is_some() {
                     return Err(())
                 }
-                grid_line.is_span = true;
+                grid_line.line_num = Some(i);
-            } else if let Ok(i) = input.try(|i| i.expect_integer()) {
-                if i == 0 || grid_line.integer.is_some() {
-                    return Err(())
-                }
-                grid_line.integer = Some(i);
             } else if let Ok(name) = input.try(|i| i.expect_ident()) {
-                if grid_line.ident.is_some() {
+                if grid_line.ident.is_some() || CustomIdent::from_ident((&*name).into(), &[]).is_err() {
                     return Err(())
                 }
                 grid_line.ident = Some(name.into_owned());
@@ -90,13 +97,19 @@ impl Parse for GridLine {
             }
         }
 
+        if grid_line.is_auto() {
+            return Err(())
+        }
+
         if grid_line.is_span {
-            if let Some(i) = grid_line.integer {
+            if let Some(i) = grid_line.line_num {
-                if i < 0 {      // disallow negative integers for grid spans
+                if i.value <= 0 {       // disallow negative integers for grid spans
                     return Err(())
                 }
+            } else if grid_line.ident.is_some() {       // integer could be omitted
+                grid_line.line_num = Some(Integer::new(1));
             } else {
-                grid_line.integer = Some(1);
+                return Err(())
             }
         }
 
@@ -128,9 +141,22 @@ pub enum TrackBreadth<L> {
     Keyword(TrackKeyword),
 }
 
+impl<L> TrackBreadth<L> {
+    /// Check whether this is a `<fixed-breadth>` (i.e., it only has `<length-percentage>`)
+    ///
+    /// https://drafts.csswg.org/css-grid/#typedef-fixed-breadth
+    #[inline]
+    pub fn is_fixed(&self) -> bool {
+        match *self {
+            TrackBreadth::Breadth(ref _lop) => true,
+            _ => false,
+        }
+    }
+}
+
 /// Parse a single flexible length.
 pub fn parse_flex(input: &mut Parser) -> Result<CSSFloat, ()> {
-    match try!(input.next()) {
+    match input.next()? {
         Token::Dimension(ref value, ref unit) if unit.eq_ignore_ascii_case("fr") && value.value.is_sign_positive()
             => Ok(value.value),
         _ => Err(()),
@@ -215,6 +241,32 @@ pub enum TrackSize<L> {
     FitContent(L),
 }
 
+impl<L> TrackSize<L> {
+    /// Check whether this is a `<fixed-size>`
+    ///
+    /// https://drafts.csswg.org/css-grid/#typedef-fixed-size
+    pub fn is_fixed(&self) -> bool {
+        match *self {
+            TrackSize::Breadth(ref breadth) => breadth.is_fixed(),
+            // For minmax function, it could be either
+            // minmax(<fixed-breadth>, <track-breadth>) or minmax(<inflexible-breadth>, <fixed-breadth>),
+            // and since both variants are a subset of minmax(<inflexible-breadth>, <track-breadth>), we only
+            // need to make sure that they're fixed. So, we don't have to modify the parsing function.
+            TrackSize::MinMax(ref breadth_1, ref breadth_2) => {
+                if breadth_1.is_fixed() {
+                    return true     // the second value is always a <track-breadth>
+                }
+
+                match *breadth_1 {
+                    TrackBreadth::Flex(_) => false,     // should be <inflexible-breadth> at this point
+                    _ => breadth_2.is_fixed(),
+                }
+            },
+            TrackSize::FitContent(_) => false,
+        }
+    }
+}
+
 impl<L> Default for TrackSize<L> {
     fn default() -> Self {
         TrackSize::Breadth(TrackBreadth::Keyword(TrackKeyword::Auto))
@@ -233,19 +285,19 @@ impl Parse for TrackSize<LengthOrPercentage> {
                     match input.try(|i| LengthOrPercentage::parse_non_negative(context, i)) {
                         Ok(lop) => TrackBreadth::Breadth(lop),
                         Err(..) => {
-                            let keyword = try!(TrackKeyword::parse(input));
+                            let keyword = TrackKeyword::parse(input)?;
                             TrackBreadth::Keyword(keyword)
                         }
                     };
 
-                try!(input.expect_comma());
+                input.expect_comma()?;
-                Ok(TrackSize::MinMax(inflexible_breadth, try!(TrackBreadth::parse(context, input))))
+                Ok(TrackSize::MinMax(inflexible_breadth, TrackBreadth::parse(context, input)?))
             });
         }
 
