Auto merge of #14789 - Manishearth:supports, r=SimonSapin

Support @supports

fixes #14786

cc @heycam @upsuper
r? @SimonSapin

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components/script/dom/bindings/trace.rs

@@ -99,6 +99,7 @@ use style::media_queries::MediaList;
 use style::properties::PropertyDeclarationBlock;
 use style::selector_parser::{PseudoElement, Snapshot};
 use style::stylesheets::{CssRules, KeyframesRule, MediaRule, NamespaceRule, StyleRule, ImportRule};
+use style::stylesheets::SupportsRule;
 use style::values::specified::Length;
 use style::viewport::ViewportRule;
 use time::Duration;
@@ -531,6 +532,12 @@ unsafe impl JSTraceable for RwLock<ImportRule> {
     }
 }
 
+unsafe impl JSTraceable for RwLock<SupportsRule> {
+    unsafe fn trace(&self, _trc: *mut JSTracer) {
+        // Do nothing.
+    }
+}
+
 unsafe impl JSTraceable for RwLock<MediaRule> {
     unsafe fn trace(&self, _trc: *mut JSTracer) {
         // Do nothing.

components/script/dom/css.rs

@@ -2,11 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use cssparser::serialize_identifier;
+use cssparser::{Parser, serialize_identifier};
+use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::error::Fallible;
 use dom::bindings::reflector::Reflector;
 use dom::bindings::str::DOMString;
 use dom::window::Window;
+use style::parser::ParserContext;
+use style::supports::{Declaration, parse_condition_or_declaration};
 
 #[dom_struct]
 pub struct CSS {
@@ -14,10 +17,31 @@ pub struct CSS {
 }
 
 impl CSS {
-    // http://dev.w3.org/csswg/cssom/#serialize-an-identifier
+    /// http://dev.w3.org/csswg/cssom/#serialize-an-identifier
     pub fn Escape(_: &Window, ident: DOMString) -> Fallible<DOMString> {
         let mut escaped = String::new();
         serialize_identifier(&ident, &mut escaped).unwrap();
         Ok(DOMString::from(escaped))
     }
+
+    /// https://drafts.csswg.org/css-conditional/#dom-css-supports
+    pub fn Supports(win: &Window, property: DOMString, value: DOMString) -> bool {
+        let decl = Declaration { prop: property.into(), val: value.into() };
+        let url = win.Document().url();
+        let context = ParserContext::new_for_cssom(&url);
+        decl.eval(&context)
+    }
+
+    /// https://drafts.csswg.org/css-conditional/#dom-css-supports
+    pub fn Supports_(win: &Window, condition: DOMString) -> bool {
+        let mut input = Parser::new(&condition);
+        let cond = parse_condition_or_declaration(&mut input);
+        if let Ok(cond) = cond {
+            let url = win.Document().url();
+            let context = ParserContext::new_for_cssom(&url);
+            cond.eval(&context)
+        } else {
+            false
+        }
+    }
 }

components/script/dom/cssconditionrule.rs

@@ -0,0 +1,53 @@
+/* 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/. */
+
+use dom::bindings::codegen::Bindings::CSSConditionRuleBinding::CSSConditionRuleMethods;
+use dom::bindings::inheritance::Castable;
+use dom::bindings::str::DOMString;
+use dom::cssgroupingrule::CSSGroupingRule;
+use dom::cssmediarule::CSSMediaRule;
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::csssupportsrule::CSSSupportsRule;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::stylesheets::CssRules as StyleCssRules;
+
+#[dom_struct]
+pub struct CSSConditionRule {
+    cssgroupingrule: CSSGroupingRule,
+}
+
+impl CSSConditionRule {
+    pub fn new_inherited(parent_stylesheet: &CSSStyleSheet,
+                         rules: Arc<RwLock<StyleCssRules>>) -> CSSConditionRule {
+        CSSConditionRule {
+            cssgroupingrule: CSSGroupingRule::new_inherited(parent_stylesheet, rules),
+        }
+    }
+
+}
+
+impl CSSConditionRuleMethods for CSSConditionRule {
+    /// https://drafts.csswg.org/css-conditional-3/#dom-cssconditionrule-conditiontext
+    fn ConditionText(&self) -> DOMString {
+        if let Some(rule) = self.downcast::<CSSMediaRule>() {
+            rule.get_condition_text()
+        } else if let Some(rule) = self.downcast::<CSSSupportsRule>() {
+            rule.get_condition_text()
+        } else {
+            unreachable!()
+        }
+    }
+
+    /// https://drafts.csswg.org/css-conditional-3/#dom-cssconditionrule-conditiontext
+    fn SetConditionText(&self, text: DOMString) {
+        if let Some(rule) = self.downcast::<CSSMediaRule>() {
+            rule.set_condition_text(text)
+        } else if let Some(rule) = self.downcast::<CSSSupportsRule>() {
+            rule.set_condition_text(text)
+        } else {
+            unreachable!()
+        }
+    }
+}

