Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1971 insertions, 0 deletions

diff --git a/servo/components/style/properties/gecko.mako.rs b/servo/components/style/properties/gecko.mako.rs
new file mode 100644
index 0000000000..4fe290980d
--- /dev/null
+++ b/servo/components/style/properties/gecko.mako.rs
@@ -0,0 +1,1971 @@
+/* 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 https://mozilla.org/MPL/2.0/. */
+
+// `data` comes from components/style/properties.mako.rs; see build.rs for more details.
+
+<%!
+    from data import to_camel_case, to_camel_case_lower
+    from data import Keyword
+%>
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+use crate::Atom;
+use app_units::Au;
+use crate::computed_value_flags::*;
+use crate::custom_properties::CustomPropertiesMap;
+use crate::gecko_bindings::bindings;
+% for style_struct in data.style_structs:
+use crate::gecko_bindings::bindings::Gecko_Construct_Default_${style_struct.gecko_ffi_name};
+use crate::gecko_bindings::bindings::Gecko_CopyConstruct_${style_struct.gecko_ffi_name};
+use crate::gecko_bindings::bindings::Gecko_Destroy_${style_struct.gecko_ffi_name};
+% endfor
+use crate::gecko_bindings::bindings::Gecko_CopyCounterStyle;
+use crate::gecko_bindings::bindings::Gecko_EnsureImageLayersLength;
+use crate::gecko_bindings::bindings::Gecko_nsStyleFont_SetLang;
+use crate::gecko_bindings::bindings::Gecko_nsStyleFont_CopyLangFrom;
+use crate::gecko_bindings::structs;
+use crate::gecko_bindings::structs::nsCSSPropertyID;
+use crate::gecko_bindings::structs::mozilla::PseudoStyleType;
+use crate::gecko::data::PerDocumentStyleData;
+use crate::logical_geometry::WritingMode;
+use crate::media_queries::Device;
+use crate::properties::longhands;
+use crate::rule_tree::StrongRuleNode;
+use crate::selector_parser::PseudoElement;
+use servo_arc::{Arc, UniqueArc};
+use std::mem::{forget, MaybeUninit, ManuallyDrop};
+use std::{cmp, ops, ptr};
+use crate::values::{self, CustomIdent, KeyframesName};
+use crate::values::computed::{BorderStyle, Percentage, Time, TransitionProperty};
+use crate::values::computed::font::FontSize;
+use crate::values::generics::column::ColumnCount;
+
+
+pub mod style_structs {
+    % for style_struct in data.style_structs:
+    pub use super::${style_struct.gecko_struct_name} as ${style_struct.name};
+
+    unsafe impl Send for ${style_struct.name} {}
+    unsafe impl Sync for ${style_struct.name} {}
+    % endfor
+}
+
+/// FIXME(emilio): This is completely duplicated with the other properties code.
+pub type ComputedValuesInner = structs::ServoComputedData;
+
+#[repr(C)]
+pub struct ComputedValues(structs::mozilla::ComputedStyle);
+
+impl ComputedValues {
+    #[inline]
+    pub (crate) fn as_gecko_computed_style(&self) -> &structs::ComputedStyle {
+        &self.0
+    }
+
+    pub fn new(
+        pseudo: Option<<&PseudoElement>,
+        custom_properties: Option<Arc<CustomPropertiesMap>>,
+        writing_mode: WritingMode,
+        flags: ComputedValueFlags,
+        rules: Option<StrongRuleNode>,
+        visited_style: Option<Arc<ComputedValues>>,
+        % for style_struct in data.style_structs:
+        ${style_struct.ident}: Arc<style_structs::${style_struct.name}>,
+        % endfor
+    ) -> Arc<Self> {
+        ComputedValuesInner::new(
+            custom_properties,
+            writing_mode,
+            flags,
+            rules,
+            visited_style,
+            % for style_struct in data.style_structs:
+            ${style_struct.ident},
+            % endfor
+        ).to_outer(pseudo)
+    }
+
+    pub fn default_values(doc: &structs::Document) -> Arc<Self> {
+        ComputedValuesInner::new(
+            /* custom_properties = */ None,
+            /* writing_mode = */ WritingMode::empty(), // FIXME(bz): This seems dubious
+            ComputedValueFlags::empty(),
+            /* rules = */ None,
+            /* visited_style = */ None,
+            % for style_struct in data.style_structs:
+            style_structs::${style_struct.name}::default(doc),
+            % endfor
+        ).to_outer(None)
+    }
+
+    /// Converts the computed values to an Arc<> from a reference.
+    pub fn to_arc(&self) -> Arc<Self> {
+        // SAFETY: We're guaranteed to be allocated as an Arc<> since the
+        // functions above are the only ones that create ComputedValues
+        // instances in Gecko (and that must be the case since ComputedValues'
+        // member is private).
+        unsafe { Arc::from_raw_addrefed(self) }
+    }
+
+    #[inline]
+    pub fn is_pseudo_style(&self) -> bool {
+        self.0.mPseudoType != PseudoStyleType::NotPseudo
+    }
+
+    #[inline]
+    pub fn pseudo(&self) -> Option<PseudoElement> {
+        if !self.is_pseudo_style() {
+            return None;
+        }
+        PseudoElement::from_pseudo_type(self.0.mPseudoType)
+    }
+
+    #[inline]
+    pub fn is_first_line_style(&self) -> bool {
+        self.pseudo() == Some(PseudoElement::FirstLine)
+    }
+
+    /// Returns true if the display property is changed from 'none' to others.
+    pub fn is_display_property_changed_from_none(
+        &self,
+        old_values: Option<<&ComputedValues>
+    ) -> bool {
+        use crate::properties::longhands::display::computed_value::T as Display;
+
+        old_values.map_or(false, |old| {
+            let old_display_style = old.get_box().clone_display();
+            let new_display_style = self.get_box().clone_display();
+            old_display_style == Display::None &&
+            new_display_style != Display::None
+        })
+    }
+
+}
+
+impl Drop for ComputedValues {
+    fn drop(&mut self) {
+        // XXX this still relies on the destructor of ComputedValuesInner to run on the rust side,
+        // that's pretty wild.
+        unsafe {
+            bindings::Gecko_ComputedStyle_Destroy(&mut self.0);
+        }
+    }
+}
+
+unsafe impl Sync for ComputedValues {}
+unsafe impl Send for ComputedValues {}
+
+impl Clone for ComputedValues {
+    fn clone(&self) -> Self {
+        unreachable!()
+    }
+}
+
+impl Clone for ComputedValuesInner {
+    fn clone(&self) -> Self {
+        ComputedValuesInner {
+            % for style_struct in data.style_structs:
+            ${style_struct.gecko_name}: Arc::into_raw(unsafe { Arc::from_raw_addrefed(self.${style_struct.name_lower}_ptr()) }) as *const _,
+            % endfor
+            custom_properties: self.custom_properties.clone(),
+            writing_mode: self.writing_mode.clone(),
+            flags: self.flags.clone(),
+            rules: self.rules.clone(),
+            visited_style: if self.visited_style.is_null() {
+                ptr::null()
+            } else {
+                Arc::into_raw(unsafe { Arc::from_raw_addrefed(self.visited_style_ptr()) }) as *const _
+            },
+        }
+    }
+}
+
+
+impl Drop for ComputedValuesInner {
+    fn drop(&mut self) {
+        % for style_struct in data.style_structs:
+        let _ = unsafe { Arc::from_raw(self.${style_struct.name_lower}_ptr()) };
+        % endfor
+        if !self.visited_style.is_null() {
+            let _ = unsafe { Arc::from_raw(self.visited_style_ptr()) };
+        }
+    }
+}
+
+impl ComputedValuesInner {
+    pub fn new(
+        custom_properties: Option<Arc<CustomPropertiesMap>>,
+        writing_mode: WritingMode,
+        flags: ComputedValueFlags,
+        rules: Option<StrongRuleNode>,
+        visited_style: Option<Arc<ComputedValues>>,
+        % for style_struct in data.style_structs:
+        ${style_struct.ident}: Arc<style_structs::${style_struct.name}>,
+        % endfor
+    ) -> Self {
+        Self {
+            custom_properties,
+            writing_mode,
+            rules,
+            visited_style: visited_style.map_or(ptr::null(), |p| Arc::into_raw(p)) as *const _,
+            flags,
+            % for style_struct in data.style_structs:
+            ${style_struct.gecko_name}: Arc::into_raw(${style_struct.ident}) as *const _,
+            % endfor
+        }
+    }
+
+    fn to_outer(self, pseudo: Option<<&PseudoElement>) -> Arc<ComputedValues> {
+        let pseudo_ty = match pseudo {
+            Some(p) => p.pseudo_type(),
+            None => structs::PseudoStyleType::NotPseudo,
+        };
+        unsafe {
+            let mut arc = UniqueArc::<ComputedValues>::new_uninit();
+            bindings::Gecko_ComputedStyle_Init(
+                arc.as_mut_ptr() as *mut _,
+                &self,
+                pseudo_ty,
+            );
+            // We're simulating move semantics by having C++ do a memcpy and
+            // then forgetting it on this end.
+            forget(self);
+            UniqueArc::assume_init(arc).shareable()
+        }
+    }
+}
+
+impl ops::Deref for ComputedValues {
+    type Target = ComputedValuesInner;
+    #[inline]
+    fn deref(&self) -> &ComputedValuesInner {
+        &self.0.mSource
+    }
+}
+
+impl ops::DerefMut for ComputedValues {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut ComputedValuesInner {
+        &mut self.0.mSource
+    }
+}
+
+impl ComputedValuesInner {
+    /// Returns true if the value of the `content` property would make a
+    /// pseudo-element not rendered.
+    #[inline]
+    pub fn ineffective_content_property(&self) -> bool {
+        self.get_counters().ineffective_content_property()
+    }
+
+    #[inline]
+    fn visited_style_ptr(&self) -> *const ComputedValues {
+        self.visited_style as *const _
+    }
+
+    /// Returns the visited style, if any.