-        try!(input.expect_function_matching("fit-content"));
+        input.expect_function_matching("fit-content")?;
-        // FIXME(emilio): This needs a parse_nested_block, doesn't it?
+        let lop = input.parse_nested_block(|i| LengthOrPercentage::parse_non_negative(context, i))?;
-        Ok(try!(LengthOrPercentage::parse(context, input).map(TrackSize::FitContent)))
+        Ok(TrackSize::FitContent(lop))
     }
 }
 
@@ -254,15 +306,15 @@ impl<L: ToCss> ToCss for TrackSize<L> {
         match *self {
             TrackSize::Breadth(ref b) => b.to_css(dest),
             TrackSize::MinMax(ref infexible, ref flexible) => {
-                try!(dest.write_str("minmax("));
+                dest.write_str("minmax(")?;
-                try!(infexible.to_css(dest));
+                infexible.to_css(dest)?;
-                try!(dest.write_str(","));
+                dest.write_str(", ")?;
-                try!(flexible.to_css(dest));
+                flexible.to_css(dest)?;
                 dest.write_str(")")
             },
             TrackSize::FitContent(ref lop) => {
-                try!(dest.write_str("fit-content("));
+                dest.write_str("fit-content(")?;
-                try!(lop.to_css(dest));
+                lop.to_css(dest)?;
                 dest.write_str(")")
             },
         }
@@ -286,7 +338,13 @@ impl<L: ToComputedValue> ToComputedValue for TrackSize<L> {
     #[inline]
     fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
         match *self {
-            TrackSize::Breadth(ref b) => TrackSize::Breadth(b.to_computed_value(context)),
+            TrackSize::Breadth(ref b) => match *b {
+                // <flex> outside `minmax()` expands to `mimmax(auto, <flex>)`
+                // https://drafts.csswg.org/css-grid/#valdef-grid-template-columns-flex
+                TrackBreadth::Flex(f) =>
+                    TrackSize::MinMax(TrackBreadth::Keyword(TrackKeyword::Auto), TrackBreadth::Flex(f)),
+                _ => TrackSize::Breadth(b.to_computed_value(context)),
+            },
             TrackSize::MinMax(ref b_1, ref b_2) =>
                 TrackSize::MinMax(b_1.to_computed_value(context), b_2.to_computed_value(context)),
             TrackSize::FitContent(ref lop) => TrackSize::FitContent(lop.to_computed_value(context)),
@@ -306,3 +364,532 @@ impl<L: ToComputedValue> ToComputedValue for TrackSize<L> {
         }
     }
 }
+
+/// Parse the grid line names into a vector of owned strings.
+///
+/// https://drafts.csswg.org/css-grid/#typedef-line-names
+pub fn parse_line_names(input: &mut Parser) -> Result<Vec<String>, ()> {
+    input.expect_square_bracket_block()?;
+    input.parse_nested_block(|input| {
+        let mut values = vec![];
+        while let Ok(ident) = input.try(|i| i.expect_ident()) {
+            if CustomIdent::from_ident((&*ident).into(), &["span"]).is_err() {
+                return Err(())
+            }
+
+            values.push(ident.into_owned());
+        }
+
+        Ok(values)
+    })
+}
+
+fn concat_serialize_idents<W>(prefix: &str, suffix: &str,
+                              slice: &[String], sep: &str, dest: &mut W) -> fmt::Result
+    where W: fmt::Write
+{
+    if let Some((ref first, rest)) = slice.split_first() {
+        dest.write_str(prefix)?;
+        serialize_identifier(first, dest)?;
+        for thing in rest {
+            dest.write_str(sep)?;
+            serialize_identifier(thing, dest)?;
+        }
+
+        dest.write_str(suffix)?;
+    }
+
+    Ok(())
+}
+
+/// The initial argument of the `repeat` function.
+///
+/// https://drafts.csswg.org/css-grid/#typedef-track-repeat
+#[derive(Clone, Copy, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+pub enum RepeatCount {
+    /// A positive integer. This is allowed only for `<track-repeat>` and `<fixed-repeat>`
+    Number(Integer),
+    /// An `<auto-fill>` keyword allowed only for `<auto-repeat>`
+    AutoFill,
+    /// An `<auto-fit>` keyword allowed only for `<auto-repeat>`
+    AutoFit,
+}
+
+impl Parse for RepeatCount {
+    fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+        if let Ok(i) = input.try(|i| Integer::parse(context, i)) {
+            if i.value > 0 {
+                Ok(RepeatCount::Number(i))
+            } else {
+                Err(())
+            }
+        } else {
+            match_ignore_ascii_case! { &input.expect_ident()?,
+                "auto-fill" => Ok(RepeatCount::AutoFill),
+                "auto-fit" => Ok(RepeatCount::AutoFit),
+                _ => Err(()),
+            }
+        }
+    }
+}
+
