helpers.mako.rs

/* 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/. */

<%!
    from data import Keyword, to_rust_ident, to_camel_case
    from data import LOGICAL_SIDES, PHYSICAL_SIDES, LOGICAL_SIZES, SYSTEM_FONT_LONGHANDS
%>

<%def name="predefined_type(name, type, initial_value, parse_method='parse',
            needs_context=True, vector=False, initial_specified_value=None, **kwargs)">
    <%def name="predefined_type_inner(name, type, initial_value, parse_method)">
        #[allow(unused_imports)]
        use app_units::Au;
        use cssparser::{Color as CSSParserColor, RGBA};
        pub use values::specified::${type} as SpecifiedValue;
        pub mod computed_value {
            pub use values::computed::${type} as T;
        }
        #[inline] pub fn get_initial_value() -> computed_value::T { ${initial_value} }
        % if initial_specified_value:
        #[inline] pub fn get_initial_specified_value() -> SpecifiedValue { ${initial_specified_value} }
        % endif
        #[allow(unused_variables)]
        #[inline]
        pub fn parse(context: &ParserContext,
                     input: &mut Parser)
                     -> Result<SpecifiedValue, ()> {
            % if needs_context:
            specified::${type}::${parse_method}(context, input)
            % else:
            specified::${type}::${parse_method}(input)
            % endif
        }
    </%def>
    % if vector:
        <%call expr="vector_longhand(name, predefined_type=type, **kwargs)">
            ${predefined_type_inner(name, type, initial_value, parse_method)}
        </%call>
    % else:
        <%call expr="longhand(name, predefined_type=type, **kwargs)">
            ${predefined_type_inner(name, type, initial_value, parse_method)}
        </%call>
    % endif
</%def>

// FIXME (Manishearth): Add computed_value_as_specified argument
// and handle the empty case correctly
<%doc>
    To be used in cases where we have a grammar like
    "<thing> [ , <thing> ]*". `gecko_only` should be set
    to True for cases where Servo takes a single value
    and Stylo supports vector values.

    Setting allow_empty to False allows for cases where the vector
    is empty. The grammar for these is usually "none | <thing> [ , <thing> ]*".
    We assume that the default/initial value is an empty vector for these.
    `initial_value` need not be defined for these.
</%doc>
<%def name="vector_longhand(name, gecko_only=False, allow_empty=False,
            delegate_animate=False, space_separated_allowed=False, **kwargs)">
    <%call expr="longhand(name, **kwargs)">
        % if not gecko_only:
            use std::fmt;
            use values::HasViewportPercentage;
            use style_traits::ToCss;

            impl HasViewportPercentage for SpecifiedValue {
                fn has_viewport_percentage(&self) -> bool {
                    let &SpecifiedValue(ref vec) = self;
                    vec.iter().any(|ref x| x.has_viewport_percentage())
                }
            }

            pub mod single_value {
                use cssparser::Parser;
                use parser::{Parse, ParserContext};
                use properties::ShorthandId;
                use values::computed::{Context, ToComputedValue};
                use values::{computed, specified};
                use values::{Auto, Either, None_, Normal};
                ${caller.body()}
            }

            /// The definition of the computed value for ${name}.
            pub mod computed_value {
                pub use super::single_value::computed_value as single_value;
                pub use self::single_value::T as SingleComputedValue;
                /// The computed value, effectively a list of single values.
                #[derive(Debug, Clone, PartialEq)]
                #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
                pub struct T(pub Vec<single_value::T>);

                % if delegate_animate:
                    use properties::animated_properties::Interpolate;
                    impl Interpolate for T {
                        fn interpolate(&self, other: &Self, progress: f64) -> Result<Self, ()> {
                            self.0.interpolate(&other.0, progress).map(T)
                        }
                    }
                % endif
            }

            impl ToCss for computed_value::T {
                fn to_css<W>(&self, dest: &mut W) -> fmt::Result
                    where W: fmt::Write,
                {
                    let mut iter = self.0.iter();
                    if let Some(val) = iter.next() {
                        try!(val.to_css(dest));
                    } else {
                        % if allow_empty:
                            try!(dest.write_str("none"));
                        % else:
                            warn!("Found empty value for property ${name}");
                        % endif
                    }
                    for i in iter {
                        try!(dest.write_str(", "));
                        try!(i.to_css(dest));
                    }
                    Ok(())
                }
            }

