Merge pull request #564 from schungx/master

Bug fixes and some enhancements.

CHANGELOG.md

@@ -8,6 +8,21 @@ Bug fixes
 ---------
 
 * Self-contained `AST` now works properly with `Engine::call_fn`.
+* Missing `to_int` from `Decimal` is added.
+* Parsing of index expressions is relaxed and many cases no longer result in an index-type error to allow for custom indexers.
+* Merging or combining a self-contained `AST` into another `AST` now works properly.
+
+Deprecated API's
+----------------
+
+* `FnPtr::num_curried` is deprecated in favor of `FnPtr::curry().len()`.
+
+Enhancements
+------------
+
+* `EvalAltResult::IndexNotFound` is added to aid in raising errors for indexers.
+* `Engine::def_tag`, `Engine::def_tag_mut` and `Engine::set_tag` are added to manage a default value for the custom evaluation state, accessible via `EvalState::tag()` (which is the same as `NativeCallContext::tag()`).
+* Originally, the debugger's custom state uses the same state as `EvalState::tag()` (which is the same as `NativeCallContext::tag()`).  It is now split into its own variable accessible under `Debugger::state()`.
 
 
 Version 1.7.0

src/api/call_fn.rs

@@ -187,7 +187,7 @@ impl Engine {
     ///
     /// # WARNING - Low Level API
     ///
-    /// This function is very low level.
+    /// This function is _extremely_ low level.
     ///
     /// A [`GlobalRuntimeState`] and [`Caches`] need to be passed into the function, which can be
     /// created via [`GlobalRuntimeState::new`] and [`Caches::new`].

src/api/compile.rs

@@ -201,11 +201,7 @@ impl Engine {
         scope: &Scope,
         scripts: impl AsRef<[S]>,
     ) -> ParseResult<AST> {
-        self.compile_with_scope_and_optimization_level(
+        self.compile_with_scope_and_optimization_level(scope, scripts, self.optimization_level)
-            scope,
-            scripts,
-            self.options.optimization_level,
-        )
     }
     /// Join a list of strings and compile into an [`AST`] using own scope at a specific optimization level.
     ///
@@ -296,6 +292,6 @@ impl Engine {
 
         let mut peekable = stream.peekable();
         let mut state = ParseState::new(self, scope, tokenizer_control);
-        self.parse_global_expr(&mut peekable, &mut state, self.options.optimization_level)
+        self.parse_global_expr(&mut peekable, &mut state, self.optimization_level)
     }
 }

src/api/custom_syntax.rs

@@ -1,14 +1,13 @@
 //! Module implementing custom syntax for [`Engine`].
 
 use crate::ast::Expr;
-use crate::eval::Caches;
 use crate::func::native::SendSync;
 use crate::parser::ParseResult;
 use crate::tokenizer::{is_valid_identifier, Token};
 use crate::types::dynamic::Variant;
 use crate::{
     reify, Engine, EvalContext, Identifier, ImmutableString, LexError, Position, RhaiResult,
-    Shared, StaticVec,
+    StaticVec,
 };
 use std::ops::Deref;
 #[cfg(feature = "no_std")]
@@ -65,6 +64,15 @@ impl<'a> From<&'a Expr> for Expression<'a> {
 }
 
 impl Expression<'_> {
+    /// Evaluate this [expression tree][Expression] within an [evaluation context][`EvalContext`].
+    ///
+    /// # WARNING - Low Level API
+    ///
+    /// This function is very low level.  It evaluates an expression from an [`AST`][crate::AST].
+    #[inline(always)]
+    pub fn eval_with_context(&self, context: &mut EvalContext) -> RhaiResult {
+        context.eval_expression_tree(self)
+    }
     /// Get the value of this expression if it is a variable name or a string constant.
     ///
     /// Returns [`None`] also if the constant is not of the specified type.
@@ -131,41 +139,13 @@ impl Deref for Expression<'_> {
     }
 }
 
-impl EvalContext<'_, '_, '_, '_, '_, '_, '_, '_> {
-    /// Evaluate an [expression tree][Expression].
-    ///
-    /// # WARNING - Low Level API
-    ///
-    /// This function is very low level.  It evaluates an expression from an [`AST`][crate::AST].
-    #[inline(always)]
-    pub fn eval_expression_tree(&mut self, expr: &Expression) -> RhaiResult {
-        let mut caches;
-
-        self.engine.eval_expr(
-            self.scope,
-            self.global,
-            match self.caches.as_mut() {
-                Some(c) => c,
-                None => {
-                    caches = Caches::new();
-                    &mut caches
-                }
-            },
-            self.lib,
-            self.this_ptr,
-            expr,
-            self.level,
-        )
-    }
-}
-
 /// Definition of a custom syntax definition.
 pub struct CustomSyntax {
     /// A parsing function to return the next token in a custom syntax based on the
     /// symbols parsed so far.
     pub parse: Box<FnCustomSyntaxParse>,
     /// Custom syntax implementation function.
-    pub func: Shared<FnCustomSyntaxEval>,
+    pub func: Box<FnCustomSyntaxEval>,
     /// Any variables added/removed in the scope?
     pub scope_may_be_changed: bool,
 }
@@ -356,7 +336,7 @@ impl Engine {
             key.into(),
             CustomSyntax {
                 parse: Box::new(parse),
-                func: (Box::new(func) as Box<FnCustomSyntaxEval>).into(),
+                func: Box::new(func),
                 scope_may_be_changed,
             }
             .into(),

src/api/deprecated.rs

@@ -259,6 +259,19 @@ impl<T> From<EvalAltResult> for RhaiResultOf<T> {
 }
 
 impl FnPtr {
+    /// Get the number of curried arguments.
+    ///
+    /// # Deprecated
+    ///
+    /// This method is deprecated. Use [`curry().len()`][`FnPtr::curry`] instead.
+    ///
+    /// This method will be removed in the next major version.
+    #[deprecated(since = "1.8.0", note = "use `curry().len()` instead")]
+    #[inline(always)]
+    #[must_use]
+    pub fn num_curried(&self) -> usize {
+        self.curry().len()
+    }
     /// Call the function pointer with curried arguments (if any).
     /// The function may be script-defined (not available under `no_function`) or native Rust.
     ///

src/api/eval.rs

@@ -67,7 +67,7 @@ impl Engine {
         let ast = self.compile_with_scope_and_optimization_level(
             scope,
             &[script],
-            self.options.optimization_level,
+            self.optimization_level,
         )?;
         self.eval_ast_with_scope(scope, &ast)
     }

src/api/json.rs

@@ -119,8 +119,8 @@ impl Engine {
             },
         );
 
-        let scope = &Scope::new();
+        let scope = Scope::new();
-        let mut state = ParseState::new(self, scope, tokenizer_control);
+        let mut state = ParseState::new(self, &scope, tokenizer_control);
 
         let ast = self.parse_global_expr(
             &mut stream.peekable(),
@@ -156,11 +156,13 @@ pub fn format_map_as_json(map: &Map) -> String {
     let mut result = String::from('{');
 
     for (key, value) in map {
+        use std::fmt::Write;
+
         if result.len() > 1 {
             result.push(',');
         }
 
-        result.push_str(&format!("{:?}", key));
+        write!(result, "{:?}", key).unwrap();
         result.push(':');
 
         if let Some(val) = value.read_lock::<Map>() {
@@ -171,7 +173,7 @@ pub fn format_map_as_json(map: &Map) -> String {
         if value.is::<()>() {
             result.push_str("null");
         } else {
-            result.push_str(&format!("{:?}", value));
+            write!(result, "{:?}", value).unwrap();
         }
     }
 

src/api/mod.rs

@@ -30,7 +30,7 @@ pub mod deprecated;
 
 use crate::engine::Precedence;
 use crate::tokenizer::Token;
-use crate::{Engine, Identifier};
+use crate::{Dynamic, Engine, Identifier};
 
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -195,4 +195,23 @@ impl Engine {
 
         Ok(self)
     }
+
+    /// Get the default value of the custom state for each evaluation run.
+    #[inline(always)]
+    #[must_use]
+    pub fn default_tag(&self) -> &Dynamic {
+        &self.def_tag
+    }
+    /// Get a mutable reference to the default value of the custom state for each evaluation run.
+    #[inline(always)]
+    #[must_use]
+    pub fn default_tag_mut(&mut self) -> &mut Dynamic {
+        &mut self.def_tag
+    }
+    /// Set the default value of the custom state for each evaluation run.
+    #[inline(always)]
+    pub fn set_default_tag(&mut self, value: impl Into<Dynamic>) -> &mut Self {
+        self.def_tag = value.into();
+        self
+    }
 }

src/api/optimize.rs

@@ -9,7 +9,7 @@ impl Engine {
     /// Not available under `no_optimize`.
     #[inline(always)]
     pub fn set_optimization_level(&mut self, optimization_level: OptimizationLevel) -> &mut Self {
-        self.options.optimization_level = optimization_level;
+        self.optimization_level = optimization_level;
         self
     }
 
@@ -20,7 +20,7 @@ impl Engine {
     #[inline(always)]
     #[must_use]
     pub const fn optimization_level(&self) -> OptimizationLevel {
-        self.options.optimization_level
+        self.optimization_level
     }
 
     /// Optimize the [`AST`] with constants defined in an external Scope.

src/api/options.rs

@@ -1,62 +1,49 @@
 //! Settings for [`Engine`]'s language options.
 
-use crate::{Engine, OptimizationLevel};
+use crate::Engine;
+use bitflags::bitflags;
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 
-/// A type containing all language options for the [`Engine`].
+bitflags! {
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+    /// Bit-flags containing all language options for the [`Engine`].
-pub struct LanguageOptions {
+    pub struct LangOptions: u8 {
-    /// Script optimization level.
+        /// Is `if`-expression allowed?
-    pub optimization_level: OptimizationLevel,
+        const IF_EXPR = 0b_00000001;
-    /// Is `if`-expression allowed?
+        /// Is `switch` expression allowed?
-    pub allow_if_expr: bool,
+        const SWITCH_EXPR = 0b_00000010;
-    /// Is `switch` expression allowed?
+        /// Is statement-expression allowed?
-    pub allow_switch_expr: bool,
+        const STMT_EXPR = 0b_00000100;
-    /// Is statement-expression allowed?
+        /// Is anonymous function allowed?
-    pub allow_stmt_expr: bool,
+        #[cfg(not(feature = "no_function"))]
-    /// Is anonymous function allowed?
+        const ANON_FN = 0b_00001000;
-    #[cfg(not(feature = "no_function"))]
+        /// Is looping allowed?
-    pub allow_anonymous_fn: bool,
+        const LOOPING = 0b_00010000;
-    /// Is looping allowed?
+        /// Is variables shadowing allowed?
-    pub allow_looping: bool,
+        const SHADOW = 0b_00100000;
-    /// Is variables shadowing allowed?
+        /// Strict variables mode?
-    pub allow_shadowing: bool,
+        const STRICT_VAR = 0b_01000000;
-    /// Strict variables mode?
+        /// Raise error if an object map property does not exist?
-    pub strict_var: bool,
+        /// Returns `()` if `false`.
-    /// Raise error if an object map property does not exist?
+        #[cfg(not(feature = "no_object"))]
-    /// Returns `()` if `false`.
+        const FAIL_ON_INVALID_MAP_PROPERTY = 0b_10000000;
-    #[cfg(not(feature = "no_object"))]
-    pub fail_on_invalid_map_property: bool,
-}
-
-impl LanguageOptions {
-    /// Create a new [`Options`] with default values.
-    #[inline(always)]
-    pub const fn new() -> Self {
-        Self {
-            #[cfg(not(feature = "no_optimize"))]
-            optimization_level: OptimizationLevel::Simple,
-            #[cfg(feature = "no_optimize")]
-            optimization_level: (),
-
-            allow_if_expr: true,
-            allow_switch_expr: true,
-            allow_stmt_expr: true,
-            #[cfg(not(feature = "no_function"))]
-            allow_anonymous_fn: true,
-            allow_looping: true,
-            strict_var: false,
-            allow_shadowing: true,
-            #[cfg(not(feature = "no_object"))]
-            fail_on_invalid_map_property: false,
-        }
     }
 }
 