+impl ToCss for RepeatCount {
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+        match *self {
+            RepeatCount::Number(ref c) => c.to_css(dest),
+            RepeatCount::AutoFill => dest.write_str("auto-fill"),
+            RepeatCount::AutoFit => dest.write_str("auto-fit"),
+        }
+    }
+}
+
+impl ComputedValueAsSpecified for RepeatCount {}
+no_viewport_percentage!(RepeatCount);
+
+/// The type of `repeat` function (only used in parsing).
+///
+/// https://drafts.csswg.org/css-grid/#typedef-track-repeat
+#[derive(Clone, Copy, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+enum RepeatType {
+    /// [`<auto-repeat>`](https://drafts.csswg.org/css-grid/#typedef-auto-repeat)
+    Auto,
+    /// [`<track-repeat>`](https://drafts.csswg.org/css-grid/#typedef-track-repeat)
+    Normal,
+    /// [`<fixed-repeat>`](https://drafts.csswg.org/css-grid/#typedef-fixed-repeat)
+    Fixed,
+}
+
+/// The structure containing `<line-names>` and `<track-size>` values.
+///
+/// It can also hold `repeat()` function parameters, which expands into the respective
+/// values in its computed form.
+#[derive(Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+pub struct TrackRepeat<L> {
+    /// The number of times for the value to be repeated (could also be `auto-fit` or `auto-fill`)
+    pub count: RepeatCount,
+    /// `<line-names>` accompanying `<track_size>` values.
+    ///
+    /// If there's no `<line-names>`, then it's represented by an empty vector.
+    /// For N `<track-size>` values, there will be N+1 `<line-names>`, and so this vector's
+    /// length is always one value more than that of the `<track-size>`.
+    pub line_names: Vec<Vec<String>>,
+    /// `<track-size>` values.
+    pub track_sizes: Vec<TrackSize<L>>,
+}
+
+impl TrackRepeat<LengthOrPercentage> {
+    fn parse_with_repeat_type(context: &ParserContext, input: &mut Parser)
+                              -> Result<(TrackRepeat<LengthOrPercentage>, RepeatType), ()> {
+        input.try(|i| i.expect_function_matching("repeat")).and_then(|_| {
+            input.parse_nested_block(|input| {
+                let count = RepeatCount::parse(context, input)?;
+                input.expect_comma()?;
+
+                let is_auto = count == RepeatCount::AutoFit || count == RepeatCount::AutoFill;
+                let mut repeat_type = if is_auto {
+                    RepeatType::Auto
+                } else {    // <fixed-size> is a subset of <track_size>, so it should work for both
+                    RepeatType::Fixed
+                };
+
+                let mut names = vec![];
+                let mut values = vec![];
+                let mut current_names;
+
+                loop {
+                    current_names = input.try(parse_line_names).unwrap_or(vec![]);
+                    if let Ok(track_size) = input.try(|i| TrackSize::parse(context, i)) {
+                        if !track_size.is_fixed() {
+                            if is_auto {
+                                return Err(())      // should be <fixed-size> for <auto-repeat>
+                            }
+
+                            if repeat_type == RepeatType::Fixed {
+                                repeat_type = RepeatType::Normal       // <track-size> for sure
+                            }
+                        }
+
+                        values.push(track_size);
+                        names.push(current_names);
+                    } else {
+                        if values.is_empty() {
+                            return Err(())      // expecting at least one <track-size>
+                        }
+
+                        names.push(current_names);      // final `<line-names>`
+                        break       // no more <track-size>, breaking
+                    }
+                }
+
+                let repeat = TrackRepeat {
+                    count: count,
+                    track_sizes: values,
+                    line_names: names,
+                };
+
+                Ok((repeat, repeat_type))
+            })
+        })
+    }
+}
+
+impl<L: ToCss> ToCss for TrackRepeat<L> {
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+        dest.write_str("repeat(")?;
+        self.count.to_css(dest)?;
+        dest.write_str(", ")?;
+
+        let mut line_names_iter = self.line_names.iter();
+        for (i, (ref size, ref names)) in self.track_sizes.iter()
+                                              .zip(&mut line_names_iter).enumerate() {
+            if i > 0 {
+                dest.write_str(" ")?;
+            }
+