            /// The specified value of ${name}.
            #[derive(Debug, Clone, PartialEq)]
            #[cfg_attr(feature = "servo", derive(HeapSizeOf))]
            pub struct SpecifiedValue(pub Vec<single_value::SpecifiedValue>);

            impl ToCss for SpecifiedValue {
                fn to_css<W>(&self, dest: &mut W) -> fmt::Result
                    where W: fmt::Write,
                {
                    let mut iter = self.0.iter();
                    if let Some(val) = iter.next() {
                        try!(val.to_css(dest));
                    } else {
                        % if allow_empty:
                            try!(dest.write_str("none"));
                        % else:
                            warn!("Found empty value for property ${name}");
                        % endif
                    }
                    for i in iter {
                        try!(dest.write_str(", "));
                        try!(i.to_css(dest));
                    }
                    Ok(())
                }
            }

            pub fn get_initial_value() -> computed_value::T {
                % if allow_empty:
                    computed_value::T(vec![])
                % else:
                    computed_value::T(vec![single_value::get_initial_value()])
                % endif
            }

            pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
                use parser::parse_space_or_comma_separated;

                <%
                    parse_func = "Parser::parse_comma_separated"
                    if space_separated_allowed:
                        parse_func = "parse_space_or_comma_separated"
                %>
                % if allow_empty:
                    if input.try(|input| input.expect_ident_matching("none")).is_ok() {
                        Ok(SpecifiedValue(Vec::new()))
                    } else {
                        ${parse_func}(input, |parser| {
                            single_value::parse(context, parser)
                        }).map(SpecifiedValue)
                    }
                % else:
                    ${parse_func}(input, |parser| {
                        single_value::parse(context, parser)
                    }).map(SpecifiedValue)
                % endif
            }

            pub use self::single_value::SpecifiedValue as SingleSpecifiedValue;

            impl ToComputedValue for SpecifiedValue {
                type ComputedValue = computed_value::T;

                #[inline]
                fn to_computed_value(&self, context: &Context) -> computed_value::T {
                    computed_value::T(self.0.iter().map(|x| x.to_computed_value(context)).collect())
                }
                #[inline]
                fn from_computed_value(computed: &computed_value::T) -> Self {
                    SpecifiedValue(computed.0.iter()
                                       .map(|x| ToComputedValue::from_computed_value(x))
                                       .collect())
                }
            }
        % else:
            ${caller.body()}
        % endif
    </%call>
</%def>
<%def name="longhand(*args, **kwargs)">
    <%
        property = data.declare_longhand(*args, **kwargs)
        if property is None:
            return ""
    %>
    /// ${property.spec}
    pub mod ${property.ident} {
        #![allow(unused_imports)]
        % if not property.derived_from:
            use cssparser::Parser;
            use parser::{Parse, ParserContext};
            use properties::{UnparsedValue, ShorthandId};
        % endif
        use values::{Auto, Either, None_, Normal};
        use cascade_info::CascadeInfo;
        use error_reporting::ParseErrorReporter;
        use properties::longhands;
        use properties::{DeclaredValue, LonghandId, LonghandIdSet};
        use properties::{CSSWideKeyword, ComputedValues, PropertyDeclaration};
        use properties::style_structs;
        use std::sync::Arc;
        use values::computed::{Context, ToComputedValue};
        use values::{computed, specified};
        use Atom;
        ${caller.body()}
        #[allow(unused_variables)]
        pub fn cascade_property(declaration: &PropertyDeclaration,
                                inherited_style: &ComputedValues,
                                default_style: &ComputedValues,
                                context: &mut computed::Context,
                                cacheable: &mut bool,
                                cascade_info: &mut Option<<&mut CascadeInfo>,
                                error_reporter: &ParseErrorReporter) {
            let declared_value = match *declaration {
                PropertyDeclaration::${property.camel_case}(ref value) => {
                    DeclaredValue::Value(value)
                },
                PropertyDeclaration::CSSWideKeyword(id, value) => {
                    debug_assert!(id == LonghandId::${property.camel_case});
                    DeclaredValue::CSSWideKeyword(value)
                },
                PropertyDeclaration::WithVariables(id, ref value) => {
                    debug_assert!(id == LonghandId::${property.camel_case});
                    DeclaredValue::WithVariables(value)
                },
                _ => panic!("entered the wrong cascade_property() implementation"),
            };