-impl Default for LanguageOptions {
+impl LangOptions {
-    fn default() -> Self {
+    /// Create a new [`Options`] with default values.
-        Self::new()
+    #[inline(always)]
+    pub fn new() -> Self {
+        Self::IF_EXPR | Self::SWITCH_EXPR | Self::STMT_EXPR | Self::LOOPING | Self::SHADOW | {
+            #[cfg(not(feature = "no_function"))]
+            {
+                Self::ANON_FN
+            }
+            #[cfg(feature = "no_function")]
+            {
+                Self::empty()
+            }
+        }
     }
 }
 
@@ -65,34 +52,34 @@ impl Engine {
     /// Default is `true`.
     #[inline(always)]
     pub const fn allow_if_expression(&self) -> bool {
-        self.options.allow_if_expr
+        self.options.contains(LangOptions::IF_EXPR)
     }
     /// Set whether `if`-expression is allowed.
     #[inline(always)]
     pub fn set_allow_if_expression(&mut self, enable: bool) {
-        self.options.allow_if_expr = enable;
+        self.options.set(LangOptions::IF_EXPR, enable)
     }
     /// Is `switch` expression allowed?
     /// Default is `true`.
     #[inline(always)]
     pub const fn allow_switch_expression(&self) -> bool {
-        self.options.allow_switch_expr
+        self.options.contains(LangOptions::SWITCH_EXPR)
     }
     /// Set whether `switch` expression is allowed.
     #[inline(always)]
     pub fn set_allow_switch_expression(&mut self, enable: bool) {
-        self.options.allow_switch_expr = enable;
+        self.options.set(LangOptions::SWITCH_EXPR, enable);
     }
     /// Is statement-expression allowed?
     /// Default is `true`.
     #[inline(always)]
     pub const fn allow_statement_expression(&self) -> bool {
-        self.options.allow_stmt_expr
+        self.options.contains(LangOptions::STMT_EXPR)
     }
     /// Set whether statement-expression is allowed.
     #[inline(always)]
     pub fn set_allow_statement_expression(&mut self, enable: bool) {
-        self.options.allow_stmt_expr = enable;
+        self.options.set(LangOptions::STMT_EXPR, enable);
     }
     /// Is anonymous function allowed?
     /// Default is `true`.
@@ -101,7 +88,7 @@ impl Engine {
     #[cfg(not(feature = "no_function"))]
     #[inline(always)]
     pub const fn allow_anonymous_fn(&self) -> bool {
-        self.options.allow_anonymous_fn
+        self.options.contains(LangOptions::ANON_FN)
     }
     /// Set whether anonymous function is allowed.
     ///
@@ -109,40 +96,40 @@ impl Engine {
     #[cfg(not(feature = "no_function"))]
     #[inline(always)]
     pub fn set_allow_anonymous_fn(&mut self, enable: bool) {
-        self.options.allow_anonymous_fn = enable;
+        self.options.set(LangOptions::ANON_FN, enable);
     }
     /// Is looping allowed?
     /// Default is `true`.
     #[inline(always)]
     pub const fn allow_looping(&self) -> bool {
-        self.options.allow_looping
+        self.options.contains(LangOptions::LOOPING)
     }
     /// Set whether looping is allowed.
     #[inline(always)]
     pub fn set_allow_looping(&mut self, enable: bool) {
-        self.options.allow_looping = enable;
+        self.options.set(LangOptions::LOOPING, enable);
     }
     /// Is variables shadowing allowed?
     /// Default is `true`.
     #[inline(always)]
     pub const fn allow_shadowing(&self) -> bool {
-        self.options.allow_shadowing
+        self.options.contains(LangOptions::SHADOW)
     }
     /// Set whether variables shadowing is allowed.
     #[inline(always)]
     pub fn set_allow_shadowing(&mut self, enable: bool) {
-        self.options.allow_shadowing = enable;
+        self.options.set(LangOptions::SHADOW, enable);
     }
     /// Is strict variables mode enabled?
     /// Default is `false`.
     #[inline(always)]
     pub const fn strict_variables(&self) -> bool {
-        self.options.strict_var
+        self.options.contains(LangOptions::STRICT_VAR)
     }
     /// Set whether strict variables mode is enabled.
     #[inline(always)]
     pub fn set_strict_variables(&mut self, enable: bool) {
-        self.options.strict_var = enable;
+        self.options.set(LangOptions::STRICT_VAR, enable);
     }
     /// Raise error if an object map property does not exist?
     /// Default is `false`.
@@ -151,7 +138,8 @@ impl Engine {
     #[cfg(not(feature = "no_object"))]
     #[inline(always)]
     pub const fn fail_on_invalid_map_property(&self) -> bool {
-        self.options.fail_on_invalid_map_property
+        self.options
+            .contains(LangOptions::FAIL_ON_INVALID_MAP_PROPERTY)
     }
     /// Set whether to raise error if an object map property does not exist.
     ///
@@ -159,6 +147,7 @@ impl Engine {
     #[cfg(not(feature = "no_object"))]
     #[inline(always)]
     pub fn set_fail_on_invalid_map_property(&mut self, enable: bool) {
-        self.options.fail_on_invalid_map_property = enable;
+        self.options
+            .set(LangOptions::FAIL_ON_INVALID_MAP_PROPERTY, enable);
     }
 }

src/api/run.rs

@@ -26,11 +26,7 @@ impl Engine {
             self.lex_raw(&scripts, self.token_mapper.as_ref().map(Box::as_ref));
         let mut state = ParseState::new(self, scope, tokenizer_control);
 
-        let ast = self.parse(
+        let ast = self.parse(&mut stream.peekable(), &mut state, self.optimization_level)?;
-            &mut stream.peekable(),
-            &mut state,
-            self.options.optimization_level,
-        )?;
 
         self.run_ast_with_scope(scope, &ast)
     }

src/ast/ast.rs

@@ -506,7 +506,7 @@ impl AST {
             lib
         };
 
-        if !other.source.is_empty() {
+        let mut _ast = if !other.source.is_empty() {
             Self::new_with_source(
                 merged,
                 #[cfg(not(feature = "no_function"))]
@@ -519,7 +519,31 @@ impl AST {
                 #[cfg(not(feature = "no_function"))]
                 lib,
             )
+        };
+
+        #[cfg(not(feature = "no_module"))]
+        match (
+            self.resolver().map_or(0, |r| r.len()),
+            other.resolver().map_or(0, |r| r.len()),
+        ) {
+            (0, 0) => (),
+            (_, 0) => {
+                _ast.set_resolver(self.resolver().unwrap().clone());
+            }
+            (0, _) => {
+                _ast.set_resolver(other.resolver().unwrap().clone());
+            }
+            (_, _) => {
+                let mut resolver = (**self.resolver().unwrap()).clone();
+                let other_resolver = (**other.resolver().unwrap()).clone();
+                for (k, v) in other_resolver {
+                    resolver.insert(k, crate::func::shared_take_or_clone(v));
+                }
+                _ast.set_resolver(resolver);
+            }
         }
+
+        _ast
     }
     /// Combine one [`AST`] with another.  The second [`AST`] is consumed.
     ///
@@ -594,6 +618,27 @@ impl AST {
             crate::func::native::shared_make_mut(&mut self.lib)
                 .merge_filtered(&other.lib, &_filter);
         }
+
+        #[cfg(not(feature = "no_module"))]
+        match (
+            self.resolver.as_ref().map_or(0, |r| r.len()),
+            other.resolver.as_ref().map_or(0, |r| r.len()),
+        ) {
+            (_, 0) => (),
+            (0, _) => {
+                self.set_resolver(other.resolver.unwrap());
+            }
+            (_, _) => {
+                let resolver =
+                    crate::func::native::shared_make_mut(self.resolver.as_mut().unwrap());
+                let other_resolver =
+                    crate::func::native::shared_take_or_clone(other.resolver.unwrap());
+                for (k, v) in other_resolver {
+                    resolver.insert(k, crate::func::shared_take_or_clone(v));
+                }
+            }
+        }
+
         self
     }
     /// Filter out the functions, retaining only some based on a filter predicate.

src/ast/expr.rs

@@ -799,6 +799,8 @@ impl Expr {
         match token {
             #[cfg(not(feature = "no_object"))]
             Token::Period => return true,
+            #[cfg(not(feature = "no_index"))]
+            Token::LeftBracket => return true,
             _ => (),
         }
 
@@ -823,15 +825,9 @@ impl Expr {
             | Self::Index(..)
             | Self::Array(..)
             | Self::Map(..)
-            | Self::Custom(..) => match token {
+            | Self::Custom(..) => false,
-                #[cfg(not(feature = "no_index"))]
-                Token::LeftBracket => true,
-                _ => false,
-            },
 
             Self::Variable(..) => match token {
-                #[cfg(not(feature = "no_index"))]
-                Token::LeftBracket => true,
                 Token::LeftParen => true,
                 Token::Unit => true,
                 Token::Bang => true,
@@ -840,8 +836,6 @@ impl Expr {
             },
 
             Self::Property(..) => match token {
-                #[cfg(not(feature = "no_index"))]
-                Token::LeftBracket => true,
                 Token::LeftParen => true,
                 _ => false,
             },

src/ast/flags.rs

@@ -15,7 +15,7 @@ pub enum FnAccess {
 }
 
 bitflags! {
-    /// _(internals)_ A type that holds a configuration option with bit-flags.
+    /// _(internals)_ Bit-flags containing [`AST`][crate::AST] node configuration options.
     /// Exported under the `internals` feature only.
     pub struct ASTFlags: u8 {
         /// No options for the [`AST`][crate::AST] node.

src/ast/namespace.rs

@@ -17,8 +17,8 @@ use std::{
 ///
 /// Not available under `no_module`.
 ///
-/// A [`u64`] offset to the current [stack of imported modules][crate::GlobalRuntimeState] is
+/// A [`u64`] offset to the current stack of imported [modules][crate::Module] in the
-/// cached for quick search purposes.
+/// [global runtime state][crate::GlobalRuntimeState] is cached for quick search purposes.
 ///
 /// A [`StaticVec`] is used because the vast majority of namespace-qualified access contains only
 /// one level, and it is wasteful to always allocate a [`Vec`] with one element.

