servo: Merge #10774 - Improve properties.mako.rs file structure, take 2 (from perlun:improve-mako-file-structure-v2); r=SimonSapin

This is a new attempt of #10586, after Simon Sapin's great cleanups in #10749 has landed. I have adjusted the changes to the new structure that was introduced, and also only done a few of the longhand ones. Will certainly continue on this as soon as we have a basic agreement that this style is reasonable.

Source-Repo: https://github.com/servo/servo
Source-Revision: 69acd8e1ccba8ff01e8f7fde4305956ba5ab866d

servo/components/style/properties/build.py

@@ -10,6 +10,7 @@ BASE = os.path.dirname(__file__)
 sys.path.insert(0, os.path.join(BASE, "Mako-0.9.1.zip"))
 
 from mako import exceptions
+from mako.lookup import TemplateLookup
 from mako.template import Template
 
 import data
@@ -43,10 +44,12 @@ def abort(message):
 
 def render(filename, **context):
     try:
+        lookup = TemplateLookup(directories=[BASE])
         template = Template(open(filename, "rb").read(),
+                            filename=filename,
                             input_encoding="utf8",
-                            strict_undefined=True,
-                            filename=filename)
+                            lookup=lookup,
+                            strict_undefined=True)
         # Uncomment to debug generated Python code:
         # write("/tmp", "mako_%s.py" % os.path.basename(filename), template.code)
         return template.render(**context).encode("utf8")