            % if not property.derived_from:
                {
                    let custom_props = context.style().custom_properties();
                    ::properties::substitute_variables_${property.ident}(
                        &declared_value, &custom_props,
                    |value| {
                        if let Some(ref mut cascade_info) = *cascade_info {
                            cascade_info.on_cascade_property(&declaration,
                                                             &value);
                        }
                        % if property.logical:
                            let wm = context.style.writing_mode;
                        % endif
                        <% maybe_wm = ", wm" if property.logical else "" %>
                        match *value {
                            DeclaredValue::Value(ref specified_value) => {
                                % if property.ident in SYSTEM_FONT_LONGHANDS and product == "gecko":
                                    if let Some(sf) = specified_value.get_system() {
                                        longhands::system_font::resolve_system_font(sf, context);
                                    }
                                % endif
                                let computed = specified_value.to_computed_value(context);
                                % if property.ident == "font_size":
                                    if let longhands::font_size::SpecifiedValue::Keyword(kw, fraction)
                                                        = **specified_value {
                                        context.mutate_style().font_size_keyword = Some((kw, fraction));
                                    } else if let Some(ratio) = specified_value.as_font_ratio() {
                                        // In case a font-size-relative value was applied to a keyword
                                        // value, we must preserve this fact in case the generic font family
                                        // changes. relative values (em and %) applied to keywords must be
                                        // recomputed from the base size for the keyword and the relative size.
                                        //
                                        // See bug 1355707
                                        if let Some((kw, fraction)) = context.inherited_style().font_size_keyword {
                                            context.mutate_style().font_size_keyword = Some((kw, fraction * ratio));
                                        } else {
                                            context.mutate_style().font_size_keyword = None;
                                        }
                                    } else {
                                        context.mutate_style().font_size_keyword = None;
                                    }
                                % endif
                                % if property.has_uncacheable_values:
                                context.mutate_style().mutate_${data.current_style_struct.name_lower}()
                                                      .set_${property.ident}(computed, cacheable ${maybe_wm});
                                % else:
                                context.mutate_style().mutate_${data.current_style_struct.name_lower}()
                                                      .set_${property.ident}(computed ${maybe_wm});
                                % endif
                            }
                            DeclaredValue::WithVariables(_) => unreachable!(),
                            DeclaredValue::CSSWideKeyword(keyword) => match keyword {
                                % if not data.current_style_struct.inherited:
                                CSSWideKeyword::Unset |
                                % endif
                                CSSWideKeyword::Initial => {
                                    % if property.ident == "font_size":
                                        // font-size's default ("medium") does not always
                                        // compute to the same value and depends on the font
                                        let computed = longhands::font_size::get_initial_specified_value()
                                                            .to_computed_value(context);
                                        context.mutate_style().mutate_${data.current_style_struct.name_lower}()
                                               .set_font_size(computed);
                                        context.mutate_style().font_size_keyword = Some((Default::default(), 1.));
                                    % else:
                                        // We assume that it's faster to use copy_*_from rather than
                                        // set_*(get_initial_value());
                                        let initial_struct = default_style
                                                            .get_${data.current_style_struct.name_lower}();
                                        context.mutate_style().mutate_${data.current_style_struct.name_lower}()
                                                            .copy_${property.ident}_from(initial_struct ${maybe_wm});
                                    % endif
                                },
                                % if data.current_style_struct.inherited:
                                CSSWideKeyword::Unset |
                                % endif
                                CSSWideKeyword::Inherit => {
                                    // This is a bit slow, but this is rare so it shouldn't
                                    // matter.
                                    //
                                    // FIXME: is it still?
                                    *cacheable = false;
                                    let inherited_struct =
                                        inherited_style.get_${data.current_style_struct.name_lower}();
                                    context.mutate_style().mutate_${data.current_style_struct.name_lower}()
                                        .copy_${property.ident}_from(inherited_struct ${maybe_wm});
                                    % if property.ident == "font_size":
                                        context.mutate_style().font_size_keyword =
                                            context.inherited_style.font_size_keyword;
                                    % endif
                                }
                            }
                        }
                    }, error_reporter);
                }

