Merge pull request #411 from schungx/master

Prepare for 0.20.1.

CHANGELOG.md

@@ -10,12 +10,14 @@ Bug fixes
 ---------
 
 * Fixed bug when position is zero in `insert` and `split_at` methods for arrays.
+* Indexing operations with pure index values are no longer considered pure due to the possibility of indexers.
 
 Breaking changes
 ----------------
 
 * `Dynamic::is_shared` and `Dynamic::is_locked` are removed under the `no_closure` feature. They used to always return `false`.
 * `Engine::call_fn` now evaluates the `AST` before calling the function.
+* `Engine::on_progress` is disabled with `unchecked`.
 
 Enhancements
 ------------

README.md

@@ -3,13 +3,15 @@ Rhai - Embedded Scripting for Rust
 
 ![GitHub last commit](https://img.shields.io/github/last-commit/rhaiscript/rhai?logo=github)
 [![Build Status](https://github.com/rhaiscript/rhai/workflows/Build/badge.svg)](https://github.com/rhaiscript/rhai/actions)
-[![stars](https://img.shields.io/github/stars/rhaiscript/rhai?logo=github)](https://github.com/rhaiscript/rhai)
+[![Stars](https://img.shields.io/github/stars/rhaiscript/rhai?logo=github)](https://github.com/rhaiscript/rhai)
-[![license](https://img.shields.io/crates/l/rhai)](https://github.com/license/rhaiscript/rhai)
+[![License](https://img.shields.io/crates/l/rhai)](https://github.com/license/rhaiscript/rhai)
 [![crates.io](https://img.shields.io/crates/v/rhai?logo=rust)](https://crates.io/crates/rhai/)
 [![crates.io](https://img.shields.io/crates/d/rhai?logo=rust)](https://crates.io/crates/rhai/)
-[![API Docs](https://docs.rs/rhai/badge.svg?logo=docs.rs)](https://docs.rs/rhai/)
+[![API Docs](https://docs.rs/rhai/badge.svg?logo=docs-rs)](https://docs.rs/rhai/)
-[![chat](https://img.shields.io/discord/767611025456889857.svg?logo=discord)](https://discord.gg/HquqbYFcZ9)
+[![VS Code plugin installs](https://img.shields.io/visual-studio-marketplace/i/rhaiscript.vscode-rhai?logo=visual-studio-code&label=vs%20code)](https://marketplace.visualstudio.com/items?itemName=rhaiscript.vscode-rhai)
-[![Reddit](https://img.shields.io/reddit/subreddit-subscribers/Rhai?logo=reddit)](https://www.reddit.com/r/Rhai)
+[![Sublime Text package downloads](https://img.shields.io/packagecontrol/dt/Rhai.svg?logo=sublime-text&label=sublime%20text)](https://packagecontrol.io/packages/Rhai)
+[![Discord Chat](https://img.shields.io/discord/767611025456889857.svg?logo=discord&label=discord)](https://discord.gg/HquqbYFcZ9)
+[![Reddit Channel](https://img.shields.io/reddit/subreddit-subscribers/Rhai?logo=reddit&label=reddit)](https://www.reddit.com/r/Rhai)
 
 [![Rhai logo](https://rhai.rs/book/images/logo/rhai-banner-transparent-colour.svg)](https://rhai.rs)
 

benches/eval_expression.rs

@@ -126,9 +126,9 @@ fn bench_eval_loop_number(bench: &mut Bencher) {
 #[bench]
 fn bench_eval_loop_strings_build(bench: &mut Bencher) {
     let script = r#"
-        let s = "hello";
+        let s;
         for x in range(0, 10000) {
-            s += "x";
+            s = "hello, world!" + "hello, world!";
         }
     "#;
 
@@ -143,9 +143,9 @@ fn bench_eval_loop_strings_build(bench: &mut Bencher) {
 #[bench]
 fn bench_eval_loop_strings_no_build(bench: &mut Bencher) {
     let script = r#"
-        let s = "hello";
+        let s;
         for x in range(0, 10000) {
-            s += "";
+            s = "hello" + "";
         }
     "#;
 

codegen/Cargo.toml

@@ -2,8 +2,8 @@
 name = "rhai_codegen"
 version = "0.3.5"
 edition = "2018"
-authors = ["jhwgh1968"]
+authors = ["jhwgh1968", "Stephen Chung"]
-description = "Procedural macro support package for Rhai, a scripting language for Rust"
+description = "Procedural macros support package for Rhai, a scripting language and engine for Rust"
 homepage = "https://rhai.rs/book/plugins/index.html"
 repository = "https://github.com/rhaiscript/rhai"
 license = "MIT OR Apache-2.0"

src/ast.rs

@@ -780,12 +780,8 @@ pub struct Ident {
 impl fmt::Debug for Ident {
     #[inline(always)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        #[cfg(not(feature = "no_position"))]
-        write!(f, "{:?} @ {:?}", self.name, self.pos)?;
-        #[cfg(feature = "no_position")]
         write!(f, "{:?}", self.name)?;
-
+        self.pos.debug_print(f)
-        Ok(())
     }
 }
 
@@ -879,10 +875,7 @@ impl fmt::Debug for StmtBlock {
     #[inline(always)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Debug::fmt(&self.0, f)?;
-        if !self.1.is_none() {
+        self.1.debug_print(f)
-            write!(f, " @ {:?}", self.1)?;
-        }
-        Ok(())
     }
 }
 
@@ -1354,13 +1347,22 @@ pub struct OpAssignment {
 }
 
 impl OpAssignment {
-    pub fn new(op: &'static str) -> Self {
+    /// Create a new [`OpAssignment`].
-        let op2 = &op[..op.len() - 1]; // extract operator without =
+    ///
+    /// # Panics
+    ///
+    /// Panics if the operator name is not an op-assignment operator.
+    pub fn new(op: Token) -> Self {
+        let op_raw = op
+            .map_op_assignment()
+            .expect("token must be an op-assignment operator")
+            .keyword_syntax();
+        let op_assignment = op.keyword_syntax();
 
         Self {
-            hash_op_assign: calc_fn_hash(empty(), op, 2),
+            hash_op_assign: calc_fn_hash(empty(), op_assignment, 2),
-            hash_op: calc_fn_hash(empty(), op2, 2),
+            hash_op: calc_fn_hash(empty(), op_raw, 2),
-            op,
+            op: op_assignment,
         }
     }
 }
@@ -1691,60 +1693,33 @@ impl Default for Expr {
 
 impl fmt::Debug for Expr {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
+        let mut display_pos = self.position();
-            #[cfg(not(feature = "no_position"))]
-            Self::DynamicConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
-            #[cfg(not(feature = "no_position"))]
-            Self::BoolConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
-            #[cfg(not(feature = "no_position"))]
-            Self::IntegerConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
-            #[cfg(not(feature = "no_float"))]
-            #[cfg(not(feature = "no_position"))]
-            Self::FloatConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
-            #[cfg(not(feature = "no_position"))]
-            Self::CharConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
-            #[cfg(not(feature = "no_position"))]
-            Self::StringConstant(value, pos) => write!(f, "{:?} @ {:?}", value, pos),
-            #[cfg(not(feature = "no_position"))]
-            Self::Unit(pos) => write!(f, "() @ {:?}", pos),
 
-            #[cfg(feature = "no_position")]
+        match self {
             Self::DynamicConstant(value, _) => write!(f, "{:?}", value),
-            #[cfg(feature = "no_position")]
             Self::BoolConstant(value, _) => write!(f, "{:?}", value),
-            #[cfg(feature = "no_position")]
             Self::IntegerConstant(value, _) => write!(f, "{:?}", value),
             #[cfg(not(feature = "no_float"))]
-            #[cfg(feature = "no_position")]
             Self::FloatConstant(value, _) => write!(f, "{:?}", value),
-            #[cfg(feature = "no_position")]
             Self::CharConstant(value, _) => write!(f, "{:?}", value),
-            #[cfg(feature = "no_position")]
             Self::StringConstant(value, _) => write!(f, "{:?}", value),
-            #[cfg(feature = "no_position")]
             Self::Unit(_) => f.write_str("()"),
 
             Self::InterpolatedString(x) => {
                 f.write_str("InterpolatedString")?;
+                return f.debug_list().entries(x.iter()).finish();
+            }
+            Self::Array(x, _) => {
+                f.write_str("Array")?;
                 f.debug_list().entries(x.iter()).finish()
             }
-            Self::Array(x, _pos) => {
+            Self::Map(x, _) => {
-                f.write_str("Array")?;
-                f.debug_list().entries(x.iter()).finish()?;
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", _pos)?;
-                Ok(())
-            }
-            Self::Map(x, _pos) => {
                 f.write_str("Map")?;
                 f.debug_map()
                     .entries(x.0.iter().map(|(k, v)| (k, v)))
-                    .finish()?;
+                    .finish()
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", _pos)?;
-                Ok(())
             }
-            Self::Variable(i, _pos, x) => {
+            Self::Variable(i, _, x) => {
                 f.write_str("Variable(")?;
                 match x.1 {
                     Some((_, ref namespace)) => write!(f, "{}", namespace)?,
@@ -1755,23 +1730,14 @@ impl fmt::Debug for Expr {
                     Some(n) => write!(f, ", {}", n)?,
                     _ => (),
                 }
-                f.write_str(")")?;
+                f.write_str(")")
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", _pos)?;
-                Ok(())
             }
-            #[cfg(not(feature = "no_position"))]
+            Self::Property(x) => write!(f, "Property({})", x.2.name),
-            Self::Property(x) => write!(f, "Property({:?} @ {:?})", x.2.name, x.2.pos),
-            #[cfg(feature = "no_position")]
-            Self::Property(x) => write!(f, "Property({:?})", x.2.name),
             Self::Stmt(x) => {
                 f.write_str("Stmt")?;
-                f.debug_list().entries(x.0.iter()).finish()?;
+                f.debug_list().entries(x.0.iter()).finish()
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", x.1)?;
-                Ok(())
             }
-            Self::FnCall(x, _pos) => {
+            Self::FnCall(x, _) => {
                 let mut ff = f.debug_struct("FnCall");
                 if let Some(ref ns) = x.namespace {
                     ff.field("namespace", ns);
@@ -1785,12 +1751,9 @@ impl fmt::Debug for Expr {
                 if x.capture {
                     ff.field("capture", &x.capture);
                 }
-                ff.finish()?;
+                ff.finish()
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", _pos)?;
-                Ok(())
             }
-            Self::Dot(x, _pos) | Self::Index(x, _pos) | Self::And(x, _pos) | Self::Or(x, _pos) => {
+            Self::Dot(x, pos) | Self::Index(x, pos) | Self::And(x, pos) | Self::Or(x, pos) => {
                 let op_name = match self {
                     Self::Dot(_, _) => "Dot",
                     Self::Index(_, _) => "Index",
@@ -1799,21 +1762,17 @@ impl fmt::Debug for Expr {
                     _ => unreachable!(),
                 };
 