+            concat_serialize_idents("[", "] ", names, " ", dest)?;
+            size.to_css(dest)?;
+        }
+
+        if let Some(line_names_last) = line_names_iter.next() {
+            concat_serialize_idents(" [", "]", line_names_last, " ", dest)?;
+        }
+
+        dest.write_str(")")?;
+        Ok(())
+    }
+}
+
+impl HasViewportPercentage for TrackRepeat<LengthOrPercentage> {
+    #[inline]
+    fn has_viewport_percentage(&self) -> bool {
+        self.track_sizes.iter().any(|ref v| v.has_viewport_percentage())
+    }
+}
+
+impl<L: ToComputedValue> ToComputedValue for TrackRepeat<L> {
+    type ComputedValue = TrackRepeat<L::ComputedValue>;
+
+    #[inline]
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        // If the repeat count is numeric, then expand the values and merge accordingly.
+        if let RepeatCount::Number(num) = self.count {
+            let mut line_names = vec![];
+            let mut track_sizes = vec![];
+            let mut prev_names = vec![];
+
+            for _ in 0..num.value {
+                let mut names_iter = self.line_names.iter();
+                for (size, names) in self.track_sizes.iter().zip(&mut names_iter) {
+                    prev_names.extend_from_slice(&names);
+                    line_names.push(mem::replace(&mut prev_names, vec![]));
+                    track_sizes.push(size.to_computed_value(context));
+                }
+
+                if let Some(names) = names_iter.next() {
+                    prev_names.extend_from_slice(&names);
+                }
+            }
+
+            line_names.push(prev_names);
+            TrackRepeat {
+                count: self.count,
+                track_sizes: track_sizes,
+                line_names: line_names,
+            }
+
+        } else {    // if it's auto-fit/auto-fill, then it's left to the layout.
+            TrackRepeat {
+                count: self.count,
+                track_sizes: self.track_sizes.iter()
+                                             .map(|l| l.to_computed_value(context))
+                                             .collect(),
+                line_names: self.line_names.clone(),
+            }
+        }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        TrackRepeat {
+            count: computed.count,
+            track_sizes: computed.track_sizes.iter()
+                                             .map(ToComputedValue::from_computed_value)
+                                             .collect(),
+            line_names: computed.line_names.clone(),
+        }
+    }
+}
+
+/// The type of a `<track-list>` as determined during parsing.
+///
+/// https://drafts.csswg.org/css-grid/#typedef-track-list
+#[derive(Clone, Copy, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+pub enum TrackListType {
+    /// [`<auto-track-list>`](https://drafts.csswg.org/css-grid/#typedef-auto-track-list)
+    ///
+    /// If this type exists, then the value at the index in `line_names` field in `TrackList`
+    /// has the `<line-names>?` list that comes before `<auto-repeat>`. If it's a specified value,
+    /// then the `repeat()` function (that follows the line names list) is also at the given index
+    /// in `values` field. On the contrary, if it's a computed value, then the `repeat()` function
+    /// is in the `auto_repeat` field.
+    Auto(u16),
+    /// [`<track-list>`](https://drafts.csswg.org/css-grid/#typedef-track-list)
+    Normal,
+    /// [`<explicit-track-list>`](https://drafts.csswg.org/css-grid/#typedef-explicit-track-list)
+    ///
+    /// Note that this is a subset of the normal `<track-list>`, and so it could be used in place
+    /// of the latter.
+    Explicit,
+}
+
+/// A grid `<track-list>` type.
+///
+/// https://drafts.csswg.org/css-grid/#typedef-track-list
+#[derive(Clone, PartialEq, Debug)]
+#[cfg_attr(feature = "servo", derive(HeapSizeOf))]
+pub struct TrackList<T> {
+    /// The type of this `<track-list>` (auto, explicit or general).
+    ///
+    /// In order to avoid parsing the same value multiple times, this does a single traversal
+    /// and arrives at the type of value it has parsed (or bails out gracefully with an error).
+    pub list_type: TrackListType,
+    /// A vector of `<track-size> | <track-repeat>` values. In its specified form, it may contain
+    /// any value, but once it's computed, it contains only `<track_size>` values.
+    ///
+    /// Note that this may also contain `<auto-repeat>` at an index. If it exists, it's
+    /// given by the index in `TrackListType::Auto`
+    pub values: Vec<T>,