                % if property.custom_cascade:
                    cascade_property_custom(declaration,
                                            inherited_style,
                                            context,
                                            cacheable,
                                            error_reporter);
                % endif
            % else:
                // Do not allow stylesheets to set derived properties.
            % endif
        }
        % if not property.derived_from:
            pub fn parse_specified(context: &ParserContext, input: &mut Parser)
                % if property.boxed:
                                   -> Result<Box<SpecifiedValue>, ()> {
                    parse(context, input).map(|result| Box::new(result))
                % else:
                                   -> Result<SpecifiedValue, ()> {
                    parse(context, input)
                % endif
            }
            pub fn parse_declared(context: &ParserContext, input: &mut Parser)
                                  -> Result<PropertyDeclaration, ()> {
                match input.try(|i| CSSWideKeyword::parse(context, i)) {
                    Ok(keyword) => Ok(PropertyDeclaration::CSSWideKeyword(LonghandId::${property.camel_case}, keyword)),
                    Err(()) => {
                        input.look_for_var_functions();
                        let start = input.position();
                        let specified = parse_specified(context, input);
                        if specified.is_err() {
                            while let Ok(_) = input.next() {}  // Look for var() after the error.
                        }
                        let var = input.seen_var_functions();
                        if specified.is_err() && var {
                            input.reset(start);
                            let (first_token_type, css) = try!(
                                ::custom_properties::parse_non_custom_with_var(input));
                            return Ok(PropertyDeclaration::WithVariables(LonghandId::${property.camel_case},
                                                                         Arc::new(UnparsedValue {
                                css: css.into_owned(),
                                first_token_type: first_token_type,
                                url_data: context.url_data.clone(),
                                from_shorthand: None,
                            })))
                        }
                        specified.map(|s| PropertyDeclaration::${property.camel_case}(s))
                    }
                }
            }
        % endif
    }
</%def>

<%def name="single_keyword_system(name, values, **kwargs)">
    <%
        keyword_kwargs = {a: kwargs.pop(a, None) for a in [
            'gecko_constant_prefix', 'gecko_enum_prefix',
            'extra_gecko_values', 'extra_servo_values',
            'custom_consts', 'gecko_inexhaustive',
        ]}
        keyword = keyword=Keyword(name, values, **keyword_kwargs)
    %>
    <%call expr="longhand(name, keyword=Keyword(name, values, **keyword_kwargs), **kwargs)">
        use values::HasViewportPercentage;
        use properties::longhands::system_font::SystemFont;
        use std::fmt;
        use style_traits::ToCss;
        no_viewport_percentage!(SpecifiedValue);

        pub mod computed_value {
            use cssparser::Parser;
            use parser::{Parse, ParserContext};

            use style_traits::ToCss;
            define_css_keyword_enum! { T:
                % for value in keyword.values_for(product):
                    "${value}" => ${to_rust_ident(value)},
                % endfor
            }

            impl Parse for T {
                fn parse(_: &ParserContext, input: &mut Parser) -> Result<Self, ()> {
                    T::parse(input)
                }
            }

            ${gecko_keyword_conversion(keyword, keyword.values_for(product), type="T", cast_to="i32")}
        }

        #[derive(Debug, Clone, PartialEq, Eq, Copy)]
        pub enum SpecifiedValue {
            Keyword(computed_value::T),
            System(SystemFont),
        }

        impl ToCss for SpecifiedValue {
            fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
                match *self {
                    SpecifiedValue::Keyword(k) => k.to_css(dest),
                    SpecifiedValue::System(_) => Ok(())
                }
            }
        }

        pub fn parse(_: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
            Ok(SpecifiedValue::Keyword(computed_value::T::parse(input)?))
        }

        impl ToComputedValue for SpecifiedValue {
            type ComputedValue = computed_value::T;
            fn to_computed_value(&self, _cx: &Context) -> Self::ComputedValue {
                match *self {
                    SpecifiedValue::Keyword(v) => v,
                    SpecifiedValue::System(_) => {
                        % if product == "gecko":
                            _cx.style.cached_system_font.as_ref().unwrap().${to_rust_ident(name)}
                        % else:
                            unreachable!()
                        % endif
                    }
                }
            }
            fn from_computed_value(other: &computed_value::T) -> Self {
                SpecifiedValue::Keyword(*other)
            }
        }

        impl From<computed_value::T> for SpecifiedValue {
            fn from(other: computed_value::T) -> Self {
                SpecifiedValue::Keyword(other)
            }
        }