+                display_pos = *pos;
+
                 f.debug_struct(op_name)
                     .field("lhs", &x.lhs)
                     .field("rhs", &x.rhs)
-                    .finish()?;
+                    .finish()
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", _pos)?;
-                Ok(())
-            }
-            Self::Custom(x, _pos) => {
-                f.debug_tuple("Custom").field(x).finish()?;
-                #[cfg(not(feature = "no_position"))]
-                write!(f, " @ {:?}", _pos)?;
-                Ok(())
-            }
             }
+            Self::Custom(x, _) => f.debug_tuple("Custom").field(x).finish(),
+        }?;
+
+        display_pos.debug_print(f)
     }
 }
 
@@ -1875,26 +1834,26 @@ impl Expr {
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, pos) => *pos,
 
-            Self::DynamicConstant(_, pos) => *pos,
+            Self::DynamicConstant(_, pos)
-            Self::BoolConstant(_, pos) => *pos,
+            | Self::BoolConstant(_, pos)
-            Self::IntegerConstant(_, pos) => *pos,
+            | Self::IntegerConstant(_, pos)
-            Self::CharConstant(_, pos) => *pos,
+            | Self::CharConstant(_, pos)
-            Self::StringConstant(_, pos) => *pos,
+            | Self::Unit(pos)
+            | Self::StringConstant(_, pos)
+            | Self::Array(_, pos)
+            | Self::Map(_, pos)
+            | Self::Variable(_, pos, _)
+            | Self::FnCall(_, pos)
+            | Self::Custom(_, pos) => *pos,
+
             Self::InterpolatedString(x) => x.first().unwrap().position(),
-            Self::Array(_, pos) => *pos,
+
-            Self::Map(_, pos) => *pos,
             Self::Property(x) => (x.2).pos,
             Self::Stmt(x) => x.1,
-            Self::Variable(_, pos, _) => *pos,
-            Self::FnCall(_, pos) => *pos,
 
-            Self::And(x, _) | Self::Or(x, _) => x.lhs.position(),
+            Self::And(x, _) | Self::Or(x, _) | Self::Dot(x, _) | Self::Index(x, _) => {
-
+                x.lhs.position()
-            Self::Unit(pos) => *pos,
+            }
-
-            Self::Dot(x, _) | Self::Index(x, _) => x.lhs.position(),
-
-            Self::Custom(_, pos) => *pos,
         }
     }
     /// Override the [position][Position] of the expression.
@@ -1904,24 +1863,28 @@ impl Expr {
             #[cfg(not(feature = "no_float"))]
             Self::FloatConstant(_, pos) => *pos = new_pos,
 
-            Self::DynamicConstant(_, pos) => *pos = new_pos,
+            Self::DynamicConstant(_, pos)
-            Self::BoolConstant(_, pos) => *pos = new_pos,
+            | Self::BoolConstant(_, pos)
-            Self::IntegerConstant(_, pos) => *pos = new_pos,
+            | Self::IntegerConstant(_, pos)
-            Self::CharConstant(_, pos) => *pos = new_pos,
+            | Self::CharConstant(_, pos)
-            Self::StringConstant(_, pos) => *pos = new_pos,
+            | Self::Unit(pos)
+            | Self::StringConstant(_, pos)
+            | Self::Array(_, pos)
+            | Self::Map(_, pos)
+            | Self::And(_, pos)
+            | Self::Or(_, pos)
+            | Self::Dot(_, pos)
+            | Self::Index(_, pos)
+            | Self::Variable(_, pos, _)
+            | Self::FnCall(_, pos)
+            | Self::Custom(_, pos) => *pos = new_pos,
+
             Self::InterpolatedString(x) => {
                 x.first_mut().unwrap().set_position(new_pos);
             }
-            Self::Array(_, pos) => *pos = new_pos,
+
-            Self::Map(_, pos) => *pos = new_pos,
-            Self::Variable(_, pos, _) => *pos = new_pos,
             Self::Property(x) => (x.2).pos = new_pos,
             Self::Stmt(x) => x.1 = new_pos,
-            Self::FnCall(_, pos) => *pos = new_pos,
-            Self::And(_, pos) | Self::Or(_, pos) => *pos = new_pos,
-            Self::Unit(pos) => *pos = new_pos,
-            Self::Dot(_, pos) | Self::Index(_, pos) => *pos = new_pos,
-            Self::Custom(_, pos) => *pos = new_pos,
         }
 
         self
@@ -1936,9 +1899,7 @@ impl Expr {
 
             Self::Map(x, _) => x.0.iter().map(|(_, v)| v).all(Self::is_pure),
 
-            Self::Index(x, _) | Self::And(x, _) | Self::Or(x, _) => {
+            Self::And(x, _) | Self::Or(x, _) => x.lhs.is_pure() && x.rhs.is_pure(),
-                x.lhs.is_pure() && x.rhs.is_pure()
-            }
 
             Self::Stmt(x) => x.0.iter().all(Stmt::is_pure),
 

src/dynamic.rs

@@ -2,7 +2,7 @@
 
 use crate::fn_native::SendSync;
 use crate::r#unsafe::{unsafe_cast_box, unsafe_try_cast};
-use crate::{FnPtr, ImmutableString, INT};
+use crate::{FnPtr, ImmutableString, SmartString, INT};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 use std::{
@@ -900,6 +900,12 @@ impl Dynamic {
                 .deref()
                 .into();
         }
+        if TypeId::of::<T>() == TypeId::of::<SmartString>() {
+            return <dyn Any>::downcast_ref::<SmartString>(&value)
+                .unwrap()
+                .clone()
+                .into();
+        }
         if TypeId::of::<T>() == TypeId::of::<()>() {
             return ().into();
         }
@@ -1173,13 +1179,13 @@ impl Dynamic {
     /// ```
     #[inline(always)]
     pub fn clone_cast<T: Any + Clone>(&self) -> T {
-        self.read_lock::<T>().unwrap().clone()
+        self.flatten_clone().cast::<T>()
     }
     /// Flatten the [`Dynamic`] and clone it.
     ///
     /// If the [`Dynamic`] is not a shared value, it returns a cloned copy.
     ///
-    /// If the [`Dynamic`] is a shared value, it a cloned copy of the shared value.
+    /// If the [`Dynamic`] is a shared value, it returns a cloned copy of the shared value.
     #[inline(always)]
     pub fn flatten_clone(&self) -> Self {
         #[cfg(not(feature = "no_closure"))]
@@ -1361,7 +1367,7 @@ impl Dynamic {
     ///
     /// Returns [`None`] if the cast fails, or if the value is shared.
     #[inline(always)]
-    pub(crate) fn downcast_ref<T: Any + Clone>(&self) -> Option<&T> {
+    pub(crate) fn downcast_ref<T: Any + Clone + ?Sized>(&self) -> Option<&T> {
         // Coded this way in order to maximally leverage potentials for dead-code removal.
 
         if TypeId::of::<T>() == TypeId::of::<INT>() {
@@ -1396,12 +1402,6 @@ impl Dynamic {
                 _ => None,
             };
         }
-        if TypeId::of::<T>() == TypeId::of::<String>() {
-            return match &self.0 {
-                Union::Str(value, _) => <dyn Any>::downcast_ref::<T>(value.as_ref() as &String),
-                _ => None,
-            };
-        }
         if TypeId::of::<T>() == TypeId::of::<char>() {
             return match &self.0 {
                 Union::Char(value, _) => <dyn Any>::downcast_ref::<T>(value),
@@ -1720,7 +1720,7 @@ impl From<&ImmutableString> for Dynamic {
         value.clone().into()
     }
 }
-#[cfg(not(feature = "no_smartstring"))]
+#[cfg(not(feature = "no_smartstring_for_identifier"))]
 impl From<&crate::Identifier> for Dynamic {
     #[inline(always)]
     fn from(value: &crate::Identifier) -> Self {

src/engine.rs

@@ -3,14 +3,14 @@
 use crate::ast::{Expr, FnCallExpr, Ident, OpAssignment, ReturnType, Stmt};
 use crate::dynamic::{map_std_type_name, AccessMode, Union, Variant};
 use crate::fn_native::{
-    CallableFunction, IteratorFn, OnDebugCallback, OnPrintCallback, OnProgressCallback,
+    CallableFunction, IteratorFn, OnDebugCallback, OnPrintCallback, OnVarCallback,
-    OnVarCallback,
 };
 use crate::module::NamespaceRef;
 use crate::optimize::OptimizationLevel;
 use crate::packages::{Package, StandardPackage};
 use crate::r#unsafe::unsafe_cast_var_name_to_lifetime;
 use crate::syntax::CustomSyntax;
+use crate::token::Token;
 use crate::utils::get_hasher;
 use crate::{
     Dynamic, EvalAltResult, Identifier, ImmutableString, Module, Position, RhaiResult, Scope,
@@ -51,35 +51,42 @@ pub type Precedence = NonZeroU8;
 // We cannot use Cow<str> here because `eval` may load a [module][Module] and
 // the module name will live beyond the AST of the eval script text.
 // The best we can do is a shared reference.
+//
+// This implementation splits the module names from the shared modules to improve data locality.
+// Most usage will be looking up a particular key from the list and then getting the module that
+// corresponds to that key.
 #[derive(Clone, Default)]
-pub struct Imports(StaticVec<Identifier>, StaticVec<Shared<Module>>);
+pub struct Imports {
+    keys: StaticVec<Identifier>,
+    modules: StaticVec<Shared<Module>>,
+}
 
