Auto merge of #18968 - mbrubeck:try, r=emilio

Use try syntax for Option where appropriate

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes do not require tests because they are refactoring only

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components/script/dom/document.rs

@@ -2089,10 +2089,9 @@ fn get_registrable_domain_suffix_of_or_is_equal_to(host_suffix_string: &str, ori
         };
 
         // Step 4.2
-        let (prefix, suffix) = match original_host.len().checked_sub(host.len()) {
-            Some(index) => original_host.split_at(index),
-            None => return None,
-        };
+        let index = original_host.len().checked_sub(host.len())?;
+        let (prefix, suffix) = original_host.split_at(index);
+
         if !prefix.ends_with(".") {
             return None;
         }
@@ -2336,11 +2335,7 @@ impl Document {
     ///
     /// Also, shouldn't return an option, I'm quite sure.
     pub fn device(&self) -> Option<Device> {
-        let window_size = match self.window().window_size() {
-            Some(ws) => ws,
-            None => return None,
-        };
-
+        let window_size = self.window().window_size()?;
         let viewport_size = window_size.initial_viewport;
         let device_pixel_ratio = window_size.device_pixel_ratio;
         Some(Device::new(MediaType::screen(), viewport_size, device_pixel_ratio))
@@ -4034,12 +4029,9 @@ impl PendingInOrderScriptVec {
 
     fn take_next_ready_to_be_executed(&self) -> Option<(DomRoot<HTMLScriptElement>, ScriptResult)> {
         let mut scripts = self.scripts.borrow_mut();
-        let pair = scripts.front_mut().and_then(PendingScript::take_result);
-        if pair.is_none() {
-            return None;
-        }
+        let pair = scripts.front_mut()?.take_result()?;
         scripts.pop_front();
-        pair
+        Some(pair)
     }
 
     fn clear(&self) {

components/script/dom/element.rs

@@ -1040,24 +1040,20 @@ impl Element {
     // https://dom.spec.whatwg.org/#locate-a-namespace-prefix
     pub fn lookup_prefix(&self, namespace: Namespace) -> Option<DOMString> {
         for node in self.upcast::<Node>().inclusive_ancestors() {
-            match node.downcast::<Element>() {
-                Some(element) => {
-                    // Step 1.
-                    if *element.namespace() == namespace {
-                        if let Some(prefix) = element.GetPrefix() {
-                            return Some(prefix);
-                        }
-                    }
+            let element = node.downcast::<Element>()?;
+            // Step 1.
+            if *element.namespace() == namespace {
+                if let Some(prefix) = element.GetPrefix() {
+                    return Some(prefix);
+                }
+            }
 
-                    // Step 2.
-                    for attr in element.attrs.borrow().iter() {
-                        if attr.prefix() == Some(&namespace_prefix!("xmlns")) &&
-                           **attr.value() == *namespace {
-                            return Some(attr.LocalName());
-                        }
-                    }
-                },
-                None => return None,
+            // Step 2.
+            for attr in element.attrs.borrow().iter() {
+                if attr.prefix() == Some(&namespace_prefix!("xmlns")) &&
+                   **attr.value() == *namespace {
+                    return Some(attr.LocalName());
+                }
             }
         }
         None

components/script/dom/htmlcanvaselement.rs

@@ -219,12 +219,7 @@ impl HTMLCanvasElement {
                 let msg = CanvasMsg::FromScript(FromScriptMsg::SendPixels(sender));
                 context.get_ipc_renderer().send(msg).unwrap();
 
-                match receiver.recv().unwrap() {
-                    Some(pixels) => pixels,
-                    None => {
-                        return None;
-                    }
-                }
+                receiver.recv().unwrap()?
             },
             Some(&CanvasContext::WebGL(_)) => {
                 // TODO: add a method in WebGLRenderingContext to get the pixels.

components/script/dom/htmliframeelement.rs

@@ -588,17 +588,13 @@ impl HTMLIFrameElementMethods for HTMLIFrameElement {
     // https://html.spec.whatwg.org/multipage/#concept-bcc-content-document
     fn GetContentDocument(&self) -> Option<DomRoot<Document>> {
         // Step 1.
-        let pipeline_id = match self.pipeline_id.get() {
-            None => return None,
-            Some(pipeline_id) => pipeline_id,
-        };
+        let pipeline_id = self.pipeline_id.get()?;
+
         // Step 2-3.
         // Note that this lookup will fail if the document is dissimilar-origin,
         // so we should return None in that case.
-        let document = match ScriptThread::find_document(pipeline_id) {
-            None => return None,
-            Some(document) => document,
-        };
+        let document = ScriptThread::find_document(pipeline_id)?;
+
         // Step 4.
         let current = GlobalScope::current().expect("No current global object").as_window().Document();
         if !current.origin().same_origin_domain(document.origin()) {

components/script/dom/htmlimageelement.rs

@@ -661,10 +661,7 @@ impl HTMLImageElement {
     }
     pub fn areas(&self) -> Option<Vec<DomRoot<HTMLAreaElement>>> {
         let elem = self.upcast::<Element>();
-        let usemap_attr = match elem.get_attribute(&ns!(), &local_name!("usemap")) {
-            Some(attr) => attr,
-            None => return None,
-        };
+        let usemap_attr = elem.get_attribute(&ns!(), &local_name!("usemap"))?;
 
         let value = usemap_attr.value();
 

components/script/dom/node.rs

@@ -1206,11 +1206,7 @@ pub struct FollowingNodeIterator {
 impl FollowingNodeIterator {
     /// Skips iterating the children of the current node
     pub fn next_skipping_children(&mut self) -> Option<DomRoot<Node>> {
-        let current = match self.current.take() {
-            None => return None,
-            Some(current) => current,
-        };
-
+        let current = self.current.take()?;
         self.next_skipping_children_impl(current)
     }
 
