Auto merge of #17601 - ferjm:bug1370502.selector.matches.element, r=emilio

stylo: Implement ServoStyleRule::SelectorMatchesElement

from https://bugzilla.mozilla.org/show_bug.cgi?id=1370502

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3 files changed, 57 insertions, 0 deletions

diff --git a/components/style/gecko/generated/bindings.rs b/components/style/gecko/generated/bindings.rs
index 96d9b3f9dd3..84e4c69cba6 100644
--- a/components/style/gecko/generated/bindings.rs
+++ b/components/style/gecko/generated/bindings.rs
@@ -2145,6 +2145,16 @@ extern "C" {
                                             count: *mut u32);
 }
 extern "C" {
+    pub fn Servo_StyleRule_SelectorMatchesElement(arg1:
+                                                      RawServoStyleRuleBorrowed,
+                                                  arg2:
+                                                      RawGeckoElementBorrowed,
+                                                  index: u32,
+                                                  pseudo_type:
+                                                      CSSPseudoElementType)
+     -> bool;
+}
+extern "C" {
     pub fn Servo_ImportRule_GetHref(rule: RawServoImportRuleBorrowed,
                                     result: *mut nsAString);
 }
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index a7aff7f3a73..3af035cd208 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -694,6 +694,11 @@ impl<'le> GeckoElement<'le> {
         let node = self.as_node();
         unsafe { Gecko_GetDocumentLWTheme(node.owner_doc()) }
     }
+
+    /// Owner document quirks mode getter.
+    pub fn owner_document_quirks_mode(&self) -> QuirksMode {
+        self.as_node().owner_doc().mCompatMode.into()
+    }
 }
 
 /// Converts flags from the layout used by rust-selectors to the layout used
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 4f47df2ebc0..2b023147b02 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -7,6 +7,7 @@ use cssparser::{Parser, ParserInput};
 use cssparser::ToCss as ParserToCss;
 use env_logger::LogBuilder;
 use selectors::Element;
+use selectors::matching::{MatchingContext, MatchingMode, matches_selector};
 use std::env;
 use std::fmt::Write;
 use std::ptr;
@@ -1256,6 +1257,47 @@ pub extern "C" fn Servo_StyleRule_GetSpecificityAtIndex(
 }
 
 #[no_mangle]
+pub extern "C" fn Servo_StyleRule_SelectorMatchesElement(rule: RawServoStyleRuleBorrowed,
+                                                         element: RawGeckoElementBorrowed,
+                                                         index: u32,
+                                                         pseudo_type: CSSPseudoElementType) -> bool {
+    read_locked_arc(rule, |rule: &StyleRule| {
+        let index = index as usize;
+        if index >= rule.selectors.0.len() {
+            return false;
+        }
+
+        let selector_and_hashes = &rule.selectors.0[index];
+        let mut matching_mode = MatchingMode::Normal;
+
+        match PseudoElement::from_pseudo_type(pseudo_type) {
+            Some(pseudo) => {
+                // We need to make sure that the requested pseudo element type
+                // matches the selector pseudo element type before proceeding.
+                match selector_and_hashes.selector.pseudo_element() {
+                    Some(selector_pseudo) if *selector_pseudo == pseudo => {
+                        matching_mode = MatchingMode::ForStatelessPseudoElement
+                    },
+                    _ => return false,
+                };
+            },
+            None => {
+                // Do not attempt to match if a pseudo element is requested and
+                // this is not a pseudo element selector, or vice versa.
+                if selector_and_hashes.selector.has_pseudo_element() {
+                    return false;
+                }
+            },
+        };
+
+        let element = GeckoElement(element);
+        let mut ctx = MatchingContext::new(matching_mode, None, element.owner_document_quirks_mode());
+        matches_selector(&selector_and_hashes.selector, 0, &selector_and_hashes.hashes,
+                         &element, &mut ctx, &mut |_, _| {})
+    })
+}
+
+#[no_mangle]
 pub extern "C" fn Servo_ImportRule_GetHref(rule: RawServoImportRuleBorrowed, result: *mut nsAString) {
     read_locked_arc(rule, |rule: &ImportRule| {
         write!(unsafe { &mut *result }, "{}", rule.url.as_str()).unwrap();