 impl Imports {
     /// Get the length of this stack of imported [modules][Module].
     #[inline(always)]
     pub fn len(&self) -> usize {
-        self.0.len()
+        self.keys.len()
     }
     /// Is this stack of imported [modules][Module] empty?
     #[inline(always)]
     pub fn is_empty(&self) -> bool {
-        self.0.is_empty()
+        self.keys.is_empty()
     }
     /// Get the imported [modules][Module] at a particular index.
     #[inline(always)]
     pub fn get(&self, index: usize) -> Option<Shared<Module>> {
-        self.1.get(index).cloned()
+        self.modules.get(index).cloned()
     }
     /// Get the imported [modules][Module] at a particular index.
     #[allow(dead_code)]
     #[inline(always)]
     pub(crate) fn get_mut(&mut self, index: usize) -> Option<&mut Shared<Module>> {
-        self.1.get_mut(index)
+        self.modules.get_mut(index)
     }
     /// Get the index of an imported [modules][Module] by name.
     #[inline(always)]
     pub fn find(&self, name: &str) -> Option<usize> {
-        self.0
+        self.keys
             .iter()
             .enumerate()
             .rev()
@@ -88,22 +95,22 @@ impl Imports {
     /// Push an imported [modules][Module] onto the stack.
     #[inline(always)]
     pub fn push(&mut self, name: impl Into<Identifier>, module: impl Into<Shared<Module>>) {
-        self.0.push(name.into());
+        self.keys.push(name.into());
-        self.1.push(module.into());
+        self.modules.push(module.into());
     }
     /// Truncate the stack of imported [modules][Module] to a particular length.
     #[inline(always)]
     pub fn truncate(&mut self, size: usize) {
-        self.0.truncate(size);
+        self.keys.truncate(size);
-        self.1.truncate(size);
+        self.modules.truncate(size);
     }
     /// Get an iterator to this stack of imported [modules][Module] in reverse order.
     #[allow(dead_code)]
     #[inline(always)]
     pub fn iter(&self) -> impl Iterator<Item = (&str, &Module)> {
-        self.0
+        self.keys
             .iter()
-            .zip(self.1.iter())
+            .zip(self.modules.iter())
             .rev()
             .map(|(name, module)| (name.as_str(), module.as_ref()))
     }
@@ -111,29 +118,32 @@ impl Imports {
     #[allow(dead_code)]
     #[inline(always)]
     pub(crate) fn iter_raw(&self) -> impl Iterator<Item = (&Identifier, &Shared<Module>)> {
-        self.0.iter().rev().zip(self.1.iter().rev())
+        self.keys.iter().rev().zip(self.modules.iter().rev())
     }
     /// Get an iterator to this stack of imported [modules][Module] in forward order.
     #[allow(dead_code)]
     #[inline(always)]
     pub(crate) fn scan_raw(&self) -> impl Iterator<Item = (&Identifier, &Shared<Module>)> {
-        self.0.iter().zip(self.1.iter())
+        self.keys.iter().zip(self.modules.iter())
     }
     /// Get a consuming iterator to this stack of imported [modules][Module] in reverse order.
     #[inline(always)]
     pub fn into_iter(self) -> impl Iterator<Item = (Identifier, Shared<Module>)> {
-        self.0.into_iter().rev().zip(self.1.into_iter().rev())
+        self.keys
+            .into_iter()
+            .rev()
+            .zip(self.modules.into_iter().rev())
     }
     /// Does the specified function hash key exist in this stack of imported [modules][Module]?
     #[allow(dead_code)]
     #[inline(always)]
     pub fn contains_fn(&self, hash: u64) -> bool {
-        self.1.iter().any(|m| m.contains_qualified_fn(hash))
+        self.modules.iter().any(|m| m.contains_qualified_fn(hash))
     }
     /// Get specified function via its hash key.
     #[inline(always)]
     pub fn get_fn(&self, hash: u64) -> Option<(&CallableFunction, Option<&Identifier>)> {
-        self.1
+        self.modules
             .iter()
             .rev()
             .find_map(|m| m.get_qualified_fn(hash).map(|f| (f, m.id_raw())))
@@ -143,12 +153,15 @@ impl Imports {
     #[allow(dead_code)]
     #[inline(always)]
     pub fn contains_iter(&self, id: TypeId) -> bool {
-        self.1.iter().any(|m| m.contains_qualified_iter(id))
+        self.modules.iter().any(|m| m.contains_qualified_iter(id))
     }
     /// Get the specified [`TypeId`][std::any::TypeId] iterator.
     #[inline(always)]
     pub fn get_iter(&self, id: TypeId) -> Option<IteratorFn> {
-        self.1.iter().rev().find_map(|m| m.get_qualified_iter(id))
+        self.modules
+            .iter()
+            .rev()
+            .find_map(|m| m.get_qualified_iter(id))
     }
 }
 
@@ -160,7 +173,7 @@ impl fmt::Debug for Imports {
             f.debug_map().finish()
         } else {
             f.debug_map()
-                .entries(self.0.iter().zip(self.1.iter()))
+                .entries(self.keys.iter().zip(self.modules.iter()))
                 .finish()
         }
     }
@@ -221,35 +234,38 @@ pub const FN_ANONYMOUS: &str = "anon$";
 /// Standard equality comparison operator.
 pub const OP_EQUALS: &str = "==";
 
-/// Standard concatenation operator.
-pub const OP_CONCAT: &str = "+=";
-
 /// Standard method function for containment testing.
 ///
 /// The `in` operator is implemented as a call to this method.
 pub const OP_CONTAINS: &str = "contains";
 
+/// Standard concatenation operator token.
+pub const TOKEN_OP_CONCAT: Token = Token::PlusAssign;
+
 /// Method of chaining.
 #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
-pub enum ChainType {
+enum ChainType {
-    /// Not a chaining type.
-    NonChaining,
     /// Indexing.
+    #[cfg(not(feature = "no_index"))]
     Index,
     /// Dotting.
+    #[cfg(not(feature = "no_object"))]
     Dot,
 }
 
 /// Value of a chaining argument.
 #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
 #[derive(Debug, Clone, Hash)]
-pub enum ChainArgument {
+enum ChainArgument {
     /// Dot-property access.
+    #[cfg(not(feature = "no_object"))]
     Property(Position),
-    /// Arguments to a dot-function call.
+    /// Arguments to a dot method call.
-    FnCallArgs(StaticVec<Dynamic>, StaticVec<Position>),
+    #[cfg(not(feature = "no_object"))]
+    MethodCallArgs(StaticVec<Dynamic>, StaticVec<Position>),
     /// Index value.
+    #[cfg(not(feature = "no_index"))]
     IndexValue(Dynamic, Position),
 }
 
@@ -264,7 +280,8 @@ impl ChainArgument {
     #[cfg(not(feature = "no_index"))]
     pub fn as_index_value(self) -> Dynamic {
         match self {
-            Self::Property(_) | Self::FnCallArgs(_, _) => {
+            #[cfg(not(feature = "no_object"))]
+            Self::Property(_) | Self::MethodCallArgs(_, _) => {
                 panic!("expecting ChainArgument::IndexValue")
             }
             Self::IndexValue(value, _) => value,
@@ -274,28 +291,32 @@ impl ChainArgument {
     ///
     /// # Panics
     ///
-    /// Panics if not `ChainArgument::FnCallArgs`.
+    /// Panics if not `ChainArgument::MethodCallArgs`.
     #[inline(always)]
     #[cfg(not(feature = "no_object"))]
     pub fn as_fn_call_args(self) -> (StaticVec<Dynamic>, StaticVec<Position>) {
         match self {
-            Self::Property(_) | Self::IndexValue(_, _) => {
+            Self::Property(_) => {
-                panic!("expecting ChainArgument::FnCallArgs")
+                panic!("expecting ChainArgument::MethodCallArgs")
             }
-            Self::FnCallArgs(values, positions) => (values, positions),
+            #[cfg(not(feature = "no_index"))]
+            Self::IndexValue(_, _) => {
+                panic!("expecting ChainArgument::MethodCallArgs")
+            }
+            Self::MethodCallArgs(values, positions) => (values, positions),
         }
     }
 }
 
-#[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
+#[cfg(not(feature = "no_object"))]
 impl From<(StaticVec<Dynamic>, StaticVec<Position>)> for ChainArgument {
     #[inline(always)]
     fn from((values, positions): (StaticVec<Dynamic>, StaticVec<Position>)) -> Self {
-        Self::FnCallArgs(values, positions)
+        Self::MethodCallArgs(values, positions)
     }
 }
 
-#[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
+#[cfg(not(feature = "no_index"))]
 impl From<(Dynamic, Position)> for ChainArgument {
     #[inline(always)]
     fn from((value, pos): (Dynamic, Position)) -> Self {
@@ -774,7 +795,8 @@ pub struct Engine {
     /// Callback closure for implementing the `debug` command.
     pub(crate) debug: OnDebugCallback,
     /// Callback closure for progress reporting.
-    pub(crate) progress: Option<OnProgressCallback>,
+    #[cfg(not(feature = "unchecked"))]
+    pub(crate) progress: Option<crate::fn_native::OnProgressCallback>,
 