src/bin/rhai-dbg.rs

@@ -60,7 +60,12 @@ fn print_current_source(
     lines: &[String],
     window: (usize, usize),
 ) {
-    let current_source = &mut *context.tag_mut().write_lock::<ImmutableString>().unwrap();
+    let current_source = &mut *context
+        .global_runtime_state_mut()
+        .debugger
+        .state_mut()
+        .write_lock::<ImmutableString>()
+        .unwrap();
     let src = source.unwrap_or("");
     if src != current_source {
         println!(

src/engine.rs

@@ -1,7 +1,7 @@
 //! Main module defining the script evaluation [`Engine`].
 
 use crate::api::custom_syntax::CustomSyntax;
-use crate::api::options::LanguageOptions;
+use crate::api::options::LangOptions;
 use crate::func::native::{
     OnDebugCallback, OnDefVarCallback, OnParseTokenCallback, OnPrintCallback, OnVarCallback,
 };
@@ -9,7 +9,8 @@ use crate::packages::{Package, StandardPackage};
 use crate::tokenizer::Token;
 use crate::types::dynamic::Union;
 use crate::{
-    Dynamic, Identifier, ImmutableString, Module, Position, RhaiResult, Shared, StaticVec,
+    Dynamic, Identifier, ImmutableString, Module, OptimizationLevel, Position, RhaiResult, Shared,
+    StaticVec,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -112,7 +113,7 @@ pub struct Engine {
     /// A map containing custom keywords and precedence to recognize.
     pub(crate) custom_keywords: BTreeMap<Identifier, Option<Precedence>>,
     /// Custom syntax.
-    pub(crate) custom_syntax: BTreeMap<Identifier, Box<CustomSyntax>>,
+    pub(crate) custom_syntax: BTreeMap<Identifier, CustomSyntax>,
     /// Callback closure for filtering variable definition.
     pub(crate) def_var_filter: Option<Box<OnDefVarCallback>>,
     /// Callback closure for resolving variable access.
@@ -129,7 +130,13 @@ pub struct Engine {
     pub(crate) progress: Option<Box<crate::func::native::OnProgressCallback>>,
 
     /// Language options.
-    pub(crate) options: LanguageOptions,
+    pub(crate) options: LangOptions,
+
+    /// Default value for the custom state.
+    pub(crate) def_tag: Dynamic,
+
+    /// Script optimization level.
+    pub(crate) optimization_level: OptimizationLevel,
 
     /// Max limits.
     #[cfg(not(feature = "unchecked"))]
@@ -155,7 +162,14 @@ impl fmt::Debug for Engine {
 
         f.field("disabled_symbols", &self.disabled_symbols)
             .field("custom_keywords", &self.custom_keywords)
-            .field("custom_syntax", &(!self.custom_syntax.is_empty()))
+            .field(
+                "custom_syntax",
+                &self
+                    .custom_syntax
+                    .keys()
+                    .map(|s| s.as_str())
+                    .collect::<String>(),
+            )
             .field("def_var_filter", &self.def_var_filter.is_some())
             .field("resolve_var", &self.resolve_var.is_some())
             .field("token_mapper", &self.token_mapper.is_some());
@@ -267,7 +281,14 @@ impl Engine {
             #[cfg(not(feature = "unchecked"))]
             progress: None,
 
-            options: LanguageOptions::new(),
+            options: LangOptions::new(),
+
+            def_tag: Dynamic::UNIT,
+
+            #[cfg(not(feature = "no_optimize"))]
+            optimization_level: OptimizationLevel::Simple,
+            #[cfg(feature = "no_optimize")]
+            optimization_level: (),
 
             #[cfg(not(feature = "unchecked"))]
             limits: crate::api::limits::Limits::new(),

src/eval/cache.rs

@@ -13,8 +13,7 @@ pub struct FnResolutionCacheEntry {
     /// Function.
     pub func: CallableFunction,
     /// Optional source.
-    /// No source if the string is empty.
+    pub source: Option<Box<Identifier>>,
-    pub source: Identifier,
 }
 
 /// _(internals)_ A function resolution cache.
@@ -22,7 +21,7 @@ pub struct FnResolutionCacheEntry {
 ///
 /// [`FnResolutionCacheEntry`] is [`Box`]ed in order to pack as many entries inside a single B-Tree
 /// level as possible.
-pub type FnResolutionCache = BTreeMap<u64, Option<Box<FnResolutionCacheEntry>>>;
+pub type FnResolutionCache = BTreeMap<u64, Option<FnResolutionCacheEntry>>;
 
 /// _(internals)_ A type containing system-wide caches.
 /// Exported under the `internals` feature only.

src/eval/chaining.rs

@@ -335,12 +335,11 @@ impl Engine {
                         let (mut new_val, op_info) = new_val.expect("`Some`");
 
                         if op_info.is_op_assignment() {
-                            let hash = crate::ast::FnCallHashes::from_native(*hash_get);
                             let args = &mut [target.as_mut()];
                             let (mut orig_val, ..) = self
-                                .exec_fn_call(
+                                .call_native_fn(
-                                    None, global, caches, lib, getter, hash, args, is_ref_mut,
+                                    global, caches, lib, getter, *hash_get, args, is_ref_mut,
-                                    true, *pos, level,
+                                    false, *pos, level,
                                 )
                                 .or_else(|err| match *err {
                                     // Try an indexer if property does not exist
@@ -371,10 +370,9 @@ impl Engine {
                             new_val = orig_val;
                         }
 
-                        let hash = crate::ast::FnCallHashes::from_native(*hash_set);
                         let args = &mut [target.as_mut(), &mut new_val];
-                        self.exec_fn_call(
+                        self.call_native_fn(
-                            None, global, caches, lib, setter, hash, args, is_ref_mut, true, *pos,
+                            global, caches, lib, setter, *hash_set, args, is_ref_mut, false, *pos,
                             level,
                         )
                         .or_else(|err| match *err {
@@ -399,10 +397,9 @@ impl Engine {
                         self.run_debugger(scope, global, lib, this_ptr, rhs, level)?;
 
                         let ((getter, hash_get), _, name) = x.as_ref();
-                        let hash = crate::ast::FnCallHashes::from_native(*hash_get);
                         let args = &mut [target.as_mut()];
-                        self.exec_fn_call(
+                        self.call_native_fn(
-                            None, global, caches, lib, getter, hash, args, is_ref_mut, true, *pos,
+                            global, caches, lib, getter, *hash_get, args, is_ref_mut, false, *pos,
                             level,
                         )
                         .map_or_else(
@@ -488,16 +485,14 @@ impl Engine {
 
                                 let ((getter, hash_get), (setter, hash_set), name) = p.as_ref();
                                 let rhs_chain = rhs.into();
-                                let hash_get = crate::ast::FnCallHashes::from_native(*hash_get);
-                                let hash_set = crate::ast::FnCallHashes::from_native(*hash_set);
                                 let mut arg_values = [target.as_mut(), &mut Dynamic::UNIT.clone()];
                                 let args = &mut arg_values[..1];
 
                                 // Assume getters are always pure
                                 let (mut val, ..) = self
-                                    .exec_fn_call(
+                                    .call_native_fn(
-                                        None, global, caches, lib, getter, hash_get, args,
+                                        global, caches, lib, getter, *hash_get, args, is_ref_mut,
-                                        is_ref_mut, true, pos, level,
+                                        false, pos, level,
                                     )
                                     .or_else(|err| match *err {
                                         // Try an indexer if property does not exist
@@ -531,9 +526,9 @@ impl Engine {
                                     // Re-use args because the first &mut parameter will not be consumed
                                     let mut arg_values = [target.as_mut(), val.as_mut()];
                                     let args = &mut arg_values;
-                                    self.exec_fn_call(
+                                    self.call_native_fn(
-                                        None, global, caches, lib, setter, hash_set, args,
+                                        global, caches, lib, setter, *hash_set, args, is_ref_mut,
-                                        is_ref_mut, true, pos, level,
+                                        false, pos, level,
                                     )
                                     .or_else(
                                         |err| match *err {
@@ -813,12 +808,13 @@ impl Engine {
         level: usize,
     ) -> RhaiResultOf<Dynamic> {
         let args = &mut [target, idx];
-        let hash_get = crate::ast::FnCallHashes::from_native(global.hash_idx_get());
+        let hash = global.hash_idx_get();
         let fn_name = crate::engine::FN_IDX_GET;
         let pos = Position::NONE;
+        let level = level + 1;
 
-        self.exec_fn_call(
+        self.call_native_fn(
-            None, global, caches, lib, fn_name, hash_get, args, true, true, pos, level,
+            global, caches, lib, fn_name, hash, args, true, false, pos, level,
         )
         .map(|(r, ..)| r)
     }
@@ -837,13 +833,14 @@ impl Engine {
         is_ref_mut: bool,
         level: usize,
     ) -> RhaiResultOf<(Dynamic, bool)> {
-        let hash_set = crate::ast::FnCallHashes::from_native(global.hash_idx_set());
+        let hash = global.hash_idx_set();
         let args = &mut [target, idx, new_val];
         let fn_name = crate::engine::FN_IDX_SET;
         let pos = Position::NONE;
+        let level = level + 1;
 
-        self.exec_fn_call(
+        self.call_native_fn(
-            None, global, caches, lib, fn_name, hash_set, args, is_ref_mut, true, pos, level,
+            global, caches, lib, fn_name, hash, args, is_ref_mut, false, pos, level,
         )
     }
 

src/eval/debugger.rs

@@ -253,17 +253,20 @@ pub struct Debugger {
     break_points: Vec<BreakPoint>,
     /// The current function call stack.
     call_stack: Vec<CallStackFrame>,
+    /// The current state.
+    state: Dynamic,
 }
 
 impl Debugger {
     /// Create a new [`Debugger`].
     #[inline(always)]
     #[must_use]
-    pub fn new(status: DebuggerStatus) -> Self {
+    pub fn new(status: DebuggerStatus, state: Dynamic) -> Self {
         Self {
             status,
             break_points: Vec::new(),
             call_stack: Vec::new(),
+            state,
         }
     }
     /// Get the current call stack.
@@ -374,6 +377,23 @@ impl Debugger {
     pub fn break_points_mut(&mut self) -> &mut Vec<BreakPoint> {
         &mut self.break_points
     }
+    /// Get the custom state.
+    #[inline(always)]
+    #[must_use]
+    pub fn state(&self) -> &Dynamic {
+        &self.state
+    }
+    /// Get a mutable reference to the custom state.
+    #[inline(always)]
+    #[must_use]
+    pub fn state_mut(&mut self) -> &mut Dynamic {
+        &mut self.state
+    }
+    /// Set the custom state.
+    #[inline(always)]
+    pub fn set_state(&mut self, state: impl Into<Dynamic>) {
+        self.state = state.into();
+    }
 }
 
 impl Engine {
@@ -496,15 +516,7 @@ impl Engine {
             Some(source.as_str())
         };
 
-        let context = crate::EvalContext {
+        let context = crate::EvalContext::new(self, scope, global, None, lib, this_ptr, level);
-            engine: self,
-            scope,
-            global,
-            caches: None,
-            lib,
-            this_ptr,
-            level,
-        };
 
         if let Some((.., ref on_debugger)) = self.debugger {
             let command = on_debugger(context, event, node, source, node.position())?;

src/eval/eval_context.rs

@@ -1,34 +1,56 @@
 //! Evaluation context.
 