        #[inline]
        pub fn get_initial_value() -> computed_value::T {
            computed_value::T::${to_rust_ident(values.split()[0])}
        }
        #[inline]
        pub fn get_initial_specified_value() -> SpecifiedValue {
            SpecifiedValue::Keyword(computed_value::T::${to_rust_ident(values.split()[0])})
        }

        impl SpecifiedValue {
            pub fn system_font(f: SystemFont) -> Self {
                SpecifiedValue::System(f)
            }
            pub fn get_system(&self) -> Option<SystemFont> {
                if let SpecifiedValue::System(s) = *self {
                    Some(s)
                } else {
                    None
                }
            }
        }
    </%call>
</%def>

<%def name="single_keyword(name, values, vector=False, **kwargs)">
    <%call expr="single_keyword_computed(name, values, vector, **kwargs)">
        % if not "extra_specified" in kwargs and ("aliases" in kwargs or (("extra_%s_aliases" % product) in kwargs)):
            impl ToComputedValue for SpecifiedValue {
                type ComputedValue = computed_value::T;

                #[inline]
                fn to_computed_value(&self, _context: &Context) -> computed_value::T {
                    match *self {
                        % for value in data.longhands_by_name[name].keyword.values_for(product):
                            SpecifiedValue::${to_rust_ident(value)} => computed_value::T::${to_rust_ident(value)},
                        % endfor
                    }
                }
                #[inline]
                fn from_computed_value(computed: &computed_value::T) -> Self {
                    match *computed {
                        % for value in data.longhands_by_name[name].keyword.values_for(product):
                            computed_value::T::${to_rust_ident(value)} => SpecifiedValue::${to_rust_ident(value)},
                        % endfor
                    }
                }
            }
        % else:
            use values::computed::ComputedValueAsSpecified;
            impl ComputedValueAsSpecified for SpecifiedValue {}
        % endif

        use values::HasViewportPercentage;
        no_viewport_percentage!(SpecifiedValue);
    </%call>
</%def>

<%def name="gecko_keyword_conversion(keyword, values=None, type='SpecifiedValue', cast_to=None)">
    <%
        if not values:
            values = keyword.values_for(product)
        maybe_cast = "as %s" % cast_to if cast_to else ""
        const_type = cast_to if cast_to else "u32"
    %>
    #[cfg(feature = "gecko")]
    impl ${type} {
        /// Obtain a specified value from a Gecko keyword value
        ///
        /// Intended for use with presentation attributes, not style structs
        pub fn from_gecko_keyword(kw: u32) -> Self {
            use gecko_bindings::structs;
            % for value in values:
                // We can't match on enum values if we're matching on a u32
                const ${to_rust_ident(value).upper()}: ${const_type}
                    = structs::${keyword.gecko_constant(value)} as ${const_type};
            % endfor
            match kw ${maybe_cast} {
                % for value in values:
                    ${to_rust_ident(value).upper()} => ${type}::${to_rust_ident(value)},
                % endfor
                x => panic!("Found unexpected value in style struct for ${keyword.name} property: {:?}", x),
            }
        }
    }
</%def>

<%def name="gecko_bitflags_conversion(bit_map, gecko_bit_prefix, type, kw_type='u8')">
    #[cfg(feature = "gecko")]
    impl ${type} {
        /// Obtain a specified value from a Gecko keyword value
        ///
        /// Intended for use with presentation attributes, not style structs
        pub fn from_gecko_keyword(kw: ${kw_type}) -> Self {
            % for gecko_bit in bit_map.values():
            use gecko_bindings::structs::${gecko_bit_prefix}${gecko_bit};
            % endfor

            let mut bits = ${type}::empty();
            % for servo_bit, gecko_bit in bit_map.iteritems():
                if kw & (${gecko_bit_prefix}${gecko_bit} as ${kw_type}) != 0 {
                    bits |= ${servo_bit};
                }
            % endfor
            bits
        }

        pub fn to_gecko_keyword(self) -> ${kw_type} {
            % for gecko_bit in bit_map.values():
            use gecko_bindings::structs::${gecko_bit_prefix}${gecko_bit};
            % endfor

            let mut bits: ${kw_type} = 0;
            // FIXME: if we ensure that the Servo bitflags storage is the same
            // as Gecko's one, we can just copy it.
            % for servo_bit, gecko_bit in bit_map.iteritems():
                if self.contains(${servo_bit}) {
                    bits |= ${gecko_bit_prefix}${gecko_bit} as ${kw_type};
                }
            % endfor
            bits
        }
    }
</%def>