+    pub fn visited_style(&self) -> Option<<&ComputedValues> {
+        unsafe { self.visited_style_ptr().as_ref() }
+    }
+
+    % for style_struct in data.style_structs:
+    #[inline]
+    fn ${style_struct.name_lower}_ptr(&self) -> *const style_structs::${style_struct.name} {
+        // This is sound because the wrapper we create is repr(transparent).
+        self.${style_struct.gecko_name} as *const _
+    }
+
+    #[inline]
+    pub fn clone_${style_struct.name_lower}(&self) -> Arc<style_structs::${style_struct.name}> {
+        unsafe { Arc::from_raw_addrefed(self.${style_struct.name_lower}_ptr()) }
+    }
+    #[inline]
+    pub fn get_${style_struct.name_lower}(&self) -> &style_structs::${style_struct.name} {
+        unsafe { &*self.${style_struct.name_lower}_ptr() }
+    }
+
+    #[inline]
+    pub fn mutate_${style_struct.name_lower}(&mut self) -> &mut style_structs::${style_struct.name} {
+        unsafe {
+            let mut arc = Arc::from_raw(self.${style_struct.name_lower}_ptr());
+            let ptr = Arc::make_mut(&mut arc) as *mut _;
+            // Sound for the same reason _ptr() is sound.
+            self.${style_struct.gecko_name} = Arc::into_raw(arc) as *const _;
+            &mut *ptr
+        }
+    }
+    % endfor
+}
+
+<%def name="impl_simple_setter(ident, gecko_ffi_name)">
+    #[allow(non_snake_case)]
+    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
+        ${set_gecko_property(gecko_ffi_name, "From::from(v)")}
+    }
+</%def>
+
+<%def name="impl_simple_clone(ident, gecko_ffi_name)">
+    #[allow(non_snake_case)]
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        From::from(self.${gecko_ffi_name}.clone())
+    }
+</%def>
+
+<%def name="impl_simple_copy(ident, gecko_ffi_name, *kwargs)">
+    #[allow(non_snake_case)]
+    pub fn copy_${ident}_from(&mut self, other: &Self) {
+        self.${gecko_ffi_name} = other.${gecko_ffi_name}.clone();
+    }
+
+    #[allow(non_snake_case)]
+    pub fn reset_${ident}(&mut self, other: &Self) {
+        self.copy_${ident}_from(other)
+    }
+</%def>
+
+<%!
+def get_gecko_property(ffi_name, self_param = "self"):
+    return "%s.%s" % (self_param, ffi_name)
+
+def set_gecko_property(ffi_name, expr):
+    return "self.%s = %s;" % (ffi_name, expr)
+%>
+
+<%def name="impl_keyword_setter(ident, gecko_ffi_name, keyword, cast_type='u8')">
+    #[allow(non_snake_case)]
+    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
+        use crate::properties::longhands::${ident}::computed_value::T as Keyword;
+        // FIXME(bholley): Align binary representations and ditch |match| for cast + static_asserts
+        let result = match v {
+            % for value in keyword.values_for('gecko'):
+                Keyword::${to_camel_case(value)} =>
+                    structs::${keyword.gecko_constant(value)} ${keyword.maybe_cast(cast_type)},
+            % endfor
+        };
+        ${set_gecko_property(gecko_ffi_name, "result")}
+    }
+</%def>
+
+<%def name="impl_keyword_clone(ident, gecko_ffi_name, keyword, cast_type='u8')">
+    #[allow(non_snake_case)]
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        use crate::properties::longhands::${ident}::computed_value::T as Keyword;
+        // FIXME(bholley): Align binary representations and ditch |match| for cast + static_asserts
+
+        // Some constant macros in the gecko are defined as negative integer(e.g. font-stretch).
+        // And they are convert to signed integer in Rust bindings. We need to cast then
+        // as signed type when we have both signed/unsigned integer in order to use them
+        // as match's arms.
+        // Also, to use same implementation here we use casted constant if we have only singed values.
+        % if keyword.gecko_enum_prefix is None:
+        % for value in keyword.values_for('gecko'):
+        const ${keyword.casted_constant_name(value, cast_type)} : ${cast_type} =
+            structs::${keyword.gecko_constant(value)} as ${cast_type};
+        % endfor
+
+        match ${get_gecko_property(gecko_ffi_name)} as ${cast_type} {
+            % for value in keyword.values_for('gecko'):
+            ${keyword.casted_constant_name(value, cast_type)} => Keyword::${to_camel_case(value)},
+            % endfor
+            % if keyword.gecko_inexhaustive:
+            _ => panic!("Found unexpected value in style struct for ${ident} property"),
+            % endif
+        }
+        % else:
+        match ${get_gecko_property(gecko_ffi_name)} {
+            % for value in keyword.values_for('gecko'):
+            structs::${keyword.gecko_constant(value)} => Keyword::${to_camel_case(value)},
+            % endfor
+            % if keyword.gecko_inexhaustive:
+            _ => panic!("Found unexpected value in style struct for ${ident} property"),
+            % endif
+        }
+        % endif
+    }
+</%def>
+
+<%def name="impl_keyword(ident, gecko_ffi_name, keyword, cast_type='u8', **kwargs)">
+<%call expr="impl_keyword_setter(ident, gecko_ffi_name, keyword, cast_type, **kwargs)"></%call>
+<%call expr="impl_simple_copy(ident, gecko_ffi_name, **kwargs)"></%call>
+<%call expr="impl_keyword_clone(ident, gecko_ffi_name, keyword, cast_type)"></%call>
+</%def>
+
+<%def name="impl_simple(ident, gecko_ffi_name)">
+<%call expr="impl_simple_setter(ident, gecko_ffi_name)"></%call>
+<%call expr="impl_simple_copy(ident, gecko_ffi_name)"></%call>
+<%call expr="impl_simple_clone(ident, gecko_ffi_name)"></%call>
+</%def>
+
+<%def name="impl_border_width(ident, gecko_ffi_name, inherit_from)">
+    #[allow(non_snake_case)]
+    pub fn set_${ident}(&mut self, v: Au) {
+        let value = v.0;
+        self.${inherit_from} = value;
+        self.${gecko_ffi_name} = value;
+    }
+
+    #[allow(non_snake_case)]
+    pub fn copy_${ident}_from(&mut self, other: &Self) {
+        self.${inherit_from} = other.${inherit_from};
+        // NOTE: This is needed to easily handle the `unset` and `initial`
+        // keywords, which are implemented calling this function.
+        //
+        // In practice, this means that we may have an incorrect value here, but
+        // we'll adjust that properly in the style fixup phase.
+        //
+        // FIXME(emilio): We could clean this up a bit special-casing the reset_
+        // function below.
+        self.${gecko_ffi_name} = other.${inherit_from};
+    }
+
+    #[allow(non_snake_case)]
+    pub fn reset_${ident}(&mut self, other: &Self) {
+        self.copy_${ident}_from(other)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn clone_${ident}(&self) -> Au {
+        Au(self.${gecko_ffi_name})
+    }
+</%def>
+
+<%def name="impl_split_style_coord(ident, gecko_ffi_name, index)">
+    #[allow(non_snake_case)]
+    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
+        self.${gecko_ffi_name}.${index} = v;
+    }
+    #[allow(non_snake_case)]
+    pub fn copy_${ident}_from(&mut self, other: &Self) {
+        self.${gecko_ffi_name}.${index} =
+            other.${gecko_ffi_name}.${index}.clone();
+    }
+    #[allow(non_snake_case)]
+    pub fn reset_${ident}(&mut self, other: &Self) {
+        self.copy_${ident}_from(other)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        self.${gecko_ffi_name}.${index}.clone()
+    }
+</%def>
+
+<%def name="copy_sides_style_coord(ident)">
+    <% gecko_ffi_name = "m" + to_camel_case(ident) %>
+    #[allow(non_snake_case)]
+    pub fn copy_${ident}_from(&mut self, other: &Self) {
+        % for side in SIDES:
+            self.${gecko_ffi_name}.data_at_mut(${side.index})
+                .copy_from(&other.${gecko_ffi_name}.data_at(${side.index}));
+        % endfor
+        ${ caller.body() }
+    }
+
+    #[allow(non_snake_case)]
+    pub fn reset_${ident}(&mut self, other: &Self) {
+        self.copy_${ident}_from(other)
+    }
+</%def>
+
+<%def name="impl_corner_style_coord(ident, gecko_ffi_name, corner)">
+    #[allow(non_snake_case)]
+    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
+        self.${gecko_ffi_name}.${corner} = v;
+    }
+    #[allow(non_snake_case)]
+    pub fn copy_${ident}_from(&mut self, other: &Self) {
+        self.${gecko_ffi_name}.${corner} =
+            other.${gecko_ffi_name}.${corner}.clone();
+    }
+    #[allow(non_snake_case)]
+    pub fn reset_${ident}(&mut self, other: &Self) {
+        self.copy_${ident}_from(other)
+    }
+    #[allow(non_snake_case)]
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        self.${gecko_ffi_name}.${corner}.clone()
+    }
+</%def>
+
+<%def name="impl_logical(name, **kwargs)">
+    ${helpers.logical_setter(name)}
+</%def>
+
+<%def name="impl_style_struct(style_struct)">
+/// A wrapper for ${style_struct.gecko_ffi_name}, to be able to manually construct / destruct /
+/// clone it.
+#[repr(transparent)]
+pub struct ${style_struct.gecko_struct_name}(ManuallyDrop<structs::${style_struct.gecko_ffi_name}>);
+
+impl ops::Deref for ${style_struct.gecko_struct_name} {
+    type Target = structs::${style_struct.gecko_ffi_name};
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl ops::DerefMut for ${style_struct.gecko_struct_name} {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut <Self as ops::Deref>::Target {
+        &mut self.0
+    }
+}
+
+impl ${style_struct.gecko_struct_name} {
+    #[allow(dead_code, unused_variables)]
+    pub fn default(document: &structs::Document) -> Arc<Self> {
+        unsafe {
+            let mut result = UniqueArc::<Self>::new_uninit();
+            // FIXME(bug 1595895): Zero the memory to keep valgrind happy, but
+            // these looks like Valgrind false-positives at a quick glance.