servo/components/style/properties/helpers.mako.rs

@@ -0,0 +1,191 @@
+/* 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 %>
+
+<%def name="longhand(name, **kwargs)">
+    <%call expr="raw_longhand(name, **kwargs)">
+        ${caller.body()}
+        % if not data.longhands_by_name[name].derived_from:
+            pub fn parse_specified(context: &ParserContext, input: &mut Parser)
+                               -> Result<DeclaredValue<SpecifiedValue>, ()> {
+                parse(context, input).map(DeclaredValue::Value)
+            }
+        % endif
+    </%call>
+</%def>
+
+<%def name="predefined_type(name, type, initial_value, parse_method='parse', products='gecko servo')">
+    <%self:longhand name="${name}" products="${products}">
+        #[allow(unused_imports)]
+        use app_units::Au;
+        pub type SpecifiedValue = specified::${type};
+        pub mod computed_value {
+            pub use values::computed::${type} as T;
+        }
+        #[inline] pub fn get_initial_value() -> computed_value::T { ${initial_value} }
+        #[inline] pub fn parse(_context: &ParserContext, input: &mut Parser)
+                               -> Result<SpecifiedValue, ()> {
+            specified::${type}::${parse_method}(input)
+        }
+    </%self:longhand>
+</%def>
+
+<%def name="raw_longhand(*args, **kwargs)">
+    <%
+        property = data.declare_longhand(*args, **kwargs)
+        if property is None:
+            return ""
+    %>
+    pub mod ${property.ident} {
+        #![allow(unused_imports)]
+        % if not property.derived_from:
+            use cssparser::Parser;
+            use parser::ParserContext;
+            use properties::{CSSWideKeyword, DeclaredValue, Shorthand};
+        % endif
+        use error_reporting::ParseErrorReporter;
+        use properties::longhands;
+        use properties::property_bit_field::PropertyBitField;
+        use properties::{ComputedValues, ServoComputedValues, PropertyDeclaration};
+        use properties::style_struct_traits::${data.current_style_struct.trait_name};
+        use properties::style_structs;
+        use std::boxed::Box as StdBox;
+        use std::collections::HashMap;
+        use std::sync::Arc;
+        use values::computed::{TContext, ToComputedValue};
+        use values::{computed, specified};
+        use string_cache::Atom;
+        ${caller.body()}
+        #[allow(unused_variables)]
+        pub fn cascade_property<C: ComputedValues>(
+                                declaration: &PropertyDeclaration,
+                                inherited_style: &C,
+                                context: &mut computed::Context<C>,
+                                seen: &mut PropertyBitField,
+                                cacheable: &mut bool,
+                                error_reporter: &mut StdBox<ParseErrorReporter + Send>) {
+            let declared_value = match *declaration {
+                PropertyDeclaration::${property.camel_case}(ref declared_value) => {
+                    declared_value
+                }
+                _ => panic!("entered the wrong cascade_property() implementation"),
+            };
+            % if not property.derived_from:
+                if seen.get_${property.ident}() {
+                    return
+                }
+                seen.set_${property.ident}();
+                {
+                    let custom_props = context.style().custom_properties();
+                    ::properties::substitute_variables_${property.ident}(
+                        declared_value, &custom_props, |value| match *value {
+                            DeclaredValue::Value(ref specified_value) => {
+                                let computed = specified_value.to_computed_value(context);
+                                context.mutate_style().mutate_${data.current_style_struct.trait_name_lower}()
+                                                      .set_${property.ident}(computed);
+                            }
+                            DeclaredValue::WithVariables { .. } => unreachable!(),
+                            DeclaredValue::Initial => {
+                                // We assume that it's faster to use copy_*_from rather than
+                                // set_*(get_initial_value());
+                                let initial_struct = C::initial_values()
+                                                      .get_${data.current_style_struct.trait_name_lower}();
+                                context.mutate_style().mutate_${data.current_style_struct.trait_name_lower}()
+                                                      .copy_${property.ident}_from(initial_struct);
+                            },
+                            DeclaredValue::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_${data.current_style_struct.trait_name_lower}();
+                                context.mutate_style().mutate_${data.current_style_struct.trait_name_lower}()
+                                       .copy_${property.ident}_from(inherited_struct);
+                            }
+                        }, error_reporter
+                    );
+                }
+
+                % if property.custom_cascade:
+                    cascade_property_custom(declaration,
+                                            inherited_style,
+                                            context,
+                                            seen,
+                                            cacheable,
+                                            error_reporter);
+                % endif
+            % else:
+                // Do not allow stylesheets to set derived properties.
+            % endif
+        }
+        % if not property.derived_from:
+            pub fn parse_declared(context: &ParserContext, input: &mut Parser)
+                               -> Result<DeclaredValue<SpecifiedValue>, ()> {
+                match input.try(CSSWideKeyword::parse) {
+                    Ok(CSSWideKeyword::InheritKeyword) => Ok(DeclaredValue::Inherit),
+                    Ok(CSSWideKeyword::InitialKeyword) => Ok(DeclaredValue::Initial),
+                    Ok(CSSWideKeyword::UnsetKeyword) => Ok(DeclaredValue::${
+                        "Inherit" if data.current_style_struct.inherited else "Initial"}),
+                    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(DeclaredValue::WithVariables {
+                                css: css.into_owned(),
+                                first_token_type: first_token_type,
+                                base_url: context.base_url.clone(),
+                                from_shorthand: None,
+                            })
+                        }
+                        specified
+                    }
+                }
+            }
+        % endif
+    }
+</%def>
+
+<%def name="single_keyword(name, values, **kwargs)">
+    <%call expr="single_keyword_computed(name, values, **kwargs)">
+        use values::computed::ComputedValueAsSpecified;
+        impl ComputedValueAsSpecified for SpecifiedValue {}
+    </%call>
+</%def>
+
+<%def name="single_keyword_computed(name, values, **kwargs)">
+    <%
+        keyword_kwargs = {a: kwargs.pop(a, None) for a in [
+            'gecko_constant_prefix', 'extra_gecko_values', 'extra_servo_values'
+        ]}
+    %>
+    <%call expr="longhand(name, keyword=Keyword(name, values.split(), **keyword_kwargs), **kwargs)">
+        pub use self::computed_value::T as SpecifiedValue;
+        ${caller.body()}
+        pub mod computed_value {
+            define_css_keyword_enum! { T:
+                % for value in data.longhands_by_name[name].keyword.values_for(product):
+                    "${value}" => ${to_rust_ident(value)},
+                % endfor
+            }
+        }
+        #[inline] pub fn get_initial_value() -> computed_value::T {
+            computed_value::T::${to_rust_ident(values.split()[0])}
+        }
+        pub fn parse(_context: &ParserContext, input: &mut Parser)
+                     -> Result<SpecifiedValue, ()> {
+            computed_value::T::parse(input)
+        }
+    </%call>
+</%def>

