Reduce usage of Default::default()

CHANGELOG.md

@@ -9,6 +9,7 @@ Bug fixes
 
 * Custom syntax starting with a disabled standard keyword now works properly.
 * When calling `Engine::call_fn`, new variables defined during evaluation of the body script are removed and no longer spill into the function call.
+* `NamespaceRef::new` is fixed.
 
 Enhancements
 ------------

codegen/src/module.rs

@@ -49,7 +49,7 @@ impl ExportedParams for ExportedModParams {
 
     fn from_info(info: ExportInfo) -> syn::Result<Self> {
         let ExportInfo { items: attrs, .. } = info;
-        let mut name = Default::default();
+        let mut name = String::new();
         let mut skip = false;
         let mut scope = None;
         for attr in attrs {

src/ast.rs

@@ -201,13 +201,7 @@ pub struct AST {
 impl Default for AST {
     #[inline(always)]
     fn default() -> Self {
-        Self {
-            source: None,
-            body: Default::default(),
-            functions: Default::default(),
-            #[cfg(not(feature = "no_module"))]
-            resolver: None,
-        }
+        Self::new_empty()
     }
 }
 
@@ -227,6 +221,18 @@ impl AST {
             resolver: None,
         }
     }
+    /// Create an empty [`AST`].
+    #[inline]
+    #[must_use]
+    pub fn new_empty() -> Self {
+        Self {
+            source: None,
+            body: Default::default(),
+            functions: Default::default(),
+            #[cfg(not(feature = "no_module"))]
+            resolver: None,
+        }
+    }
     /// Create a new [`AST`] with a source name.
     #[inline(always)]
     #[must_use]

src/bin/rhai-repl.rs

@@ -163,9 +163,9 @@ fn main() {
 
     // REPL loop
     let mut input = String::new();
-    let mut main_ast: AST = Default::default();
-    let mut ast_u: AST = Default::default();
-    let mut ast: AST = Default::default();
+    let mut main_ast = AST::new_empty();
+    let mut ast_u = AST::new_empty();
+    let mut ast = AST::new_empty();
 
     'main_loop: loop {
         print!("rhai-repl> ");

src/custom_syntax.rs

@@ -198,7 +198,7 @@ impl Engine {
     ) -> Result<&mut Self, ParseError> {
         use markers::*;
 
-        let mut segments: StaticVec<ImmutableString> = Default::default();
+        let mut segments = StaticVec::<ImmutableString>::new();
 
         for s in symbols {
             let s = s.as_ref().trim();

src/engine.rs

@@ -2766,7 +2766,7 @@ impl Engine {
                             }
                             #[cfg(not(feature = "no_object"))]
                             _ => {
-                                let mut err_map: Map = Default::default();
+                                let mut err_map = Map::new();
                                 let err_pos = err.take_position();
 
                                 err_map.insert("message".into(), err.to_string().into());

src/engine_api.rs

@@ -961,7 +961,7 @@ impl Engine {
                 let remainder = iter.next().expect("name contains separator").trim();
 
                 if !root.contains_key(sub_module) {
-                    let mut m: Module = Default::default();
+                    let mut m = Module::new();
                     register_static_module_raw(m.sub_modules_mut(), remainder, module);
                     m.build_index();
                     root.insert(sub_module.into(), m.into());
@@ -1351,7 +1351,7 @@ impl Engine {
             json: &str,
             has_null: bool,
         ) -> Result<Map, Box<EvalAltResult>> {
-            let mut scope = Default::default();
+            let mut scope = Scope::new();
             let json_text = json.trim_start();
             let scripts = if json_text.starts_with(Token::MapStart.literal_syntax()) {
                 [json_text, ""]
@@ -1860,7 +1860,7 @@ impl Engine {
         name: impl AsRef<str>,
         args: impl crate::FuncArgs,
     ) -> Result<T, Box<EvalAltResult>> {
-        let mut arg_values: crate::StaticVec<_> = Default::default();
+        let mut arg_values = crate::StaticVec::new();
         args.parse(&mut arg_values);
         let mut args: crate::StaticVec<_> = arg_values.iter_mut().collect();
         let name = name.as_ref();
@@ -2053,7 +2053,7 @@ impl Engine {
     #[inline]
     #[must_use]
     pub fn gen_fn_signatures(&self, include_packages: bool) -> Vec<String> {
-        let mut signatures: Vec<_> = Default::default();
+        let mut signatures = Vec::new();
 
         signatures.extend(self.global_namespace().gen_fn_signatures());
 

src/lib.rs

@@ -264,7 +264,7 @@ pub use module::NamespaceRef;
 /// being the third number, be reached, then, lobbest thou thy `SmallVec` towards thy heap, who,
 /// being slow and cache-naughty in My sight, shall snuff it."
 ///
-/// # Explanation on the Number Three
+/// # Why Three
 ///
 /// `StaticVec` is used frequently to keep small lists of items in inline (non-heap) storage in
 /// order to improve cache friendliness and reduce indirections.
@@ -274,14 +274,14 @@ pub use module::NamespaceRef;
 /// in that matter) contain fewer than 4 arguments, the exception being closures that capture a
 /// large number of external variables.
 ///
-/// In addition, most script blocks either contain many statements, or just a few lines;
+/// In addition, most script blocks either contain many statements, or just one or two lines;
 /// most scripts load fewer than 4 external modules; most module paths contain fewer than 4 levels
-/// (e.g. `std::collections::map::HashMap` is 4 levels).
+/// (e.g. `std::collections::map::HashMap` is 4 levels and it is just about as long as they get).
 #[cfg(not(feature = "internals"))]
 type StaticVec<T> = smallvec::SmallVec<[T; 3]>;
 