 use super::{Caches, GlobalRuntimeState};
-use crate::{Dynamic, Engine, Module, Scope};
+use crate::{Dynamic, Engine, Expression, Module, RhaiResult, Scope};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 
 /// Context of a script evaluation process.
 #[derive(Debug)]
-pub struct EvalContext<'a, 's, 'ps, 'm, 'pm, 'c, 't, 'pt> {
+pub struct EvalContext<'a, 's, 'ps, 'g, 'pg, 'c, 't, 'pt> {
     /// The current [`Engine`].
-    pub(crate) engine: &'a Engine,
+    engine: &'a Engine,
     /// The current [`Scope`].
-    pub(crate) scope: &'s mut Scope<'ps>,
+    scope: &'s mut Scope<'ps>,
     /// The current [`GlobalRuntimeState`].
-    pub(crate) global: &'m mut GlobalRuntimeState<'pm>,
+    global: &'g mut GlobalRuntimeState<'pg>,
     /// The current [caches][Caches], if available.
-    pub(crate) caches: Option<&'c mut Caches>,
+    caches: Option<&'c mut Caches>,
     /// The current stack of imported [modules][Module].
-    pub(crate) lib: &'a [&'a Module],
+    lib: &'a [&'a Module],
     /// The current bound `this` pointer, if any.
-    pub(crate) this_ptr: &'t mut Option<&'pt mut Dynamic>,
+    this_ptr: &'t mut Option<&'pt mut Dynamic>,
     /// The current nesting level of function calls.
-    pub(crate) level: usize,
+    level: usize,
 }
 
-impl<'s, 'ps, 'm, 'pm, 'pt> EvalContext<'_, 's, 'ps, 'm, 'pm, '_, '_, 'pt> {
+impl<'a, 's, 'ps, 'g, 'pg, 'c, 't, 'pt> EvalContext<'a, 's, 'ps, 'g, 'pg, 'c, 't, 'pt> {
+    /// Create a new [`EvalContext`].
+    #[inline(always)]
+    #[must_use]
+    pub fn new(
+        engine: &'a Engine,
+        scope: &'s mut Scope<'ps>,
+        global: &'g mut GlobalRuntimeState<'pg>,
+        caches: Option<&'c mut Caches>,
+        lib: &'a [&'a Module],
+        this_ptr: &'t mut Option<&'pt mut Dynamic>,
+        level: usize,
+    ) -> Self {
+        Self {
+            engine,
+            scope,
+            global,
+            caches,
+            lib,
+            this_ptr,
+            level,
+        }
+    }
     /// The current [`Engine`].
     #[inline(always)]
     #[must_use]
-    pub const fn engine(&self) -> &Engine {
+    pub const fn engine(&self) -> &'a Engine {
         self.engine
     }
     /// The current source.
@@ -85,7 +107,7 @@ impl<'s, 'ps, 'm, 'pm, 'pt> EvalContext<'_, 's, 'ps, 'm, 'pm, '_, '_, 'pt> {
     #[cfg(feature = "internals")]
     #[inline(always)]
     #[must_use]
-    pub fn global_runtime_state_mut(&mut self) -> &mut &'m mut GlobalRuntimeState<'pm> {
+    pub fn global_runtime_state_mut(&mut self) -> &mut &'g mut GlobalRuntimeState<'pg> {
         &mut self.global
     }
     /// Get an iterator over the namespaces containing definition of all script-defined functions.
@@ -110,8 +132,8 @@ impl<'s, 'ps, 'm, 'pm, 'pt> EvalContext<'_, 's, 'ps, 'm, 'pm, '_, '_, 'pt> {
     /// Mutable reference to the current bound `this` pointer, if any.
     #[inline(always)]
     #[must_use]
-    pub fn this_ptr_mut(&mut self) -> Option<&mut &'pt mut Dynamic> {
+    pub fn this_ptr_mut(&mut self) -> &mut Option<&'pt mut Dynamic> {
-        self.this_ptr.as_mut()
+        &mut self.this_ptr
     }
     /// The current nesting level of function calls.
     #[inline(always)]
@@ -119,4 +141,29 @@ impl<'s, 'ps, 'm, 'pm, 'pt> EvalContext<'_, 's, 'ps, 'm, 'pm, '_, '_, 'pt> {
     pub const fn call_level(&self) -> usize {
         self.level
     }
+
+    /// Evaluate an [expression tree][Expression] within this [evaluation context][`EvalContext`].
+    ///
+    /// # WARNING - Low Level API
+    ///
+    /// This function is very low level.  It evaluates an expression from an [`AST`][crate::AST].
+    #[inline(always)]
+    pub fn eval_expression_tree(&mut self, expr: &Expression) -> RhaiResult {
+        let mut new_caches = Caches::new();
+
+        let caches = match self.caches.as_mut() {
+            Some(c) => c,
+            None => &mut new_caches,
+        };
+
+        self.engine.eval_expr(
+            self.scope,
+            self.global,
+            caches,
+            self.lib,
+            self.this_ptr,
+            expr,
+            self.level,
+        )
+    }
 }

src/eval/expr.rs

@@ -151,15 +151,7 @@ impl Engine {
 
         // Check the variable resolver, if any
         if let Some(ref resolve_var) = self.resolve_var {
-            let context = EvalContext {
+            let context = EvalContext::new(self, scope, global, None, lib, this_ptr, level);
-                engine: self,
-                scope,
-                global,
-                caches: None,
-                lib,
-                this_ptr,
-                level,
-            };
             let var_name = expr.get_variable_name(true).expect("`Expr::Variable`");
             match resolve_var(var_name, index, context) {
                 Ok(Some(mut result)) => {
@@ -480,15 +472,8 @@ impl Engine {
                         *pos,
                     ))
                 })?;
-                let mut context = EvalContext {
+                let mut context =
-                    engine: self,
+                    EvalContext::new(self, scope, global, Some(caches), lib, this_ptr, level);
-                    scope,
-                    global,
-                    caches: Some(caches),
-                    lib,
-                    this_ptr,
-                    level,
-                };
 
                 let result = (custom_def.func)(&mut context, &expressions);
 

src/eval/global_state.rs

@@ -78,8 +78,6 @@ impl GlobalRuntimeState<'_> {
     #[inline(always)]
     #[must_use]
     pub fn new(engine: &Engine) -> Self {
-        let _engine = engine;
-
         Self {
             #[cfg(not(feature = "no_module"))]
             keys: crate::StaticVec::new_const(),
@@ -98,21 +96,21 @@ impl GlobalRuntimeState<'_> {
             #[cfg(not(feature = "no_function"))]
             constants: None,
 
-            #[cfg(not(feature = "debugging"))]
+            tag: engine.default_tag().clone(),
-            tag: Dynamic::UNIT,
-            #[cfg(feature = "debugging")]
-            tag: if let Some((ref init, ..)) = engine.debugger {
-                init()
-            } else {
-                Dynamic::UNIT
-            },
 
             #[cfg(feature = "debugging")]
-            debugger: crate::eval::Debugger::new(if engine.debugger.is_some() {
+            debugger: crate::eval::Debugger::new(
-                crate::eval::DebuggerStatus::Init
+                if engine.debugger.is_some() {
-            } else {
+                    crate::eval::DebuggerStatus::Init
-                crate::eval::DebuggerStatus::CONTINUE
+                } else {
-            }),
+                    crate::eval::DebuggerStatus::CONTINUE
+                },
+                if let Some((ref init, ..)) = engine.debugger {
+                    init()
+                } else {
+                    Dynamic::UNIT
+                },
+            ),
 
             dummy: PhantomData::default(),
         }

src/eval/stmt.rs

@@ -831,15 +831,7 @@ impl Engine {
                         nesting_level,
                         will_shadow,
                     };
-                    let context = EvalContext {
+                    let context = EvalContext::new(self, scope, global, None, lib, this_ptr, level);
-                        engine: self,
-                        scope,
-                        global,
-                        caches: None,
-                        lib,
-                        this_ptr,
-                        level,
-                    };
 
                     match filter(true, info, context) {
                         Ok(true) => None,

src/func/call.rs

@@ -12,8 +12,8 @@ use crate::engine::{
 use crate::eval::{Caches, FnResolutionCacheEntry, GlobalRuntimeState};
 use crate::{
     calc_fn_hash, calc_fn_params_hash, combine_hashes, Dynamic, Engine, FnArgsVec, FnPtr,
-    Identifier, ImmutableString, Module, OptimizationLevel, Position, RhaiError, RhaiResult,
+    ImmutableString, Module, OptimizationLevel, Position, RhaiError, RhaiResult, RhaiResultOf,
-    RhaiResultOf, Scope, ERR,
+    Scope, ERR,
 };
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
@@ -214,14 +214,14 @@ impl Engine {
                         .find_map(|&m| {
                             m.get_fn(hash).cloned().map(|func| FnResolutionCacheEntry {
                                 func,
-                                source: m.id_raw().clone(),
+                                source: m.id().map(|s| Box::new(s.into())),
                             })
                         })
                         .or_else(|| {
                             self.global_modules.iter().find_map(|m| {
                                 m.get_fn(hash).cloned().map(|func| FnResolutionCacheEntry {
                                     func,
-                                    source: m.id_raw().clone(),
+                                    source: m.id().map(|s| Box::new(s.into())),
                                 })
                             })
                         });
@@ -232,8 +232,7 @@ impl Engine {
                             _global.get_qualified_fn(hash).map(|(func, source)| {
                                 FnResolutionCacheEntry {
                                     func: func.clone(),
-                                    source: source
+                                    source: source.map(|s| Box::new(s.into())),
-                                        .map_or_else(|| Identifier::new_const(), Into::into),
                                 }
                             })
                         })
@@ -242,7 +241,7 @@ impl Engine {
                                 m.get_qualified_fn(hash).cloned().map(|func| {
                                     FnResolutionCacheEntry {
                                         func,
-                                        source: m.id_raw().clone(),
+                                        source: m.id().map(|s| Box::new(s.into())),
                                     }
                                 })
                             })
@@ -250,7 +249,7 @@ impl Engine {
 
                     match func {
                         // Specific version found
-                        Some(f) => return Some(Box::new(f)),
+                        Some(f) => return Some(f),
 
                         // Stop when all permutations are exhausted
                         None if bitmask >= max_bitmask => {
@@ -265,7 +264,7 @@ impl Engine {
                                             func: CallableFunction::from_method(
                                                 Box::new(f) as Box<FnAny>
                                             ),
-                                            source: Identifier::new_const(),
+                                            source: None,
                                         }
                                     })
                                 } else {
@@ -276,10 +275,9 @@ impl Engine {
                                             func: CallableFunction::from_method(
                                                 Box::new(f) as Box<FnAny>
                                             ),
-                                            source: Identifier::new_const(),
+                                            source: None,
                                         })
                                 }
-                                .map(Box::new)
                             });
                         }
 
@@ -308,7 +306,7 @@ impl Engine {
                 }
             });
 
-        result.as_ref().map(Box::as_ref)
+        result.as_ref()
     }
 
     /// # Main Entry-Point
@@ -370,9 +368,10 @@ impl Engine {
                     backup.change_first_arg_to_copy(args);
                 }
 