+            ptr::write_bytes::<Self>(result.as_mut_ptr(), 0, 1);
+            Gecko_Construct_Default_${style_struct.gecko_ffi_name}(
+                result.as_mut_ptr() as *mut _,
+                document,
+            );
+            UniqueArc::assume_init(result).shareable()
+        }
+    }
+}
+
+impl Drop for ${style_struct.gecko_struct_name} {
+    fn drop(&mut self) {
+        unsafe {
+            Gecko_Destroy_${style_struct.gecko_ffi_name}(&mut **self);
+        }
+    }
+}
+impl Clone for ${style_struct.gecko_struct_name} {
+    fn clone(&self) -> Self {
+        unsafe {
+            let mut result = MaybeUninit::<Self>::uninit();
+            // FIXME(bug 1595895): Zero the memory to keep valgrind happy, but
+            // these looks like Valgrind false-positives at a quick glance.
+            ptr::write_bytes::<Self>(result.as_mut_ptr(), 0, 1);
+            Gecko_CopyConstruct_${style_struct.gecko_ffi_name}(result.as_mut_ptr() as *mut _, &**self);
+            result.assume_init()
+        }
+    }
+}
+</%def>
+
+<%def name="impl_simple_type_with_conversion(ident, gecko_ffi_name)">
+    #[allow(non_snake_case)]
+    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
+        self.${gecko_ffi_name} = From::from(v)
+    }
+
+    <% impl_simple_copy(ident, gecko_ffi_name) %>
+
+    #[allow(non_snake_case)]
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        From::from(self.${gecko_ffi_name})
+    }
+</%def>
+
+<%def name="impl_font_settings(ident, gecko_type, tag_type, value_type, gecko_value_type)">
+    <%
+    gecko_ffi_name = to_camel_case_lower(ident)
+    %>
+
+    pub fn set_${ident}(&mut self, v: longhands::${ident}::computed_value::T) {
+        let iter = v.0.iter().map(|other| structs::${gecko_type} {
+            mTag: other.tag.0,
+            mValue: other.value as ${gecko_value_type},
+        });
+        self.mFont.${gecko_ffi_name}.assign_from_iter_pod(iter);
+    }
+
+    pub fn copy_${ident}_from(&mut self, other: &Self) {
+        let iter = other.mFont.${gecko_ffi_name}.iter().map(|s| *s);
+        self.mFont.${gecko_ffi_name}.assign_from_iter_pod(iter);
+    }
+
+    pub fn reset_${ident}(&mut self, other: &Self) {
+        self.copy_${ident}_from(other)
+    }
+
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        use crate::values::generics::font::{FontSettings, FontTag, ${tag_type}};
+
+        FontSettings(
+            self.mFont.${gecko_ffi_name}.iter().map(|gecko_font_setting| {
+                ${tag_type} {
+                    tag: FontTag(gecko_font_setting.mTag),
+                    value: gecko_font_setting.mValue as ${value_type},
+                }
+            }).collect::<Vec<_>>().into_boxed_slice()
+        )
+    }
+</%def>
+
+<%def name="impl_trait(style_struct_name, skip_longhands='')">
+<%
+    style_struct = next(x for x in data.style_structs if x.name == style_struct_name)
+    longhands = [x for x in style_struct.longhands
+                if not (skip_longhands == "*" or x.name in skip_longhands.split())]
+
+    def longhand_method(longhand):
+        args = dict(ident=longhand.ident, gecko_ffi_name=longhand.gecko_ffi_name)
+
+        # get the method and pass additional keyword or type-specific arguments
+        if longhand.logical:
+            method = impl_logical
+            args.update(name=longhand.name)
+        elif longhand.keyword:
+            method = impl_keyword
+            args.update(keyword=longhand.keyword)
+            if "font" in longhand.ident:
+                args.update(cast_type=longhand.cast_type)
+        else:
+            method = impl_simple
+
+        method(**args)
+%>
+impl ${style_struct.gecko_struct_name} {
+    /*
+     * Manually-Implemented Methods.
+     */
+    ${caller.body().strip()}
+
+    /*
+     * Auto-Generated Methods.
+     */
+    <%
+    for longhand in longhands:
+        longhand_method(longhand)
+    %>
+}
+</%def>
+
+<%!
+class Side(object):
+    def __init__(self, name, index):
+        self.name = name
+        self.ident = name.lower()
+        self.index = index
+
+SIDES = [Side("Top", 0), Side("Right", 1), Side("Bottom", 2), Side("Left", 3)]
+CORNERS = ["top_left", "top_right", "bottom_right", "bottom_left"]
+%>
+
+#[allow(dead_code)]
+fn static_assert() {
+    // Note: using the above technique with an enum hits a rust bug when |structs| is in a different crate.
+    % for side in SIDES:
+    { const DETAIL: u32 = [0][(structs::Side::eSide${side.name} as usize != ${side.index}) as usize]; let _ = DETAIL; }
+    % endfor
+}
+
+
+<% skip_border_longhands = " ".join(["border-{0}-{1}".format(x.ident, y)
+                                     for x in SIDES
+                                     for y in ["style", "width"]] +
+                                    ["border-{0}-radius".format(x.replace("_", "-"))
+                                     for x in CORNERS]) %>
+
+<%self:impl_trait style_struct_name="Border"
+                  skip_longhands="${skip_border_longhands} border-image-repeat">
+    % for side in SIDES:
+    pub fn set_border_${side.ident}_style(&mut self, v: BorderStyle) {
+        self.mBorderStyle[${side.index}] = v;
+
+        // This is needed because the initial mComputedBorder value is set to
+        // zero.
+        //
+        // In order to compute stuff, we start from the initial struct, and keep
+        // going down the tree applying properties.
+        //
+        // That means, effectively, that when we set border-style to something
+        // non-hidden, we should use the initial border instead.
+        //
+        // Servo stores the initial border-width in the initial struct, and then
+        // adjusts as needed in the fixup phase. This means that the initial
+        // struct is technically not valid without fixups, and that you lose
+        // pretty much any sharing of the initial struct, which is kind of
+        // unfortunate.
+        //
+        // Gecko has two fields for this, one that stores the "specified"
+        // border, and other that stores the actual computed one. That means
+        // that when we set border-style, border-width may change and we need to
+        // sync back to the specified one. This is what this function does.
+        //
+        // Note that this doesn't impose any dependency in the order of
+        // computation of the properties. This is only relevant if border-style
+        // is specified, but border-width isn't. If border-width is specified at
+        // some point, the two mBorder and mComputedBorder fields would be the
+        // same already.
+        //
+        // Once we're here, we know that we'll run style fixups, so it's fine to
+        // just copy the specified border here, we'll adjust it if it's
+        // incorrect later.
+        self.mComputedBorder.${side.ident} = self.mBorder.${side.ident};
+    }
+
+    pub fn copy_border_${side.ident}_style_from(&mut self, other: &Self) {
+        self.set_border_${side.ident}_style(other.mBorderStyle[${side.index}]);
+    }
+
+    pub fn reset_border_${side.ident}_style(&mut self, other: &Self) {
+        self.copy_border_${side.ident}_style_from(other);
+    }
+
+    #[inline]
+    pub fn clone_border_${side.ident}_style(&self) -> BorderStyle {
+        self.mBorderStyle[${side.index}]
+    }
+
+    ${impl_border_width("border_%s_width" % side.ident, "mComputedBorder.%s" % side.ident, "mBorder.%s" % side.ident)}
+
+    pub fn border_${side.ident}_has_nonzero_width(&self) -> bool {
+        self.mComputedBorder.${side.ident} != 0
+    }
+    % endfor
+
+    % for corner in CORNERS:
+    <% impl_corner_style_coord("border_%s_radius" % corner,
+                               "mBorderRadius",
+                               corner) %>
+    % endfor
+
+    <%
+    border_image_repeat_keywords = ["Stretch", "Repeat", "Round", "Space"]
+    %>
+
+    pub fn set_border_image_repeat(&mut self, v: longhands::border_image_repeat::computed_value::T) {
+        use crate::values::specified::border::BorderImageRepeatKeyword;
+        use crate::gecko_bindings::structs::StyleBorderImageRepeat;
+
+        % for i, side in enumerate(["H", "V"]):
+            self.mBorderImageRepeat${side} = match v.${i} {
+                % for keyword in border_image_repeat_keywords:
+                BorderImageRepeatKeyword::${keyword} => StyleBorderImageRepeat::${keyword},
+                % endfor
+            };
+        % endfor
+    }
+
+    pub fn copy_border_image_repeat_from(&mut self, other: &Self) {
+        self.mBorderImageRepeatH = other.mBorderImageRepeatH;
+        self.mBorderImageRepeatV = other.mBorderImageRepeatV;
+    }
+
+    pub fn reset_border_image_repeat(&mut self, other: &Self) {
+        self.copy_border_image_repeat_from(other)
+    }
+
+    pub fn clone_border_image_repeat(&self) -> longhands::border_image_repeat::computed_value::T {
+        use crate::values::specified::border::BorderImageRepeatKeyword;
+        use crate::gecko_bindings::structs::StyleBorderImageRepeat;
+
+        % for side in ["H", "V"]:
+        let servo_${side.lower()} = match self.mBorderImageRepeat${side} {
+            % for keyword in border_image_repeat_keywords:
+            StyleBorderImageRepeat::${keyword} => BorderImageRepeatKeyword::${keyword},
+            % endfor
+        };
+        % endfor
+        longhands::border_image_repeat::computed_value::T(servo_h, servo_v)
+    }
+</%self:impl_trait>
+
+<% skip_scroll_margin_longhands = " ".join(["scroll-margin-%s" % x.ident for x in SIDES]) %>
+<% skip_margin_longhands = " ".join(["margin-%s" % x.ident for x in SIDES]) %>
+<%self:impl_trait style_struct_name="Margin"
+                  skip_longhands="${skip_margin_longhands}
+                                  ${skip_scroll_margin_longhands}">
+    % for side in SIDES:
+    <% impl_split_style_coord("margin_%s" % side.ident,
+                              "mMargin",
+                              side.index) %>
+    <% impl_split_style_coord("scroll_margin_%s" % side.ident,
+                              "mScrollMargin",
+                              side.index) %>
+    % endfor
+</%self:impl_trait>
+
+<% skip_scroll_padding_longhands = " ".join(["scroll-padding-%s" % x.ident for x in SIDES]) %>
+<% skip_padding_longhands = " ".join(["padding-%s" % x.ident for x in SIDES]) %>
+<%self:impl_trait style_struct_name="Padding"
+                  skip_longhands="${skip_padding_longhands}
+                                  ${skip_scroll_padding_longhands}">
+
+    % for side in SIDES:
+    <% impl_split_style_coord("padding_%s" % side.ident,
+                              "mPadding",
+                              side.index) %>
+    <% impl_split_style_coord("scroll_padding_%s" % side.ident, "mScrollPadding", side.index) %>
+    % endfor
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Page">
+</%self:impl_trait>
+
+<% skip_position_longhands = " ".join(x.ident for x in SIDES) %>
+<%self:impl_trait style_struct_name="Position"
+                  skip_longhands="${skip_position_longhands}
+                                  masonry-auto-flow">
+    % for side in SIDES:
+    <% impl_split_style_coord(side.ident, "mOffset", side.index) %>
+    % endfor
+    pub fn set_computed_justify_items(&mut self, v: values::specified::JustifyItems) {
+        debug_assert_ne!(v.0, crate::values::specified::align::AlignFlags::LEGACY);
+        self.mJustifyItems.computed = v;
+    }
+
+    ${impl_simple_type_with_conversion("masonry_auto_flow", "mMasonryAutoFlow")}
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Outline"
+                  skip_longhands="outline-style outline-width">
+
+    pub fn set_outline_style(&mut self, v: longhands::outline_style::computed_value::T) {
+        self.mOutlineStyle = v;
+        // NB: This is needed to correctly handling the initial value of
+        // outline-width when outline-style changes, see the
+        // update_border_${side.ident} comment for more details.