servo/components/style/properties/longhand/border.mako.rs

@@ -0,0 +1,64 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<% from data import Method %>
+
+<% data.new_style_struct("Border", inherited=False, gecko_ffi_name="nsStyleBorder",
+                   additional_methods=[Method("border_" + side + "_is_none_or_hidden_and_has_nonzero_width",
+                                              "bool") for side in ["top", "right", "bottom", "left"]]) %>
+
+% for side in ["top", "right", "bottom", "left"]:
+    ${helpers.predefined_type("border-%s-color" % side, "CSSColor", "::cssparser::Color::CurrentColor")}
+% endfor
+
+% for side in ["top", "right", "bottom", "left"]:
+    ${helpers.predefined_type("border-%s-style" % side, "BorderStyle", "specified::BorderStyle::none")}
+% endfor
+
+% for side in ["top", "right", "bottom", "left"]:
+    <%helpers:longhand name="border-${side}-width">
+        use app_units::Au;
+        use cssparser::ToCss;
+        use std::fmt;
+
+        impl ToCss for SpecifiedValue {
+            fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+                self.0.to_css(dest)
+            }
+        }
+
+        #[inline]
+        pub fn parse(_context: &ParserContext, input: &mut Parser)
+                               -> Result<SpecifiedValue, ()> {
+            specified::parse_border_width(input).map(SpecifiedValue)
+        }
+        #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+        pub struct SpecifiedValue(pub specified::Length);
+        pub mod computed_value {
+            use app_units::Au;
+            pub type T = Au;
+        }
+        #[inline] pub fn get_initial_value() -> computed_value::T {
+            Au::from_px(3)  // medium
+        }
+
+        impl ToComputedValue for SpecifiedValue {
+            type ComputedValue = computed_value::T;
+
+            #[inline]
+            fn to_computed_value<Cx: TContext>(&self, context: &Cx) -> computed_value::T {
+                self.0.to_computed_value(context)
+            }
+        }
+    </%helpers:longhand>
+% endfor
+
+// FIXME(#4126): when gfx supports painting it, make this Size2D<LengthOrPercentage>
+% for corner in ["top-left", "top-right", "bottom-right", "bottom-left"]:
+    ${helpers.predefined_type("border-" + corner + "-radius", "BorderRadiusSize",
+                              "computed::BorderRadiusSize::zero()",
+                              "parse")}
+% endfor

