servo: Merge #17538 - Implement CSSStyleRule.selectorText (from jyc:s…

…electorText); r=Manishearth

We parse when assigning using the namespaces of the stylesheet. It isn't
clear if the spec says to do that (Firefox doesn't support the setter at
all, Chrome does, Safari doesn't); the spec issue is here:
w3c/csswg-drafts#1511

Also fix ToCss implementation of AttrSelectorOperator to not pad with
spaces, to conform with CSSOM. This means we have to update some unit
tests that expect operators with spaces around them in attribute
selectors to roundtrip.

See the "attribute selector" section of "Serializing Selectors" here:
https://drafts.csswg.org/cssom/#serializing-selectors

CSSStyleRule.selectorText is specified here:
https://drafts.csswg.org/cssom/#dom-cssstylerule-selectortext

<!-- Please describe your changes on the following line: -->

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes is part of a series to fix #17182

<!-- Either: -->
I am running this to identify what tests will fail; as the other PRs in the series are merged, I believe the tests that pass will change as well.

- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

Source-Repo: https://github.com/servo/servo
Source-Revision: 4b6e79337ef975e3ec752513b76ae6a6284c1199

servo/components/script/dom/cssstyledeclaration.rs

@@ -104,6 +104,8 @@ impl CSSStyleOwner {
                     f(&mut *pdb.write_with(&mut guard), &mut changed)
                 };
                 if changed {
+                    // If this is changed, see also
+                    // CSSStyleRule::SetSelectorText, which does the same thing.
                     rule.global().as_window().Document().invalidate_stylesheets();
                 }
                 result

servo/components/script/dom/cssstylerule.rs

@@ -2,7 +2,10 @@
  * 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 as CssParser, ParserInput as CssParserInput};
+use cssparser::ToCss;
 use dom::bindings::codegen::Bindings::CSSStyleRuleBinding::{self, CSSStyleRuleMethods};
+use dom::bindings::codegen::Bindings::WindowBinding::WindowBinding::WindowMethods;
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::{JS, MutNullableJS, Root};
 use dom::bindings::reflector::{DomObject, reflect_dom_object};
@@ -12,9 +15,12 @@ use dom::cssstyledeclaration::{CSSModificationAccess, CSSStyleDeclaration, CSSSt
 use dom::cssstylesheet::CSSStyleSheet;
 use dom::window::Window;
 use dom_struct::dom_struct;
+use selectors::parser::SelectorList;
+use std::mem;
+use style::selector_parser::SelectorParser;
 use style::shared_lock::{Locked, ToCssWithGuard};
 use style::stylearc::Arc;
-use style::stylesheets::StyleRule;
+use style::stylesheets::{StyleRule, Origin};
 
 #[dom_struct]
 pub struct CSSStyleRule {
@@ -71,4 +77,33 @@ impl CSSStyleRuleMethods for CSSStyleRule {
             )
         })
     }
+
+    // https://drafts.csswg.org/cssom/#dom-cssstylerule-selectortext
+    fn SelectorText(&self) -> DOMString {
+        let guard = self.cssrule.shared_lock().read();
+        let stylerule = self.stylerule.read_with(&guard);
+        return DOMString::from_string(stylerule.selectors.to_css_string());
+    }
+
+    // https://drafts.csswg.org/cssom/#dom-cssstylerule-selectortext
+    fn SetSelectorText(&self, value: DOMString) {
+        // It's not clear from the spec if we should use the stylesheet's namespaces.
+        // https://github.com/w3c/csswg-drafts/issues/1511
+        let namespaces = self.cssrule.parent_stylesheet().style_stylesheet().contents.namespaces.read();
+        let parser = SelectorParser {
+            stylesheet_origin: Origin::Author,
+            namespaces: &namespaces,
+        };
+        let mut css_parser = CssParserInput::new(&*value);
+        let mut css_parser = CssParser::new(&mut css_parser);
+        if let Ok(mut s) = SelectorList::parse(&parser, &mut css_parser) {
+            // This mirrors what we do in CSSStyleOwner::mutate_associated_block.
+            let mut guard = self.cssrule.shared_lock().write();
+            let mut stylerule = self.stylerule.write_with(&mut guard);
+            mem::swap(&mut stylerule.selectors, &mut s);
+            // It seems like we will want to avoid having to invalidate all
+            // stylesheets eventually!
+            self.global().as_window().Document().invalidate_stylesheets();
+        }
+    }
 }

servo/components/script/dom/webidls/CSSStyleRule.webidl

@@ -5,6 +5,6 @@
 // https://drafts.csswg.org/cssom/#the-cssstylerule-interface
 [Exposed=Window]
 interface CSSStyleRule : CSSRule {
-  // attribute DOMString selectorText;
+  attribute DOMString selectorText;
   [SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
 };

servo/components/selectors/attr.rs

@@ -78,13 +78,15 @@ pub enum AttrSelectorOperator {
 
 impl ToCss for AttrSelectorOperator {
     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
+        // https://drafts.csswg.org/cssom/#serializing-selectors
+        // See "attribute selector".
         dest.write_str(match *self {
-            AttrSelectorOperator::Equal => " = ",
-            AttrSelectorOperator::Includes => " ~= ",
-            AttrSelectorOperator::DashMatch => " |= ",
-            AttrSelectorOperator::Prefix => " ^= ",
-            AttrSelectorOperator::Substring => " *= ",
-            AttrSelectorOperator::Suffix => " $= ",
+            AttrSelectorOperator::Equal => "=",
+            AttrSelectorOperator::Includes => "~=",
+            AttrSelectorOperator::DashMatch => "|=",
+            AttrSelectorOperator::Prefix => "^=",
+            AttrSelectorOperator::Substring => "*=",
+            AttrSelectorOperator::Suffix => "$=",
         })
     }
 }

servo/components/selectors/parser.rs

@@ -1953,7 +1953,7 @@ pub mod tests {
                 ].into_boxed_slice())
             ), specificity(0, 0, 1))
         ))));
-        assert_eq!(parse("[attr |= \"foo\"]"), Ok(SelectorList::from_vec(vec!(
+        assert_eq!(parse("[attr|=\"foo\"]"), Ok(SelectorList::from_vec(vec!(
             Selector::from_vec(vec!(
                 Component::AttributeInNoNamespace {
                     local_name: DummyAtom::from("attr"),
@@ -2012,7 +2012,7 @@ pub mod tests {
         parser.default_ns = None;
         assert!(parse(":not(#provel.old)").is_err());
         assert!(parse(":not(#provel > old)").is_err());
-        assert!(parse("table[rules]:not([rules = \"none\"]):not([rules = \"\"])").is_ok());
+        assert!(parse("table[rules]:not([rules=\"none\"]):not([rules=\"\"])").is_ok());
         assert_eq!(parse(":not(#provel)"), Ok(SelectorList::from_vec(vec!(
             Selector::from_vec(vec!(Component::Negation(vec!(
                     Component::ID(DummyAtom::from("provel")),

servo/tests/unit/style/parsing/selectors.rs

@@ -23,5 +23,5 @@ fn test_selectors() {
     assert_roundtrip!(parse_selector, "div");
     assert_roundtrip!(parse_selector, "svg|circle");
     assert_roundtrip!(parse_selector, "p:before", "p::before");
-    assert_roundtrip!(parse_selector, "[border = \"0\"]:-servo-nonzero-border ~ ::-servo-details-summary");
+    assert_roundtrip!(parse_selector, "[border=\"0\"]:-servo-nonzero-border ~ ::-servo-details-summary");
 }