+        self.mActualOutlineWidth = self.mOutlineWidth;
+    }
+
+    pub fn copy_outline_style_from(&mut self, other: &Self) {
+        self.set_outline_style(other.mOutlineStyle);
+    }
+
+    pub fn reset_outline_style(&mut self, other: &Self) {
+        self.copy_outline_style_from(other)
+    }
+
+    pub fn clone_outline_style(&self) -> longhands::outline_style::computed_value::T {
+        self.mOutlineStyle.clone()
+    }
+
+    ${impl_border_width("outline_width", "mActualOutlineWidth", "mOutlineWidth")}
+
+    pub fn outline_has_nonzero_width(&self) -> bool {
+        self.mActualOutlineWidth != 0
+    }
+</%self:impl_trait>
+
+<% skip_font_longhands = """font-family font-size font-size-adjust font-weight
+                            font-style font-stretch -x-lang
+                            font-variant-alternates font-variant-east-asian
+                            font-variant-ligatures font-variant-numeric
+                            font-language-override font-feature-settings
+                            font-variation-settings -moz-min-font-size-ratio""" %>
+<%self:impl_trait style_struct_name="Font"
+    skip_longhands="${skip_font_longhands}">
+
+    // Negative numbers are invalid at parse time, but <integer> is still an
+    // i32.
+    <% impl_font_settings("font_feature_settings", "gfxFontFeature", "FeatureTagValue", "i32", "u32") %>
+    <% impl_font_settings("font_variation_settings", "gfxFontVariation", "VariationValue", "f32", "f32") %>
+
+    pub fn unzoom_fonts(&mut self, device: &Device) {
+        use crate::values::generics::NonNegative;
+        self.mSize = NonNegative(device.unzoom_text(self.mSize.0));
+        self.mScriptUnconstrainedSize = NonNegative(device.unzoom_text(self.mScriptUnconstrainedSize.0));
+        self.mFont.size = NonNegative(device.unzoom_text(self.mFont.size.0));
+    }
+
+    pub fn copy_font_size_from(&mut self, other: &Self) {
+        self.mScriptUnconstrainedSize = other.mScriptUnconstrainedSize;
+
+        self.mSize = other.mScriptUnconstrainedSize;
+        // NOTE: Intentionally not copying from mFont.size. The cascade process
+        // recomputes the used size as needed.
+        self.mFont.size = other.mSize;
+        self.mFontSizeKeyword = other.mFontSizeKeyword;
+
+        // TODO(emilio): Should we really copy over these two?
+        self.mFontSizeFactor = other.mFontSizeFactor;
+        self.mFontSizeOffset = other.mFontSizeOffset;
+    }
+
+    pub fn reset_font_size(&mut self, other: &Self) {
+        self.copy_font_size_from(other)
+    }
+
+    pub fn set_font_size(&mut self, v: FontSize) {
+        let computed_size = v.computed_size;
+        self.mScriptUnconstrainedSize = computed_size;
+
+        // These two may be changed from Cascade::fixup_font_stuff.
+        self.mSize = computed_size;
+        // NOTE: Intentionally not copying from used_size. The cascade process
+        // recomputes the used size as needed.
+        self.mFont.size = computed_size;
+
+        self.mFontSizeKeyword = v.keyword_info.kw;
+        self.mFontSizeFactor = v.keyword_info.factor;
+        self.mFontSizeOffset = v.keyword_info.offset;
+    }
+
+    pub fn clone_font_size(&self) -> FontSize {
+        use crate::values::specified::font::KeywordInfo;
+
+        FontSize {
+            computed_size: self.mSize,
+            used_size: self.mFont.size,
+            keyword_info: KeywordInfo {
+                kw: self.mFontSizeKeyword,
+                factor: self.mFontSizeFactor,
+                offset: self.mFontSizeOffset,
+            }
+        }
+    }
+
+    ${impl_simple('font_weight', 'mFont.weight')}
+    ${impl_simple('font_stretch', 'mFont.stretch')}
+    ${impl_simple('font_style', 'mFont.style')}
+
+    ${impl_simple("font_variant_alternates", "mFont.variantAlternates")}
+
+    ${impl_simple("font_size_adjust", "mFont.sizeAdjust")}
+
+    ${impl_simple("font_family", "mFont.family")}
+
+    #[allow(non_snake_case)]
+    pub fn set__x_lang(&mut self, v: longhands::_x_lang::computed_value::T) {
+        let ptr = v.0.as_ptr();
+        forget(v);
+        unsafe {
+            Gecko_nsStyleFont_SetLang(&mut **self, ptr);
+        }
+    }
+
+    #[allow(non_snake_case)]
+    pub fn copy__x_lang_from(&mut self, other: &Self) {
+        unsafe {
+            Gecko_nsStyleFont_CopyLangFrom(&mut **self, &**other);
+        }
+    }
+
+    #[allow(non_snake_case)]
+    pub fn reset__x_lang(&mut self, other: &Self) {
+        self.copy__x_lang_from(other)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn clone__x_lang(&self) -> longhands::_x_lang::computed_value::T {
+        longhands::_x_lang::computed_value::T(unsafe {
+            Atom::from_raw(self.mLanguage.mRawPtr)
+        })
+    }
+
+
+    ${impl_simple_type_with_conversion("font_language_override", "mFont.languageOverride")}
+    ${impl_simple_type_with_conversion("font_variant_ligatures", "mFont.variantLigatures")}
+    ${impl_simple_type_with_conversion("font_variant_east_asian", "mFont.variantEastAsian")}
+    ${impl_simple_type_with_conversion("font_variant_numeric", "mFont.variantNumeric")}
+
+    #[allow(non_snake_case)]
+    pub fn clone__moz_min_font_size_ratio(
+        &self,
+    ) -> longhands::_moz_min_font_size_ratio::computed_value::T {
+        Percentage(self.mMinFontSizeRatio as f32 / 100.)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn set__moz_min_font_size_ratio(&mut self, v: longhands::_moz_min_font_size_ratio::computed_value::T) {
+        let scaled = v.0 * 100.;
+        let percentage = if scaled > 255. {
+            255.
+        } else if scaled < 0. {
+            0.