servo/components/style/properties/longhand/box.mako.rs

@@ -0,0 +1,129 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<% from data import Method, to_rust_ident %>
+
+<% data.new_style_struct("Box",
+                         inherited=False,
+                         gecko_ffi_name="nsStyleDisplay",
+                         additional_methods=[Method("clone_display", "longhands::display::computed_value::T"),
+                                             Method("clone_position", "longhands::position::computed_value::T"),
+                                             Method("is_floated", "bool"),
+                                             Method("overflow_x_is_visible", "bool"),
+                                             Method("overflow_y_is_visible", "bool"),
+                                             Method("transition_count", "usize")]) %>
+
+// TODO(SimonSapin): don't parse `inline-table`, since we don't support it
+<%helpers:longhand name="display" custom_cascade="${product == 'servo'}">
+    <%
+        values = """inline block inline-block
+            table inline-table table-row-group table-header-group table-footer-group
+            table-row table-column-group table-column table-cell table-caption
+            list-item flex
+            none
+        """.split()
+        experimental_values = set("flex".split())
+    %>
+    pub use self::computed_value::T as SpecifiedValue;
+    use values::computed::{Context, ComputedValueAsSpecified};
+
+    pub mod computed_value {
+        #[allow(non_camel_case_types)]
+        #[derive(Clone, Eq, PartialEq, Copy, Hash, RustcEncodable, Debug, HeapSizeOf)]
+        #[derive(Deserialize, Serialize)]
+        pub enum T {
+            % for value in values:
+                ${to_rust_ident(value)},
+            % endfor
+        }
+
+        impl ::cssparser::ToCss for T {
+            fn to_css<W>(&self, dest: &mut W) -> ::std::fmt::Result
+            where W: ::std::fmt::Write {
+                match *self {
+                    % for value in values:
+                        T::${to_rust_ident(value)} => dest.write_str("${value}"),
+                    % endfor
+                }
+            }
+        }
+    }
+    #[inline] pub fn get_initial_value() -> computed_value::T {
+        computed_value::T::${to_rust_ident(values[0])}
+    }
+    pub fn parse(_context: &ParserContext, input: &mut Parser)
+                 -> Result<SpecifiedValue, ()> {
+        match_ignore_ascii_case! { try!(input.expect_ident()),
+            % for value in values:
+                "${value}" => {
+                    % if value in experimental_values:
+                        if !::util::prefs::get_pref("layout.${value}.enabled")
+                            .as_boolean().unwrap_or(false) {
+                            return Err(())
+                        }
+                    % endif
+                    Ok(computed_value::T::${to_rust_ident(value)})
+                },
+            % endfor
+            _ => Err(())
+        }
+    }
+
+    impl ComputedValueAsSpecified for SpecifiedValue {}
+
+    % if product == "servo":
+        fn cascade_property_custom<C: ComputedValues>(
+                                   _declaration: &PropertyDeclaration,
+                                   _inherited_style: &C,
+                                   context: &mut computed::Context<C>,
+                                   _seen: &mut PropertyBitField,
+                                   _cacheable: &mut bool,
+                                   _error_reporter: &mut StdBox<ParseErrorReporter + Send>) {
+            longhands::_servo_display_for_hypothetical_box::derive_from_display(context);
+            longhands::_servo_text_decorations_in_effect::derive_from_display(context);
+        }
+    % endif
+
+</%helpers:longhand>
+
+${helpers.single_keyword("position", "static absolute relative fixed", extra_gecko_values="sticky")}
+
+<%helpers:single_keyword_computed name="float" values="none left right" gecko_ffi_name="mFloats">
+    impl ToComputedValue for SpecifiedValue {
+        type ComputedValue = computed_value::T;
+
+        #[inline]
+        fn to_computed_value<Cx: TContext>(&self, context: &Cx) -> computed_value::T {
+            let positioned = matches!(context.style().get_box().clone_position(),
+                longhands::position::SpecifiedValue::absolute |
+                longhands::position::SpecifiedValue::fixed);
+            if positioned {
+                SpecifiedValue::none
+            } else {
+                *self
+            }
+        }
+    }
+
+</%helpers:single_keyword_computed>
+
+${helpers.single_keyword("clear", "none left right both", gecko_ffi_name="mBreakType")}
+
+<%helpers:longhand name="-servo-display-for-hypothetical-box" derived_from="display" products="servo">
+    pub use super::display::{SpecifiedValue, get_initial_value};
+    pub use super::display::{parse};
+
+    pub mod computed_value {
+        pub type T = super::SpecifiedValue;
+    }
+
+    #[inline]
+    pub fn derive_from_display<Cx: TContext>(context: &mut Cx) {
+        let d = context.style().get_box().clone_display();
+        context.mutate_style().mutate_box().set__servo_display_for_hypothetical_box(d);
+    }
+
+</%helpers:longhand>

servo/components/style/properties/longhand/margin.mako.rs

@@ -0,0 +1,12 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<% data.new_style_struct("Margin", inherited=False, gecko_ffi_name="nsStyleMargin") %>
+
+% for side in ["top", "right", "bottom", "left"]:
+    ${helpers.predefined_type("margin-" + side, "LengthOrPercentageOrAuto",
+                              "computed::LengthOrPercentageOrAuto::Length(Au(0))")}
+% endfor

