Auto merge of #27282 - camelid:rc-domstring, r=jdm

Use `Rc` instead of cloning the `DOMString`

<!-- Please describe your changes on the following line: -->
I changed the `text` field of `ScriptOrigin` from a `DOMString` to an `Rc<DOMString>`. Then I updated all the related code to work with an `Rc`.

---
<!-- 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 fix #27254 (GitHub issue number if applicable)

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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because this doesn't introduce new code and should only need to be checked by the compiler

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components/script/dom/htmlscriptelement.rs

@@ -49,6 +49,7 @@ use std::fs::{create_dir_all, read_to_string, File};
 use std::io::{Read, Seek, Write};
 use std::path::PathBuf;
 use std::process::Command;
+use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 use style::str::{StaticStringVec, HTML_SPACE_CHARACTERS};
 use uuid::Uuid;
@@ -150,14 +151,15 @@ pub enum ScriptType {
 
 #[derive(JSTraceable, MallocSizeOf)]
 pub struct ScriptOrigin {
-    text: DOMString,
+    #[ignore_malloc_size_of = "Rc is hard"]
+    text: Rc<DOMString>,
     url: ServoUrl,
     external: bool,
     type_: ScriptType,
 }
 
 impl ScriptOrigin {
-    pub fn internal(text: DOMString, url: ServoUrl, type_: ScriptType) -> ScriptOrigin {
+    pub fn internal(text: Rc<DOMString>, url: ServoUrl, type_: ScriptType) -> ScriptOrigin {
         ScriptOrigin {
             text: text,
             url: url,
@@ -166,7 +168,7 @@ impl ScriptOrigin {
         }
     }
 
-    pub fn external(text: DOMString, url: ServoUrl, type_: ScriptType) -> ScriptOrigin {
+    pub fn external(text: Rc<DOMString>, url: ServoUrl, type_: ScriptType) -> ScriptOrigin {
         ScriptOrigin {
             text: text,
             url: url,
@@ -175,8 +177,8 @@ impl ScriptOrigin {
         }
     }
 
-    pub fn text(&self) -> DOMString {
-        self.text.clone()
+    pub fn text(&self) -> Rc<DOMString> {
+        Rc::clone(&self.text)
     }
 }
 
@@ -257,7 +259,7 @@ impl FetchResponseListener for ClassicContext {
             // Step 7.
             let (source_text, _, _) = encoding.decode(&self.data);
             ScriptOrigin::external(
-                DOMString::from(source_text),
+                Rc::new(DOMString::from(source_text)),
                 metadata.final_url,
                 ScriptType::Classic,
             )
@@ -611,9 +613,11 @@ impl HTMLScriptElement {
             // Step 25.
             assert!(!text.is_empty());
 
+            let text_rc = Rc::new(text);
+
             // Step 25-1. & 25-2.
             let result = Ok(ScriptOrigin::internal(
-                text.clone(),
+                Rc::clone(&text_rc),
                 base_url.clone(),
                 script_type.clone(),
             ));
@@ -647,7 +651,7 @@ impl HTMLScriptElement {
 
                     fetch_inline_module_script(
                         ModuleOwner::Window(Trusted::new(self)),
-                        text.clone(),
+                        text_rc,
                         base_url.clone(),
                         self.id.clone(),
                         credentials_mode.unwrap(),
@@ -679,7 +683,7 @@ impl HTMLScriptElement {
                     let mut script_content = String::new();
                     output.seek(std::io::SeekFrom::Start(0)).unwrap();
                     output.read_to_string(&mut script_content).unwrap();
-                    script.text = DOMString::from(script_content);
+                    script.text = Rc::new(DOMString::from(script_content));
                 },
                 _ => {
                     warn!("Failed to execute js-beautify. Will store unmodified script");
@@ -757,7 +761,7 @@ impl HTMLScriptElement {
         match read_to_string(path.clone()) {
             Ok(local_script) => {
                 debug!("Found script stored at: {:?}", path);
-                script.text = DOMString::from(local_script);
+                script.text = Rc::new(DOMString::from(local_script));
             },
             Err(why) => warn!("Could not restore script from file {:?}", why),
         }

components/script/script_module.rs

@@ -143,7 +143,7 @@ impl ModuleIdentity {
 #[derive(JSTraceable)]
 pub struct ModuleTree {
     url: ServoUrl,
-    text: DomRefCell<DOMString>,
+    text: DomRefCell<Rc<DOMString>>,
     record: DomRefCell<Option<ModuleObject>>,
     status: DomRefCell<ModuleStatus>,
     // The spec maintains load order for descendants, so we use an indexset for descendants and
@@ -171,7 +171,7 @@ impl ModuleTree {
     pub fn new(url: ServoUrl, external: bool, visited_urls: HashSet<ServoUrl>) -> Self {
         ModuleTree {
             url,
-            text: DomRefCell::new(DOMString::new()),
+            text: DomRefCell::new(Rc::new(DOMString::new())),
             record: DomRefCell::new(None),
             status: DomRefCell::new(ModuleStatus::Initial),
             parent_identities: DomRefCell::new(IndexSet::new()),
@@ -217,11 +217,11 @@ impl ModuleTree {
         *self.network_error.borrow_mut() = Some(network_error);
     }
 
-    pub fn get_text(&self) -> &DomRefCell<DOMString> {
+    pub fn get_text(&self) -> &DomRefCell<Rc<DOMString>> {
         &self.text
     }
 
-    pub fn set_text(&self, module_text: DOMString) {
+    pub fn set_text(&self, module_text: Rc<DOMString>) {
         *self.text.borrow_mut() = module_text;
     }
 
@@ -351,7 +351,7 @@ impl ModuleTree {
     fn compile_module_script(
         &self,
         global: &GlobalScope,
-        module_script_text: DOMString,
+        module_script_text: Rc<DOMString>,
         url: ServoUrl,
     ) -> Result<ModuleObject, RethrowError> {
         let module: Vec<u16> = module_script_text.encode_utf16().collect();
@@ -852,12 +852,12 @@ impl ModuleOwner {
                         Some(network_error) => Err(network_error.clone()),
                         None => match module_identity {
                             ModuleIdentity::ModuleUrl(script_src) => Ok(ScriptOrigin::external(
-                                module_tree.get_text().borrow().clone(),
+                                Rc::clone(&module_tree.get_text().borrow()),
                                 script_src.clone(),
                                 ScriptType::Module,
                             )),
                             ModuleIdentity::ScriptId(_) => Ok(ScriptOrigin::internal(
-                                module_tree.get_text().borrow().clone(),
+                                Rc::clone(&module_tree.get_text().borrow()),
                                 document.base_url().clone(),
                                 ScriptType::Module,
                             )),
@@ -980,7 +980,7 @@ impl FetchResponseListener for ModuleContext {
             // Step 10.
             let (source_text, _, _) = UTF_8.decode(&self.data);
             Ok(ScriptOrigin::external(
-                DOMString::from(source_text),
+                Rc::new(DOMString::from(source_text)),
                 meta.final_url,
                 ScriptType::Module,
             ))
@@ -1302,7 +1302,7 @@ pub fn fetch_single_module_script(
 /// https://html.spec.whatwg.org/multipage/#fetch-an-inline-module-script-graph
 pub fn fetch_inline_module_script(
     owner: ModuleOwner,
-    module_script_text: DOMString,
+    module_script_text: Rc<DOMString>,
     url: ServoUrl,
     script_id: ScriptId,
     credentials_mode: CredentialsMode,