+        } else {
+            scaled
+        };
+
+        self.mMinFontSizeRatio = percentage as u8;
+    }
+
+    ${impl_simple_copy('_moz_min_font_size_ratio', 'mMinFontSizeRatio')}
+</%self:impl_trait>
+
+<%def name="impl_coordinated_property_copy(type, ident, gecko_ffi_name)">
+    #[allow(non_snake_case)]
+    pub fn copy_${type}_${ident}_from(&mut self, other: &Self) {
+        self.m${to_camel_case(type)}s.ensure_len(other.m${to_camel_case(type)}s.len());
+
+        let count = other.m${to_camel_case(type)}${gecko_ffi_name}Count;
+        self.m${to_camel_case(type)}${gecko_ffi_name}Count = count;
+
+        let iter = self.m${to_camel_case(type)}s.iter_mut().take(count as usize).zip(
+            other.m${to_camel_case(type)}s.iter()
+        );
+
+        for (ours, others) in iter {
+            ours.m${gecko_ffi_name} = others.m${gecko_ffi_name}.clone();
+        }
+    }
+    #[allow(non_snake_case)]
+    pub fn reset_${type}_${ident}(&mut self, other: &Self) {
+        self.copy_${type}_${ident}_from(other)
+    }
+</%def>
+
+<%def name="impl_coordinated_property_count(type, ident, gecko_ffi_name)">
+    #[allow(non_snake_case)]
+    pub fn ${type}_${ident}_count(&self) -> usize {
+        self.m${to_camel_case(type)}${gecko_ffi_name}Count as usize
+    }
+</%def>
+
+<%def name="impl_coordinated_property(type, ident, gecko_ffi_name)">
+    #[allow(non_snake_case)]
+    pub fn set_${type}_${ident}<I>(&mut self, v: I)
+    where
+        I: IntoIterator<Item = longhands::${type}_${ident}::computed_value::single_value::T>,
+        I::IntoIter: ExactSizeIterator + Clone
+    {
+        let v = v.into_iter();
+        debug_assert_ne!(v.len(), 0);
+        let input_len = v.len();
+        self.m${to_camel_case(type)}s.ensure_len(input_len);
+
+        self.m${to_camel_case(type)}${gecko_ffi_name}Count = input_len as u32;
+        for (gecko, servo) in self.m${to_camel_case(type)}s.iter_mut().take(input_len as usize).zip(v) {
+            gecko.m${gecko_ffi_name} = servo;
+        }
+    }
+    #[allow(non_snake_case)]
+    pub fn ${type}_${ident}_at(&self, index: usize)
+        -> longhands::${type}_${ident}::computed_value::SingleComputedValue {
+        self.m${to_camel_case(type)}s[index % self.${type}_${ident}_count()].m${gecko_ffi_name}.clone()
+    }
+    ${impl_coordinated_property_copy(type, ident, gecko_ffi_name)}
+    ${impl_coordinated_property_count(type, ident, gecko_ffi_name)}
+</%def>
+
+<%def name="impl_animation_keyword(ident, gecko_ffi_name, keyword, cast_type='u8')">
+    #[allow(non_snake_case)]
+    pub fn set_animation_${ident}<I>(&mut self, v: I)
+    where
+        I: IntoIterator<Item = longhands::animation_${ident}::computed_value::single_value::T>,
+        I::IntoIter: ExactSizeIterator + Clone
+    {
+        use crate::properties::longhands::animation_${ident}::single_value::computed_value::T as Keyword;
+
+        let v = v.into_iter();
+
+        debug_assert_ne!(v.len(), 0);
+        let input_len = v.len();
+        self.mAnimations.ensure_len(input_len);
+
+        self.mAnimation${gecko_ffi_name}Count = input_len as u32;
+
+        for (gecko, servo) in self.mAnimations.iter_mut().take(input_len as usize).zip(v) {
+            let result = match servo {
+                % for value in keyword.values_for("gecko"):
+                    Keyword::${to_camel_case(value)} =>
+                        structs::${keyword.gecko_constant(value)} ${keyword.maybe_cast(cast_type)},
+                % endfor
+            };
+            gecko.m${gecko_ffi_name} = result;
+        }
+    }
+    #[allow(non_snake_case)]
+    pub fn animation_${ident}_at(&self, index: usize)
+        -> longhands::animation_${ident}::computed_value::SingleComputedValue {
+        use crate::properties::longhands::animation_${ident}::single_value::computed_value::T as Keyword;
+        match self.mAnimations[index].m${gecko_ffi_name} ${keyword.maybe_cast("u32")} {
+            % for value in keyword.values_for("gecko"):
+                structs::${keyword.gecko_constant(value)} => Keyword::${to_camel_case(value)},
+            % endfor
+            % if keyword.gecko_inexhaustive:
+            _ => panic!("Found unexpected value for animation-${ident}"),
+            % endif
+        }
+    }
+    ${impl_coordinated_property_copy('animation', ident, gecko_ffi_name)}
+    ${impl_coordinated_property_count('animation', ident, gecko_ffi_name)}
+</%def>
+
+<% skip_box_longhands= """display contain""" %>
+<%self:impl_trait style_struct_name="Box" skip_longhands="${skip_box_longhands}">
+    #[inline]
+    pub fn set_display(&mut self, v: longhands::display::computed_value::T) {
+        self.mDisplay = v;
+        self.mOriginalDisplay = v;
+    }
+
+    #[inline]
+    pub fn copy_display_from(&mut self, other: &Self) {
+        self.set_display(other.mDisplay);
+    }
+
+    #[inline]
+    pub fn reset_display(&mut self, other: &Self) {
+        self.copy_display_from(other)
+    }
+
+    #[inline]
+    pub fn set_adjusted_display(
+        &mut self,
+        v: longhands::display::computed_value::T,
+        _is_item_or_root: bool
+    ) {
+        self.mDisplay = v;
+    }
+
+    #[inline]
+    pub fn clone_display(&self) -> longhands::display::computed_value::T {
+        self.mDisplay
+    }
+
+    #[inline]
+    pub fn set_contain(&mut self, v: longhands::contain::computed_value::T) {
+        self.mContain = v;
+        self.mEffectiveContainment = v;
+    }
+
+    #[inline]
+    pub fn copy_contain_from(&mut self, other: &Self) {
+        self.set_contain(other.mContain);
+    }
+
+    #[inline]
+    pub fn reset_contain(&mut self, other: &Self) {
+        self.copy_contain_from(other)
+    }
+
+    #[inline]
+    pub fn clone_contain(&self) -> longhands::contain::computed_value::T {
+        self.mContain
+    }
+
+    #[inline]
+    pub fn set_effective_containment(
+        &mut self,
+        v: longhands::contain::computed_value::T
+    ) {
+        self.mEffectiveContainment = v;
+    }
+
+    #[inline]
+    pub fn clone_effective_containment(&self) -> longhands::contain::computed_value::T {
+        self.mEffectiveContainment
+    }
+</%self:impl_trait>
+
+<%def name="simple_image_array_property(name, shorthand, field_name)">
+    <%
+        image_layers_field = "mImage" if shorthand == "background" else "mMask"
+        copy_simple_image_array_property(name, shorthand, image_layers_field, field_name)
+    %>
+
+    pub fn set_${shorthand}_${name}<I>(&mut self, v: I)
+        where I: IntoIterator<Item=longhands::${shorthand}_${name}::computed_value::single_value::T>,
+              I::IntoIter: ExactSizeIterator
+    {
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+        let v = v.into_iter();
+
+        unsafe {
+          Gecko_EnsureImageLayersLength(&mut self.${image_layers_field}, v.len(),
+                                        LayerType::${shorthand.title()});
+        }
+
+        self.${image_layers_field}.${field_name}Count = v.len() as u32;
+        for (servo, geckolayer) in v.zip(self.${image_layers_field}.mLayers.iter_mut()) {
+            geckolayer.${field_name} = {
+                ${caller.body()}
+            };
+        }
+    }
+</%def>
+
+<%def name="copy_simple_image_array_property(name, shorthand, layers_field_name, field_name)">
+    pub fn copy_${shorthand}_${name}_from(&mut self, other: &Self) {
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+
+        let count = other.${layers_field_name}.${field_name}Count;
+        unsafe {
+            Gecko_EnsureImageLayersLength(&mut self.${layers_field_name},
+                                          count as usize,
+                                          LayerType::${shorthand.title()});
+        }
+        // FIXME(emilio): This may be bogus in the same way as bug 1426246.