components/script/dom/cssmediarule.rs

@@ -2,24 +2,26 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use cssparser::Parser;
 use dom::bindings::codegen::Bindings::CSSMediaRuleBinding;
 use dom::bindings::codegen::Bindings::CSSMediaRuleBinding::CSSMediaRuleMethods;
 use dom::bindings::js::{MutNullableJS, Root};
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
 use dom::bindings::str::DOMString;
-use dom::cssgroupingrule::CSSGroupingRule;
+use dom::cssconditionrule::CSSConditionRule;
 use dom::cssrule::SpecificCSSRule;
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::medialist::MediaList;
 use dom::window::Window;
 use parking_lot::RwLock;
 use std::sync::Arc;
+use style::media_queries::parse_media_query_list;
 use style::stylesheets::MediaRule;
 use style_traits::ToCss;
 
 #[dom_struct]
 pub struct CSSMediaRule {
-    cssrule: CSSGroupingRule,
+    cssrule: CSSConditionRule,
     #[ignore_heap_size_of = "Arc"]
     mediarule: Arc<RwLock<MediaRule>>,
     medialist: MutNullableJS<MediaList>,
@@ -30,7 +32,7 @@ impl CSSMediaRule {
                      -> CSSMediaRule {
         let list = mediarule.read().rules.clone();
         CSSMediaRule {
-            cssrule: CSSGroupingRule::new_inherited(parent_stylesheet, list),
+            cssrule: CSSConditionRule::new_inherited(parent_stylesheet, list),
             mediarule: mediarule,
             medialist: MutNullableJS::new(None),
         }
@@ -48,6 +50,22 @@ impl CSSMediaRule {
         self.medialist.or_init(|| MediaList::new(self.global().as_window(),
                                                  self.mediarule.read().media_queries.clone()))
     }
+
+    /// https://drafts.csswg.org/css-conditional-3/#the-cssmediarule-interface
+    pub fn get_condition_text(&self) -> DOMString {
+        let rule = self.mediarule.read();
+        let list = rule.media_queries.read();
+        list.to_css_string().into()
+    }
+
+    /// https://drafts.csswg.org/css-conditional-3/#the-cssmediarule-interface
+    pub fn set_condition_text(&self, text: DOMString) {
+        let mut input = Parser::new(&text);
+        let new_medialist = parse_media_query_list(&mut input);
+        let rule = self.mediarule.read();
+        let mut list = rule.media_queries.write();
+        *list = new_medialist;
+    }
 }
 
 impl SpecificCSSRule for CSSMediaRule {

components/script/dom/cssrule.rs

@@ -15,6 +15,7 @@ use dom::cssmediarule::CSSMediaRule;
 use dom::cssnamespacerule::CSSNamespaceRule;
 use dom::cssstylerule::CSSStyleRule;
 use dom::cssstylesheet::CSSStyleSheet;
+use dom::csssupportsrule::CSSSupportsRule;
 use dom::cssviewportrule::CSSViewportRule;
 use dom::window::Window;
 use std::cell::Cell;
@@ -59,6 +60,8 @@ impl CSSRule {
             rule as &SpecificCSSRule
         } else if let Some(rule) = self.downcast::<CSSImportRule>() {
             rule as &SpecificCSSRule
+        } else if let Some(rule) = self.downcast::<CSSSupportsRule>() {
+            rule as &SpecificCSSRule
         } else {
             unreachable!()
         }
@@ -77,6 +80,7 @@ impl CSSRule {
             StyleCssRule::Media(s) => Root::upcast(CSSMediaRule::new(window, parent_stylesheet, s)),
             StyleCssRule::Namespace(s) => Root::upcast(CSSNamespaceRule::new(window, parent_stylesheet, s)),
             StyleCssRule::Viewport(s) => Root::upcast(CSSViewportRule::new(window, parent_stylesheet, s)),
+            StyleCssRule::Supports(s) => Root::upcast(CSSSupportsRule::new(window, parent_stylesheet, s)),
         }
     }
 