<%def name="single_keyword_computed(name, values, vector=False,
            extra_specified=None, needs_conversion=False, **kwargs)">
    <%
        keyword_kwargs = {a: kwargs.pop(a, None) for a in [
            'gecko_constant_prefix', 'gecko_enum_prefix',
            'extra_gecko_values', 'extra_servo_values',
            'aliases', 'extra_gecko_aliases', 'extra_servo_aliases',
            'custom_consts', 'gecko_inexhaustive',
        ]}
    %>

    <%def name="inner_body(keyword, extra_specified=None, needs_conversion=False)">
        % if extra_specified or keyword.aliases_for(product):
            use style_traits::ToCss;
            define_css_keyword_enum! { SpecifiedValue:
                values {
                    % for value in keyword.values_for(product) + (extra_specified or "").split():
                        "${value}" => ${to_rust_ident(value)},
                    % endfor
                }
                aliases {
                    % for alias, value in keyword.aliases_for(product).iteritems():
                        "${alias}" => ${to_rust_ident(value)},
                    % endfor
                }
            }
        % else:
            pub use self::computed_value::T as SpecifiedValue;
        % endif
        pub mod computed_value {
            use style_traits::ToCss;
            define_css_keyword_enum! { T:
                % for value in data.longhands_by_name[name].keyword.values_for(product):
                    "${value}" => ${to_rust_ident(value)},
                % endfor
            }
        }
        #[inline]
        pub fn get_initial_value() -> computed_value::T {
            computed_value::T::${to_rust_ident(values.split()[0])}
        }
        #[inline]
        pub fn get_initial_specified_value() -> SpecifiedValue {
            SpecifiedValue::${to_rust_ident(values.split()[0])}
        }
        #[inline]
        pub fn parse(_context: &ParserContext, input: &mut Parser)
                     -> Result<SpecifiedValue, ()> {
            SpecifiedValue::parse(input)
        }
        impl Parse for SpecifiedValue {
            #[inline]
            fn parse(_context: &ParserContext, input: &mut Parser)
                         -> Result<SpecifiedValue, ()> {
                SpecifiedValue::parse(input)
            }
        }

        % if needs_conversion:
            <%
                conversion_values = keyword.values_for(product)
                if extra_specified:
                    conversion_values += extra_specified.split()
                conversion_values += keyword.aliases_for(product).keys()
            %>
            ${gecko_keyword_conversion(keyword, values=conversion_values)}
        % endif
    </%def>
    % if vector:
        <%call expr="vector_longhand(name, keyword=Keyword(name, values, **keyword_kwargs), **kwargs)">
            ${inner_body(Keyword(name, values, **keyword_kwargs))}
            ${caller.body()}
        </%call>
    % else:
        <%call expr="longhand(name, keyword=Keyword(name, values, **keyword_kwargs), **kwargs)">
            ${inner_body(Keyword(name, values, **keyword_kwargs),
                         extra_specified=extra_specified, needs_conversion=needs_conversion)}
            ${caller.body()}
        </%call>
    % endif
</%def>

<%def name="shorthand(name, sub_properties, experimental=False, **kwargs)">
<%
    shorthand = data.declare_shorthand(name, sub_properties.split(), experimental=experimental,
                                       **kwargs)
%>
    % if shorthand:
    /// ${shorthand.spec}
    pub mod ${shorthand.ident} {
        #[allow(unused_imports)]
        use cssparser::Parser;
        use parser::ParserContext;
        use properties::{PropertyDeclaration, ParsedDeclaration};
        use properties::{ShorthandId, UnparsedValue, longhands};
        use std::fmt;
        use std::sync::Arc;
        use style_traits::ToCss;

        pub struct Longhands {
            % for sub_property in shorthand.sub_properties:
                pub ${sub_property.ident}: longhands::${sub_property.ident}::SpecifiedValue,
            % endfor
        }