+        for (layer, other) in self.${layers_field_name}.mLayers.iter_mut()
+                                  .zip(other.${layers_field_name}.mLayers.iter())
+                                  .take(count as usize) {
+            layer.${field_name} = other.${field_name}.clone();
+        }
+        self.${layers_field_name}.${field_name}Count = count;
+    }
+
+    pub fn reset_${shorthand}_${name}(&mut self, other: &Self) {
+        self.copy_${shorthand}_${name}_from(other)
+    }
+</%def>
+
+<%def name="impl_simple_image_array_property(name, shorthand, layer_field_name, field_name, struct_name)">
+    <%
+        ident = "%s_%s" % (shorthand, name)
+        style_struct = next(x for x in data.style_structs if x.name == struct_name)
+        longhand = next(x for x in style_struct.longhands if x.ident == ident)
+        keyword = longhand.keyword
+    %>
+
+    <% copy_simple_image_array_property(name, shorthand, layer_field_name, field_name) %>
+
+    pub fn set_${ident}<I>(&mut self, v: I)
+    where
+        I: IntoIterator<Item=longhands::${ident}::computed_value::single_value::T>,
+        I::IntoIter: ExactSizeIterator,
+    {
+        use crate::properties::longhands::${ident}::single_value::computed_value::T as Keyword;
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+
+        let v = v.into_iter();
+
+        unsafe {
+          Gecko_EnsureImageLayersLength(&mut self.${layer_field_name}, v.len(),
+                                        LayerType::${shorthand.title()});
+        }
+
+        self.${layer_field_name}.${field_name}Count = v.len() as u32;
+        for (servo, geckolayer) in v.zip(self.${layer_field_name}.mLayers.iter_mut()) {
+            geckolayer.${field_name} = {
+                match servo {
+                    % for value in keyword.values_for("gecko"):
+                    Keyword::${to_camel_case(value)} =>
+                        structs::${keyword.gecko_constant(value)} ${keyword.maybe_cast('u8')},
+                    % endfor
+                }
+            };
+        }
+    }
+
+    pub fn clone_${ident}(&self) -> longhands::${ident}::computed_value::T {
+        use crate::properties::longhands::${ident}::single_value::computed_value::T as Keyword;
+
+        % if keyword.needs_cast():
+        % for value in keyword.values_for('gecko'):
+        const ${keyword.casted_constant_name(value, "u8")} : u8 =
+            structs::${keyword.gecko_constant(value)} as u8;
+        % endfor
+        % endif
+
+        longhands::${ident}::computed_value::List(
+            self.${layer_field_name}.mLayers.iter()
+                .take(self.${layer_field_name}.${field_name}Count as usize)
+                .map(|ref layer| {
+                    match layer.${field_name} {
+                        % for value in longhand.keyword.values_for("gecko"):
+                        % if keyword.needs_cast():
+                        ${keyword.casted_constant_name(value, "u8")}
+                        % else:
+                        structs::${keyword.gecko_constant(value)}
+                        % endif
+                            => Keyword::${to_camel_case(value)},
+                        % endfor
+                        % if keyword.gecko_inexhaustive:
+                        _ => panic!("Found unexpected value in style struct for ${ident} property"),
+                        % endif
+                    }
+                }).collect()
+        )
+    }
+</%def>
+
+<%def name="impl_common_image_layer_properties(shorthand)">
+    <%
+        if shorthand == "background":
+            image_layers_field = "mImage"
+            struct_name = "Background"
+        else:
+            image_layers_field = "mMask"
+            struct_name = "SVG"
+    %>
+
+    <%self:simple_image_array_property name="repeat" shorthand="${shorthand}" field_name="mRepeat">
+        use crate::values::specified::background::BackgroundRepeatKeyword;
+        use crate::gecko_bindings::structs::nsStyleImageLayers_Repeat;
+        use crate::gecko_bindings::structs::StyleImageLayerRepeat;
+
+        fn to_ns(repeat: BackgroundRepeatKeyword) -> StyleImageLayerRepeat {
+            match repeat {
+                BackgroundRepeatKeyword::Repeat => StyleImageLayerRepeat::Repeat,
+                BackgroundRepeatKeyword::Space => StyleImageLayerRepeat::Space,
+                BackgroundRepeatKeyword::Round => StyleImageLayerRepeat::Round,
+                BackgroundRepeatKeyword::NoRepeat => StyleImageLayerRepeat::NoRepeat,
+            }
+        }
+
+        let repeat_x = to_ns(servo.0);
+        let repeat_y = to_ns(servo.1);
+        nsStyleImageLayers_Repeat {
+              mXRepeat: repeat_x,
+              mYRepeat: repeat_y,
+        }
+    </%self:simple_image_array_property>
+
+    pub fn clone_${shorthand}_repeat(&self) -> longhands::${shorthand}_repeat::computed_value::T {
+        use crate::properties::longhands::${shorthand}_repeat::single_value::computed_value::T;
+        use crate::values::specified::background::BackgroundRepeatKeyword;
+        use crate::gecko_bindings::structs::StyleImageLayerRepeat;
+
+        fn to_servo(repeat: StyleImageLayerRepeat) -> BackgroundRepeatKeyword {
+            match repeat {
+                StyleImageLayerRepeat::Repeat => BackgroundRepeatKeyword::Repeat,
+                StyleImageLayerRepeat::Space => BackgroundRepeatKeyword::Space,
+                StyleImageLayerRepeat::Round => BackgroundRepeatKeyword::Round,
+                StyleImageLayerRepeat::NoRepeat => BackgroundRepeatKeyword::NoRepeat,
+                _ => panic!("Found unexpected value in style struct for ${shorthand}_repeat property"),
+            }
+        }
+
+        longhands::${shorthand}_repeat::computed_value::List(
+            self.${image_layers_field}.mLayers.iter()
+                .take(self.${image_layers_field}.mRepeatCount as usize)
+                .map(|ref layer| {
+                    T(to_servo(layer.mRepeat.mXRepeat), to_servo(layer.mRepeat.mYRepeat))
+                }).collect()
+        )
+    }
+
+    <% impl_simple_image_array_property("clip", shorthand, image_layers_field, "mClip", struct_name) %>
+    <% impl_simple_image_array_property("origin", shorthand, image_layers_field, "mOrigin", struct_name) %>
+
+    % for (orientation, keyword) in [("x", "horizontal"), ("y", "vertical")]:
+    pub fn copy_${shorthand}_position_${orientation}_from(&mut self, other: &Self) {
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+
+        let count = other.${image_layers_field}.mPosition${orientation.upper()}Count;
+
+        unsafe {
+            Gecko_EnsureImageLayersLength(&mut self.${image_layers_field},
+                                          count as usize,
+                                          LayerType::${shorthand.capitalize()});
+        }
+
+        for (layer, other) in self.${image_layers_field}.mLayers.iter_mut()
+                                  .zip(other.${image_layers_field}.mLayers.iter())
+                                  .take(count as usize) {
+            layer.mPosition.${keyword} = other.mPosition.${keyword}.clone();
+        }
+        self.${image_layers_field}.mPosition${orientation.upper()}Count = count;
+    }
+
+    pub fn reset_${shorthand}_position_${orientation}(&mut self, other: &Self) {
+        self.copy_${shorthand}_position_${orientation}_from(other)
+    }
+
+    pub fn clone_${shorthand}_position_${orientation}(&self)
+        -> longhands::${shorthand}_position_${orientation}::computed_value::T {
+        longhands::${shorthand}_position_${orientation}::computed_value::List(
+            self.${image_layers_field}.mLayers.iter()
+                .take(self.${image_layers_field}.mPosition${orientation.upper()}Count as usize)
+                .map(|position| position.mPosition.${keyword}.clone())
+                .collect()
+        )
+    }
+
+    pub fn set_${shorthand}_position_${orientation[0]}<I>(&mut self,
+                                     v: I)
+        where I: IntoIterator<Item = longhands::${shorthand}_position_${orientation[0]}
+                                              ::computed_value::single_value::T>,
+              I::IntoIter: ExactSizeIterator
+    {
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+
+        let v = v.into_iter();
+
+        unsafe {
+            Gecko_EnsureImageLayersLength(&mut self.${image_layers_field}, v.len(),
+                                        LayerType::${shorthand.capitalize()});
+        }
+
+        self.${image_layers_field}.mPosition${orientation[0].upper()}Count = v.len() as u32;
+        for (servo, geckolayer) in v.zip(self.${image_layers_field}
+                                                           .mLayers.iter_mut()) {
+            geckolayer.mPosition.${keyword} = servo;
+        }
+    }
+    % endfor
+
+    <%self:simple_image_array_property name="size" shorthand="${shorthand}" field_name="mSize">
+        servo
+    </%self:simple_image_array_property>
+
+    pub fn clone_${shorthand}_size(&self) -> longhands::${shorthand}_size::computed_value::T {
+        longhands::${shorthand}_size::computed_value::List(
+            self.${image_layers_field}.mLayers.iter().map(|layer| layer.mSize.clone()).collect()
+        )
+    }
+
+    pub fn copy_${shorthand}_image_from(&mut self, other: &Self) {
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+        unsafe {
+            let count = other.${image_layers_field}.mImageCount;
+            Gecko_EnsureImageLayersLength(&mut self.${image_layers_field},
+                                          count as usize,
+                                          LayerType::${shorthand.capitalize()});
+
+            for (layer, other) in self.${image_layers_field}.mLayers.iter_mut()
+                                      .zip(other.${image_layers_field}.mLayers.iter())
+                                      .take(count as usize) {
+                layer.mImage = other.mImage.clone();
+            }
+            self.${image_layers_field}.mImageCount = count;
+        }
+    }
+
+    pub fn reset_${shorthand}_image(&mut self, other: &Self) {
+        self.copy_${shorthand}_image_from(other)
+    }
+
+    #[allow(unused_variables)]
+    pub fn set_${shorthand}_image<I>(&mut self, images: I)
+        where I: IntoIterator<Item = longhands::${shorthand}_image::computed_value::single_value::T>,
+              I::IntoIter: ExactSizeIterator
+    {
+        use crate::gecko_bindings::structs::nsStyleImageLayers_LayerType as LayerType;
+
+        let images = images.into_iter();
+
+        unsafe {
+            Gecko_EnsureImageLayersLength(
+                &mut self.${image_layers_field},
+                images.len(),
+                LayerType::${shorthand.title()},
+            );
+        }
+
+        self.${image_layers_field}.mImageCount = images.len() as u32;
+        for (image, geckoimage) in images.zip(self.${image_layers_field}
+                                                  .mLayers.iter_mut()) {
+            geckoimage.mImage = image;
+        }
+    }
+
+    pub fn clone_${shorthand}_image(&self) -> longhands::${shorthand}_image::computed_value::T {
+        longhands::${shorthand}_image::computed_value::List(
+            self.${image_layers_field}.mLayers.iter()
+                .take(self.${image_layers_field}.mImageCount as usize)
+                .map(|layer| layer.mImage.clone())
+                .collect()
+        )
+    }
+
+    <%
+        fill_fields = "mRepeat mClip mOrigin mPositionX mPositionY mImage mSize"
+        if shorthand == "background":
+            fill_fields += " mAttachment mBlendMode"
+        else:
+            # mSourceURI uses mImageCount
+            fill_fields += " mMaskMode mComposite"
+    %>
+    pub fn fill_arrays(&mut self) {
+        use crate::gecko_bindings::bindings::Gecko_FillAllImageLayers;
+        use std::cmp;
+        let mut max_len = 1;
+        % for member in fill_fields.split():
+            max_len = cmp::max(max_len, self.${image_layers_field}.${member}Count);
+        % endfor
+        unsafe {
+            // While we could do this manually, we'd need to also manually
+            // run all the copy constructors, so we just delegate to gecko
+            Gecko_FillAllImageLayers(&mut self.${image_layers_field}, max_len);
+        }
+    }
+</%def>
+
+// TODO: Gecko accepts lists in most background-related properties. We just use
+// the first element (which is the common case), but at some point we want to
+// add support for parsing these lists in servo and pushing to nsTArray's.
