style: Get rid of GetParentAllowServo in implementation of CSS 'justify-items' property.

Bug: 1384542
Reviewed-by: heycam
MozReview-Commit-ID: 4qydjqSoVXs

components/style/properties/gecko.mako.rs

@@ -60,7 +60,7 @@ use selector_parser::PseudoElement;
 use servo_arc::{Arc, RawOffsetArc};
 use std::mem::{forget, uninitialized, transmute, zeroed};
 use std::{cmp, ops, ptr};
-use values::{Auto, CustomIdent, Either, KeyframesName};
+use values::{self, Auto, CustomIdent, Either, KeyframesName};
 use values::computed::ToComputedValue;
 use values::computed::effects::{BoxShadow, Filter, SimpleShadow};
 use values::computed::length::Percentage;
@@ -1366,8 +1366,35 @@ fn static_assert() {
     % for kind in ["align", "justify"]:
     ${impl_simple_type_with_conversion(kind + "_content")}
     ${impl_simple_type_with_conversion(kind + "_self")}
-    ${impl_simple_type_with_conversion(kind + "_items")}
     % endfor
+    ${impl_simple_type_with_conversion("align_items")}
+
+    pub fn set_justify_items(&mut self, v: longhands::justify_items::computed_value::T) {
+        self.gecko.mSpecifiedJustifyItems = v.specified.into();
+        self.set_computed_justify_items(v.computed);
+    }
+
+    pub fn set_computed_justify_items(&mut self, v: values::specified::JustifyItems) {
+        debug_assert!(v.0 != ::values::specified::align::ALIGN_AUTO);
+        self.gecko.mJustifyItems = v.into();
+    }
+
+    pub fn reset_justify_items(&mut self, reset_style: &Self) {
+        self.gecko.mJustifyItems = reset_style.gecko.mJustifyItems;
+        self.gecko.mSpecifiedJustifyItems = reset_style.gecko.mSpecifiedJustifyItems;
+    }
+
+    pub fn copy_justify_items_from(&mut self, other: &Self) {
+        self.gecko.mJustifyItems = other.gecko.mJustifyItems;
+        self.gecko.mSpecifiedJustifyItems = other.gecko.mJustifyItems;
+    }
+
+    pub fn clone_justify_items(&self) -> longhands::justify_items::computed_value::T {
+        longhands::justify_items::computed_value::T {
+            computed: self.gecko.mJustifyItems.into(),
+            specified: self.gecko.mSpecifiedJustifyItems.into(),
+        }
+    }
 
     pub fn set_order(&mut self, v: longhands::order::computed_value::T) {
         self.gecko.mOrder = v;

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

@@ -108,7 +108,7 @@ ${helpers.single_keyword("flex-wrap", "nowrap wrap wrap-reverse",
 
     ${helpers.predefined_type(name="justify-items",
                               type="JustifyItems",
-                              initial_value="specified::JustifyItems::auto()",
+                              initial_value="computed::JustifyItems::auto()",
                               spec="https://drafts.csswg.org/css-align/#propdef-justify-items",
                               animation_value_type="discrete")}
 

components/style/properties/properties.mako.rs

@@ -2606,13 +2606,13 @@ impl<'a> StyleBuilder<'a> {
     /// Inherit `${property.ident}` from our parent style.
     #[allow(non_snake_case)]
     pub fn inherit_${property.ident}(&mut self) {
-        % if property.style_struct.inherited:
         let inherited_struct =
+        % if property.style_struct.inherited:
             self.inherited_style.get_${property.style_struct.name_lower}();
         % else:
-        let inherited_struct =
             self.inherited_style_ignoring_first_line.get_${property.style_struct.name_lower}();
         % endif
+
         self.${property.style_struct.ident}.mutate()
             .copy_${property.ident}_from(
                 inherited_struct,
@@ -2625,14 +2625,21 @@ impl<'a> StyleBuilder<'a> {
     /// Reset `${property.ident}` to the initial value.
     #[allow(non_snake_case)]
     pub fn reset_${property.ident}(&mut self) {
-        let reset_struct = self.reset_style.get_${property.style_struct.name_lower}();
-        self.${property.style_struct.ident}.mutate()
-            .copy_${property.ident}_from(
-                reset_struct,
-                % if property.logical:
-                self.writing_mode,
-                % endif
-            );
+        let reset_struct =
+            self.reset_style.get_${property.style_struct.name_lower}();
+        % if property.ident == "justify_items":
+            // TODO(emilio): Generalise this!
+            self.${property.style_struct.ident}.mutate()
+                .reset_${property.ident}(reset_struct)
+        % else:
+            self.${property.style_struct.ident}.mutate()
+                .copy_${property.ident}_from(
+                    reset_struct,
+                    % if property.logical:
+                    self.writing_mode,
+                    % endif
+                );
+        % endif
     }
 