     /// Optimize the AST after compilation.
     pub(crate) optimization_level: OptimizationLevel,
@@ -838,7 +860,7 @@ fn default_debug(_s: &str, _source: Option<&str>, _pos: Position) {
     #[cfg(not(feature = "no_std"))]
     #[cfg(not(any(target_arch = "wasm32", target_arch = "wasm64")))]
     if let Some(source) = _source {
-        println!("{} @ {:?} | {}", source, _pos, _s);
+        println!("{}{:?} | {}", source, _pos, _s);
     } else if _pos.is_none() {
         println!("{}", _s);
     } else {
@@ -878,6 +900,7 @@ impl Engine {
             debug: Box::new(default_debug),
 
             // progress callback
+            #[cfg(not(feature = "unchecked"))]
             progress: None,
 
             // optimization level
@@ -938,6 +961,8 @@ impl Engine {
 
             print: Box::new(|_| {}),
             debug: Box::new(|_, _, _| {}),
+
+            #[cfg(not(feature = "unchecked"))]
             progress: None,
 
             optimization_level: if cfg!(feature = "no_optimize") {
@@ -1125,14 +1150,14 @@ impl Engine {
         level: usize,
         new_val: Option<((Dynamic, Position), (Option<OpAssignment>, Position))>,
     ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
-        assert!(chain_type != ChainType::NonChaining);
-
         let is_ref = target.is_ref();
 
-        let next_chain = match rhs {
+        let rhs_chain = match rhs {
-            Expr::Index(_, _) => ChainType::Index,
+            #[cfg(not(feature = "no_index"))]
-            Expr::Dot(_, _) => ChainType::Dot,
+            Expr::Index(_, _) => Some(ChainType::Index),
-            _ => ChainType::NonChaining,
+            #[cfg(not(feature = "no_object"))]
+            Expr::Dot(_, _) => Some(ChainType::Dot),
+            _ => None,
         };
 
         // Pop the last index value
@@ -1151,9 +1176,10 @@ impl Engine {
                         let obj_ptr = &mut self.get_indexed_mut(
                             mods, state, lib, target, idx_val, idx_pos, false, is_ref, true, level,
                         )?;
+                        let rhs_chain = rhs_chain.unwrap();
 
                         self.eval_dot_index_chain_helper(
-                            mods, state, lib, this_ptr, obj_ptr, &x.rhs, idx_values, next_chain,
+                            mods, state, lib, this_ptr, obj_ptr, &x.rhs, idx_values, rhs_chain,
                             level, new_val,
                         )
                         .map_err(|err| err.fill_position(*x_pos))
@@ -1336,9 +1362,10 @@ impl Engine {
                             // Others - syntax error
                             expr => unreachable!("invalid dot expression: {:?}", expr),
                         };
+                        let rhs_chain = rhs_chain.unwrap();
 
                         self.eval_dot_index_chain_helper(
-                            mods, state, lib, this_ptr, &mut val, &x.rhs, idx_values, next_chain,
+                            mods, state, lib, this_ptr, &mut val, &x.rhs, idx_values, rhs_chain,
                             level, new_val,
                         )
                         .map_err(|err| err.fill_position(*x_pos))
@@ -1350,6 +1377,7 @@ impl Engine {
                             Expr::Property(p) => {
                                 let ((getter, hash_get), (setter, hash_set), Ident { pos, .. }) =
                                     p.as_ref();
+                                let rhs_chain = rhs_chain.unwrap();
                                 let hash_get = FnCallHashes::from_native(*hash_get);
                                 let hash_set = FnCallHashes::from_native(*hash_set);
                                 let arg_values = &mut [target.as_mut(), &mut Default::default()];
@@ -1370,7 +1398,7 @@ impl Engine {
                                         &mut val.into(),
                                         &x.rhs,
                                         idx_values,
-                                        next_chain,
+                                        rhs_chain,
                                         level,
                                         new_val,
                                     )
@@ -1401,6 +1429,7 @@ impl Engine {
                             // xxx.fn_name(arg_expr_list)[expr] | xxx.fn_name(arg_expr_list).expr
                             Expr::FnCall(f, pos) if !f.is_qualified() => {
                                 let FnCallExpr { name, hashes, .. } = f.as_ref();
+                                let rhs_chain = rhs_chain.unwrap();
                                 let mut args = idx_val.as_fn_call_args();
                                 let (mut val, _) = self.make_method_call(
                                     mods, state, lib, name, *hashes, target, &mut args, *pos, level,
@@ -1410,7 +1439,7 @@ impl Engine {
 
                                 self.eval_dot_index_chain_helper(
                                     mods, state, lib, this_ptr, target, &x.rhs, idx_values,
-                                    next_chain, level, new_val,
+                                    rhs_chain, level, new_val,
                                 )
                                 .map_err(|err| err.fill_position(*pos))
                             }
@@ -1426,8 +1455,6 @@ impl Engine {
                     _ => EvalAltResult::ErrorDotExpr("".into(), rhs.position()).into(),
                 }
             }
-
-            chain_type => unreachable!("invalid ChainType: {:?}", chain_type),
         }
     }
 
@@ -1445,7 +1472,9 @@ impl Engine {
         new_val: Option<((Dynamic, Position), (Option<OpAssignment>, Position))>,
     ) -> RhaiResult {
         let (crate::ast::BinaryExpr { lhs, rhs }, chain_type, op_pos) = match expr {
+            #[cfg(not(feature = "no_index"))]
             Expr::Index(x, pos) => (x.as_ref(), ChainType::Index, *pos),
+            #[cfg(not(feature = "no_object"))]
             Expr::Dot(x, pos) => (x.as_ref(), ChainType::Dot, *pos),
             _ => unreachable!("index or dot chain expected, but gets {:?}", expr),
         };
@@ -1458,8 +1487,9 @@ impl Engine {
 
         match lhs {
             // id.??? or id[???]
-            Expr::Variable(_, var_pos, x) => {
+            Expr::Variable(_, _var_pos, x) => {
-                self.inc_operations(state, *var_pos)?;
+                #[cfg(not(feature = "unchecked"))]
+                self.inc_operations(state, *_var_pos)?;
 
                 let (target, pos) =
                     self.search_namespace(scope, mods, state, lib, this_ptr, lhs)?;
@@ -1505,15 +1535,17 @@ impl Engine {
         lib: &[&Module],
         this_ptr: &mut Option<&mut Dynamic>,
         expr: &Expr,
-        parent_chain_type: ChainType,
+        _parent_chain_type: ChainType,
         idx_values: &mut StaticVec<ChainArgument>,
         size: usize,
         level: usize,
     ) -> Result<(), Box<EvalAltResult>> {
+        #[cfg(not(feature = "unchecked"))]
         self.inc_operations(state, expr.position())?;
 
         match expr {
-            Expr::FnCall(x, _) if parent_chain_type == ChainType::Dot && !x.is_qualified() => {
+            #[cfg(not(feature = "no_object"))]
+            Expr::FnCall(x, _) if _parent_chain_type == ChainType::Dot && !x.is_qualified() => {
                 let mut arg_positions: StaticVec<_> = Default::default();
 
                 let mut arg_values = x
@@ -1533,11 +1565,13 @@ impl Engine {
 
                 idx_values.push((arg_values, arg_positions).into());
             }
-            Expr::FnCall(_, _) if parent_chain_type == ChainType::Dot => {
+            #[cfg(not(feature = "no_object"))]
+            Expr::FnCall(_, _) if _parent_chain_type == ChainType::Dot => {
                 unreachable!("function call in dot chain should not be namespace-qualified")
             }
 
-            Expr::Property(x) if parent_chain_type == ChainType::Dot => {
+            #[cfg(not(feature = "no_object"))]
+            Expr::Property(x) if _parent_chain_type == ChainType::Dot => {
                 idx_values.push(ChainArgument::Property(x.2.pos))
             }
             Expr::Property(_) => unreachable!("unexpected Expr::Property for indexing"),
@@ -1547,12 +1581,15 @@ impl Engine {
 
                 // Evaluate in left-to-right order
                 let lhs_val = match lhs {
-                    Expr::Property(x) if parent_chain_type == ChainType::Dot => {
+                    #[cfg(not(feature = "no_object"))]
+                    Expr::Property(x) if _parent_chain_type == ChainType::Dot => {
                         ChainArgument::Property(x.2.pos)
                     }
                     Expr::Property(_) => unreachable!("unexpected Expr::Property for indexing"),
+
+                    #[cfg(not(feature = "no_object"))]
                     Expr::FnCall(x, _)
-                        if parent_chain_type == ChainType::Dot && !x.is_qualified() =>
+                        if _parent_chain_type == ChainType::Dot && !x.is_qualified() =>
                     {
                         let mut arg_positions: StaticVec<_> = Default::default();
 
@@ -1573,17 +1610,26 @@ impl Engine {
 
                         (arg_values, arg_positions).into()
                     }
-                    Expr::FnCall(_, _) if parent_chain_type == ChainType::Dot => {
+                    #[cfg(not(feature = "no_object"))]
+                    Expr::FnCall(_, _) if _parent_chain_type == ChainType::Dot => {
                         unreachable!("function call in dot chain should not be namespace-qualified")
                     }
-                    _ => self
+                    #[cfg(not(feature = "no_object"))]
+                    expr if _parent_chain_type == ChainType::Dot => {
+                        unreachable!("invalid dot expression: {:?}", expr);
+                    }
+                    #[cfg(not(feature = "no_index"))]
+                    _ if _parent_chain_type == ChainType::Index => self
                         .eval_expr(scope, mods, state, lib, this_ptr, lhs, level)
                         .map(|v| (v.flatten(), lhs.position()).into())?,
+                    expr => unreachable!("unknown chained expression: {:?}", expr),
                 };
 
                 // Push in reverse order
                 let chain_type = match expr {
+                    #[cfg(not(feature = "no_index"))]
                     Expr::Index(_, _) => ChainType::Index,
+                    #[cfg(not(feature = "no_object"))]
                     Expr::Dot(_, _) => ChainType::Dot,
                     _ => unreachable!("index or dot chain expected, but gets {:?}", expr),
                 };
@@ -1594,10 +1640,16 @@ impl Engine {
                 idx_values.push(lhs_val);
             }
 