+<% skip_background_longhands = """background-repeat
+                                  background-image background-clip
+                                  background-origin background-attachment
+                                  background-size background-position
+                                  background-blend-mode
+                                  background-position-x
+                                  background-position-y""" %>
+<%self:impl_trait style_struct_name="Background"
+                  skip_longhands="${skip_background_longhands}">
+
+    <% impl_common_image_layer_properties("background") %>
+    <% impl_simple_image_array_property("attachment", "background", "mImage", "mAttachment", "Background") %>
+    <% impl_simple_image_array_property("blend_mode", "background", "mImage", "mBlendMode", "Background") %>
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="List" skip_longhands="list-style-type">
+    pub fn set_list_style_type(&mut self, v: longhands::list_style_type::computed_value::T) {
+        use nsstring::{nsACString, nsCStr};
+        use self::longhands::list_style_type::computed_value::T;
+        match v {
+            T::None => unsafe {
+                bindings::Gecko_SetCounterStyleToNone(&mut self.mCounterStyle)
+            }
+            T::CounterStyle(s) => s.to_gecko_value(&mut self.mCounterStyle),
+            T::String(s) => unsafe {
+                bindings::Gecko_SetCounterStyleToString(
+                    &mut self.mCounterStyle,
+                    &nsCStr::from(&s) as &nsACString,
+                )
+            }
+        }
+    }
+
+    pub fn copy_list_style_type_from(&mut self, other: &Self) {
+        unsafe {
+            Gecko_CopyCounterStyle(&mut self.mCounterStyle, &other.mCounterStyle);
+        }
+    }
+
+    pub fn reset_list_style_type(&mut self, other: &Self) {
+        self.copy_list_style_type_from(other)
+    }
+
+    pub fn clone_list_style_type(&self) -> longhands::list_style_type::computed_value::T {
+        use self::longhands::list_style_type::computed_value::T;
+        use crate::values::Either;
+        use crate::values::generics::CounterStyle;
+        use crate::gecko_bindings::bindings;
+
+        let name = unsafe {
+            bindings::Gecko_CounterStyle_GetName(&self.mCounterStyle)
+        };
+        if !name.is_null() {
+            let name = unsafe { Atom::from_raw(name) };
+            if name == atom!("none") {
+                return T::None;
+            }
+        }
+        let result = CounterStyle::from_gecko_value(&self.mCounterStyle);
+        match result {
+            Either::First(counter_style) => T::CounterStyle(counter_style),
+            Either::Second(string) => T::String(string),
+        }
+    }
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Table">
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Effects">
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="InheritedBox">
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="InheritedTable"
+                  skip_longhands="border-spacing">
+
+    pub fn set_border_spacing(&mut self, v: longhands::border_spacing::computed_value::T) {
+        self.mBorderSpacingCol = v.horizontal().0;
+        self.mBorderSpacingRow = v.vertical().0;
+    }
+
+    pub fn copy_border_spacing_from(&mut self, other: &Self) {
+        self.mBorderSpacingCol = other.mBorderSpacingCol;
+        self.mBorderSpacingRow = other.mBorderSpacingRow;
+    }
+
+    pub fn reset_border_spacing(&mut self, other: &Self) {
+        self.copy_border_spacing_from(other)
+    }
+
+    pub fn clone_border_spacing(&self) -> longhands::border_spacing::computed_value::T {
+        longhands::border_spacing::computed_value::T::new(
+            Au(self.mBorderSpacingCol).into(),
+            Au(self.mBorderSpacingRow).into()
+        )
+    }
+</%self:impl_trait>
+
+
+<%self:impl_trait style_struct_name="InheritedText">
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Text" skip_longhands="initial-letter">
+    pub fn set_initial_letter(&mut self, v: longhands::initial_letter::computed_value::T) {
+        use crate::values::generics::text::InitialLetter;
+        match v {
+            InitialLetter::Normal => {
+                self.mInitialLetterSize = 0.;
+                self.mInitialLetterSink = 0;
+            },
+            InitialLetter::Specified(size, sink) => {
+                self.mInitialLetterSize = size;
+                if let Some(sink) = sink {
+                    self.mInitialLetterSink = sink;
+                } else {
+                    self.mInitialLetterSink = size.floor() as i32;
+                }
+            }
+        }
+    }
+
+    pub fn copy_initial_letter_from(&mut self, other: &Self) {
+        self.mInitialLetterSize = other.mInitialLetterSize;
+        self.mInitialLetterSink = other.mInitialLetterSink;
+    }
+
+    pub fn reset_initial_letter(&mut self, other: &Self) {
+        self.copy_initial_letter_from(other)
+    }
+
+    pub fn clone_initial_letter(&self) -> longhands::initial_letter::computed_value::T {
+        use crate::values::generics::text::InitialLetter;
+
+        if self.mInitialLetterSize == 0. && self.mInitialLetterSink == 0 {
+            InitialLetter::Normal
+        } else if self.mInitialLetterSize.floor() as i32 == self.mInitialLetterSink {
+            InitialLetter::Specified(self.mInitialLetterSize, None)
+        } else {
+            InitialLetter::Specified(self.mInitialLetterSize, Some(self.mInitialLetterSink))
+        }
+    }
+</%self:impl_trait>
+
+<% skip_svg_longhands = """
+mask-mode mask-repeat mask-clip mask-origin mask-composite mask-position-x mask-position-y mask-size mask-image
+"""
+%>
+<%self:impl_trait style_struct_name="SVG"
+                  skip_longhands="${skip_svg_longhands}">
+    <% impl_common_image_layer_properties("mask") %>
+    <% impl_simple_image_array_property("mode", "mask", "mMask", "mMaskMode", "SVG") %>
+    <% impl_simple_image_array_property("composite", "mask", "mMask", "mComposite", "SVG") %>
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="InheritedSVG">
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="InheritedUI">
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Column"
+                  skip_longhands="column-count column-rule-width column-rule-style">
+
+    #[allow(unused_unsafe)]
+    pub fn set_column_count(&mut self, v: longhands::column_count::computed_value::T) {
+        use crate::gecko_bindings::structs::{nsStyleColumn_kColumnCountAuto, nsStyleColumn_kMaxColumnCount};
+
+        self.mColumnCount = match v {
+            ColumnCount::Integer(integer) => {
+                cmp::min(integer.0 as u32, unsafe { nsStyleColumn_kMaxColumnCount })
+            },
+            ColumnCount::Auto => nsStyleColumn_kColumnCountAuto
+        };
+    }
+
+    ${impl_simple_copy('column_count', 'mColumnCount')}
+
+    pub fn clone_column_count(&self) -> longhands::column_count::computed_value::T {
+        use crate::gecko_bindings::structs::{nsStyleColumn_kColumnCountAuto, nsStyleColumn_kMaxColumnCount};
+        if self.mColumnCount != nsStyleColumn_kColumnCountAuto {
+            debug_assert!(self.mColumnCount >= 1 &&
+                          self.mColumnCount <= nsStyleColumn_kMaxColumnCount);
+            ColumnCount::Integer((self.mColumnCount as i32).into())
+        } else {
+            ColumnCount::Auto
+        }
+    }
+
+    pub fn set_column_rule_style(&mut self, v: longhands::column_rule_style::computed_value::T) {
+        self.mColumnRuleStyle = v;
+        // NB: This is needed to correctly handling the initial value of
+        // column-rule-width when colun-rule-style changes, see the
+        // update_border_${side.ident} comment for more details.
+        self.mActualColumnRuleWidth = self.mColumnRuleWidth;
+    }
+
+    pub fn copy_column_rule_style_from(&mut self, other: &Self) {
+        self.set_column_rule_style(other.mColumnRuleStyle);
+    }
+
+    pub fn reset_column_rule_style(&mut self, other: &Self) {
+        self.copy_column_rule_style_from(other)
+    }
+
+    pub fn clone_column_rule_style(&self) -> longhands::column_rule_style::computed_value::T {
+        self.mColumnRuleStyle.clone()
+    }
+
+    ${impl_border_width("column_rule_width", "mActualColumnRuleWidth", "mColumnRuleWidth")}
+
+    pub fn column_rule_has_nonzero_width(&self) -> bool {
+        self.mActualColumnRuleWidth != 0
+    }
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="Counters">
+    pub fn ineffective_content_property(&self) -> bool {
+        !self.mContent.is_items()
+    }
+</%self:impl_trait>
+
+<% skip_ui_longhands = """animation-name animation-delay animation-duration
+                          animation-direction animation-fill-mode
+                          animation-play-state animation-iteration-count
+                          animation-timing-function animation-composition animation-timeline
+                          transition-duration transition-delay
+                          transition-timing-function transition-property
+                          scroll-timeline-name scroll-timeline-axis
+                          view-timeline-name view-timeline-axis view-timeline-inset""" %>
+
+<%self:impl_trait style_struct_name="UI" skip_longhands="${skip_ui_longhands}">
+    ${impl_coordinated_property('transition', 'delay', 'Delay')}
+    ${impl_coordinated_property('transition', 'duration', 'Duration')}
+    ${impl_coordinated_property('transition', 'timing_function', 'TimingFunction')}
+
+    pub fn transition_combined_duration_at(&self, index: usize) -> Time {
+        // https://drafts.csswg.org/css-transitions/#transition-combined-duration
+        Time::from_seconds(
+            self.transition_duration_at(index).seconds().max(0.0) +
+            self.transition_delay_at(index).seconds()
+        )
+    }
+
+    pub fn set_transition_property<I>(&mut self, v: I)
+    where
+        I: IntoIterator<Item = longhands::transition_property::computed_value::single_value::T>,
+        I::IntoIter: ExactSizeIterator
+    {
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_no_properties;
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_variable;
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSProperty_UNKNOWN;
+
+        let v = v.into_iter();
+
+        if v.len() != 0 {
+            self.mTransitions.ensure_len(v.len());
+            self.mTransitionPropertyCount = v.len() as u32;
+            for (servo, gecko) in v.zip(self.mTransitions.iter_mut()) {
+                unsafe { gecko.mUnknownProperty.clear() };
+
+                match servo {
+                    TransitionProperty::Unsupported(ident) => {
+                        gecko.mProperty = eCSSProperty_UNKNOWN;
+                        gecko.mUnknownProperty.mRawPtr = ident.0.into_addrefed();
+                    },
+                    TransitionProperty::Custom(name) => {
+                        gecko.mProperty = eCSSPropertyExtra_variable;
+                        gecko.mUnknownProperty.mRawPtr = name.into_addrefed();
+                    }
+                    _ => gecko.mProperty = servo.to_nscsspropertyid().unwrap(),
+                }
+            }
+        } else {
+            // In gecko |none| is represented by eCSSPropertyExtra_no_properties.