        /// Represents a serializable set of all of the longhand properties that
        /// correspond to a shorthand.
        pub struct LonghandsToSerialize<'a> {
            % for sub_property in shorthand.sub_properties:
                pub ${sub_property.ident}:
                    &'a longhands::${sub_property.ident}::SpecifiedValue,
            % endfor
        }

        impl<'a> LonghandsToSerialize<'a> {
            /// Tries to get a serializable set of longhands given a set of
            /// property declarations.
            pub fn from_iter<I>(iter: I) -> Result<Self, ()>
                where I: Iterator<Item=&'a PropertyDeclaration>,
            {
                // Define all of the expected variables that correspond to the shorthand
                % for sub_property in shorthand.sub_properties:
                    let mut ${sub_property.ident} = None;
                % endfor

                // Attempt to assign the incoming declarations to the expected variables
                for longhand in iter {
                    match *longhand {
                        % for sub_property in shorthand.sub_properties:
                            PropertyDeclaration::${sub_property.camel_case}(ref value) => {
                                ${sub_property.ident} = Some(value)
                            },
                        % endfor
                        _ => {}
                    };
                }

                // If any of the expected variables are missing, return an error
                match (
                    % for sub_property in shorthand.sub_properties:
                        ${sub_property.ident},
                    % endfor
                ) {

                    (
                    % for sub_property in shorthand.sub_properties:
                        Some(${sub_property.ident}),
                    % endfor
                    ) =>
                    Ok(LonghandsToSerialize {
                        % for sub_property in shorthand.sub_properties:
                            ${sub_property.ident}: ${sub_property.ident},
                        % endfor
                    }),
                    _ => Err(())
                }
            }
        }

        /// Parse the given shorthand and fill the result into the
        /// `declarations` vector.
        pub fn parse(context: &ParserContext, input: &mut Parser) -> Result<ParsedDeclaration, ()> {
            input.look_for_var_functions();
            let start = input.position();
            let value = input.parse_entirely(|input| parse_value(context, input));
            if value.is_err() {
                while let Ok(_) = input.next() {}  // Look for var() after the error.
            }
            let var = input.seen_var_functions();
            if let Ok(value) = value {
                Ok(ParsedDeclaration::${shorthand.camel_case}(value))
            } else if var {
                input.reset(start);
                let (first_token_type, css) = try!(
                    ::custom_properties::parse_non_custom_with_var(input));
                Ok(ParsedDeclaration::${shorthand.camel_case}WithVariables(Arc::new(UnparsedValue {
                    css: css.into_owned(),
                    first_token_type: first_token_type,
                    url_data: context.url_data.clone(),
                    from_shorthand: Some(ShorthandId::${shorthand.camel_case}),
                })))
            } else {
                Err(())
            }
        }

        ${caller.body()}
    }
    % endif
</%def>

<%def name="four_sides_shorthand(name, sub_property_pattern, parser_function, needs_context=True, **kwargs)">
    <% sub_properties=' '.join(sub_property_pattern % side for side in ['top', 'right', 'bottom', 'left']) %>
    <%call expr="self.shorthand(name, sub_properties=sub_properties, **kwargs)">
        #[allow(unused_imports)]
        use parser::Parse;
        use super::parse_four_sides;
        use values::specified;

        pub fn parse_value(context: &ParserContext, input: &mut Parser) -> Result<Longhands, ()> {
            let (top, right, bottom, left) =
            % if needs_context:
                try!(parse_four_sides(input, |i| ${parser_function}(context, i)));
            % else:
                try!(parse_four_sides(input, ${parser_function}));
                let _unused = context;
            % endif
            Ok(Longhands {
                % for side in ["top", "right", "bottom", "left"]:
                    ${to_rust_ident(sub_property_pattern % side)}: ${side},
                % endfor
            })
        }

        impl<'a> ToCss for LonghandsToSerialize<'a> {
            fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
                super::serialize_four_sides(
                    dest,
                    self.${to_rust_ident(sub_property_pattern % 'top')},
                    self.${to_rust_ident(sub_property_pattern % 'right')},
                    self.${to_rust_ident(sub_property_pattern % 'bottom')},
                    self.${to_rust_ident(sub_property_pattern % 'left')}
                )
            }
        }
    </%call>
</%def>