-            _ => idx_values.push(
+            #[cfg(not(feature = "no_object"))]
+            _ if _parent_chain_type == ChainType::Dot => {
+                unreachable!("invalid dot expression: {:?}", expr);
+            }
+            #[cfg(not(feature = "no_index"))]
+            _ if _parent_chain_type == ChainType::Index => idx_values.push(
                 self.eval_expr(scope, mods, state, lib, this_ptr, expr, level)
                     .map(|v| (v.flatten(), expr.position()).into())?,
             ),
+            _ => unreachable!("unknown chained expression: {:?}", expr),
         }
 
         Ok(())
@@ -1619,6 +1671,7 @@ impl Engine {
         _indexers: bool,
         _level: usize,
     ) -> Result<Target<'t>, Box<EvalAltResult>> {
+        #[cfg(not(feature = "unchecked"))]
         self.inc_operations(state, Position::NONE)?;
 
         match target {
@@ -1631,6 +1684,7 @@ impl Engine {
 
                 let arr_len = arr.len();
 
+                #[cfg(not(feature = "unchecked"))]
                 let arr_idx = if index < 0 {
                     // Count from end if negative
                     arr_len
@@ -1650,6 +1704,13 @@ impl Engine {
                 } else {
                     index as usize
                 };
+                #[cfg(feature = "unchecked")]
+                let arr_idx = if index < 0 {
+                    // Count from end if negative
+                    arr_len - index.abs() as usize
+                } else {
+                    index as usize
+                };
 
                 arr.get_mut(arr_idx)
                     .map(Target::from)
@@ -1670,21 +1731,22 @@ impl Engine {
                 Ok(map
                     .get_mut(index.as_str())
                     .map(Target::from)
-                    .unwrap_or_else(|| Target::from(())))
+                    .unwrap_or_else(|| Target::from(Dynamic::UNIT)))
             }
 
             #[cfg(not(feature = "no_index"))]
             Dynamic(Union::Str(s, _)) => {
                 // val_string[idx]
-                let chars_len = s.chars().count();
                 let index = _idx
                     .as_int()
                     .map_err(|err| self.make_type_mismatch_err::<crate::INT>(err, idx_pos))?;
 
                 let (ch, offset) = if index >= 0 {
+                    // Count from end if negative
                     let offset = index as usize;
                     (
                         s.chars().nth(offset).ok_or_else(|| {
+                            let chars_len = s.chars().count();
                             EvalAltResult::ErrorStringBounds(chars_len, index, idx_pos)
                         })?,
                         offset,
@@ -1693,11 +1755,13 @@ impl Engine {
                     let offset = index as usize;
                     (
                         s.chars().rev().nth(offset - 1).ok_or_else(|| {
+                            let chars_len = s.chars().count();
                             EvalAltResult::ErrorStringBounds(chars_len, index, idx_pos)
                         })?,
                         offset,
                     )
                 } else {
+                    let chars_len = s.chars().count();
                     return EvalAltResult::ErrorStringBounds(chars_len, index, idx_pos).into();
                 };
 
@@ -1710,6 +1774,7 @@ impl Engine {
                 let args = &mut [target, &mut _idx];
                 let hash_get =
                     FnCallHashes::from_native(calc_fn_hash(std::iter::empty(), FN_IDX_GET, 2));
+
                 self.exec_fn_call(
                     _mods, state, _lib, FN_IDX_GET, hash_get, args, _is_ref, true, idx_pos, None,
                     _level,
@@ -1745,6 +1810,7 @@ impl Engine {
         expr: &Expr,
         level: usize,
     ) -> RhaiResult {
+        #[cfg(not(feature = "unchecked"))]
         self.inc_operations(state, expr.position())?;
 
         let result = match expr {
@@ -1792,7 +1858,7 @@ impl Engine {
                         mods,
                         state,
                         lib,
-                        Some(OpAssignment::new(OP_CONCAT)),
+                        Some(OpAssignment::new(TOKEN_OP_CONCAT)),
                         pos,
                         (&mut result).into(),
                         item,
@@ -2082,6 +2148,7 @@ impl Engine {
         stmt: &Stmt,
         level: usize,
     ) -> RhaiResult {
+        #[cfg(not(feature = "unchecked"))]
         self.inc_operations(state, stmt.position())?;
 
         let result = match stmt {
@@ -2110,6 +2177,7 @@ impl Engine {
                     .into();
                 }
 
+                #[cfg(not(feature = "unchecked"))]
                 self.inc_operations(state, pos)?;
 
                 if lhs_ptr.is_read_only() {
@@ -2304,7 +2372,6 @@ impl Engine {
             // For loop
             Stmt::For(expr, x, _) => {
                 let (Ident { name, .. }, statements) = x.as_ref();
-                let pos = statements.position();
                 let iter_obj = self
                     .eval_expr(scope, mods, state, lib, this_ptr, expr, level)?
                     .flatten();
@@ -2358,7 +2425,8 @@ impl Engine {
                             *loop_var = value;
                         }
 
-                        self.inc_operations(state, pos)?;
+                        #[cfg(not(feature = "unchecked"))]
+                        self.inc_operations(state, statements.position())?;
 
                         if statements.is_empty() {
                             continue;
@@ -2800,6 +2868,7 @@ impl Engine {
     }
 
     /// Check if the number of operations stay within limit.
+    #[cfg(not(feature = "unchecked"))]
     pub(crate) fn inc_operations(
         &self,
         state: &mut State,
@@ -2807,7 +2876,6 @@ impl Engine {
     ) -> Result<(), Box<EvalAltResult>> {
         state.operations += 1;
 
-        #[cfg(not(feature = "unchecked"))]
         // Guard against too many operations
         if self.max_operations() > 0 && state.operations > self.max_operations() {
             return EvalAltResult::ErrorTooManyOperations(pos).into();

src/engine_api.rs

@@ -1074,7 +1074,7 @@ impl Engine {
                     Some(Ok(module_ast)) => {
                         collect_imports(&module_ast, &mut resolver, &mut imports)
                     }
-                    Some(err @ Err(_)) => return err,
+                    Some(err) => return err,
                     None => (),
                 }
 
@@ -2105,6 +2105,7 @@ impl Engine {
     /// # Ok(())
     /// # }
     /// ```
+    #[cfg(not(feature = "unchecked"))]
     #[inline(always)]
     pub fn on_progress(
         &mut self,

src/fn_call.rs

@@ -294,6 +294,7 @@ impl Engine {
         is_op_assignment: bool,
         pos: Position,
     ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
+        #[cfg(not(feature = "unchecked"))]
         self.inc_operations(state, pos)?;
 
         let state_source = state.source.clone();
@@ -483,6 +484,7 @@ impl Engine {
             .into()
         }
 
+        #[cfg(not(feature = "unchecked"))]
         self.inc_operations(state, pos)?;
 
         if fn_def.body.is_empty() {
@@ -844,10 +846,11 @@ impl Engine {
         state: &mut State,
         lib: &[&Module],
         script: &str,
-        pos: Position,
+        _pos: Position,
         level: usize,
     ) -> RhaiResult {
-        self.inc_operations(state, pos)?;
+        #[cfg(not(feature = "unchecked"))]
+        self.inc_operations(state, _pos)?;
 
         let script = script.trim();
         if script.is_empty() {
@@ -1305,14 +1308,15 @@ impl Engine {
                     .chain(constant_args.iter().map(|(v, _)| Ok(v.clone())))
                     .collect::<Result<_, _>>()?;
 
-                let (mut target, pos) =
+                let (mut target, _pos) =
                     self.search_namespace(scope, mods, state, lib, this_ptr, &args_expr[0])?;
 
                 if target.as_ref().is_read_only() {
                     target = target.into_owned();
                 }
 
-                self.inc_operations(state, pos)?;
+                #[cfg(not(feature = "unchecked"))]
+                self.inc_operations(state, _pos)?;
 
                 #[cfg(not(feature = "no_closure"))]
                 let target_is_shared = target.is_shared();
@@ -1396,10 +1400,11 @@ impl Engine {
                     .collect::<Result<_, _>>()?;
 
                 // Get target reference to first argument
-                let (target, pos) =
+                let (target, _pos) =
                     self.search_scope_only(scope, mods, state, lib, this_ptr, &args_expr[0])?;
 
-                self.inc_operations(state, pos)?;
+                #[cfg(not(feature = "unchecked"))]
+                self.inc_operations(state, _pos)?;
 
                 #[cfg(not(feature = "no_closure"))]
                 let target_is_shared = target.is_shared();
@@ -1439,6 +1444,7 @@ impl Engine {
         let func = match module.get_qualified_fn(hash) {
             // Then search in Rust functions
             None => {
+                #[cfg(not(feature = "unchecked"))]
                 self.inc_operations(state, pos)?;
 
                 let hash_params = calc_fn_params_hash(args.iter().map(|a| a.type_id()));

src/fn_native.rs

@@ -418,9 +418,11 @@ pub type FnPlugin = dyn PluginFunction;
 pub type FnPlugin = dyn PluginFunction + Send + Sync;
 
 /// A standard callback function for progress reporting.
+#[cfg(not(feature = "unchecked"))]
 #[cfg(not(feature = "sync"))]
 pub type OnProgressCallback = Box<dyn Fn(u64) -> Option<Dynamic> + 'static>;
 /// A standard callback function for progress reporting.
+#[cfg(not(feature = "unchecked"))]
 #[cfg(feature = "sync")]
 pub type OnProgressCallback = Box<dyn Fn(u64) -> Option<Dynamic> + Send + Sync + 'static>;
 

src/lib.rs

@@ -140,11 +140,11 @@ pub use utils::ImmutableString;
 
 /// An identifier in Rhai. [`SmartString`](https://crates.io/crates/smartstring) is used because most
 /// identifiers are ASCII and short, fewer than 23 characters, so they can be stored inline.
-#[cfg(not(feature = "no_smartstring"))]
+#[cfg(not(feature = "no_smartstring_for_identifier"))]
-pub type Identifier = smartstring::SmartString<smartstring::Compact>;
+pub type Identifier = SmartString;
 