-                let source = match (source.as_str(), parent_source.as_str()) {
+                let source = match (source, parent_source.as_str()) {
-                    ("", "") => None,
+                    (None, "") => None,
-                    ("", s) | (s, ..) => Some(s),
+                    (None, s) => Some(s),
+                    (Some(s), ..) => Some(s.as_str()),
                 };
 
                 #[cfg(feature = "debugging")]
@@ -626,7 +625,7 @@ impl Engine {
 
         // Script-defined function call?
         #[cfg(not(feature = "no_function"))]
-        if let Some(FnResolutionCacheEntry { func, mut source }) = self
+        if let Some(FnResolutionCacheEntry { func, ref source }) = self
             .resolve_fn(
                 global,
                 caches,
@@ -657,7 +656,13 @@ impl Engine {
                 }
             };
 
-            mem::swap(&mut global.source, &mut source);
+            let orig_source = mem::replace(
+                &mut global.source,
+                source
+                    .as_ref()
+                    .map(|s| (**s).clone())
+                    .unwrap_or(crate::Identifier::new_const()),
+            );
 
             let result = if _is_method_call {
                 // Method call of script function - map first argument to `this`
@@ -695,7 +700,7 @@ impl Engine {
             };
 
             // Restore the original source
-            mem::swap(&mut global.source, &mut source);
+            global.source = orig_source;
 
             return Ok((result?, false));
         }
@@ -731,6 +736,42 @@ impl Engine {
         })
     }
 
+    /// Evaluate an argument.
+    #[inline]
+    pub(crate) fn get_arg_value(
+        &self,
+        scope: &mut Scope,
+        global: &mut GlobalRuntimeState,
+        caches: &mut Caches,
+        lib: &[&Module],
+        this_ptr: &mut Option<&mut Dynamic>,
+        arg_expr: &Expr,
+        level: usize,
+    ) -> RhaiResultOf<(Dynamic, Position)> {
+        #[cfg(feature = "debugging")]
+        if self.debugger.is_some() {
+            if let Some(value) = arg_expr.get_literal_value() {
+                #[cfg(feature = "debugging")]
+                self.run_debugger(scope, global, lib, this_ptr, arg_expr, level)?;
+                return Ok((value, arg_expr.start_position()));
+            }
+        }
+
+        // Do not match function exit for arguments
+        #[cfg(feature = "debugging")]
+        let reset_debugger = global.debugger.clear_status_if(|status| {
+            matches!(status, crate::eval::DebuggerStatus::FunctionExit(..))
+        });
+
+        let result = self.eval_expr(scope, global, caches, lib, this_ptr, arg_expr, level);
+
+        // Restore function exit status
+        #[cfg(feature = "debugging")]
+        global.debugger.reset_status(reset_debugger);
+
+        Ok((result?, arg_expr.start_position()))
+    }
+
     /// Call a dot method.
     #[cfg(not(feature = "no_object"))]
     pub(crate) fn make_method_call(
@@ -757,7 +798,7 @@ impl Engine {
                 // Recalculate hashes
                 let new_hash = calc_fn_hash(fn_name, args_len).into();
                 // Arguments are passed as-is, adding the curried arguments
-                let mut curry = FnArgsVec::with_capacity(fn_ptr.num_curried());
+                let mut curry = FnArgsVec::with_capacity(fn_ptr.curry().len());
                 curry.extend(fn_ptr.curry().iter().cloned());
                 let mut args = FnArgsVec::with_capacity(curry.len() + call_args.len());
                 args.extend(curry.iter_mut());
@@ -792,7 +833,7 @@ impl Engine {
                     calc_fn_hash(fn_name, args_len + 1),
                 );
                 // Replace the first argument with the object pointer, adding the curried arguments
-                let mut curry = FnArgsVec::with_capacity(fn_ptr.num_curried());
+                let mut curry = FnArgsVec::with_capacity(fn_ptr.curry().len());
                 curry.extend(fn_ptr.curry().iter().cloned());
                 let mut args = FnArgsVec::with_capacity(curry.len() + call_args.len() + 1);
                 args.push(target.as_mut());
@@ -887,42 +928,6 @@ impl Engine {
         Ok((result, updated))
     }
 
-    /// Evaluate an argument.
-    #[inline]
-    pub(crate) fn get_arg_value(
-        &self,
-        scope: &mut Scope,
-        global: &mut GlobalRuntimeState,
-        caches: &mut Caches,
-        lib: &[&Module],
-        this_ptr: &mut Option<&mut Dynamic>,
-        arg_expr: &Expr,
-        level: usize,
-    ) -> RhaiResultOf<(Dynamic, Position)> {
-        #[cfg(feature = "debugging")]
-        if self.debugger.is_some() {
-            if let Some(value) = arg_expr.get_literal_value() {
-                #[cfg(feature = "debugging")]
-                self.run_debugger(scope, global, lib, this_ptr, arg_expr, level)?;
-                return Ok((value, arg_expr.start_position()));
-            }
-        }
-
-        // Do not match function exit for arguments
-        #[cfg(feature = "debugging")]
-        let reset_debugger = global.debugger.clear_status_if(|status| {
-            matches!(status, crate::eval::DebuggerStatus::FunctionExit(..))
-        });
-
-        let result = self.eval_expr(scope, global, caches, lib, this_ptr, arg_expr, level);
-
-        // Restore function exit status
-        #[cfg(feature = "debugging")]
-        global.debugger.reset_status(reset_debugger);
-
-        Ok((result?, arg_expr.start_position()))
-    }
-
     /// Call a function in normal function-call style.
     pub(crate) fn make_function_call(
         &self,

src/lib.rs

@@ -44,7 +44,7 @@
 //! #   #[cfg(not(target_family = "wasm"))]
 //! #   
 //!     // Evaluate the script, expecting a 'bool' result
-//!     let result = engine.eval_file::<bool>("my_script.rhai".into())?;
+//!     let result: bool = engine.eval_file("my_script.rhai".into())?;
 //!
 //!     assert_eq!(result, true);
 //!

src/module/mod.rs

@@ -81,7 +81,7 @@ impl Ord for FnMetadata {
 #[derive(Debug, Clone)]
 pub struct FuncInfo {
     /// Function instance.
-    pub func: Shared<CallableFunction>,
+    pub func: CallableFunction,
     /// Parameter types (if applicable).
     pub param_types: StaticVec<TypeId>,
     /// Function metadata.
@@ -246,7 +246,7 @@ pub struct Module {
     functions: BTreeMap<u64, Box<FuncInfo>>,
     /// Flattened collection of all external Rust functions, native or scripted.
     /// including those in sub-modules.
-    all_functions: BTreeMap<u64, Shared<CallableFunction>>,
+    all_functions: BTreeMap<u64, CallableFunction>,
     /// Iterator functions, keyed by the type producing the iterator.
     type_iterators: BTreeMap<TypeId, Shared<IteratorFn>>,
     /// Flattened collection of iterator functions, including those in sub-modules.
@@ -1452,7 +1452,7 @@ impl Module {
     #[must_use]
     pub(crate) fn get_fn(&self, hash_fn: u64) -> Option<&CallableFunction> {
         if !self.functions.is_empty() {
-            self.functions.get(&hash_fn).map(|f| f.func.as_ref())
+            self.functions.get(&hash_fn).map(|f| &f.func)
         } else {
             None
         }
@@ -1479,9 +1479,7 @@ impl Module {
     #[must_use]
     pub(crate) fn get_qualified_fn(&self, hash_qualified_fn: u64) -> Option<&CallableFunction> {
         if !self.all_functions.is_empty() {
-            self.all_functions
+            self.all_functions.get(&hash_qualified_fn)
-                .get(&hash_qualified_fn)
-                .map(|f| f.as_ref())
         } else {
             None
         }
@@ -1932,7 +1930,7 @@ impl Module {
             module: &'a Module,
             path: &mut Vec<&'a str>,
             variables: &mut BTreeMap<u64, Dynamic>,
-            functions: &mut BTreeMap<u64, Shared<CallableFunction>>,
+            functions: &mut BTreeMap<u64, CallableFunction>,
             type_iterators: &mut BTreeMap<TypeId, Shared<IteratorFn>>,
         ) -> bool {
             let mut contains_indexed_global_functions = false;

src/packages/array_basic.rs

@@ -639,15 +639,15 @@ pub mod array_functions {
     ///
     /// print(y);       // prints "[0, 2, 6, 12, 20]"
     /// ```
-    #[rhai_fn(return_raw, pure)]
+    #[rhai_fn(return_raw)]
-    pub fn map(ctx: NativeCallContext, array: &mut Array, mapper: FnPtr) -> RhaiResultOf<Array> {
+    pub fn map(ctx: NativeCallContext, array: Array, mapper: FnPtr) -> RhaiResultOf<Array> {
         if array.is_empty() {
-            return Ok(array.clone());
+            return Ok(array);
         }
 
         let mut ar = Array::with_capacity(array.len());
 
-        for (i, item) in array.iter().enumerate() {
+        for (i, item) in array.into_iter().enumerate() {
             ar.push(
                 mapper
                     .call_raw(&ctx, None, [item.clone()])
@@ -655,7 +655,7 @@ pub mod array_functions {
                         ERR::ErrorFunctionNotFound(fn_sig, ..)
                             if fn_sig.starts_with(mapper.fn_name()) =>
                         {
-                            mapper.call_raw(&ctx, None, [item.clone(), (i as INT).into()])
+                            mapper.call_raw(&ctx, None, [item, (i as INT).into()])
                         }
                         _ => Err(err),
                     })
@@ -699,10 +699,10 @@ pub mod array_functions {
     ///
     /// print(y);       // prints "[0, 2, 6, 12, 20]"
     /// ```
-    #[rhai_fn(name = "map", return_raw, pure)]
+    #[rhai_fn(name = "map", return_raw)]
     pub fn map_by_fn_name(
         ctx: NativeCallContext,
-        array: &mut Array,
+        array: Array,
         mapper: &str,
     ) -> RhaiResultOf<Array> {
         map(ctx, array, FnPtr::new(mapper)?)
@@ -729,15 +729,15 @@ pub mod array_functions {
     ///
     /// print(y);       // prints "[12, 20]"
     /// ```
-    #[rhai_fn(return_raw, pure)]
+    #[rhai_fn(return_raw)]
-    pub fn filter(ctx: NativeCallContext, array: &mut Array, filter: FnPtr) -> RhaiResultOf<Array> {
+    pub fn filter(ctx: NativeCallContext, array: Array, filter: FnPtr) -> RhaiResultOf<Array> {
         if array.is_empty() {
-            return Ok(array.clone());
+            return Ok(array);
         }
 
         let mut ar = Array::new();
 
-        for (i, item) in array.iter().enumerate() {
+        for (i, item) in array.into_iter().enumerate() {
             if filter
                 .call_raw(&ctx, None, [item.clone()])
                 .or_else(|err| match *err {
@@ -759,7 +759,7 @@ pub mod array_functions {
                 .as_bool()
                 .unwrap_or(false)
             {
-                ar.push(item.clone());
+                ar.push(item);
             }
         }
 
@@ -790,10 +790,10 @@ pub mod array_functions {
     ///
     /// print(y);       // prints "[12, 20]"
     /// ```
-    #[rhai_fn(name = "filter", return_raw, pure)]
+    #[rhai_fn(name = "filter", return_raw)]
     pub fn filter_by_fn_name(
         ctx: NativeCallContext,
-        array: &mut Array,
+        array: Array,
         filter_func: &str,
     ) -> RhaiResultOf<Array> {
         filter(ctx, array, FnPtr::new(filter_func)?)

