Simplify match.

src/ast/expr.rs

@@ -288,8 +288,8 @@ pub enum Expr {
     Unit(Position),
     /// Variable access - (optional long index, namespace, namespace hash, variable name), optional short index, position
     ///
-    /// The short index is [`u8`] which is used when the index is <= 255, which should be the vast
+    /// The short index is [`u8`] which is used when the index is <= 255, which should be
-    /// majority of cases (unless there are more than 255 variables defined!).
+    /// the vast majority of cases (unless there are more than 255 variables defined!).
     /// This is to avoid reading a pointer redirection during each variable access.
     Variable(
         Box<(Option<NonZeroUsize>, Namespace, u64, ImmutableString)>,
@@ -315,15 +315,15 @@ pub enum Expr {
     ///
     /// ### Flags
     ///
-    /// [`NEGATED`][ASTFlags::NEGATED] = `?.` (`.` if unset)
+    /// * [`NEGATED`][ASTFlags::NEGATED] = `?.` (`.` if unset)
-    /// [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
+    /// * [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
     Dot(Box<BinaryExpr>, ASTFlags, Position),
     /// lhs `[` rhs `]`
     ///
     /// ### Flags
     ///
-    /// [`NEGATED`][ASTFlags::NEGATED] = `?[` ... `]` (`[` ... `]` if unset)
+    /// * [`NEGATED`][ASTFlags::NEGATED] = `?[` ... `]` (`[` ... `]` if unset)
-    /// [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
+    /// * [`BREAK`][ASTFlags::BREAK] = terminate the chain (recurse into the chain if unset)
     Index(Box<BinaryExpr>, ASTFlags, Position),
     /// lhs `&&` rhs
     And(Box<BinaryExpr>, Position),

src/defer.rs

@@ -65,8 +65,8 @@ macro_rules! defer {
 /// Run custom restoration logic upon the end of scope.
 #[must_use]
 pub struct Deferred<'a, T: ?Sized, R: FnOnce(&mut T)> {
-    value: &'a mut T,
+    lock: &'a mut T,
-    restore: Option<R>,
+    defer: Option<R>,
 }
 
 impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deferred<'a, T, R> {
@@ -78,8 +78,8 @@ impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deferred<'a, T, R> {
     #[inline(always)]
     pub fn lock(value: &'a mut T, restore: R) -> Self {
         Self {
-            value,
+            lock: value,
-            restore: Some(restore),
+            defer: Some(restore),
         }
     }
 }
@@ -87,7 +87,7 @@ impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deferred<'a, T, R> {
 impl<'a, T: ?Sized, R: FnOnce(&mut T)> Drop for Deferred<'a, T, R> {
     #[inline(always)]
     fn drop(&mut self) {
-        self.restore.take().unwrap()(self.value);
+        self.defer.take().unwrap()(self.lock);
     }
 }
 
@@ -96,13 +96,13 @@ impl<'a, T: ?Sized, R: FnOnce(&mut T)> Deref for Deferred<'a, T, R> {
 
     #[inline(always)]
     fn deref(&self) -> &Self::Target {
-        self.value
+        self.lock
     }
 }
 
 impl<'a, T: ?Sized, R: FnOnce(&mut T)> DerefMut for Deferred<'a, T, R> {
     #[inline(always)]
     fn deref_mut(&mut self) -> &mut Self::Target {
-        self.value
+        self.lock
     }
 }

src/eval/chaining.rs

@@ -362,21 +362,14 @@ impl Engine {
             Expr::Property(..) if chain_type == ChainType::Dotting => (),
             #[cfg(not(feature = "no_object"))]
             Expr::Property(..) => unreachable!("unexpected Expr::Property for indexing"),
-            // Short-circuit for simple method call: {expr}.func()
-            #[cfg(not(feature = "no_object"))]
-            Expr::FnCall(x, ..) if chain_type == ChainType::Dotting && x.args.is_empty() => (),
-            // Short-circuit for method call with all literal arguments: {expr}.func(1, 2, 3)
-            #[cfg(not(feature = "no_object"))]
-            Expr::FnCall(x, ..)
-                if chain_type == ChainType::Dotting && x.args.iter().all(Expr::is_constant) =>
-            {
-                idx_values.extend(x.args.iter().map(|expr| expr.get_literal_value().unwrap()))
-            }
             // Short-circuit for indexing with literal: {expr}[1]
             #[cfg(not(feature = "no_index"))]
             _ if chain_type == ChainType::Indexing && rhs.is_constant() => {
                 idx_values.push(rhs.get_literal_value().unwrap())
             }
+            // Short-circuit for simple method call: {expr}.func()
+            #[cfg(not(feature = "no_object"))]
+            Expr::MethodCall(x, ..) if chain_type == ChainType::Dotting && x.args.is_empty() => (),
             // All other patterns - evaluate the arguments chain
             _ => self.eval_dot_index_chain_arguments(
                 global,
@@ -439,27 +432,25 @@ impl Engine {
     ) -> RhaiResultOf<()> {
         self.track_operation(global, expr.position())?;
 