+    /// `<line-names>` accompanying `<track-size> | <track-repeat>` values.
+    ///
+    /// If there's no `<line-names>`, then it's represented by an empty vector.
+    /// For N values, there will be N+1 `<line-names>`, and so this vector's
+    /// length is always one value more than that of the `<track-size>`.
+    pub line_names: Vec<Vec<String>>,
+    /// `<auto-repeat>` value after computation. This field is necessary, because
+    /// the `values` field (after computation) will only contain `<track-size>` values, and
+    /// we need something to represent this function.
+    pub auto_repeat: Option<TrackRepeat<computed::LengthOrPercentage>>,
+}
+
+/// Either a `<track-size>` or `<track-repeat>` component of `<track-list>`
+///
+/// This is required only for the specified form of `<track-list>`, and will become
+/// `TrackSize<LengthOrPercentage>` in its computed form.
+pub type TrackSizeOrRepeat = Either<TrackSize<LengthOrPercentage>, TrackRepeat<LengthOrPercentage>>;
+
+impl Parse for TrackList<TrackSizeOrRepeat> {
+    fn parse(context: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
+        let mut current_names;
+        let mut names = vec![];
+        let mut values = vec![];
+
+        let mut list_type = TrackListType::Explicit;    // assume it's the simplest case
+        // marker to check whether we've already encountered <auto-repeat> along the way
+        let mut is_auto = false;
+        // assume that everything is <fixed-size>. This flag is useful when we encounter <auto-repeat>
+        let mut atleast_one_not_fixed = false;
+
+        loop {
+            current_names = input.try(parse_line_names).unwrap_or(vec![]);
+            if let Ok(track_size) = input.try(|i| TrackSize::parse(context, i)) {
+                if !track_size.is_fixed() {
+                    atleast_one_not_fixed = true;
+                    if is_auto {
+                        return Err(())      // <auto-track-list> only accepts <fixed-size> and <fixed-repeat>
+                    }
+                }
+
+                names.push(current_names);
+                values.push(Either::First(track_size));
+            } else if let Ok((repeat, type_)) = input.try(|i| TrackRepeat::parse_with_repeat_type(context, i)) {
+                if list_type == TrackListType::Explicit {
+                    list_type = TrackListType::Normal;      // <explicit-track-list> doesn't contain repeat()
+                }
+
+                match type_ {
+                    RepeatType::Normal => {
+                        atleast_one_not_fixed = true;
+                        if is_auto {            // only <fixed-repeat>
+                            return Err(())
+                        }
+                    },
+                    RepeatType::Auto => {
+                        if is_auto || atleast_one_not_fixed {
+                            // We've either seen <auto-repeat> earlier, or there's at least one non-fixed value
+                            return Err(())
+                        }
+
+                        is_auto = true;
+                        list_type = TrackListType::Auto(values.len() as u16);
+                    },
+                    RepeatType::Fixed => (),
+                }
+
+                names.push(current_names);
+                values.push(Either::Second(repeat));
+            } else {
+                if values.is_empty() {
+                    return Err(())
+                }
+
+                names.push(current_names);
+                break
+            }
+        }
+
+        Ok(TrackList {
+            list_type: list_type,
+            values: values,
+            line_names: names,
+            auto_repeat: None,      // filled only in computation
+        })
+    }
+}
+
+impl<T: ToCss> ToCss for TrackList<T> {
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+        let auto_idx = match self.list_type {
+            TrackListType::Auto(i) => i as usize,
+            _ => usize::MAX,
+        };
+
+        let mut values_iter = self.values.iter().peekable();
+        let mut line_names_iter = self.line_names.iter().peekable();
+
+        for idx in 0.. {
+            let names = line_names_iter.next().unwrap();    // This should exist!
+            concat_serialize_idents("[", "]", names, " ", dest)?;
+
+            match self.auto_repeat {
+                Some(ref repeat) if idx == auto_idx => {
+                    if !names.is_empty() {
+                        dest.write_str(" ")?;
+                    }
+
+                    repeat.to_css(dest)?;
+                },
+                _ => match values_iter.next() {