@@ -1244,10 +1240,7 @@ impl Iterator for FollowingNodeIterator {
 
     // https://dom.spec.whatwg.org/#concept-tree-following
     fn next(&mut self) -> Option<DomRoot<Node>> {
-        let current = match self.current.take() {
-            None => return None,
-            Some(current) => current,
-        };
+        let current = self.current.take()?;
 
         if let Some(first_child) = current.GetFirstChild() {
             self.current = Some(first_child);
@@ -1268,10 +1261,7 @@ impl Iterator for PrecedingNodeIterator {
 
     // https://dom.spec.whatwg.org/#concept-tree-preceding
     fn next(&mut self) -> Option<DomRoot<Node>> {
-        let current = match self.current.take() {
-            None => return None,
-            Some(current) => current,
-        };
+        let current = self.current.take()?;
 
         self.current = if self.root == current {
             None
@@ -1323,10 +1313,7 @@ impl TreeIterator {
     }
 
     pub fn next_skipping_children(&mut self) -> Option<DomRoot<Node>> {
-        let current = match self.current.take() {
-            None => return None,
-            Some(current) => current,
-        };
+        let current = self.current.take()?;
 
         self.next_skipping_children_impl(current)
     }
@@ -1353,10 +1340,7 @@ impl Iterator for TreeIterator {
 
     // https://dom.spec.whatwg.org/#concept-tree-order
     fn next(&mut self) -> Option<DomRoot<Node>> {
-        let current = match self.current.take() {
-            None => return None,
-            Some(current) => current,
-        };
+        let current = self.current.take()?;
         if let Some(first_child) = current.GetFirstChild() {
             self.current = Some(first_child);
             self.depth += 1;

components/script/dom/servoparser/mod.rs

@@ -480,10 +480,7 @@ impl<I> Iterator for FragmentParsingResult<I>
     type Item = DomRoot<Node>;
 
     fn next(&mut self) -> Option<DomRoot<Node>> {
-        let next = match self.inner.next() {
-            Some(next) => next,
-            None => return None,
-        };
+        let next = self.inner.next()?;
         next.remove_self();
         Some(next)
     }

components/script/dom/treewalker.rs

@@ -395,13 +395,9 @@ impl TreeWalker {
             None => {
                 let mut candidate = DomRoot::from_ref(node);
                 while !self.is_root_node(&candidate) && candidate.GetNextSibling().is_none() {
-                    match candidate.GetParentNode() {
-                        None =>
-                            // This can happen if the user set the current node to somewhere
-                            // outside of the tree rooted at the original root.
-                            return None,
-                        Some(n) => candidate = n
-                    }
+                    // This can return None if the user set the current node to somewhere
+                    // outside of the tree rooted at the original root.
+                    candidate = candidate.GetParentNode()?;
                 }
                 if self.is_root_node(&candidate) {
                     None

components/script/dom/window.rs

@@ -591,15 +591,11 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-frameelement
     fn GetFrameElement(&self) -> Option<DomRoot<Element>> {
         // Steps 1-3.
-        let window_proxy = match self.window_proxy.get() {
-            None => return None,
-            Some(window_proxy) => window_proxy,
-        };
+        let window_proxy = self.window_proxy.get()?;
+
         // Step 4-5.
-        let container = match window_proxy.frame_element() {
-            None => return None,
-            Some(container) => container,
-        };
+        let container = window_proxy.frame_element()?;
+
         // Step 6.
         let container_doc = document_from_node(container);
         let current_doc = GlobalScope::current().expect("No current global object").as_window().Document();
@@ -687,10 +683,8 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-parent
     fn GetParent(&self) -> Option<DomRoot<WindowProxy>> {
         // Steps 1-3.
-        let window_proxy = match self.undiscarded_window_proxy() {
-            Some(window_proxy) => window_proxy,
-            None => return None,
-        };
+        let window_proxy = self.undiscarded_window_proxy()?;
+
         // Step 4.
         if let Some(parent) = window_proxy.parent() {
             return Some(DomRoot::from_ref(parent));
@@ -702,10 +696,8 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-top
     fn GetTop(&self) -> Option<DomRoot<WindowProxy>> {
         // Steps 1-3.
-        let window_proxy = match self.undiscarded_window_proxy() {
-            Some(window_proxy) => window_proxy,
-            None => return None,
-        };
+        let window_proxy = self.undiscarded_window_proxy()?;
+
         // Steps 4-5.
         Some(DomRoot::from_ref(window_proxy.top()))
     }