 /// An identifier in Rhai.
-#[cfg(feature = "no_smartstring")]
+#[cfg(feature = "no_smartstring_for_identifier")]
 pub type Identifier = ImmutableString;
 
 /// A trait to enable registering Rust functions.
@@ -305,6 +305,12 @@ type StaticVec<T> = smallvec::SmallVec<[T; 4]>;
 #[cfg(feature = "internals")]
 pub type StaticVec<T> = smallvec::SmallVec<[T; 4]>;
 
+#[cfg(not(feature = "internals"))]
+pub(crate) type SmartString = smartstring::SmartString<smartstring::Compact>;
+
+#[cfg(feature = "internals")]
+pub type SmartString = smartstring::SmartString<smartstring::Compact>;
+
 // Compiler guards against mutually-exclusive feature flags
 
 #[cfg(feature = "no_float")]

src/module/mod.rs

@@ -1661,6 +1661,16 @@ impl fmt::Debug for NamespaceRef {
     }
 }
 
+impl fmt::Display for NamespaceRef {
+    #[inline(always)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for Ident { name, .. } in self.path.iter() {
+            write!(f, "{}{}", name, Token::DoubleColon.syntax())?;
+        }
+        Ok(())
+    }
+}
+
 impl Deref for NamespaceRef {
     type Target = StaticVec<Ident>;
 
@@ -1677,16 +1687,6 @@ impl DerefMut for NamespaceRef {
     }
 }
 
-impl fmt::Display for NamespaceRef {
-    #[inline(always)]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        for Ident { name, .. } in self.path.iter() {
-            write!(f, "{}{}", name, Token::DoubleColon.syntax())?;
-        }
-        Ok(())
-    }
-}
-
 impl From<StaticVec<Ident>> for NamespaceRef {
     #[inline(always)]
     fn from(path: StaticVec<Ident>) -> Self {

src/module/resolvers/file.rs

@@ -342,7 +342,7 @@ impl ModuleResolver for FileModuleResolver {
                 ast.set_source(path);
                 Some(Ok(ast))
             }
-            err @ Err(_) => Some(err),
+            err => Some(err),
         }
     }
 }

src/optimize.rs

@@ -1,10 +1,11 @@
 //! Module implementing the [`AST`] optimizer.
 
-use crate::ast::{Expr, Stmt};
+use crate::ast::{Expr, OpAssignment, Stmt};
 use crate::dynamic::AccessMode;
 use crate::engine::{KEYWORD_DEBUG, KEYWORD_EVAL, KEYWORD_FN_PTR, KEYWORD_PRINT, KEYWORD_TYPE_OF};
 use crate::fn_builtin::get_builtin_binary_op_fn;
 use crate::parser::map_dynamic_to_expr;
+use crate::token::Token;
 use crate::utils::get_hasher;
 use crate::{
     calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, FnPtr, ImmutableString,
@@ -238,29 +239,18 @@ fn optimize_stmt_block(
             .find_map(|(i, stmt)| match stmt {
                 stmt if !is_pure(stmt) => Some(i),
 
-                Stmt::Noop(_) | Stmt::Return(_, None, _) => None,
+                Stmt::Let(e, _, _, _) | Stmt::Const(e, _, _, _) | Stmt::Expr(e)
-
+                    if !e.is_constant() =>
-                Stmt::Let(e, _, _, _)
-                | Stmt::Const(e, _, _, _)
-                | Stmt::Expr(e)
-                | Stmt::Return(_, Some(e), _)
-                    if e.is_constant() =>
                 {
-                    None
+                    Some(i)
                 }
 
                 #[cfg(not(feature = "no_module"))]
-                Stmt::Import(e, _, _) if e.is_constant() => None,
+                Stmt::Import(e, _, _) if !e.is_constant() => Some(i),
 
-                #[cfg(not(feature = "no_module"))]
+                _ => None,
-                Stmt::Export(_, _) => None,
-
-                #[cfg(not(feature = "no_closure"))]
-                Stmt::Share(_) => None,
-
-                _ => Some(i),
             })
-            .map_or(0, |n| statements.len() - n);
+            .map_or(0, |n| statements.len() - n - 1);
 
         while index < statements.len() {
             if preserve_result && index >= statements.len() - 1 {
@@ -381,6 +371,33 @@ fn optimize_stmt_block(
 /// Optimize a [statement][Stmt].
 fn optimize_stmt(stmt: &mut Stmt, state: &mut State, preserve_result: bool) {
     match stmt {
+        // var = var op expr => var op= expr
+        Stmt::Assignment(x, _)
+            if x.1.is_none()
+                && x.0.is_variable_access(true)
+                && matches!(&x.2, Expr::FnCall(x2, _)
+                        if Token::lookup_from_syntax(&x2.name).map(|t| t.has_op_assignment()).unwrap_or(false)
+                        && x2.args_count() == 2 && x2.args.len() >= 1
+                        && x2.args[0].get_variable_name(true) == x.0.get_variable_name(true)
+                ) =>
+        {
+            match &mut x.2 {
+                Expr::FnCall(x2, _) => {
+                    state.set_dirty();
+                    let op = Token::lookup_from_syntax(&x2.name).unwrap();
+                    let op_assignment = op.make_op_assignment().unwrap();
+                    x.1 = Some(OpAssignment::new(op_assignment));
+                    x.2 = if x2.args.len() > 1 {
+                        mem::take(&mut x2.args[1])
+                    } else {
+                        let (value, pos) = mem::take(&mut x2.constant_args[0]);
+                        Expr::DynamicConstant(Box::new(value), pos)
+                    };
+                }
+                _ => unreachable!(),
+            }
+        }
+
         // expr op= expr
         Stmt::Assignment(x, _) => match x.0 {
             Expr::Variable(_, _, _) => optimize_expr(&mut x.2, state),

src/packages/iter_basic.rs

@@ -10,10 +10,6 @@ use num_traits::{CheckedAdd as Add, CheckedSub as Sub};
 #[cfg(feature = "unchecked")]
 use std::ops::{Add, Sub};
 
-fn get_range<T: Variant + Clone>(from: T, to: T) -> Result<Range<T>, Box<EvalAltResult>> {
-    Ok(from..to)
-}
-
 // Register range function with step
 #[derive(Debug, Clone, Copy, Hash, Eq, PartialEq)]
 struct StepRange<T>(T, T, T)
@@ -130,18 +126,11 @@ where
     }
 }
 
-fn get_step_range<T>(from: T, to: T, step: T) -> Result<StepRange<T>, Box<EvalAltResult>>
-where
-    T: Variant + Copy + PartialOrd + Add<Output = T> + Sub<Output = T>,
-{
-    StepRange::<T>::new(from, to, step)
-}
-
 macro_rules! reg_range {
     ($lib:ident | $x:expr => $( $y:ty ),*) => {
         $(
             $lib.set_iterator::<Range<$y>>();
-            let _hash = $lib.set_native_fn($x, get_range::<$y>);
+            let _hash = $lib.set_native_fn($x, |from: $y, to: $y| Ok(from..to));
 
             #[cfg(feature = "metadata")]
             $lib.update_fn_metadata(_hash, &[
@@ -154,7 +143,7 @@ macro_rules! reg_range {
     ($lib:ident | step $x:expr => $( $y:ty ),*) => {
         $(
             $lib.set_iterator::<StepRange<$y>>();
-            let _hash = $lib.set_native_fn($x, get_step_range::<$y>);
+            let _hash = $lib.set_native_fn($x, |from: $y, to: $y, step: $y| StepRange::new(from, to, step));
 
             #[cfg(feature = "metadata")]
             $lib.update_fn_metadata(_hash, &[
@@ -192,12 +181,72 @@ def_package!(crate:BasicIteratorPackage:"Basic range iterators.", lib, {
         }
     }
 
+    #[cfg(not(feature = "no_float"))]
+    {
+        use crate::FLOAT;
+
+        #[derive(Debug, Clone, Copy, PartialEq)]
+        struct StepFloatRange(FLOAT, FLOAT, FLOAT);
+
+        impl StepFloatRange {
+            pub fn new(from: FLOAT, to: FLOAT, step: FLOAT) -> Result<Self, Box<EvalAltResult>> {
+                #[cfg(not(feature = "unchecked"))]
+                if step == 0.0 {
+                    return EvalAltResult::ErrorInFunctionCall("range".to_string(), "".to_string(),
+                        Box::new(EvalAltResult::ErrorArithmetic("step value cannot be zero".to_string(), crate::Position::NONE)),
+                        crate::Position::NONE,
+                    ).into();
+                }
+
+                Ok(Self(from, to, step))
+            }
+        }
+
+        impl Iterator for StepFloatRange {
+            type Item = FLOAT;
+
+            fn next(&mut self) -> Option<FLOAT> {
+                if self.0 == self.1 {
+                    None
+                } else if self.0 < self.1 {
+                    #[cfg(not(feature = "unchecked"))]
+                    if self.2 < 0.0 {
+                        return None;
+                    }
+
+                    let v = self.0;
+                    let n = self.0 + self.2;
+
+                    self.0 = if n >= self.1 { self.1 } else { n };
+                    Some(v)
+                } else {
+                    #[cfg(not(feature = "unchecked"))]
+                    if self.2 > 0.0 {
+                        return None;
+                    }
+
+                    let v = self.0;
+                    let n = self.0 + self.2;
+
+                    self.0 = if n <= self.1 { self.1 } else { n };
+                    Some(v)
+                }
+            }
+        }
+
+        impl std::iter::FusedIterator for StepFloatRange {}
+
+        lib.set_iterator::<StepFloatRange>();
+
+        let _hash = lib.set_native_fn("range", |from, to, step| StepFloatRange::new(from, to, step));
+        #[cfg(feature = "metadata")]
+        lib.update_fn_metadata(_hash, &["from: FLOAT", "to: FLOAT", "step: FLOAT", "Iterator<Item=FLOAT>"]);
+    }
+
     #[cfg(feature = "decimal")]
     {
-        use rust_decimal::{
+        use rust_decimal::Decimal;
-            prelude::{One, Zero},
+        use num_traits::Zero;
-            Decimal,
-        };
 