src/packages/math_basic.rs

@@ -311,10 +311,10 @@ mod float_functions {
     pub fn is_infinite(x: FLOAT) -> bool {
         x.is_infinite()
     }
-    /// Return the integral part of the floating-point number.
+    /// Convert the floating-point number into an integer.
     #[rhai_fn(name = "to_int", return_raw)]
     pub fn f32_to_int(x: f32) -> RhaiResultOf<INT> {
-        if cfg!(not(feature = "unchecked")) && x > (INT::MAX as f32) {
+        if cfg!(not(feature = "unchecked")) && (x > (INT::MAX as f32) || x < (INT::MIN as f32)) {
             Err(
                 ERR::ErrorArithmetic(format!("Integer overflow: to_int({})", x), Position::NONE)
                     .into(),
@@ -323,10 +323,10 @@ mod float_functions {
             Ok(x.trunc() as INT)
         }
     }
-    /// Return the integral part of the floating-point number.
+    /// Convert the floating-point number into an integer.
     #[rhai_fn(name = "to_int", return_raw)]
     pub fn f64_to_int(x: f64) -> RhaiResultOf<INT> {
-        if cfg!(not(feature = "unchecked")) && x > (INT::MAX as f64) {
+        if cfg!(not(feature = "unchecked")) && (x > (INT::MAX as f64) || x < (INT::MIN as f64)) {
             Err(
                 ERR::ErrorArithmetic(format!("Integer overflow: to_int({})", x), Position::NONE)
                     .into(),
@@ -365,6 +365,7 @@ mod float_functions {
 #[cfg(feature = "decimal")]
 #[export_module]
 mod decimal_functions {
+    use num_traits::ToPrimitive;
     use rust_decimal::{
         prelude::{FromStr, RoundingStrategy},
         Decimal, MathematicalOps,
@@ -553,6 +554,30 @@ mod decimal_functions {
 
         Ok(x.round_dp_with_strategy(digits as u32, RoundingStrategy::MidpointTowardZero))
     }
+    /// Convert the decimal number into an integer.
+    #[rhai_fn(return_raw)]
+    pub fn to_int(x: Decimal) -> RhaiResultOf<INT> {
+        let n = x.to_i64().and_then(|n| {
+            #[cfg(feature = "only_i32")]
+            return if n > (INT::MAX as i64) || n < (INT::MIN as i64) {
+                None
+            } else {
+                Some(n as i32)
+            };
+
+            #[cfg(not(feature = "only_i32"))]
+            return Some(n);
+        });
+
+        match n {
+            Some(n) => Ok(n),
+            _ => Err(ERR::ErrorArithmetic(
+                format!("Integer overflow: to_int({})", x),
+                Position::NONE,
+            )
+            .into()),
+        }
+    }
     /// Return the integral part of the decimal number.
     #[rhai_fn(name = "int", get = "int")]
     pub fn int(x: Decimal) -> Decimal {

src/packages/string_basic.rs

@@ -195,12 +195,16 @@ mod print_debug_functions {
         result.push_str("#{");
 
         map.iter_mut().enumerate().for_each(|(i, (k, v))| {
-            result.push_str(&format!(
+            use std::fmt::Write;
+
+            write!(
+                result,
                 "{:?}: {}{}",
                 k,
                 &print_with_func(FUNC_TO_DEBUG, &ctx, v),
                 if i < len - 1 { ", " } else { "" }
-            ));
+            )
+            .unwrap();
         });
 
         result.push('}');

src/parser.rs

@@ -2,7 +2,7 @@
 
 use crate::api::custom_syntax::{markers::*, CustomSyntax};
 use crate::api::events::VarDefInfo;
-use crate::api::options::LanguageOptions;
+use crate::api::options::LangOptions;
 use crate::ast::{
     ASTFlags, BinaryExpr, ConditionalStmtBlock, CustomExpr, Expr, FnCallExpr, FnCallHashes, Ident,
     OpAssignment, ScriptFnDef, Stmt, StmtBlock, StmtBlockContainer, SwitchCases, TryCatchBlock,
@@ -215,7 +215,7 @@ struct ParseSettings {
     /// Is the current position inside a loop?
     is_breakable: bool,
     /// Language options in effect (overrides Engine options).
-    options: LanguageOptions,
+    options: LangOptions,
     /// Current expression nesting level.
     level: usize,
     /// Current position.
@@ -387,6 +387,7 @@ fn match_token(input: &mut TokenStream, token: Token) -> (bool, Position) {
 }
 
 /// Parse a variable name.
+#[inline]
 fn parse_var_name(input: &mut TokenStream) -> ParseResult<(SmartString, Position)> {
     match input.next().expect(NEVER_ENDS) {
         // Variable name
@@ -403,6 +404,7 @@ fn parse_var_name(input: &mut TokenStream) -> ParseResult<(SmartString, Position
 }
 
 /// Parse a symbol.
+#[inline]
 fn parse_symbol(input: &mut TokenStream) -> ParseResult<(SmartString, Position)> {
     match input.next().expect(NEVER_ENDS) {
         // Symbol
@@ -499,7 +501,10 @@ impl Engine {
                     #[cfg(feature = "no_function")]
                     let relax = false;
 
-                    if !relax && settings.options.strict_var && index.is_none() {
+                    if !relax
+                        && settings.options.contains(LangOptions::STRICT_VAR)
+                        && index.is_none()
+                    {
                         return Err(PERR::ModuleUndefined(namespace.root().to_string())
                             .into_err(namespace.position()));
                     }
@@ -559,7 +564,10 @@ impl Engine {
                         #[cfg(feature = "no_function")]
                         let relax = false;
 
-                        if !relax && settings.options.strict_var && index.is_none() {
+                        if !relax
+                            && settings.options.contains(LangOptions::STRICT_VAR)
+                            && index.is_none()
+                        {
                             return Err(PERR::ModuleUndefined(namespace.root().to_string())
                                 .into_err(namespace.position()));
                         }
@@ -631,6 +639,7 @@ impl Engine {
         state: &mut ParseState,
         lib: &mut FnLib,
         lhs: Expr,
+        check_index_type: bool,
         settings: ParseSettings,
     ) -> ParseResult<Expr> {
         #[cfg(not(feature = "unchecked"))]
@@ -640,113 +649,100 @@ impl Engine {
 
         let idx_expr = self.parse_expr(input, state, lib, settings.level_up())?;
 
-        // Check type of indexing - must be integer or string
+        // Check types of indexing that cannot be overridden
-        match idx_expr {
+        // - arrays, maps, strings, bit-fields
-            Expr::IntegerConstant(.., pos) => match lhs {
+        match lhs {
-                Expr::IntegerConstant(..)
+            _ if !check_index_type => (),
-                | Expr::Array(..)
-                | Expr::StringConstant(..)
-                | Expr::InterpolatedString(..) => (),
 
-                Expr::Map(..) => {
+            Expr::Map(..) => match idx_expr {
+                // lhs[int]
+                Expr::IntegerConstant(..) => {
                     return Err(PERR::MalformedIndexExpr(
-                        "Object map access expects string index, not a number".into(),
+                        "Object map expects string index, not a number".into(),
-                    )
-                    .into_err(pos))
-                }
-
-                #[cfg(not(feature = "no_float"))]
-                Expr::FloatConstant(..) => {
-                    return Err(PERR::MalformedIndexExpr(
-                        "Only arrays, object maps and strings can be indexed".into(),
-                    )
-                    .into_err(lhs.start_position()))
-                }
-
-                Expr::CharConstant(..)
-                | Expr::And(..)
-                | Expr::Or(..)
-                | Expr::BoolConstant(..)
-                | Expr::Unit(..) => {
-                    return Err(PERR::MalformedIndexExpr(
-                        "Only arrays, object maps and strings can be indexed".into(),
-                    )
-                    .into_err(lhs.start_position()))
-                }
-
-                _ => (),
-            },
-
-            // lhs[string]
-            Expr::StringConstant(..) | Expr::InterpolatedString(..) => match lhs {
-                Expr::Map(..) => (),
-
-                Expr::Array(..) | Expr::StringConstant(..) | Expr::InterpolatedString(..) => {
-                    return Err(PERR::MalformedIndexExpr(
-                        "Array or string expects numeric index, not a string".into(),
                     )
                     .into_err(idx_expr.start_position()))
                 }
 
+                // lhs[string]
+                Expr::StringConstant(..) | Expr::InterpolatedString(..) => (),
+
+                // lhs[float]
                 #[cfg(not(feature = "no_float"))]
                 Expr::FloatConstant(..) => {
                     return Err(PERR::MalformedIndexExpr(
-                        "Only arrays, object maps and strings can be indexed".into(),
+                        "Object map expects string index, not a float".into(),
                     )
-                    .into_err(lhs.start_position()))
+                    .into_err(idx_expr.start_position()))
                 }
-
+                // lhs[char]
-                Expr::CharConstant(..)
+                Expr::CharConstant(..) => {
-                | Expr::And(..)
-                | Expr::Or(..)
-                | Expr::BoolConstant(..)
-                | Expr::Unit(..) => {
                     return Err(PERR::MalformedIndexExpr(
-                        "Only arrays, object maps and strings can be indexed".into(),
+                        "Object map expects string index, not a character".into(),
                     )
-                    .into_err(lhs.start_position()))
+                    .into_err(idx_expr.start_position()))
+                }
+                // lhs[()]
+                Expr::Unit(..) => {
+                    return Err(PERR::MalformedIndexExpr(
+                        "Object map expects string index, not ()".into(),
+                    )
+                    .into_err(idx_expr.start_position()))
+                }
+                // lhs[??? && ???], lhs[??? || ???], lhs[true], lhs[false]
+                Expr::And(..) | Expr::Or(..) | Expr::BoolConstant(..) => {
+                    return Err(PERR::MalformedIndexExpr(
+                        "Object map expects string index, not a boolean".into(),
+                    )
+                    .into_err(idx_expr.start_position()))
                 }
-
                 _ => (),
             },
 