-/// _(internals)_ Alias to [`smallvec`](https://crates.io/crates/smallvec), which is a specialized
-/// [`Vec`] backed by a small, inline, fixed-size array when there are ≤ 3 items stored.
+/// _(internals)_ Alias to [`smallvec::SmallVec<[T; 3]>`](https://crates.io/crates/smallvec),
+/// which is a [`Vec`] backed by a small, inline, fixed-size array when there are ≤ 3 items stored.
 /// Exported under the `internals` feature only.
 ///
 /// # History
@@ -299,7 +299,7 @@ type StaticVec<T> = smallvec::SmallVec<[T; 3]>;
 /// being the third number, be reached, then, lobbest thou thy `SmallVec` towards thy heap, who,
 /// being slow and cache-naughty in My sight, shall snuff it."
 ///
-/// # Explanation on the Number Three
+/// # Why Three
 ///
 /// `StaticVec` is used frequently to keep small lists of items in inline (non-heap) storage in
 /// order to improve cache friendliness and reduce indirections.
@@ -309,9 +309,9 @@ type StaticVec<T> = smallvec::SmallVec<[T; 3]>;
 /// in that matter) contain fewer than 4 arguments, the exception being closures that capture a
 /// large number of external variables.
 ///
-/// In addition, most script blocks either contain many statements, or just a few lines;
+/// In addition, most script blocks either contain many statements, or just one or two lines;
 /// most scripts load fewer than 4 external modules; most module paths contain fewer than 4 levels
-/// (e.g. `std::collections::map::HashMap` is 4 levels).
+/// (e.g. `std::collections::map::HashMap` is 4 levels and it is just about as long as they get).
 #[cfg(feature = "internals")]
 pub type StaticVec<T> = smallvec::SmallVec<[T; 3]>;
 

src/packages/array_basic.rs

@@ -179,7 +179,7 @@ mod array_functions {
                 if n as usize > array.len() {
                     mem::take(array)
                 } else {
-                    let mut result: Array = Default::default();
+                    let mut result = Array::new();
                     result.extend(array.drain(array.len() - n as usize..));
                     result
                 }
@@ -189,7 +189,7 @@ mod array_functions {
         } else if start as usize >= array.len() {
             Default::default()
         } else {
-            let mut result: Array = Default::default();
+            let mut result = Array::new();
             result.extend(array.drain(start as usize..));
             result
         }

src/packages/fn_basic.rs

@@ -92,7 +92,7 @@ fn collect_fn_metadata(ctx: NativeCallContext) -> crate::Array {
     .map(|&s| s.into())
     .collect();
 
-    let mut list: Array = Default::default();
+    let mut list = Array::new();
 
     ctx.iter_namespaces()
         .flat_map(|m| m.iter_script_fn())

src/parse.rs

@@ -82,7 +82,7 @@ pub struct ParseState<'e> {
     /// Interned strings.
     interned_strings: IdentifierBuilder,
     /// Encapsulates a local stack with variable names to simulate an actual runtime scope.
-    stack: Vec<(Identifier, AccessMode)>,
+    stack: StaticVec<(Identifier, AccessMode)>,
     /// Size of the local variables stack upon entry of the current block scope.
     entry_stack_len: usize,
     /// Tracks a list of external variables (variables that are not explicitly declared in the scope).
@@ -124,7 +124,7 @@ impl<'e> ParseState<'e> {
             #[cfg(not(feature = "no_closure"))]
             allow_capture: true,
             interned_strings: Default::default(),
-            stack: Vec::with_capacity(16),
+            stack: Default::default(),
             entry_stack_len: 0,
             #[cfg(not(feature = "no_module"))]
             modules: Default::default(),
@@ -828,8 +828,8 @@ fn parse_map_literal(
     // #{ ...
     settings.pos = eat_token(input, Token::MapStart);
 
-    let mut map: StaticVec<(Ident, Expr)> = Default::default();
-    let mut template: BTreeMap<Identifier, crate::Dynamic> = Default::default();
+    let mut map = StaticVec::<(Ident, Expr)>::new();
+    let mut template = BTreeMap::<Identifier, crate::Dynamic>::new();
 
     loop {
         const MISSING_RBRACE: &str = "to end this object map literal";
@@ -1179,7 +1179,7 @@ fn parse_primary(
 