-        let chain_type = ChainType::from(parent);
+        match (expr, ChainType::from(parent)) {
-
-        match expr {
             #[cfg(not(feature = "no_object"))]
-            Expr::MethodCall(x, ..) if chain_type == ChainType::Dotting && !x.is_qualified() => {
+            (Expr::MethodCall(x, ..), ChainType::Dotting) => {
+                debug_assert!(
+                    !x.is_qualified(),
+                    "function call in dot chain should not be namespace-qualified"
+                );
+
                 for expr in &x.args {
                     let arg_value =
                         self.get_arg_value(global, caches, scope, this_ptr.as_deref_mut(), expr)?;
                     idx_values.push(arg_value.0.flatten());
                 }
             }
-            #[cfg(not(feature = "no_object"))]
-            Expr::MethodCall(..) if chain_type == ChainType::Dotting => {
-                unreachable!("function call in dot chain should not be namespace-qualified")
-            }
 
             #[cfg(not(feature = "no_object"))]
-            Expr::Property(..) if chain_type == ChainType::Dotting => (),
+            (Expr::Property(..), ChainType::Dotting) => (),
-            Expr::Property(..) => unreachable!("unexpected Expr::Property for indexing"),
 
-            Expr::Index(x, ..) | Expr::Dot(x, ..)
+            (Expr::Index(x, ..), chain_type) | (Expr::Dot(x, ..), chain_type)
                 if !parent.options().contains(ASTFlags::BREAK) =>
             {
                 let BinaryExpr { lhs, rhs, .. } = &**x;
@@ -467,37 +458,34 @@ impl Engine {
                 let mut _arg_values = FnArgsVec::new_const();
 
                 // Evaluate in left-to-right order
-                match lhs {
+                match (lhs, chain_type) {
                     #[cfg(not(feature = "no_object"))]
-                    Expr::Property(..) if chain_type == ChainType::Dotting => (),
+                    (Expr::Property(..), ChainType::Dotting) => (),
-                    Expr::Property(..) => unreachable!("unexpected Expr::Property for indexing"),
 
                     #[cfg(not(feature = "no_object"))]
-                    Expr::MethodCall(x, ..)
+                    (Expr::MethodCall(x, ..), ChainType::Dotting) => {
-                        if chain_type == ChainType::Dotting && !x.is_qualified() =>
+                        debug_assert!(
-                    {
+                            !x.is_qualified(),
+                            "function call in dot chain should not be namespace-qualified"
+                        );
+
                         for expr in &x.args {
                             let tp = this_ptr.as_deref_mut();
                             let arg_value = self.get_arg_value(global, caches, scope, tp, expr)?;
                             _arg_values.push(arg_value.0.flatten());
                         }
                     }
-                    #[cfg(not(feature = "no_object"))]
-                    Expr::MethodCall(..) if chain_type == ChainType::Dotting => {
-                        unreachable!("function call in dot chain should not be namespace-qualified")
-                    }
-                    #[cfg(not(feature = "no_object"))]
-                    expr if chain_type == ChainType::Dotting => {
-                        unreachable!("invalid dot expression: {:?}", expr);
-                    }
                     #[cfg(not(feature = "no_index"))]
-                    _ if chain_type == ChainType::Indexing => {
+                    (_, ChainType::Indexing) => {
                         _arg_values.push(
                             self.eval_expr(global, caches, scope, this_ptr.as_deref_mut(), lhs)?
                                 .flatten(),
                         );
                     }
-                    expr => unreachable!("unknown chained expression: {:?}", expr),
+                    #[allow(unreachable_patterns)]
+                    (expr, chain_type) => {
+                        unreachable!("unknown {:?} expression: {:?}", chain_type, expr)
+                    }
                 }
 
                 // Push in reverse order
@@ -508,16 +496,13 @@ impl Engine {
                 idx_values.extend(_arg_values);
             }
 
-            #[cfg(not(feature = "no_object"))]
-            _ if chain_type == ChainType::Dotting => {
-                unreachable!("invalid dot expression: {:?}", expr);
-            }
             #[cfg(not(feature = "no_index"))]
-            _ if chain_type == ChainType::Indexing => idx_values.push(
+            (_, ChainType::Indexing) => idx_values.push(
                 self.eval_expr(global, caches, scope, this_ptr, expr)?
                     .flatten(),
             ),
-            _ => unreachable!("unknown chained expression: {:?}", expr),
+            #[allow(unreachable_patterns)]
+            (expr, chain_type) => unreachable!("unknown {:?} expression: {:?}", chain_type, expr),
         }
 
         Ok(())

src/eval/expr.rs

@@ -259,17 +259,18 @@ impl Engine {
                 self.eval_fn_call_expr(global, caches, scope, this_ptr, x, *pos)
             }
 
-            Expr::Variable(x, index, var_pos) => {
+            Expr::Variable(x, index, var_pos)
-                if index.is_none() && x.0.is_none() && x.3 == KEYWORD_THIS {
+                if index.is_none() && x.0.is_none() && x.3 == KEYWORD_THIS =>
+            {
                 this_ptr
                     .ok_or_else(|| ERR::ErrorUnboundThis(*var_pos).into())
                     .cloned()
-                } else {
-                    self.search_namespace(global, caches, scope, this_ptr, expr)
-                        .map(Target::take_or_clone)
-                }
             }
 
+            Expr::Variable(..) => self
+                .search_namespace(global, caches, scope, this_ptr, expr)
+                .map(Target::take_or_clone),
+
             Expr::InterpolatedString(x, _) => {
                 let mut concat = SmartString::new_const();