         #[derive(Debug, Clone, Copy, Hash, Eq, PartialEq)]
         struct StepDecimalRange(Decimal, Decimal, Decimal);
@@ -252,10 +301,6 @@ def_package!(crate:BasicIteratorPackage:"Basic range iterators.", lib, {
 
         lib.set_iterator::<StepDecimalRange>();
 
-        let _hash = lib.set_native_fn("range", |from, to| StepDecimalRange::new(from, to, Decimal::one()));
-        #[cfg(feature = "metadata")]
-        lib.update_fn_metadata(_hash, &["from: Decimal", "to: Decimal", "Iterator<Item=Decimal>"]);
-
         let _hash = lib.set_native_fn("range", |from, to, step| StepDecimalRange::new(from, to, step));
         #[cfg(feature = "metadata")]
         lib.update_fn_metadata(_hash, &["from: Decimal", "to: Decimal", "step: Decimal", "Iterator<Item=Decimal>"]);

src/parser.rs

@@ -1409,7 +1409,7 @@ fn parse_unary(
 
 /// Make an assignment statement.
 fn make_assignment_stmt<'a>(
-    op: &'static str,
+    op: Option<Token>,
     state: &mut ParseState,
     lhs: Expr,
     rhs: Expr,
@@ -1432,11 +1432,7 @@ fn make_assignment_stmt<'a>(
         }
     }
 
-    let op_info = if op.is_empty() {
+    let op_info = op.map(|v| OpAssignment::new(v));
-        None
-    } else {
-        Some(OpAssignment::new(op))
-    };
 
     match &lhs {
         // const_expr = rhs
@@ -1516,25 +1512,12 @@ fn parse_op_assignment_stmt(
     let (token, token_pos) = input.peek().unwrap();
     settings.pos = *token_pos;
 
-    let op = match token {
+    let (op, pos) = match token {
-        Token::Equals => "",
+        Token::Equals => (None, input.next().unwrap().1),
-
+        _ if token.is_op_assignment() => input.next().map(|(op, pos)| (Some(op), pos)).unwrap(),
-        Token::PlusAssign
-        | Token::MinusAssign
-        | Token::MultiplyAssign
-        | Token::DivideAssign
-        | Token::LeftShiftAssign
-        | Token::RightShiftAssign
-        | Token::ModuloAssign
-        | Token::PowerOfAssign
-        | Token::AndAssign
-        | Token::OrAssign
-        | Token::XOrAssign => token.keyword_syntax(),
-
         _ => return Ok(Stmt::Expr(lhs)),
     };
 
-    let (_, pos) = input.next().unwrap();
     let rhs = parse_expr(input, state, lib, settings.level_up())?;
     make_assignment_stmt(op, state, lhs, rhs, pos)
 }

src/token.rs

@@ -185,6 +185,16 @@ impl Position {
         #[cfg(feature = "no_position")]
         return true;
     }
+    /// Print this [`Position`] for debug purposes.
+    #[inline(always)]
+    pub(crate) fn debug_print(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        #[cfg(not(feature = "no_position"))]
+        if !self.is_none() {
+            write!(_f, " @ {:?}", self)?;
+        }
+
+        Ok(())
+    }
 }
 
 impl Default for Position {
@@ -568,6 +578,80 @@ impl Token {
         }
     }
 
+    /// Is this token an op-assignment operator?
+    #[inline]
+    pub fn is_op_assignment(&self) -> bool {
+        match self {
+            Self::PlusAssign
+            | Self::MinusAssign
+            | Self::MultiplyAssign
+            | Self::DivideAssign
+            | Self::LeftShiftAssign
+            | Self::RightShiftAssign
+            | Self::ModuloAssign
+            | Self::PowerOfAssign
+            | Self::AndAssign
+            | Self::OrAssign
+            | Self::XOrAssign => true,
+            _ => false,
+        }
+    }
+
+    /// Get the corresponding operator of the token if it is an op-assignment operator.
+    pub fn map_op_assignment(&self) -> Option<Self> {
+        Some(match self {
+            Self::PlusAssign => Self::Plus,
+            Self::MinusAssign => Self::Minus,
+            Self::MultiplyAssign => Self::Multiply,
+            Self::DivideAssign => Self::Divide,
+            Self::LeftShiftAssign => Self::LeftShift,
+            Self::RightShiftAssign => Self::RightShift,
+            Self::ModuloAssign => Self::Modulo,
+            Self::PowerOfAssign => Self::PowerOf,
+            Self::AndAssign => Self::Ampersand,
+            Self::OrAssign => Self::Pipe,
+            Self::XOrAssign => Self::XOr,
+            _ => return None,
+        })
+    }
+
+    /// Has this token a corresponding op-assignment operator?
+    #[inline]
+    pub fn has_op_assignment(&self) -> bool {
+        match self {
+            Self::Plus
+            | Self::Minus
+            | Self::Multiply
+            | Self::Divide
+            | Self::LeftShift
+            | Self::RightShift
+            | Self::Modulo
+            | Self::PowerOf
+            | Self::Ampersand
+            | Self::Pipe
+            | Self::XOr => true,
+            _ => false,
+        }
+    }
+
+    /// Get the corresponding op-assignment operator of the token.
+    pub fn make_op_assignment(&self) -> Option<Self> {
+        Some(match self {
+            Self::Plus => Self::PlusAssign,
+            Self::Minus => Self::MinusAssign,
+            Self::Multiply => Self::MultiplyAssign,
+            Self::Divide => Self::DivideAssign,
+            Self::LeftShift => Self::LeftShiftAssign,
+            Self::RightShift => Self::RightShiftAssign,
+            Self::Modulo => Self::ModuloAssign,
+            Self::PowerOf => Self::PowerOfAssign,
+            Self::Ampersand => Self::AndAssign,
+            Self::Pipe => Self::OrAssign,
+            Self::XOr => Self::XOrAssign,
+            _ => return None,
+        })
+    }
+
     /// Reverse lookup a token from a piece of syntax.
     pub fn lookup_from_syntax(syntax: &str) -> Option<Self> {
         use Token::*;

src/utils.rs

@@ -1,7 +1,7 @@
 //! Module containing various utility types and functions.
 
 use crate::fn_native::{shared_make_mut, shared_take};
-use crate::{Identifier, Shared};
+use crate::{Identifier, Shared, SmartString};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 use std::{
@@ -141,10 +141,10 @@ pub(crate) fn combine_hashes(a: u64, b: u64) -> u64 {
 /// assert_eq!(s, "hello, world!");
 /// ```
 #[derive(Clone, Eq, Ord, Hash, Default)]
-pub struct ImmutableString(Shared<String>);
+pub struct ImmutableString(Shared<SmartString>);
 
 impl Deref for ImmutableString {
-    type Target = String;
+    type Target = SmartString;
 
     #[inline(always)]
     fn deref(&self) -> &Self::Target {
@@ -152,9 +152,9 @@ impl Deref for ImmutableString {
     }
 }
 
-impl AsRef<String> for ImmutableString {
+impl AsRef<SmartString> for ImmutableString {
     #[inline(always)]
-    fn as_ref(&self) -> &String {
+    fn as_ref(&self) -> &SmartString {
         &self.0
     }
 }
@@ -166,9 +166,9 @@ impl AsRef<str> for ImmutableString {
     }
 }
 
-impl Borrow<String> for ImmutableString {
+impl Borrow<SmartString> for ImmutableString {
     #[inline(always)]
-    fn borrow(&self) -> &String {
+    fn borrow(&self) -> &SmartString {
         &self.0
     }
 }
@@ -183,33 +183,31 @@ impl Borrow<str> for ImmutableString {
 impl From<&str> for ImmutableString {
     #[inline(always)]
     fn from(value: &str) -> Self {
-        Self(value.to_string().into())
+        Self(Into::<SmartString>::into(value).into())
     }
 }
 impl From<&String> for ImmutableString {
     #[inline(always)]
     fn from(value: &String) -> Self {
-        Self(value.to_string().into())
+        Self(Into::<SmartString>::into(value).into())
     }
 }
 impl From<String> for ImmutableString {
     #[inline(always)]
     fn from(value: String) -> Self {
+        Self(Into::<SmartString>::into(value).into())
+    }
+}
+impl From<SmartString> for ImmutableString {
+    #[inline(always)]
+    fn from(value: SmartString) -> Self {
         Self(value.into())
     }
 }
-
+impl From<ImmutableString> for SmartString {
-impl From<Box<String>> for ImmutableString {
     #[inline(always)]
-    fn from(value: Box<String>) -> Self {
+    fn from(mut value: ImmutableString) -> Self {
-        Self(value.into())
+        std::mem::take(shared_make_mut(&mut value.0))
-    }
-}
-
-impl From<ImmutableString> for String {
-    #[inline(always)]
-    fn from(value: ImmutableString) -> Self {
-        value.into_owned()
     }
 }
 
@@ -218,35 +216,35 @@ impl FromStr for ImmutableString {
 
     #[inline(always)]
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        Ok(Self(s.to_string().into()))
+        Ok(Self(Into::<SmartString>::into(s).into()))
     }
 }
 
 impl FromIterator<char> for ImmutableString {
     #[inline(always)]
     fn from_iter<T: IntoIterator<Item = char>>(iter: T) -> Self {
-        Self(iter.into_iter().collect::<String>().into())
+        Self(iter.into_iter().collect::<SmartString>().into())
     }
 }
 
 impl<'a> FromIterator<&'a char> for ImmutableString {
     #[inline(always)]
     fn from_iter<T: IntoIterator<Item = &'a char>>(iter: T) -> Self {
-        Self(iter.into_iter().cloned().collect::<String>().into())
+        Self(iter.into_iter().cloned().collect::<SmartString>().into())
     }
 }
 
 impl<'a> FromIterator<&'a str> for ImmutableString {
     #[inline(always)]
     fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self {
-        Self(iter.into_iter().collect::<String>().into())
+        Self(iter.into_iter().collect::<SmartString>().into())
     }
 }
 
 impl<'a> FromIterator<String> for ImmutableString {
     #[inline(always)]
     fn from_iter<T: IntoIterator<Item = String>>(iter: T) -> Self {
-        Self(iter.into_iter().collect::<String>().into())
+        Self(iter.into_iter().collect::<SmartString>().into())
     }
 }
 