+                    Some(value) => {
+                        if !names.is_empty() {
+                            dest.write_str(" ")?;
+                        }
+
+                        value.to_css(dest)?;
+                    },
+                    None => break,
+                },
+            }
+
+            if values_iter.peek().is_some() || line_names_iter.peek().map_or(false, |v| !v.is_empty()) {
+                dest.write_str(" ")?;
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl HasViewportPercentage for TrackList<TrackSizeOrRepeat> {
+    #[inline]
+    fn has_viewport_percentage(&self) -> bool {
+        self.values.iter().any(|ref v| v.has_viewport_percentage())
+    }
+}
+
+impl ToComputedValue for TrackList<TrackSizeOrRepeat> {
+    type ComputedValue = TrackList<TrackSize<computed::LengthOrPercentage>>;
+
+    #[inline]
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        // Merge the line names while computing values. The resulting values will
+        // all be a bunch of `<track-size>`.
+        //
+        // For example,
+        // `[a b] 100px [c d] repeat(1, 30px [g]) [h]` will be merged as `[a b] 100px [c d] 30px [g h]`
+        //  whereas, `[a b] repeat(2, [c] 50px [d]) [e f] repeat(auto-fill, [g] 12px) 10px [h]` will be merged as
+        // `[a b c] 50px [d c] 50px [d e f] repeat(auto-fill, [g] 12px) 10px [h]`, with the `<auto-repeat>` value
+        // set in the `auto_repeat` field, and the `idx` in TrackListType::Auto pointing to the values after
+        // `<auto-repeat>` (in this case, `10px [h]`).
+        let mut line_names = vec![];
+        let mut list_type = self.list_type;
+        let mut values = vec![];
+        let mut prev_names = vec![];
+        let mut auto_repeat = None;
+
+        let mut names_iter = self.line_names.iter();
+        for (size_or_repeat, names) in self.values.iter().zip(&mut names_iter) {
+            prev_names.extend_from_slice(names);
+
+            match *size_or_repeat {
+                Either::First(ref size) => values.push(size.to_computed_value(context)),
+                Either::Second(ref repeat) => {
+                    let mut computed = repeat.to_computed_value(context);
+                    if computed.count == RepeatCount::AutoFit || computed.count == RepeatCount::AutoFill {
+                        line_names.push(mem::replace(&mut prev_names, vec![]));     // don't merge for auto
+                        list_type = TrackListType::Auto(values.len() as u16);
+                        auto_repeat = Some(computed);
+                        continue
+                    }
+
+                    let mut repeat_names_iter = computed.line_names.drain(..);
+                    for (size, mut names) in computed.track_sizes.drain(..).zip(&mut repeat_names_iter) {
+                        prev_names.append(&mut names);
+                        line_names.push(mem::replace(&mut prev_names, vec![]));
+                        values.push(size);
+                    }
+
+                    if let Some(mut names) = repeat_names_iter.next() {
+                        prev_names.append(&mut names);
+                    }
+
+                    continue    // last `<line-names>` in repeat() may merge with the next set
+                }
+            }
+
+            line_names.push(mem::replace(&mut prev_names, vec![]));
+        }
+
+        if let Some(names) = names_iter.next() {
+            prev_names.extend_from_slice(names);
+        }
+
+        line_names.push(mem::replace(&mut prev_names, vec![]));
+
+        TrackList {
+            list_type: list_type,
+            values: values,
+            line_names: line_names,
+            auto_repeat: auto_repeat,
+        }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        let auto_idx = if let TrackListType::Auto(idx) = computed.list_type {
+            idx as usize
+        } else {
+            usize::MAX
+        };
+
+        let mut values = Vec::with_capacity(computed.values.len() + 1);
+        for (i, value) in computed.values.iter().map(ToComputedValue::from_computed_value).enumerate() {
+            if i == auto_idx {
+                let value = TrackRepeat::from_computed_value(computed.auto_repeat.as_ref().unwrap());
+                values.push(Either::Second(value));
+            }
+
+            values.push(Either::First(value));
+        }
+
+        TrackList {
+            list_type: computed.list_type,
+            values: values,
+            line_names: computed.line_names.clone(),
+            auto_repeat: None,
+        }
+    }
+}