     % if not property.is_vector:

components/style/style_adjuster.rs

@@ -454,6 +454,36 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         }
     }
 
+    /// Resolves "justify-items: auto" based on the inherited style if needed to
+    /// comply with:
+    ///
+    /// https://drafts.csswg.org/css-align/#valdef-justify-items-legacy
+    ///
+    /// (Note that "auto" is being renamed to "legacy")
+    #[cfg(feature = "gecko")]
+    fn adjust_for_justify_items(&mut self) {
+        use values::specified::align;
+        let justify_items = self.style.get_position().clone_justify_items();
+        if justify_items.specified.0 != align::ALIGN_AUTO {
+            return;
+        }
+
+        let parent_justify_items =
+            self.style.get_parent_position().clone_justify_items();
+
+        if !parent_justify_items.computed.0.contains(align::ALIGN_LEGACY) {
+            return;
+        }
+
+        if parent_justify_items.computed == justify_items.computed {
+            return;
+        }
+
+        self.style
+            .mutate_position()
+            .set_computed_justify_items(parent_justify_items.computed);
+    }
+
     /// Adjusts the style to account for various fixups that don't fit naturally
     /// into the cascade.
     ///
@@ -478,6 +508,7 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
             self.adjust_for_table_text_align();
             self.adjust_for_contain();
             self.adjust_for_mathvariant();
+            self.adjust_for_justify_items();
         }
         #[cfg(feature = "servo")]
         {

components/style/values/computed/align.rs

@@ -0,0 +1,75 @@
+/* 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/. */
+
+//! Values for CSS Box Alignment properties
+//!
+//! https://drafts.csswg.org/css-align/
+
+use std::fmt;
+use style_traits::ToCss;
+use values::computed::{ComputedValueAsSpecified, Context, ToComputedValue};
+use values::specified;
+
+pub use super::specified::{AlignItems, AlignJustifyContent, AlignJustifySelf};
+
+/// The computed value for the `justify-items` property.
+///
+/// Need to carry around both the specified and computed value to handle the
+/// special legacy keyword. Sigh.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct JustifyItems {
+    /// The specified value for the property. Can contain `auto`.
+    pub specified: specified::JustifyItems,
+    /// The computed value for the property. Cannot contain `auto`.
+    pub computed: specified::JustifyItems,
+}
+
+impl ToCss for JustifyItems {
+    fn to_css<W>(&self, dest: &mut W) -> fmt::Result
+        where W: fmt::Write,
+    {
+        self.computed.to_css(dest)
+    }
+}
+
+impl JustifyItems {
+    /// Returns the `auto` value.
+    pub fn auto() -> Self {
+        Self {
+            specified: specified::JustifyItems::auto(),
+            computed: specified::JustifyItems::normal(),
+        }
+    }
+}
+
+impl ToComputedValue for specified::JustifyItems {
+    type ComputedValue = JustifyItems;
+
+    /// https://drafts.csswg.org/css-align/#valdef-justify-items-legacy
+    fn to_computed_value(&self, _context: &Context) -> JustifyItems {
+        use values::specified::align;
+        let specified = *self;
+        let computed =
+            if self.0 != align::ALIGN_AUTO {
+                *self
+            } else {
+                // If the inherited value of `justify-items` includes the
+                // `legacy` keyword, `auto` computes to the inherited value,
+                // but we assume it computes to `normal`, and handle that
+                // special-case in StyleAdjuster.
+                Self::normal()
+            };
+
+        JustifyItems { specified, computed }
+    }
+
+    #[inline]
+    fn from_computed_value(computed: &JustifyItems) -> Self {
+        computed.specified
+    }
+}
+
+impl ComputedValueAsSpecified for AlignItems {}
+impl ComputedValueAsSpecified for AlignJustifyContent {}
+impl ComputedValueAsSpecified for AlignJustifySelf {}

