Use flexstr for message storage

boa_engine/Cargo.toml

@@ -51,6 +51,7 @@ dyn-clone = "1.0.9"
 once_cell = "1.14.0"
 tap = "1.0.1"
 thiserror = "1.0.35"
+flexstr = "0.9.2"
 icu_locale_canonicalizer = { version = "0.6.0", features = ["serde"], optional = true }
 icu_locid = { version = "0.6.0", features = ["serde"], optional = true }
 icu_datetime = { version = "0.6.0", features = ["serde"], optional = true }

boa_engine/src/error/mod.rs → boa_engine/src/error.rs

@@ -1,5 +1,3 @@
-mod vos;
-
 use crate::{
     builtins::{error::ErrorKind, Array},
     object::JsObject,
@@ -9,9 +7,9 @@ use crate::{
     Context, JsResult, JsValue,
 };
 use boa_gc::{Finalize, Trace};
-use std::borrow::Cow;
+use flexstr::LocalStr;
+use std::{borrow::Cow, fmt::Display};
 use thiserror::Error;
-use vos::ViewStr;
 
 /// The error type returned by all operations related
 /// to the execution of Javascript code.
@@ -170,14 +168,13 @@ impl JsError {
                         let message = if obj.has_property("message", context)? {
                             obj.get("message", context)?
                                 .as_string()
-                                .map(ToString::to_string)
+                                .map(LocalStr::from_ref)
                                 .ok_or_else(|| {
                                     JsNativeError::typ()
                                         .with_message("invalid type for field `message`")
                                 })?
-                                .into()
                         } else {
-                            "".into()
+                            JsNativeError::DEFAULT_MSG
                         };
 
                         let cause = obj
@@ -293,7 +290,7 @@ impl From<JsNativeError> for JsError {
     }
 }
 
-impl std::fmt::Display for JsError {
+impl Display for JsError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match &self.inner {
             Repr::Native(e) => e.fmt(f),
@@ -330,15 +327,16 @@ pub struct JsNativeError {
     /// The kind of native error (e.g. `TypeError`, `SyntaxError`, etc.)
     pub kind: JsNativeErrorKind,
     #[unsafe_ignore_trace]
-    message: ViewStr,
+    message: LocalStr,
     #[source]
     cause: Option<Box<JsError>>,
 }
 
 impl JsNativeError {
+    const DEFAULT_MSG: LocalStr = LocalStr::from_static("");
     /// Creates a new `JsNativeError` from its `kind`, `message` and (optionally)
     /// its `cause`.
-    fn new(kind: JsNativeErrorKind, message: ViewStr, cause: Option<Box<JsError>>) -> Self {
+    fn new(kind: JsNativeErrorKind, message: LocalStr, cause: Option<Box<JsError>>) -> Self {
         Self {
             kind,
             message,
@@ -365,7 +363,11 @@ impl JsNativeError {
     /// ));
     /// ```
     pub fn aggregate(errors: Vec<JsError>) -> Self {
-        Self::new(JsNativeErrorKind::Aggregate(errors), "".into(), None)
+        Self::new(
+            JsNativeErrorKind::Aggregate(errors),
+            Self::DEFAULT_MSG,
+            None,
+        )
     }
 
     /// Creates a new `JsNativeError` of kind `Error`, with empty `message`
@@ -380,7 +382,7 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Error));
     /// ```
     pub fn error() -> Self {
-        Self::new(JsNativeErrorKind::Error, "".into(), None)
+        Self::new(JsNativeErrorKind::Error, Self::DEFAULT_MSG, None)
     }
 
     /// Creates a new `JsNativeError` of kind `EvalError`, with empty `message`
@@ -395,7 +397,7 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Eval));
     /// ```
     pub fn eval() -> Self {
-        Self::new(JsNativeErrorKind::Eval, "".into(), None)
+        Self::new(JsNativeErrorKind::Eval, Self::DEFAULT_MSG, None)
     }
 
     /// Creates a new `JsNativeError` of kind `RangeError`, with empty `message`
@@ -410,7 +412,7 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Range));
     /// ```
     pub fn range() -> Self {
-        Self::new(JsNativeErrorKind::Range, "".into(), None)
+        Self::new(JsNativeErrorKind::Range, Self::DEFAULT_MSG, None)
     }
 
     /// Creates a new `JsNativeError` of kind `ReferenceError`, with empty `message`
@@ -425,7 +427,7 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Reference));
     /// ```
     pub fn reference() -> Self {
-        Self::new(JsNativeErrorKind::Reference, "".into(), None)
+        Self::new(JsNativeErrorKind::Reference, Self::DEFAULT_MSG, None)
     }
 
     /// Creates a new `JsNativeError` of kind `SyntaxError`, with empty `message`
@@ -440,7 +442,7 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Syntax));
     /// ```
     pub fn syntax() -> Self {
-        Self::new(JsNativeErrorKind::Syntax, "".into(), None)
+        Self::new(JsNativeErrorKind::Syntax, Self::DEFAULT_MSG, None)
     }
 
     /// Creates a new `JsNativeError` of kind `TypeError`, with empty `message`
@@ -455,7 +457,7 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Type));
     /// ```
     pub fn typ() -> Self {
-        Self::new(JsNativeErrorKind::Type, "".into(), None)
+        Self::new(JsNativeErrorKind::Type, Self::DEFAULT_MSG, None)
     }
 
     /// Creates a new `JsNativeError` of kind `UriError`, with empty `message`
@@ -470,15 +472,15 @@ impl JsNativeError {
     /// assert!(matches!(error.kind, JsNativeErrorKind::Uri));
     /// ```
     pub fn uri() -> Self {
-        Self::new(JsNativeErrorKind::Uri, "".into(), None)
+        Self::new(JsNativeErrorKind::Uri, Self::DEFAULT_MSG, None)
     }
 
     /// Appends a message to this error.
     ///
     /// # Note
     ///
     /// A static [`str`] will be stored as a simple pointer,
-    /// while a [`String`] will be converted to a [`Rc<str>`][std::rc::Rc<str>] in order
+    /// while a [`String`] will be converted to a <code>[Rc]<[str]></code> in order
     /// to make clones more efficient. Prefer static `str`s if you want
     /// efficiency, and [`String`] s if you prefer descriptive error messages.
     ///
@@ -495,7 +497,11 @@ impl JsNativeError {
     where
         S: Into<Cow<'static, str>>,
     {
-        self.message = message.into().into();
+        let message = match message.into() {
+            Cow::Borrowed(str) => LocalStr::from_static(str),
+            Cow::Owned(string) => LocalStr::from_ref(string),
+        };
+        self.message = message;
         self
     }
 
@@ -727,7 +733,7 @@ pub enum JsNativeErrorKind {
     Uri,
 }
 
-impl std::fmt::Display for JsNativeErrorKind {
+impl Display for JsNativeErrorKind {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             JsNativeErrorKind::Aggregate(_) => "AggregateError",