-            // lhs[float]
+            Expr::IntegerConstant(..)
-            #[cfg(not(feature = "no_float"))]
+            | Expr::Array(..)
-            x @ Expr::FloatConstant(..) => {
+            | Expr::StringConstant(..)
-                return Err(PERR::MalformedIndexExpr(
+            | Expr::InterpolatedString(..) => match idx_expr {
-                    "Array access expects integer index, not a float".into(),
+                // lhs[int]
-                )
+                Expr::IntegerConstant(..) => (),
-                .into_err(x.start_position()))
+
-            }
+                // lhs[string]
-            // lhs[char]
+                Expr::StringConstant(..) | Expr::InterpolatedString(..) => {
-            x @ Expr::CharConstant(..) => {
+                    return Err(PERR::MalformedIndexExpr(
-                return Err(PERR::MalformedIndexExpr(
+                        "Array, string or bit-field expects numeric index, not a string".into(),
-                    "Array access expects integer index, not a character".into(),
+                    )
-                )
+                    .into_err(idx_expr.start_position()))
-                .into_err(x.start_position()))
+                }
-            }
+                // lhs[float]
-            // lhs[()]
+                #[cfg(not(feature = "no_float"))]
-            x @ Expr::Unit(..) => {
+                Expr::FloatConstant(..) => {
-                return Err(PERR::MalformedIndexExpr(
+                    return Err(PERR::MalformedIndexExpr(
-                    "Array access expects integer index, not ()".into(),
+                        "Array, string or bit-field expects integer index, not a float".into(),
-                )
+                    )
-                .into_err(x.start_position()))
+                    .into_err(idx_expr.start_position()))
-            }
+                }
-            // lhs[??? && ???], lhs[??? || ???]
+                // lhs[char]
-            x @ Expr::And(..) | x @ Expr::Or(..) => {
+                Expr::CharConstant(..) => {
-                return Err(PERR::MalformedIndexExpr(
+                    return Err(PERR::MalformedIndexExpr(
-                    "Array access expects integer index, not a boolean".into(),
+                        "Array, string or bit-field expects integer index, not a character".into(),
-                )
+                    )
-                .into_err(x.start_position()))
+                    .into_err(idx_expr.start_position()))
-            }
+                }
-            // lhs[true], lhs[false]
+                // lhs[()]
-            x @ Expr::BoolConstant(..) => {
+                Expr::Unit(..) => {
-                return Err(PERR::MalformedIndexExpr(
+                    return Err(PERR::MalformedIndexExpr(
-                    "Array access expects integer index, not a boolean".into(),
+                        "Array, string or bit-field expects integer index, not ()".into(),
-                )
+                    )
-                .into_err(x.start_position()))
+                    .into_err(idx_expr.start_position()))
-            }
+                }
-            // All other expressions
+                // lhs[??? && ???], lhs[??? || ???], lhs[true], lhs[false]
+                Expr::And(..) | Expr::Or(..) | Expr::BoolConstant(..) => {
+                    return Err(PERR::MalformedIndexExpr(
+                        "Array, string or bit-field expects integer index, not a boolean".into(),
+                    )
+                    .into_err(idx_expr.start_position()))
+                }
+                _ => (),
+            },
             _ => (),
         }
 
@@ -767,6 +763,7 @@ impl Engine {
                             state,
                             lib,
                             idx_expr,
+                            false,
                             settings.level_up(),
                         )?;
                         // Indexing binds to right
@@ -1243,7 +1240,7 @@ impl Engine {
             }
 
             // { - block statement as expression
-            Token::LeftBrace if settings.options.allow_stmt_expr => {
+            Token::LeftBrace if settings.options.contains(LangOptions::STMT_EXPR) => {
                 match self.parse_block(input, state, lib, settings.level_up())? {
                     block @ Stmt::Block(..) => Expr::Stmt(Box::new(block.into())),
                     stmt => unreachable!("Stmt::Block expected but gets {:?}", stmt),
@@ -1254,19 +1251,21 @@ impl Engine {
             Token::LeftParen => self.parse_paren_expr(input, state, lib, settings.level_up())?,
 
             // If statement is allowed to act as expressions
-            Token::If if settings.options.allow_if_expr => Expr::Stmt(Box::new(
+            Token::If if settings.options.contains(LangOptions::IF_EXPR) => Expr::Stmt(Box::new(
                 self.parse_if(input, state, lib, settings.level_up())?
                     .into(),
             )),
             // Switch statement is allowed to act as expressions
-            Token::Switch if settings.options.allow_switch_expr => Expr::Stmt(Box::new(
+            Token::Switch if settings.options.contains(LangOptions::SWITCH_EXPR) => {
-                self.parse_switch(input, state, lib, settings.level_up())?
+                Expr::Stmt(Box::new(
-                    .into(),
+                    self.parse_switch(input, state, lib, settings.level_up())?
-            )),
+                        .into(),
+                ))
+            }
 
             // | ...
             #[cfg(not(feature = "no_function"))]
-            Token::Pipe | Token::Or if settings.options.allow_anonymous_fn => {
+            Token::Pipe | Token::Or if settings.options.contains(LangOptions::ANON_FN) => {
                 let mut new_state =
                     ParseState::new(self, state.scope, state.tokenizer_control.clone());
 
@@ -1275,6 +1274,17 @@ impl Engine {
                     new_state.max_expr_depth = self.max_function_expr_depth();
                 }
 
+                let mut options = self.options;
+                options.set(
+                    LangOptions::STRICT_VAR,
+                    if cfg!(feature = "no_closure") {
+                        settings.options.contains(LangOptions::STRICT_VAR)
+                    } else {
+                        // A capturing closure can access variables not defined locally
+                        false
+                    },
+                );
+
                 let new_settings = ParseSettings {
                     is_global: false,
                     is_function_scope: true,
@@ -1282,15 +1292,7 @@ impl Engine {
                     is_closure_scope: true,
                     is_breakable: false,
                     level: 0,
-                    options: LanguageOptions {
+                    options,
-                        strict_var: if cfg!(feature = "no_closure") {
-                            settings.options.strict_var
-                        } else {
-                            // A capturing closure can access variables not defined locally
-                            false
-                        },
-                        ..self.options
-                    },
                     ..settings
                 };
 
@@ -1301,7 +1303,7 @@ impl Engine {
                     |crate::ast::Ident { name, pos }| {
                         let index = state.access_var(name, *pos);
 
-                        if settings.options.strict_var
+                        if settings.options.contains(LangOptions::STRICT_VAR)
                             && !settings.is_closure_scope
                             && index.is_none()
                             && !state.scope.contains(name)
@@ -1448,7 +1450,7 @@ impl Engine {
                     _ => {
                         let index = state.access_var(&s, settings.pos);
 
-                        if settings.options.strict_var
+                        if settings.options.contains(LangOptions::STRICT_VAR)
                             && index.is_none()
                             && !state.scope.contains(&s)
                         {
@@ -1628,7 +1630,7 @@ impl Engine {
                 // Indexing
                 #[cfg(not(feature = "no_index"))]
                 (expr, Token::LeftBracket) => {
-                    self.parse_index_chain(input, state, lib, expr, settings.level_up())?
+                    self.parse_index_chain(input, state, lib, expr, true, settings.level_up())?
                 }
                 // Property access
                 #[cfg(not(feature = "no_object"))]
@@ -1683,7 +1685,10 @@ impl Engine {
                     #[cfg(feature = "no_function")]
                     let relax = false;
 
-                    if !relax && settings.options.strict_var && index.is_none() {
+                    if !relax
+                        && settings.options.contains(LangOptions::STRICT_VAR)
+                        && index.is_none()
+                    {
                         return Err(PERR::ModuleUndefined(namespace.root().to_string())
                             .into_err(namespace.position()));
                     }
@@ -2715,15 +2720,16 @@ impl Engine {
                 nesting_level: level,
                 will_shadow,
             };
-            let context = EvalContext {
+            let mut this_ptr = None;
-                engine: self,
+            let context = EvalContext::new(
-                scope: &mut state.stack,
+                self,
-                global: &mut state.global,
+                &mut state.stack,
-                caches: None,
+                &mut state.global,
-                lib: &[],
+                None,
-                this_ptr: &mut None,
+                &[],
+                &mut this_ptr,
                 level,
-            };
+            );
 
             match filter(false, info, context) {
                 Ok(true) => (),
@@ -3080,6 +3086,12 @@ impl Engine {
                             new_state.max_expr_depth = self.max_function_expr_depth();
                         }
 
+                        let mut options = self.options;
+                        options.set(
+                            LangOptions::STRICT_VAR,
+                            settings.options.contains(LangOptions::STRICT_VAR),
+                        );
+
                         let new_settings = ParseSettings {
                             is_global: false,
                             is_function_scope: true,
@@ -3087,10 +3099,7 @@ impl Engine {
                             is_closure_scope: false,
                             is_breakable: false,
                             level: 0,
-                            options: LanguageOptions {
+                            options,
-                                strict_var: settings.options.strict_var,
-                                ..self.options
-                            },
                             pos,
                             ..settings
                         };
@@ -3549,6 +3558,11 @@ impl Engine {
     ) -> ParseResult<AST> {
         let mut functions = BTreeMap::new();
 
+        let mut options = self.options;
+        options.remove(LangOptions::IF_EXPR | LangOptions::SWITCH_EXPR | LangOptions::STMT_EXPR);
+        #[cfg(not(feature = "no_function"))]
+        options.remove(LangOptions::ANON_FN);
+
         let settings = ParseSettings {
             is_global: true,
             #[cfg(not(feature = "no_function"))]
@@ -3558,14 +3572,7 @@ impl Engine {
             is_closure_scope: false,
             is_breakable: false,
             level: 0,
-            options: LanguageOptions {
+            options,
-                allow_if_expr: false,
-                allow_switch_expr: false,
-                allow_stmt_expr: false,
-                #[cfg(not(feature = "no_function"))]
-                allow_anonymous_fn: false,
-                ..self.options
-            },
             pos: Position::NONE,
         };
         let expr = self.parse_expr(input, state, &mut functions, settings)?;

src/types/error.rs

@@ -42,6 +42,8 @@ pub enum EvalAltResult {
     ErrorVariableNotFound(String, Position),
     /// Access of an unknown object map property. Wrapped value is the property name.
     ErrorPropertyNotFound(String, Position),
+    /// Access of an invalid index. Wrapped value is the index name.
+    ErrorIndexNotFound(Dynamic, Position),
     /// Call to an unknown function. Wrapped value is the function signature.
     ErrorFunctionNotFound(String, Position),
     /// Usage of an unknown [module][crate::Module]. Wrapped value is the [module][crate::Module] name.
@@ -149,10 +151,11 @@ impl fmt::Display for EvalAltResult {
             }
             Self::ErrorInModule(s, err, ..) => write!(f, "Error in module '{}' > {}", s, err)?,
 
-            Self::ErrorVariableExists(s, ..) => write!(f, "Variable is already defined: {}", s)?,
+            Self::ErrorVariableExists(s, ..) => write!(f, "Variable already defined: {}", s)?,
             Self::ErrorForbiddenVariable(s, ..) => write!(f, "Forbidden variable name: {}", s)?,
             Self::ErrorVariableNotFound(s, ..) => write!(f, "Variable not found: {}", s)?,
             Self::ErrorPropertyNotFound(s, ..) => write!(f, "Property not found: {}", s)?,
+            Self::ErrorIndexNotFound(s, ..) => write!(f, "Invalid index: {}", s)?,
             Self::ErrorFunctionNotFound(s, ..) => write!(f, "Function not found: {}", s)?,
             Self::ErrorModuleNotFound(s, ..) => write!(f, "Module not found: {}", s)?,
             Self::ErrorDataRace(s, ..) => {
@@ -162,9 +165,9 @@ impl fmt::Display for EvalAltResult {
                 "" => f.write_str("Malformed dot expression"),
                 s => f.write_str(s),
             }?,
-            Self::ErrorIndexingType(s, ..) => write!(f, "Indexer not registered: {}", s)?,
+            Self::ErrorIndexingType(s, ..) => write!(f, "Indexer unavailable: {}", s)?,
-            Self::ErrorUnboundThis(..) => f.write_str("'this' is not bound")?,
+            Self::ErrorUnboundThis(..) => f.write_str("'this' not bound")?,
-            Self::ErrorFor(..) => f.write_str("For loop expects a type that is iterable")?,
+            Self::ErrorFor(..) => f.write_str("For loop expects an iterable type")?,
             Self::ErrorTooManyOperations(..) => f.write_str("Too many operations")?,
             Self::ErrorTooManyModules(..) => f.write_str("Too many modules imported")?,
             Self::ErrorStackOverflow(..) => f.write_str("Stack overflow")?,
@@ -181,14 +184,14 @@ impl fmt::Display for EvalAltResult {
 