<%def name="logical_setter_helper(name)">
    <%
        side = None
        size = None
        maybe_side = [s for s in LOGICAL_SIDES if s in name]
        maybe_size = [s for s in LOGICAL_SIZES if s in name]
        if len(maybe_side) == 1:
            side = maybe_side[0]
        elif len(maybe_size) == 1:
            size = maybe_size[0]
        def phys_ident(side, phy_side):
            return to_rust_ident(name.replace(side, phy_side).replace("offset-", ""))
    %>
    % if side is not None:
        use logical_geometry::PhysicalSide;
        match wm.${to_rust_ident(side)}_physical_side() {
            % for phy_side in PHYSICAL_SIDES:
                PhysicalSide::${phy_side.title()} => {
                    ${caller.inner(physical_ident=phys_ident(side, phy_side))}
                }
            % endfor
        }
    % elif size is not None:
        <%
            # (horizontal, vertical)
            physical_size = ("height", "width")
            if size == "inline-size":
                physical_size = ("width", "height")
        %>
        if wm.is_vertical() {
            ${caller.inner(physical_ident=phys_ident(size, physical_size[1]))}
        } else {
            ${caller.inner(physical_ident=phys_ident(size, physical_size[0]))}
        }
    % else:
        <% raise Exception("Don't know what to do with logical property %s" % name) %>
    % endif
</%def>

<%def name="logical_setter(name, need_clone=False)">
    /// Set the appropriate physical property for ${name} given a writing mode.
    pub fn set_${to_rust_ident(name)}(&mut self,
                                      v: longhands::${to_rust_ident(name)}::computed_value::T,
                                      wm: WritingMode) {
        <%self:logical_setter_helper name="${name}">
            <%def name="inner(physical_ident)">
                self.set_${physical_ident}(v)
            </%def>
        </%self:logical_setter_helper>
    }

    /// Copy the appropriate physical property from another struct for ${name}
    /// given a writing mode.
    pub fn copy_${to_rust_ident(name)}_from(&mut self,
                                            other: &Self,
                                            wm: WritingMode) {
        <%self:logical_setter_helper name="${name}">
            <%def name="inner(physical_ident)">
                self.copy_${physical_ident}_from(other)
            </%def>
        </%self:logical_setter_helper>
    }
    % if need_clone:
        /// Get the computed value for the appropriate physical property for
        /// ${name} given a writing mode.
        pub fn clone_${to_rust_ident(name)}(&self, wm: WritingMode)
            -> longhands::${to_rust_ident(name)}::computed_value::T {
        <%self:logical_setter_helper name="${name}">
            <%def name="inner(physical_ident)">
                self.clone_${physical_ident}()
            </%def>
        </%self:logical_setter_helper>
        }
    % endif
</%def>

<%def name="alias_to_nscsspropertyid(alias)">
    <%
        return "nsCSSPropertyID::eCSSPropertyAlias_%s" % to_camel_case(alias)
    %>
</%def>

<%def name="to_nscsspropertyid(ident)">
    <%
        if ident == "float":
            ident = "float_"
        return "nsCSSPropertyID::eCSSProperty_%s" % ident
    %>
</%def>

/// Macro for defining Interpolate trait for tuple struct which has Option<T>,
/// e.g. struct T(pub Option<Au>).
<%def name="impl_interpolate_for_option_tuple(value_for_none)">
    impl Interpolate for T {
        #[inline]
        fn interpolate(&self, other: &Self, progress: f64) -> Result<Self, ()> {
            match (self, other) {
                (&T(Some(ref this)), &T(Some(ref other))) => {
                    Ok(T(this.interpolate(other, progress).ok()))
                },
                (&T(Some(ref this)), &T(None)) => {
                    Ok(T(this.interpolate(&${value_for_none}, progress).ok()))
                },
                (&T(None), &T(Some(ref other))) => {
                    Ok(T(${value_for_none}.interpolate(other, progress).ok()))
                },
                (&T(None), &T(None)) => {
                    Ok(T(None))
                },
            }
        }
    }
</%def>