From e272bfed70819d25911285bebf9fb3397bb3dbae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Tue, 11 Jun 2019 17:42:49 +0000
Subject: [PATCH] style: Implement GeckoElement::each_part.

This should make all the pieces come together.

Note that we don't need to look at the snapshot for ::part() for now (other than
when selector-matching normally) because I decided to just restyle the element
for now when the part attribute changes.

::part() can't affect descendants anyway (as long as we don't do the forwarding
stuff), and eager pseudo-elements are handled during the normal element restyle,
so it seems to me that adding all the complexity that we have for classes to
part may not be worth it at least yet.

Differential Revision: https://phabricator.services.mozilla.com/D32648
---
 components/style/gecko/snapshot.rs         |  2 +-
 components/style/gecko/snapshot_helpers.rs |  4 ++--
 components/style/gecko/wrapper.rs          | 14 +++++++++++++-
 3 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/components/style/gecko/snapshot.rs b/components/style/gecko/snapshot.rs
index d294939baeb..cffb78d3e9e 100644
--- a/components/style/gecko/snapshot.rs
+++ b/components/style/gecko/snapshot.rs
@@ -211,7 +211,7 @@ impl ElementSnapshot for GeckoElementSnapshot {
             return;
         }
 
-        snapshot_helpers::each_class(&self.mClass, callback)
+        snapshot_helpers::each_class_or_part(&self.mClass, callback)
     }
 
     #[inline]
diff --git a/components/style/gecko/snapshot_helpers.rs b/components/style/gecko/snapshot_helpers.rs
index aaa2254dbd7..b8b31bc87dd 100644
--- a/components/style/gecko/snapshot_helpers.rs
+++ b/components/style/gecko/snapshot_helpers.rs
@@ -107,9 +107,9 @@ pub fn has_class_or_part(
 }
 
 /// Given an item, a callback, and a getter, execute `callback` for each class
-/// this `item` has.
+/// or part name this `item` has.
 #[inline(always)]
-pub fn each_class<F>(attr: &structs::nsAttrValue, mut callback: F)
+pub fn each_class_or_part<F>(attr: &structs::nsAttrValue, mut callback: F)
 where
     F: FnMut(&Atom),
 {
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 17c1cfaf35d..ba2951f6f25 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -1372,7 +1372,19 @@ impl<'le> TElement for GeckoElement<'le> {
             None => return,
         };
 
-        snapshot_helpers::each_class(attr, callback)
+        snapshot_helpers::each_class_or_part(attr, callback)
+    }
+
+    fn each_part<F>(&self, callback: F)
+    where
+        F: FnMut(&Atom),
+    {
+        let attr = match self.get_part_attr() {
+            Some(c) => c,
+            None => return,
+        };
+
+        snapshot_helpers::each_class_or_part(attr, callback)
     }
 
     #[inline]