components/script/dom/csssupportsrule.rs

@@ -0,0 +1,77 @@
+/* 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/. */
+
+use cssparser::Parser;
+use dom::bindings::codegen::Bindings::CSSSupportsRuleBinding;
+use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::{DomObject, reflect_dom_object};
+use dom::bindings::str::DOMString;
+use dom::cssconditionrule::CSSConditionRule;
+use dom::cssrule::SpecificCSSRule;
+use dom::cssstylesheet::CSSStyleSheet;
+use dom::window::Window;
+use parking_lot::RwLock;
+use std::sync::Arc;
+use style::parser::ParserContext;
+use style::stylesheets::SupportsRule;
+use style::supports::SupportsCondition;
+use style_traits::ToCss;
+
+#[dom_struct]
+pub struct CSSSupportsRule {
+    cssrule: CSSConditionRule,
+    #[ignore_heap_size_of = "Arc"]
+    supportsrule: Arc<RwLock<SupportsRule>>,
+}
+
+impl CSSSupportsRule {
+    fn new_inherited(parent_stylesheet: &CSSStyleSheet, supportsrule: Arc<RwLock<SupportsRule>>)
+                     -> CSSSupportsRule {
+        let list = supportsrule.read().rules.clone();
+        CSSSupportsRule {
+            cssrule: CSSConditionRule::new_inherited(parent_stylesheet, list),
+            supportsrule: supportsrule,
+        }
+    }
+
+    #[allow(unrooted_must_root)]
+    pub fn new(window: &Window, parent_stylesheet: &CSSStyleSheet,
+               supportsrule: Arc<RwLock<SupportsRule>>) -> Root<CSSSupportsRule> {
+        reflect_dom_object(box CSSSupportsRule::new_inherited(parent_stylesheet, supportsrule),
+                           window,
+                           CSSSupportsRuleBinding::Wrap)
+    }
+
+    /// https://drafts.csswg.org/css-conditional-3/#the-csssupportsrule-interface
+    pub fn get_condition_text(&self) -> DOMString {
+        let rule = self.supportsrule.read();
+        rule.condition.to_css_string().into()
+    }
+
+    /// https://drafts.csswg.org/css-conditional-3/#the-csssupportsrule-interface
+    pub fn set_condition_text(&self, text: DOMString) {
+        let mut input = Parser::new(&text);
+        let cond = SupportsCondition::parse(&mut input);
+        if let Ok(cond) = cond {
+            let url = self.global().as_window().Document().url();
+            let context = ParserContext::new_for_cssom(&url);
+            let enabled = cond.eval(&context);
+            let mut rule = self.supportsrule.write();
+            rule.condition = cond;
+            rule.enabled = enabled;
+        }
+    }
+}
+
+impl SpecificCSSRule for CSSSupportsRule {
+    fn ty(&self) -> u16 {
+        use dom::bindings::codegen::Bindings::CSSRuleBinding::CSSRuleConstants;
+        CSSRuleConstants::SUPPORTS_RULE
+    }
+
+    fn get_css(&self) -> DOMString {
+        self.supportsrule.read().to_css_string().into()
+    }
+}

components/script/dom/mod.rs

@@ -240,6 +240,7 @@ pub mod console;
 mod create;
 pub mod crypto;
 pub mod css;
+pub mod cssconditionrule;
 pub mod cssfontfacerule;
 pub mod cssgroupingrule;
 pub mod cssimportrule;
@@ -252,6 +253,7 @@ pub mod cssrulelist;
 pub mod cssstyledeclaration;
 pub mod cssstylerule;
 pub mod cssstylesheet;
+pub mod csssupportsrule;
 pub mod cssviewportrule;
 pub mod customevent;
 pub mod dedicatedworkerglobalscope;

components/script/dom/webidls/CSS.webidl

@@ -11,3 +11,9 @@ interface CSS {
   [Throws]
   static DOMString escape(DOMString ident);
 };
+
+// https://drafts.csswg.org/css-conditional-3/#the-css-interface
+partial interface CSS {
+  static boolean supports(DOMString property, DOMString value);
+  static boolean supports(DOMString conditionText);
+};

components/script/dom/webidls/CSSConditionRule.webidl

@@ -0,0 +1,9 @@
+/* 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/. */
+
+// https://drafts.csswg.org/css-conditional/#cssconditionrule
+[Abstract, Exposed=Window]
+interface CSSConditionRule : CSSGroupingRule {
+    attribute DOMString conditionText;
+};

components/script/dom/webidls/CSSMediaRule.webidl

@@ -3,7 +3,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://drafts.csswg.org/cssom/#the-cssmediarule-interface
+// https://drafts.csswg.org/css-conditional/#cssmediarule
 [Exposed=Window]
-interface CSSMediaRule : CSSGroupingRule {
+interface CSSMediaRule : CSSConditionRule {
   [SameObject, PutForwards=mediaText] readonly attribute MediaList media;
 };

components/script/dom/webidls/CSSRule.webidl

@@ -31,3 +31,7 @@ partial interface CSSRule {
     const unsigned short VIEWPORT_RULE = 15;
 };
 
+// https://drafts.csswg.org/css-conditional-3/#extentions-to-cssrule-interface
+partial interface CSSRule {
+    const unsigned short SUPPORTS_RULE = 12;
+};

components/script/dom/webidls/CSSSupportsRule.webidl

@@ -0,0 +1,8 @@
+/* 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/. */
+
+// https://drafts.csswg.org/css-conditional/#csssupportsrule
+[Exposed=Window]
+interface CSSSupportsRule : CSSConditionRule {
+};