             Self::ErrorAssignmentToConstant(s, ..) => write!(f, "Cannot modify constant: {}", s)?,
             Self::ErrorMismatchOutputType(e, a, ..) => match (a.as_str(), e.as_str()) {
-                ("", e) => write!(f, "Output type is incorrect, expecting {}", e),
+                ("", e) => write!(f, "Output type incorrect, expecting {}", e),
-                (a, "") => write!(f, "Output type is incorrect: {}", a),
+                (a, "") => write!(f, "Output type incorrect: {}", a),
-                (a, e) => write!(f, "Output type is incorrect: {} (expecting {})", a, e),
+                (a, e) => write!(f, "Output type incorrect: {} (expecting {})", a, e),
             }?,
             Self::ErrorMismatchDataType(e, a, ..) => match (a.as_str(), e.as_str()) {
-                ("", e) => write!(f, "Data type is incorrect, expecting {}", e),
+                ("", e) => write!(f, "Data type incorrect, expecting {}", e),
-                (a, "") => write!(f, "Data type is incorrect: {}", a),
+                (a, "") => write!(f, "Data type incorrect: {}", a),
-                (a, e) => write!(f, "Data type is incorrect: {} (expecting {})", a, e),
+                (a, e) => write!(f, "Data type incorrect: {} (expecting {})", a, e),
             }?,
             Self::ErrorArithmetic(s, ..) => match s.as_str() {
                 "" => f.write_str("Arithmetic error"),
@@ -204,12 +207,12 @@ impl fmt::Display for EvalAltResult {
                 0 => write!(f, "Array index {} out of bounds: array is empty", index),
                 1 => write!(
                     f,
-                    "Array index {} out of bounds: only 1 element in the array",
+                    "Array index {} out of bounds: only 1 element in array",
                     index
                 ),
                 _ => write!(
                     f,
-                    "Array index {} out of bounds: only {} elements in the array",
+                    "Array index {} out of bounds: only {} elements in array",
                     index, max
                 ),
             }?,
@@ -217,18 +220,18 @@ impl fmt::Display for EvalAltResult {
                 0 => write!(f, "String index {} out of bounds: string is empty", index),
                 1 => write!(
                     f,
-                    "String index {} out of bounds: only 1 character in the string",
+                    "String index {} out of bounds: only 1 character in string",
                     index
                 ),
                 _ => write!(
                     f,
-                    "String index {} out of bounds: only {} characters in the string",
+                    "String index {} out of bounds: only {} characters in string",
                     index, max
                 ),
             }?,
             Self::ErrorBitFieldBounds(max, index, ..) => write!(
                 f,
-                "Bit-field index {} out of bounds: only {} bits in the bit-field",
+                "Bit-field index {} out of bounds: only {} bits in bit-field",
                 index, max
             )?,
             Self::ErrorDataTooLarge(typ, ..) => write!(f, "{} exceeds maximum limit", typ)?,
@@ -291,6 +294,7 @@ impl EvalAltResult {
             | Self::ErrorForbiddenVariable(..)
             | Self::ErrorVariableNotFound(..)
             | Self::ErrorPropertyNotFound(..)
+            | Self::ErrorIndexNotFound(..)
             | Self::ErrorModuleNotFound(..)
             | Self::ErrorDataRace(..)
             | Self::ErrorAssignmentToConstant(..)
@@ -388,6 +392,9 @@ impl EvalAltResult {
             | Self::ErrorAssignmentToConstant(v, ..) => {
                 map.insert("variable".into(), v.into());
             }
+            Self::ErrorIndexNotFound(v, ..) => {
+                map.insert("index".into(), v.clone());
+            }
             Self::ErrorModuleNotFound(m, ..) => {
                 map.insert("module".into(), m.into());
             }
@@ -448,6 +455,7 @@ impl EvalAltResult {
             | Self::ErrorForbiddenVariable(.., pos)
             | Self::ErrorVariableNotFound(.., pos)
             | Self::ErrorPropertyNotFound(.., pos)
+            | Self::ErrorIndexNotFound(.., pos)
             | Self::ErrorModuleNotFound(.., pos)
             | Self::ErrorDataRace(.., pos)
             | Self::ErrorAssignmentToConstant(.., pos)
@@ -499,6 +507,7 @@ impl EvalAltResult {
             | Self::ErrorForbiddenVariable(.., pos)
             | Self::ErrorVariableNotFound(.., pos)
             | Self::ErrorPropertyNotFound(.., pos)
+            | Self::ErrorIndexNotFound(.., pos)
             | Self::ErrorModuleNotFound(.., pos)
             | Self::ErrorDataRace(.., pos)
             | Self::ErrorAssignmentToConstant(.., pos)

src/types/fn_ptr.rs

@@ -88,12 +88,6 @@ impl FnPtr {
     pub fn is_curried(&self) -> bool {
         !self.1.is_empty()
     }
-    /// Get the number of curried arguments.
-    #[inline(always)]
-    #[must_use]
-    pub fn num_curried(&self) -> usize {
-        self.1.len()
-    }
     /// Does the function pointer refer to an anonymous function?
     ///
     /// Not available under `no_function`.
@@ -219,8 +213,8 @@ impl FnPtr {
         let mut arg_values = arg_values.as_mut();
         let mut args_data;
 
-        if self.num_curried() > 0 {
+        if self.is_curried() {
-            args_data = StaticVec::with_capacity(self.num_curried() + arg_values.len());
+            args_data = StaticVec::with_capacity(self.curry().len() + arg_values.len());
             args_data.extend(self.curry().iter().cloned());
             args_data.extend(arg_values.iter_mut().map(mem::take));
             arg_values = args_data.as_mut();

tests/arrays.rs

@@ -1,5 +1,5 @@
 #![cfg(not(feature = "no_index"))]
-use rhai::{Array, Dynamic, Engine, EvalAltResult, INT};
+use rhai::{Array, Dynamic, Engine, EvalAltResult, ParseErrorType, INT};
 
 #[test]
 fn test_arrays() -> Result<(), Box<EvalAltResult>> {
@@ -172,6 +172,53 @@ fn test_arrays() -> Result<(), Box<EvalAltResult>> {
     Ok(())
 }
 
+#[test]
+fn test_array_index_types() -> Result<(), Box<EvalAltResult>> {
+    let engine = Engine::new();
+
+    engine.compile("[1, 2, 3][0]['x']")?;
+
+    assert!(matches!(
+        *engine
+            .compile("[1, 2, 3]['x']")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    #[cfg(not(feature = "no_float"))]
+    assert!(matches!(
+        *engine
+            .compile("[1, 2, 3][123.456]")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    assert!(matches!(
+        *engine.compile("[1, 2, 3][()]").expect_err("should error").0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    assert!(matches!(
+        *engine
+            .compile(r#"[1, 2, 3]["hello"]"#)
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    assert!(matches!(
+        *engine
+            .compile("[1, 2, 3][true && false]")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    Ok(())
+}
+
 #[test]
 #[cfg(not(feature = "no_object"))]
 fn test_array_with_structs() -> Result<(), Box<EvalAltResult>> {

tests/debugging.rs

@@ -57,10 +57,18 @@ fn test_debugger_state() -> Result<(), Box<EvalAltResult>> {
         },
         |mut context, _, _, _, _| {
             // Print debugger state - which is an object map
-            println!("Current state = {}", context.tag());
+            println!(
+                "Current state = {}",
+                context.global_runtime_state_mut().debugger.state()
+            );
 
             // Modify state
-            let mut state = context.tag_mut().write_lock::<Map>().unwrap();
+            let mut state = context
+                .global_runtime_state_mut()
+                .debugger
+                .state_mut()
+                .write_lock::<Map>()
+                .unwrap();
             let hello = state.get("hello").unwrap().as_int().unwrap();
             state.insert("hello".into(), (hello + 1).into());
             state.insert("foo".into(), true.into());

tests/get_set.rs

@@ -314,14 +314,13 @@ fn test_get_set_indexer() -> Result<(), Box<EvalAltResult>> {
         .register_type_with_name::<MyMap>("MyMap")
         .register_fn("new_map", || MyMap::new())
         .register_indexer_get_result(|map: &mut MyMap, index: &str| {
-            map.get(index)
+            map.get(index).cloned().ok_or_else(|| {
-                .cloned()
+                EvalAltResult::ErrorIndexNotFound(index.into(), rhai::Position::NONE).into()
-                .ok_or_else(|| format!("Index `{}` not found!", index).into())
+            })
         })
         .register_indexer_set(|map: &mut MyMap, index: &str, value: INT| {
             map.insert(index.to_string(), value);
-        })
+        });
-        .register_fn("to_string", |map: &mut MyMap| format!("{:?}", map));
 
     assert_eq!(
         engine.eval::<INT>(

tests/maps.rs

@@ -124,6 +124,57 @@ fn test_map_prop() -> Result<(), Box<EvalAltResult>> {
     Ok(())
 }
 
+#[cfg(not(feature = "no_index"))]
+#[test]
+fn test_map_index_types() -> Result<(), Box<EvalAltResult>> {
+    let engine = Engine::new();
+
+    engine.compile(r#"#{a:1, b:2, c:3}["a"]['x']"#)?;
+
+    assert!(matches!(
+        *engine
+            .compile("#{a:1, b:2, c:3}['x']")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    assert!(matches!(
+        *engine
+            .compile("#{a:1, b:2, c:3}[1]")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    #[cfg(not(feature = "no_float"))]
+    assert!(matches!(
+        *engine
+            .compile("#{a:1, b:2, c:3}[123.456]")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    assert!(matches!(
+        *engine
+            .compile("#{a:1, b:2, c:3}[()]")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    assert!(matches!(
+        *engine
+            .compile("#{a:1, b:2, c:3}[true && false]")
+            .expect_err("should error")
+            .0,
+        ParseErrorType::MalformedIndexExpr(..)
+    ));
+
+    Ok(())
+}
+
 #[test]
 fn test_map_assign() -> Result<(), Box<EvalAltResult>> {
     let engine = Engine::new();

tests/modules.rs

@@ -282,6 +282,23 @@ fn test_module_resolver() -> Result<(), Box<EvalAltResult>> {
         let result: INT = engine.call_fn(&mut Scope::new(), &ast, "foo", (2 as INT,))?;
 
         assert_eq!(result, 84);
+
+        let mut ast2 = engine.compile("fn foo(x) { 42 }")?;
+
+        #[cfg(feature = "internals")]
+        let len = ast.resolver().unwrap().len();
+
+        ast2 += ast;
+
+        #[cfg(feature = "internals")]
+        {
+            assert!(ast2.resolver().is_some());
+            assert_eq!(ast2.resolver().unwrap().len(), len);
+        }
+
+        let result: INT = engine.call_fn(&mut Scope::new(), &ast2, "foo", (2 as INT,))?;
+
+        assert_eq!(result, 84);
     }
 
     Ok(())