@@ -397,9 +395,15 @@ impl Add<String> for &ImmutableString {
 impl AddAssign<String> for ImmutableString {
     #[inline(always)]
     fn add_assign(&mut self, rhs: String) {
+        if !rhs.is_empty() {
+            if self.is_empty() {
+                self.0 = Into::<SmartString>::into(rhs).into();
+            } else {
                 self.make_mut().push_str(&rhs);
             }
         }
+    }
+}
 
 impl Add<char> for ImmutableString {
     type Output = Self;
@@ -466,7 +470,7 @@ impl SubAssign<&ImmutableString> for ImmutableString {
             if self.is_empty() {
                 self.0 = rhs.0.clone();
             } else {
-                self.0 = self.replace(rhs.as_str(), "").into();
+                self.0 = Into::<SmartString>::into(self.replace(rhs.as_str(), "")).into();
             }
         }
     }
@@ -479,7 +483,7 @@ impl SubAssign<ImmutableString> for ImmutableString {
             if self.is_empty() {
                 self.0 = rhs.0;
             } else {
-                self.0 = self.replace(rhs.as_str(), "").into();
+                self.0 = Into::<SmartString>::into(self.replace(rhs.as_str(), "")).into();
             }
         }
     }
@@ -518,7 +522,7 @@ impl Sub<String> for &ImmutableString {
 impl SubAssign<String> for ImmutableString {
     #[inline(always)]
     fn sub_assign(&mut self, rhs: String) {
-        self.0 = self.replace(&rhs, "").into();
+        self.0 = Into::<SmartString>::into(self.replace(&rhs, "")).into();
     }
 }
 
@@ -543,7 +547,7 @@ impl Sub<char> for &ImmutableString {
 impl SubAssign<char> for ImmutableString {
     #[inline(always)]
     fn sub_assign(&mut self, rhs: char) {
-        self.0 = self.replace(rhs, "").into();
+        self.0 = Into::<SmartString>::into(self.replace(rhs, "")).into();
     }
 }
 
@@ -588,34 +592,18 @@ impl PartialOrd<ImmutableString> for String {
     }
 }
 
-#[cfg(not(feature = "no_smartstring"))]
-impl From<ImmutableString> for Identifier {
-    #[inline(always)]
-    fn from(value: ImmutableString) -> Self {
-        value.into_owned().into()
-    }
-}
-
-#[cfg(not(feature = "no_smartstring"))]
-impl From<Identifier> for ImmutableString {
-    #[inline(always)]
-    fn from(value: Identifier) -> Self {
-        value.to_string().into()
-    }
-}
-
 impl ImmutableString {
     /// Consume the [`ImmutableString`] and convert it into a [`String`].
     /// If there are other references to the same string, a cloned copy is returned.
     #[inline(always)]
     pub fn into_owned(mut self) -> String {
         self.make_mut(); // Make sure it is unique reference
-        shared_take(self.0) // Should succeed
+        shared_take(self.0).into() // Should succeed
     }
     /// Make sure that the [`ImmutableString`] is unique (i.e. no other outstanding references).
-    /// Then return a mutable reference to the [`String`].
+    /// Then return a mutable reference to the [`SmartString`].
     #[inline(always)]
-    pub fn make_mut(&mut self) -> &mut String {
+    pub(crate) fn make_mut(&mut self) -> &mut SmartString {
         shared_make_mut(&mut self.0)
     }
 }
@@ -630,17 +618,17 @@ impl ImmutableString {
 /// yet interned.
 #[derive(Debug, Clone, Default, Hash)]
 pub struct IdentifierBuilder(
-    #[cfg(feature = "no_smartstring")] std::collections::BTreeSet<Identifier>,
+    #[cfg(feature = "no_smartstring_for_identifier")] std::collections::BTreeSet<Identifier>,
 );
 
 impl IdentifierBuilder {
     /// Get an identifier from a text string.
     #[inline(always)]
     pub fn get(&mut self, text: impl AsRef<str> + Into<Identifier>) -> Identifier {
-        #[cfg(not(feature = "no_smartstring"))]
+        #[cfg(not(feature = "no_smartstring_for_identifier"))]
         return text.as_ref().into();
 
-        #[cfg(feature = "no_smartstring")]
+        #[cfg(feature = "no_smartstring_for_identifier")]
         return self.0.get(text.as_ref()).cloned().unwrap_or_else(|| {
             let s: Identifier = text.into();
             self.0.insert(s.clone());

tests/for.rs

@@ -1,11 +1,20 @@
 use rhai::{Engine, EvalAltResult, Module, INT};
 
-#[cfg(not(feature = "no_index"))]
+#[cfg(not(feature = "no_float"))]
+use rhai::FLOAT;
+
+#[cfg(feature = "decimal")]
+#[cfg(not(feature = "no_float"))]
+use rust_decimal::Decimal;
+
 #[test]
-fn test_for() -> Result<(), Box<EvalAltResult>> {
+fn test_for_loop() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();
 
-    let script = "
+    #[cfg(not(feature = "no_index"))]
+    assert_eq!(
+        engine.eval::<INT>(
+            "
                 let sum1 = 0;
                 let sum2 = 0;
                 let inputs = [1, 2, 3, 4, 5];
@@ -23,9 +32,21 @@ fn test_for() -> Result<(), Box<EvalAltResult>> {
                 }
 
                 sum1 + sum2
-    ";
+            "
+        )?,
+        35
+    );
 
-    assert_eq!(engine.eval::<INT>(script)?, 35);
+    assert_eq!(
+        engine.eval::<INT>(
+            "
+                let sum = 0;
+                for x in range(1, 10) { sum += x; }
+                sum
+            "
+        )?,
+        45
+    );
 
     assert_eq!(
         engine.eval::<INT>(
@@ -38,6 +59,7 @@ fn test_for() -> Result<(), Box<EvalAltResult>> {
         25
     );
 
+    #[cfg(not(feature = "unchecked"))]
     assert_eq!(
         engine.eval::<INT>(
             "
@@ -49,6 +71,7 @@ fn test_for() -> Result<(), Box<EvalAltResult>> {
         0
     );
 
+    #[cfg(not(feature = "unchecked"))]
     assert_eq!(
         engine.eval::<INT>(
             "
@@ -71,6 +94,105 @@ fn test_for() -> Result<(), Box<EvalAltResult>> {
         30
     );
 
+    #[cfg(not(feature = "no_float"))]
+    {
+        assert_eq!(
+            engine.eval::<FLOAT>(
+                "
+                    let sum = 0.0;
+                    for x in range(1.0, 10.0, 2.0) { sum += x; }
+                    sum
+                "
+            )?,
+            25.0
+        );
+
+        #[cfg(not(feature = "unchecked"))]
+        assert_eq!(
+            engine.eval::<FLOAT>(
+                "
+                    let sum = 0.0;
+                    for x in range(10.0, 1.0, 2.0) { sum += x; }
+                    sum
+                "
+            )?,
+            0.0
+        );
+
+        #[cfg(not(feature = "unchecked"))]
+        assert_eq!(
+            engine.eval::<FLOAT>(
+                "
+                    let sum = 0.0;
+                    for x in range(1.0, 10.0, -2.0) { sum += x; }
+                    sum
+                "
+            )?,
+            0.0
+        );
+
+        assert_eq!(
+            engine.eval::<FLOAT>(
+                "
+                    let sum = 0.0;
+                    for x in range(10.0, 1.0, -2.0) { sum += x; }
+                    sum
+                "
+            )?,
+            30.0
+        );
+    }
+
+    #[cfg(not(feature = "no_float"))]
+    #[cfg(feature = "decimal")]
+    {
+        assert_eq!(
+            engine.eval::<Decimal>(
+                "
+                    let sum = to_decimal(0);
+                    for x in range(to_decimal(1), to_decimal(10), to_decimal(2)) { sum += x; }
+                    sum
+                "
+            )?,
+            Decimal::from(25)
+        );
+
+        #[cfg(not(feature = "unchecked"))]
+        assert_eq!(
+            engine.eval::<Decimal>(
+                "
+                    let sum = to_decimal(0);
+                    for x in range(to_decimal(10), to_decimal(1), to_decimal(2)) { sum += x; }
+                    sum
+                "
+            )?,
+            Decimal::from(0)
+        );
+
+        #[cfg(not(feature = "unchecked"))]
+        assert_eq!(
+            engine.eval::<Decimal>(
+                "
+                    let sum = to_decimal(0);
+                    for x in range(to_decimal(1), to_decimal(10), to_decimal(-2)) { sum += x; }
+                    sum
+                "
+            )?,
+            Decimal::from(0)
+        );
+
+        assert_eq!(
+            engine.eval::<Decimal>(
+                "
+                    let sum = to_decimal(0);
+                    for x in range(to_decimal(10), to_decimal(1), to_decimal(-2)) { sum += x; }
+                    sum
+                "
+            )?,
+            Decimal::from(30)
+        );
+    }
+
     Ok(())
 }
 

tests/maps.rs

@@ -205,7 +205,7 @@ fn test_map_json() -> Result<(), Box<EvalAltResult>> {
 
     assert!(matches!(
         *engine.parse_json("   123", true).expect_err("should error"),
-        EvalAltResult::ErrorParsing(ParseErrorType::MissingToken(token, _), pos)
+        EvalAltResult::ErrorParsing(ParseErrorType::MissingToken(token, _), _)
             if token == "{"
     ));