components/style/values/computed/mod.rs

@@ -25,6 +25,8 @@ use super::specified;
 
 pub use app_units::Au;
 pub use properties::animated_properties::TransitionProperty;
+#[cfg(feature = "gecko")]
+pub use self::align::{AlignItems, AlignJustifyContent, AlignJustifySelf, JustifyItems};
 pub use self::background::BackgroundSize;
 pub use self::border::{BorderImageSlice, BorderImageWidth, BorderImageSideWidth};
 pub use self::border::{BorderRadius, BorderCornerRadius};
@@ -36,8 +38,6 @@ pub use self::image::{Gradient, GradientItem, Image, ImageLayer, LineDirection,
 pub use self::gecko::ScrollSnapPoint;
 pub use self::rect::LengthOrNumberRect;
 pub use super::{Auto, Either, None_};
-#[cfg(feature = "gecko")]
-pub use super::specified::{AlignItems, AlignJustifyContent, AlignJustifySelf, JustifyItems};
 pub use super::specified::{BorderStyle, UrlOrNone};
 pub use super::generics::grid::GridLine;
 pub use super::specified::url::SpecifiedUrl;
@@ -47,6 +47,8 @@ pub use self::position::Position;
 pub use self::text::{InitialLetter, LetterSpacing, LineHeight, WordSpacing};
 pub use self::transform::{TimingFunction, TransformOrigin};
 
+#[cfg(feature = "gecko")]
+pub mod align;
 pub mod background;
 pub mod basic_shape;
 pub mod border;
@@ -396,36 +398,6 @@ impl ToCss for Time {
     }
 }
 
-#[cfg(feature = "gecko")]
-impl ToComputedValue for specified::JustifyItems {
-    type ComputedValue = JustifyItems;
-
-    // https://drafts.csswg.org/css-align/#valdef-justify-items-auto
-    fn to_computed_value(&self, context: &Context) -> JustifyItems {
-        use values::specified::align;
-        // If the inherited value of `justify-items` includes the `legacy` keyword, `auto` computes
-        // to the inherited value.
-        if self.0 == align::ALIGN_AUTO {
-            let inherited = context.builder.get_parent_position().clone_justify_items();
-            if inherited.0.contains(align::ALIGN_LEGACY) {
-                return inherited
-            }
-        }
-        return *self
-    }
-
-    #[inline]
-    fn from_computed_value(computed: &JustifyItems) -> Self {
-        *computed
-    }
-}
-
-#[cfg(feature = "gecko")]
-impl ComputedValueAsSpecified for specified::AlignItems {}
-#[cfg(feature = "gecko")]
-impl ComputedValueAsSpecified for specified::AlignJustifyContent {}
-#[cfg(feature = "gecko")]
-impl ComputedValueAsSpecified for specified::AlignJustifySelf {}
 impl ComputedValueAsSpecified for specified::BorderStyle {}
 
 /// A `<number>` value.

components/style/values/specified/align.rs

@@ -292,6 +292,12 @@ impl JustifyItems {
         JustifyItems(ALIGN_AUTO)
     }
 
+    /// The value 'normal'
+    #[inline]
+    pub fn normal() -> Self {
+        JustifyItems(ALIGN_NORMAL)
+    }
+
     /// Whether this value has extra flags.
     #[inline]
     pub fn has_extra_flags(self) -> bool {