components/style/values/specified/mod.rs

@@ -13,6 +13,7 @@ use euclid::size::Size2D;
 use itoa;
 use parser::{ParserContext, Parse};
 use self::grid::{TrackBreadth as GenericTrackBreadth, TrackSize as GenericTrackSize};
+use self::grid::{TrackList as GenericTrackList, TrackSizeOrRepeat};
 use self::url::SpecifiedUrl;
 use std::ascii::AsciiExt;
 use std::f32;
@@ -942,6 +943,13 @@ pub type TrackBreadth = GenericTrackBreadth<LengthOrPercentage>;
 /// The specified value of a grid `<track-size>`
 pub type TrackSize = GenericTrackSize<LengthOrPercentage>;
 
+/// The specified value of a grid `<track-list>`
+/// (could also be `<auto-track-list>` or `<explicit-track-list>`)
+pub type TrackList = GenericTrackList<TrackSizeOrRepeat>;
+
+/// `<track-list> | none`
+pub type TrackListOrNone = Either<TrackList, None_>;
+
 #[derive(Debug, Clone, PartialEq)]
 #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
 #[allow(missing_docs)]

components/style_traits/values.rs

@@ -74,6 +74,7 @@ macro_rules! impl_to_css_for_predefined_type {
 
 impl_to_css_for_predefined_type!(f32);
 impl_to_css_for_predefined_type!(i32);
+impl_to_css_for_predefined_type!(u16);
 impl_to_css_for_predefined_type!(u32);
 impl_to_css_for_predefined_type!(::cssparser::Token<'a>);
 impl_to_css_for_predefined_type!(::cssparser::RGBA);

tests/unit/style/parsing/mod.rs

@@ -5,10 +5,16 @@
 //! Tests for parsing and serialization of values/properties
 
 use cssparser::Parser;
+use euclid::size::TypedSize2D;
 use media_queries::CSSErrorReporterTest;
 use style::context::QuirksMode;
+use style::font_metrics::ServoMetricsProvider;
+use style::media_queries::{Device, MediaType};
 use style::parser::{PARSING_MODE_DEFAULT, ParserContext};
+use style::properties::{ComputedValues, StyleBuilder};
 use style::stylesheets::{CssRuleType, Origin};
+use style::values::computed::{Context, ToComputedValue};
+use style_traits::ToCss;
 
 fn parse<T, F: Fn(&ParserContext, &mut Parser) -> Result<T, ()>>(f: F, s: &str) -> Result<T, ()> {
     let url = ::servo_url::ServoUrl::parse("http://localhost").unwrap();
@@ -24,6 +30,32 @@ fn parse_entirely<T, F: Fn(&ParserContext, &mut Parser) -> Result<T, ()>>(f: F,
     parse(|context, parser| parser.parse_entirely(|p| f(context, p)), s)
 }
 
+fn assert_computed_serialization<C, F, T>(f: F, input: &str, output: &str)
+    where F: Fn(&ParserContext, &mut Parser) -> Result<T, ()>,
+          T: ToComputedValue<ComputedValue=C>, C: ToCss
+{
+    let viewport_size = TypedSize2D::new(0., 0.);
+    let initial_style = ComputedValues::initial_values();
+    let device = Device::new(MediaType::Screen, viewport_size);
+
+    let context = Context {
+        is_root_element: true,
+        device: &device,
+        inherited_style: initial_style,
+        layout_parent_style: initial_style,
+        style: StyleBuilder::for_derived_style(&initial_style),
+        cached_system_font: None,
+        font_metrics_provider: &ServoMetricsProvider,
+        in_media_query: false,
+        quirks_mode: QuirksMode::NoQuirks,
+    };
+
+    let parsed = parse(f, input).unwrap();
+    let computed = parsed.to_computed_value(&context);
+    let serialized = ToCss::to_css_string(&computed);
+    assert_eq!(serialized, output);
+}
+
 // This is a macro so that the file/line information
 // is preserved in the panic
 macro_rules! assert_roundtrip_with_context {