+            self.mTransitionPropertyCount = 1;
+            self.mTransitions[0].mProperty = eCSSPropertyExtra_no_properties;
+        }
+    }
+
+    /// Returns whether there are any transitions specified.
+    pub fn specifies_transitions(&self) -> bool {
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_all_properties;
+        if self.mTransitionPropertyCount == 1 &&
+            self.mTransitions[0].mProperty == eCSSPropertyExtra_all_properties &&
+            self.transition_combined_duration_at(0).seconds() <= 0.0f32 {
+            return false;
+        }
+
+        self.mTransitionPropertyCount > 0
+    }
+
+    pub fn transition_property_at(&self, index: usize)
+        -> longhands::transition_property::computed_value::SingleComputedValue {
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_no_properties;
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_variable;
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSProperty_UNKNOWN;
+
+        let property = self.mTransitions[index].mProperty;
+        if property == eCSSProperty_UNKNOWN {
+            let atom = self.mTransitions[index].mUnknownProperty.mRawPtr;
+            debug_assert!(!atom.is_null());
+            TransitionProperty::Unsupported(CustomIdent(unsafe{
+                Atom::from_raw(atom)
+            }))
+        } else if property == eCSSPropertyExtra_variable {
+            let atom = self.mTransitions[index].mUnknownProperty.mRawPtr;
+            debug_assert!(!atom.is_null());
+            TransitionProperty::Custom(unsafe{
+                Atom::from_raw(atom)
+            })
+        } else if property == eCSSPropertyExtra_no_properties {
+            // Actually, we don't expect TransitionProperty::Unsupported also
+            // represents "none", but if the caller wants to convert it, it is
+            // fine. Please use it carefully.
+            //
+            // FIXME(emilio): This is a hack, is this reachable?
+            TransitionProperty::Unsupported(CustomIdent(atom!("none")))
+        } else {
+            property.into()
+        }
+    }
+
+    pub fn transition_nscsspropertyid_at(&self, index: usize) -> nsCSSPropertyID {
+        self.mTransitions[index].mProperty
+    }
+
+    pub fn copy_transition_property_from(&mut self, other: &Self) {
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSPropertyExtra_variable;
+        use crate::gecko_bindings::structs::nsCSSPropertyID::eCSSProperty_UNKNOWN;
+        self.mTransitions.ensure_len(other.mTransitions.len());
+
+        let count = other.mTransitionPropertyCount;
+        self.mTransitionPropertyCount = count;
+
+        for (index, transition) in self.mTransitions.iter_mut().enumerate().take(count as usize) {
+            transition.mProperty = other.mTransitions[index].mProperty;
+            unsafe { transition.mUnknownProperty.clear() };
+            if transition.mProperty == eCSSProperty_UNKNOWN ||
+               transition.mProperty == eCSSPropertyExtra_variable {
+                let atom = other.mTransitions[index].mUnknownProperty.mRawPtr;
+                debug_assert!(!atom.is_null());
+                transition.mUnknownProperty.mRawPtr = unsafe { Atom::from_raw(atom) }.into_addrefed();
+            }
+        }
+    }
+
+    pub fn reset_transition_property(&mut self, other: &Self) {
+        self.copy_transition_property_from(other)
+    }
+
+    ${impl_coordinated_property_count('transition', 'property', 'Property')}
+
+    pub fn animations_equals(&self, other: &Self) -> bool {
+        return self.mAnimationNameCount == other.mAnimationNameCount
+            && self.mAnimationDelayCount == other.mAnimationDelayCount
+            && self.mAnimationDirectionCount == other.mAnimationDirectionCount
+            && self.mAnimationDurationCount == other.mAnimationDurationCount
+            && self.mAnimationFillModeCount == other.mAnimationFillModeCount
+            && self.mAnimationIterationCountCount == other.mAnimationIterationCountCount
+            && self.mAnimationPlayStateCount == other.mAnimationPlayStateCount
+            && self.mAnimationTimingFunctionCount == other.mAnimationTimingFunctionCount
+            && self.mAnimationCompositionCount == other.mAnimationCompositionCount
+            && self.mAnimationTimelineCount == other.mAnimationTimelineCount
+            && unsafe { bindings::Gecko_StyleAnimationsEquals(&self.mAnimations, &other.mAnimations) }
+    }
+
+    pub fn set_animation_name<I>(&mut self, v: I)
+    where
+        I: IntoIterator<Item = longhands::animation_name::computed_value::single_value::T>,
+        I::IntoIter: ExactSizeIterator
+    {
+        let v = v.into_iter();
+        debug_assert_ne!(v.len(), 0);
+        self.mAnimations.ensure_len(v.len());
+
+        self.mAnimationNameCount = v.len() as u32;
+        for (servo, gecko) in v.zip(self.mAnimations.iter_mut()) {
+            let atom = servo.0.as_atom().clone();
+            unsafe { bindings::Gecko_SetAnimationName(gecko, atom.into_addrefed()); }
+        }
+    }
+    pub fn animation_name_at(&self, index: usize)
+        -> longhands::animation_name::computed_value::SingleComputedValue {
+        use crate::properties::longhands::animation_name::single_value::SpecifiedValue as AnimationName;
+
+        let atom = self.mAnimations[index].mName.mRawPtr;
+        AnimationName(KeyframesName::from_atom(unsafe { Atom::from_raw(atom) }))
+    }
+    pub fn copy_animation_name_from(&mut self, other: &Self) {
+        self.mAnimationNameCount = other.mAnimationNameCount;
+        unsafe { bindings::Gecko_CopyAnimationNames(&mut self.mAnimations, &other.mAnimations); }
+    }
+
+    pub fn reset_animation_name(&mut self, other: &Self) {
+        self.copy_animation_name_from(other)
+    }
+
+    ${impl_coordinated_property_count('animation', 'name', 'Name')}
+    ${impl_coordinated_property('animation', 'delay', 'Delay')}
+    ${impl_coordinated_property('animation', 'duration', 'Duration')}
+    ${impl_animation_keyword('direction', 'Direction',
+                             data.longhands_by_name["animation-direction"].keyword)}
+    ${impl_animation_keyword('fill_mode', 'FillMode',
+                             data.longhands_by_name["animation-fill-mode"].keyword)}
+    ${impl_animation_keyword('play_state', 'PlayState',
+                             data.longhands_by_name["animation-play-state"].keyword)}
+    ${impl_animation_keyword('composition', 'Composition',
+                             data.longhands_by_name["animation-composition"].keyword)}
+    ${impl_coordinated_property('animation', 'iteration_count', 'IterationCount')}
+    ${impl_coordinated_property('animation', 'timeline', 'Timeline')}
+    ${impl_coordinated_property('animation', 'timing_function', 'TimingFunction')}
+
+    ${impl_coordinated_property('scroll_timeline', 'name', 'Name')}
+    ${impl_coordinated_property('scroll_timeline', 'axis', 'Axis')}
+
+    pub fn scroll_timelines_equals(&self, other: &Self) -> bool {
+        self.mScrollTimelineNameCount == other.mScrollTimelineNameCount
+            && self.mScrollTimelineAxisCount == other.mScrollTimelineAxisCount
+            && unsafe {
+                bindings::Gecko_StyleScrollTimelinesEquals(
+                    &self.mScrollTimelines,
+                    &other.mScrollTimelines,
+                )
+            }
+    }
+
+    ${impl_coordinated_property('view_timeline', 'name', 'Name')}
+    ${impl_coordinated_property('view_timeline', 'axis', 'Axis')}
+    ${impl_coordinated_property('view_timeline', 'inset', 'Inset')}
+
+    pub fn view_timelines_equals(&self, other: &Self) -> bool {
+        self.mViewTimelineNameCount == other.mViewTimelineNameCount
+            && self.mViewTimelineAxisCount == other.mViewTimelineAxisCount
+            && self.mViewTimelineInsetCount == other.mViewTimelineInsetCount
+            && unsafe {
+                bindings::Gecko_StyleViewTimelinesEquals(
+                    &self.mViewTimelines,
+                    &other.mViewTimelines,
+                )
+            }
+    }
+</%self:impl_trait>
+
+<%self:impl_trait style_struct_name="XUL">
+</%self:impl_trait>
+
+% for style_struct in data.style_structs:
+${impl_style_struct(style_struct)}
+% endfor
+
+/// Assert that the initial values set in Gecko style struct constructors
+/// match the values returned by `get_initial_value()` for each longhand.
+#[cfg(feature = "gecko")]
+#[inline]
+pub fn assert_initial_values_match(data: &PerDocumentStyleData) {
+    if cfg!(debug_assertions) {
+        let data = data.borrow();
+        let cv = data.stylist.device().default_computed_values();
+        <%
+            # Skip properties with initial values that change at computed
+            # value time, or whose initial value depends on the document
+            # / other prefs.
+            SKIPPED = [
+                "border-top-width",
+                "border-bottom-width",
+                "border-left-width",
+                "border-right-width",
+                "column-rule-width",
+                "font-family",
+                "font-size",
+                "outline-width",
+                "color",
+            ]
+            TO_TEST = [p for p in data.longhands if p.enabled_in != "" and not p.logical and not p.name in SKIPPED]
+        %>
+        % for property in TO_TEST:
+        assert_eq!(
+            cv.clone_${property.ident}(),
+            longhands::${property.ident}::get_initial_value(),
+            concat!(
+                "initial value in Gecko style struct for ",
+                stringify!(${property.ident}),
+                " must match longhands::",
+                stringify!(${property.ident}),
+                "::get_initial_value()"
+            )
+        );
+        % endfor
+    }
+}