servo/components/style/properties/longhand/outline.mako.rs

@@ -0,0 +1,63 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<% from data import Method %>
+
+<% data.new_style_struct("Outline",
+                         inherited=False,
+                         gecko_ffi_name="nsStyleOutline",
+                         additional_methods=[Method("outline_is_none_or_hidden_and_has_nonzero_width", "bool")]) %>
+
+// TODO(pcwalton): `invert`
+${helpers.predefined_type("outline-color", "CSSColor", "::cssparser::Color::CurrentColor")}
+
+<%helpers:longhand name="outline-style">
+    pub use values::specified::BorderStyle as SpecifiedValue;
+    pub fn get_initial_value() -> SpecifiedValue { SpecifiedValue::none }
+    pub mod computed_value {
+        pub use values::specified::BorderStyle as T;
+    }
+    pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+        match SpecifiedValue::parse(input) {
+            Ok(SpecifiedValue::hidden) => Err(()),
+            result => result
+        }
+    }
+</%helpers:longhand>
+
+<%helpers:longhand name="outline-width">
+    use app_units::Au;
+    use cssparser::ToCss;
+    use std::fmt;
+    use values::AuExtensionMethods;
+
+    impl ToCss for SpecifiedValue {
+        fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+            self.0.to_css(dest)
+        }
+    }
+
+    pub fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+        specified::parse_border_width(input).map(SpecifiedValue)
+    }
+    #[derive(Debug, Clone, PartialEq, HeapSizeOf)]
+    pub struct SpecifiedValue(pub specified::Length);
+    pub mod computed_value {
+        use app_units::Au;
+        pub type T = Au;
+    }
+    pub use super::border_top_width::get_initial_value;
+    impl ToComputedValue for SpecifiedValue {
+        type ComputedValue = computed_value::T;
+
+        #[inline]
+        fn to_computed_value<Cx: TContext>(&self, context: &Cx) -> computed_value::T {
+            self.0.to_computed_value(context)
+        }
+    }
+</%helpers:longhand>
+
+${helpers.predefined_type("outline-offset", "Length", "Au(0)")}

servo/components/style/properties/longhand/padding.mako.rs

@@ -0,0 +1,13 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<% data.new_style_struct("Padding", inherited=False, gecko_ffi_name="nsStylePadding") %>
+
+% for side in ["top", "right", "bottom", "left"]:
+    ${helpers.predefined_type("padding-" + side, "LengthOrPercentage",
+                               "computed::LengthOrPercentage::Length(Au(0))",
+                               "parse_non_negative")}
+% endfor

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

@@ -0,0 +1,58 @@
+/* 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/. */
+
+<%namespace name="helpers" file="/helpers.mako.rs" />
+
+<% data.new_style_struct("Position", inherited=False, gecko_ffi_name="nsStylePosition") %>
+
+% for side in ["top", "right", "bottom", "left"]:
+    ${helpers.predefined_type(side, "LengthOrPercentageOrAuto",
+                              "computed::LengthOrPercentageOrAuto::Auto")}
+% endfor
+
+<%helpers:longhand name="z-index">
+    use values::computed::ComputedValueAsSpecified;
+
+    impl ComputedValueAsSpecified for SpecifiedValue {}
+    pub type SpecifiedValue = computed_value::T;
+    pub mod computed_value {
+        use cssparser::ToCss;
+        use std::fmt;
+
+        #[derive(PartialEq, Clone, Eq, Copy, Debug, HeapSizeOf)]
+        pub enum T {
+            Auto,
+            Number(i32),
+        }
+
+        impl ToCss for T {
+            fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+                match *self {
+                    T::Auto => dest.write_str("auto"),
+                    T::Number(number) => write!(dest, "{}", number),
+                }
+            }
+        }
+
+        impl T {
+            pub fn number_or_zero(self) -> i32 {
+                match self {
+                    T::Auto => 0,
+                    T::Number(value) => value,
+                }
+            }
+        }
+    }
+    #[inline]
+    pub fn get_initial_value() -> computed_value::T {
+        computed_value::T::Auto
+    }
+    fn parse(_context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
+        if input.try(|input| input.expect_ident_matching("auto")).is_ok() {
+            Ok(computed_value::T::Auto)
+        } else {
+            specified::parse_integer(input).map(computed_value::T::Number)
+        }
+    }
+</%helpers:longhand>

servo/python/tidy/servo_tidy/tidy.py

@@ -277,7 +277,7 @@ def check_toml(file_name, lines):
 
 def check_rust(file_name, lines):
     if not file_name.endswith(".rs") or \
-       file_name.endswith("properties.mako.rs") or \
+       file_name.endswith(".mako.rs") or \
        file_name.endswith(os.path.join("style", "build.rs")) or \
        file_name.endswith(os.path.join("geckolib", "build.rs")) or \
        file_name.endswith(os.path.join("unit", "style", "stylesheets.rs")):