         // Interpolated string
         Token::InterpolatedString(_) => {
-            let mut segments: StaticVec<Expr> = Default::default();
+            let mut segments = StaticVec::<Expr>::new();
 
             if let (Token::InterpolatedString(s), pos) = input.next().expect(NEVER_ENDS) {
                 segments.push(Expr::StringConstant(s.into(), pos));
@@ -1389,7 +1389,7 @@ fn parse_primary(
                 if let Some((ref mut namespace, _)) = namespace {
                     namespace.push(var_name_def);
                 } else {
-                    let mut ns: NamespaceRef = Default::default();
+                    let mut ns = NamespaceRef::new();
                     ns.push(var_name_def);
                     namespace = Some((ns, 42));
                 }
@@ -1977,9 +1977,9 @@ fn parse_custom_syntax(
     pos: Position,
 ) -> Result<Expr, ParseError> {
     let mut settings = settings;
-    let mut keywords: StaticVec<Expr> = Default::default();
-    let mut segments: StaticVec<_> = Default::default();
-    let mut tokens: StaticVec<_> = Default::default();
+    let mut keywords = StaticVec::<Expr>::new();
+    let mut segments = StaticVec::new();
+    let mut tokens = StaticVec::new();
 
     // Adjust the variables stack
     if syntax.scope_may_be_changed {
@@ -2699,7 +2699,7 @@ fn parse_stmt(
     #[cfg(not(feature = "no_function"))]
     #[cfg(feature = "metadata")]
     let comments = {
-        let mut comments: StaticVec<String> = Default::default();
+        let mut comments = StaticVec::<String>::new();
         let mut comments_pos = Position::NONE;
 
         // Handle doc-comments.
@@ -2982,7 +2982,7 @@ fn parse_fn(
         (_, pos) => return Err(PERR::FnMissingParams(name).into_err(*pos)),
     };
 
-    let mut params: StaticVec<_> = Default::default();
+    let mut params = StaticVec::new();
 
     if !match_token(input, Token::RightParen).0 {
         let sep_err = format!("to separate the parameters of function '{}'", name);
@@ -3115,7 +3115,7 @@ fn parse_anon_fn(
     #[cfg(not(feature = "unchecked"))]
     settings.ensure_level_within_max_limit(state.max_expr_depth)?;
 
-    let mut params_list: StaticVec<_> = Default::default();
+    let mut params_list = StaticVec::new();
 
     if input.next().expect(NEVER_ENDS).0 != Token::Or && !match_token(input, Token::Pipe).0 {
         loop {

src/serde/deserialize.rs

@@ -142,7 +142,7 @@ impl<'d> Visitor<'d> for DynamicVisitor {
 
     #[cfg(not(feature = "no_index"))]
     fn visit_seq<A: SeqAccess<'d>>(self, mut seq: A) -> Result<Self::Value, A::Error> {
-        let mut arr: Array = Default::default();
+        let mut arr = Array::new();
 
         while let Some(v) = seq.next_element()? {
             arr.push(v);
@@ -153,7 +153,7 @@ impl<'d> Visitor<'d> for DynamicVisitor {
 
     #[cfg(not(feature = "no_object"))]
     fn visit_map<M: MapAccess<'d>>(self, mut map: M) -> Result<Self::Value, M::Error> {
-        let mut m: Map = Default::default();
+        let mut m = Map::new();
 
         while let Some((k, v)) = map.next_entry::<&str, _>()? {
             m.insert(k.into(), v);

src/serde/metadata.rs

@@ -207,6 +207,13 @@ struct ModuleMetadata {
     pub functions: Vec<FnMetadata>,
 }
 
+impl ModuleMetadata {
+    #[inline(always)]
+    pub fn new() -> Self {
+        Default::default()
+    }
+}
+
 impl From<&crate::Module> for ModuleMetadata {
     fn from(module: &crate::Module) -> Self {
         let mut functions: Vec<_> = module.iter_fn().map(|f| f.into()).collect();
@@ -239,7 +246,7 @@ impl Engine {
         include_global: bool,
     ) -> serde_json::Result<String> {
         let _ast = ast;
-        let mut global: ModuleMetadata = Default::default();
+        let mut global = ModuleMetadata::new();
 
         if include_global {
             self.global_modules

src/token.rs

@@ -1421,7 +1421,7 @@ fn get_next_token_inner(
 
             // digit ...
             ('0'..='9', _) => {
-                let mut result: smallvec::SmallVec<[char; 16]> = Default::default();
+                let mut result = smallvec::SmallVec::<[char; 16]>::new();
                 let mut radix_base: Option<u32> = None;
                 let mut valid: fn(char) -> bool = is_numeric_digit;
                 result.push(c);
@@ -1951,7 +1951,7 @@ fn get_identifier(
     start_pos: Position,
     first_char: char,
 ) -> Option<(Token, Position)> {
-    let mut result: smallvec::SmallVec<[char; 8]> = Default::default();
+    let mut result = smallvec::SmallVec::<[char; 8]>::new();
     result.push(first_char);
 
     while let Some(next_char) = stream.peek_next() {