tests/unit/style/parsing/position.rs

@@ -2,7 +2,7 @@
  * 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 parsing::{parse, parse_entirely};
+use parsing::{assert_computed_serialization, parse, parse_entirely};
 use style::parser::Parse;
 use style::values::specified::position::*;
 use style_traits::ToCss;
@@ -168,3 +168,68 @@ fn test_grid_auto_flow() {
     assert!(parse(grid_auto_flow::parse, "column 'dense'").is_err());
     assert!(parse(grid_auto_flow::parse, "column 2px dense").is_err());
 }
+
+#[test]
+fn test_grid_auto_rows_columns() {
+    use style::properties::longhands::grid_auto_rows;
+
+    // the grammar is <track-size>+ but gecko supports only a single value, so we've clamped ourselves
+    assert_roundtrip_with_context!(grid_auto_rows::parse, "55%");
+    assert_roundtrip_with_context!(grid_auto_rows::parse, "0.5fr");
+    assert_roundtrip_with_context!(grid_auto_rows::parse, "fit-content(11%)");
+    // only <inflexible-breadth> is allowed in first arg of minmax
+    assert!(parse(grid_auto_rows::parse, "minmax(1fr, max-content)").is_err());
+}
+
+#[test]
+fn test_grid_template_rows_columns() {
+    use style::properties::longhands::grid_template_rows;
+
+    assert_roundtrip_with_context!(grid_template_rows::parse, "none");      // none keyword
+    // <track-size>{2} with `<track-breadth> minmax(<inflexible-breadth>, <track-breadth>)`
+    assert_roundtrip_with_context!(grid_template_rows::parse, "1fr minmax(min-content, 1fr)");
+    // <track-size> with <track-breadth> as <length-percentage>
+    assert_roundtrip_with_context!(grid_template_rows::parse, "calc(4em + 5px)");
+    // <track-size> with <length> followed by <track-repeat> with `<track-size>{3}` (<flex>, auto, minmax)
+    assert_roundtrip_with_context!(grid_template_rows::parse, "10px repeat(2, 1fr auto minmax(200px, 1fr))");
+    // <track-repeat> with `<track-size> <line-names>` followed by <track-size>
+    assert_roundtrip_with_context!(grid_template_rows::parse, "repeat(4, 10px [col-start] 250px [col-end]) 10px");
+    // mixture of <track-size>, <track-repeat> and <line-names>
+    assert_roundtrip_with_context!(grid_template_rows::parse,
+        "[a] auto [b] minmax(min-content, 1fr) [b c d] repeat(2, [e] 40px) repeat(5, [f g] auto [h]) [i]");
+
+    // no span allowed in <line-names>
+    assert!(parse(grid_template_rows::parse, "[a span] 10px").is_err());
+    // <track-list> needs at least one <track-size> | <track-repeat>
+    assert!(parse(grid_template_rows::parse, "[a b c]").is_err());
+    // at least one argument of <fixed-size> should be a <fixed-breadth> (i.e., <length-percentage>)
+    assert!(parse(grid_template_rows::parse, "[a b] repeat(auto-fill, 50px) minmax(auto, 1fr)").is_err());
+    // fit-content is not a <fixed-size>
+    assert!(parse(grid_template_rows::parse, "[a b] repeat(auto-fill, fit-content(20%))").is_err());
+    // <auto-track-list> only allows <fixed-size> | <fixed-repeat>
+    assert!(parse(grid_template_rows::parse, "[a] repeat(2, auto) repeat(auto-fill, 10px)").is_err());
+    // only <inflexible-breadth> allowed in <auto-track-repeat>
+    assert!(parse(grid_template_rows::parse, "[a] repeat(auto-fill, 1fr)").is_err());
+    // <auto-track-repeat> is allowed only once
+    assert!(parse(grid_template_rows::parse, "[a] repeat(auto-fit, [b] 8px) [c] repeat(auto-fill, [c] 8px)").is_err());
+}
+
+#[test]
+fn test_computed_grid_template_rows_colums() {
+    use style::properties::longhands::grid_template_rows;
+
+    assert_computed_serialization(grid_template_rows::parse,
+        "[a] repeat(calc(1 + 1), [b] auto)", "[a b] auto [b] auto");
+
+    assert_computed_serialization(grid_template_rows::parse,
+        "[a] repeat(2, [b c] auto [e] auto [d])",
+        "[a b c] auto [e] auto [d b c] auto [e] auto [d]");
+
+    assert_computed_serialization(grid_template_rows::parse,
+        "[a] 50px [b] 10% [b c d] repeat(2, [e] 40px [f]) [g] repeat(auto-fill, [h i] 20px [j]) [k] 10px [l]",
+        "[a] 50px [b] 10% [b c d e] 40px [f e] 40px [f g] repeat(auto-fill, [h i] 20px [j]) [k] 10px [l]");
+
+    assert_computed_serialization(grid_template_rows::parse,
+        "10px repeat(2, 1fr auto minmax(200px, 1fr))",
+        "10px minmax(auto, 1fr) auto minmax(200px, 1fr) minmax(auto, 1fr) auto minmax(200px, 1fr)");
+}