Code cleanup and refactor.

Cargo.toml

@@ -43,7 +43,7 @@ serde_json = { version = "1.0", default-features = false, features = ["alloc"] }
 [features]
 default = ["std", "ahash/runtime-rng"]  # ahash/runtime-rng trumps ahash/compile-time-rng
 std = ["ahash/std", "num-traits/std", "smartstring/std"]
-unchecked = []                  # unchecked arithmetic
+unchecked = []                  # disable safety checks
 sync = []                       # restrict to only types that implement Send + Sync
 no_position = []                # do not track position in the parser
 no_optimize = []                # no script optimizer

src/api/custom_syntax.rs

@@ -4,7 +4,7 @@
 use crate::ast::Expr;
 use crate::func::SendSync;
 use crate::parser::ParseResult;
-use crate::tokenizer::{is_valid_identifier, Token};
+use crate::tokenizer::{is_valid_identifier, Token, NO_TOKEN};
 use crate::types::dynamic::Variant;
 use crate::{
     reify, Dynamic, Engine, EvalContext, Identifier, ImmutableString, LexError, Position,
@@ -166,6 +166,7 @@ impl Deref for Expression<'_> {
     type Target = Expr;
 
     #[inline(always)]
+    #[must_use]
     fn deref(&self) -> &Self::Target {
         self.0
     }
@@ -230,11 +231,11 @@ impl Engine {
                 continue;
             }
 
-            let token = Token::lookup_symbol_from_syntax(s).or_else(|| {
+            let token = Token::lookup_symbol_from_syntax(s).unwrap_or_else(|| {
                 if Token::is_reserved_keyword(s) {
-                    Some(Token::Reserved(Box::new(s.into())))
+                    Token::Reserved(Box::new(s.into()))
                 } else {
-                    None
+                    NO_TOKEN
                 }
             });
 
@@ -255,16 +256,16 @@ impl Engine {
                 #[cfg(not(feature = "no_float"))]
                 CUSTOM_SYNTAX_MARKER_FLOAT if !segments.is_empty() => s.into(),
                 // Standard or reserved keyword/symbol not in first position
-                _ if !segments.is_empty() && token.is_some() => {
+                _ if !segments.is_empty() && token != NO_TOKEN => {
                     // Make it a custom keyword/symbol if it is disabled or reserved
                     if (self
                         .disabled_symbols
                         .as_deref()
                         .map_or(false, |m| m.contains(s))
-                        || token.map_or(false, |v| v.is_reserved()))
+                        || token.is_reserved())
                         && !self
                             .custom_keywords
-                            .as_ref()
+                            .as_deref()
                             .map_or(false, |m| m.contains_key(s))
                     {
                         self.custom_keywords
@@ -275,10 +276,10 @@ impl Engine {
                 }
                 // Standard keyword in first position but not disabled
                 _ if segments.is_empty()
-                    && token.as_ref().map_or(false, Token::is_standard_keyword)
+                    && token.is_standard_keyword()
                     && !self
                         .disabled_symbols
-                        .as_ref()
+                        .as_deref()
                         .map_or(false, |m| m.contains(s)) =>
                 {
                     return Err(LexError::ImproperSymbol(
@@ -295,12 +296,12 @@ impl Engine {
                     // Make it a custom keyword/symbol if it is disabled or reserved
                     if self
                         .disabled_symbols
-                        .as_ref()
+                        .as_deref()
                         .map_or(false, |m| m.contains(s))
-                        || (token.map_or(false, |v| v.is_reserved())
+                        || (token.is_reserved()
                             && !self
                                 .custom_keywords
-                                .as_ref()
+                                .as_deref()
                                 .map_or(false, |m| m.contains_key(s)))
                     {
                         self.custom_keywords

src/api/definitions/mod.rs

@@ -461,7 +461,7 @@ impl Module {
                     || def
                         .engine
                         .custom_keywords
-                        .as_ref()
+                        .as_deref()
                         .map_or(false, |m| m.contains_key(f.metadata.name.as_str()));
 
                 f.write_definition(writer, def, operator)?;

src/api/json.rs

@@ -64,8 +64,8 @@ impl Engine {
 
         let (stream, tokenizer_control) = self.lex_raw(
             &scripts,
-            if has_null {
+            Some(if has_null {
-                Some(&|token, _, _| {
+                &|token, _, _| {
                     match token {
                         // `null` => `()`
                         Token::Reserved(s) if &*s == "null" => Token::Unit,
@@ -86,9 +86,9 @@ impl Engine {
                         // All others
                         _ => token,
                     }
-                })
+                }
             } else {
-                Some(&|token, _, _| {
+                &|token, _, _| {
                     match token {
                         Token::Reserved(s) if &*s == "null" => Token::LexError(
                             LexError::ImproperSymbol("null".to_string(), String::new()).into(),
@@ -97,24 +97,21 @@ impl Engine {
                         Token::LeftBrace => Token::MapStart,
                         // Disallowed syntax
                         t @ (Token::Unit | Token::MapStart) => Token::LexError(
-                            LexError::ImproperSymbol(
+                            LexError::ImproperSymbol(t.literal_syntax().to_string(), String::new())
-                                t.literal_syntax().to_string(),
+                                .into(),
-                                "Invalid JSON syntax".to_string(),
-                            )
-                            .into(),
                         ),
                         Token::InterpolatedString(..) => Token::LexError(
                             LexError::ImproperSymbol(
                                 "interpolated string".to_string(),
-                                "Invalid JSON syntax".to_string(),
+                                String::new(),
                             )
                             .into(),
                         ),
                         // All others
                         _ => token,
                     }
-                })
+                }
-            },
+            }),
         );
 
         let ast = {

src/api/limits_unchecked.rs

@@ -0,0 +1,70 @@
+#![cfg(feature = "unchecked")]
+
+use crate::Engine;
+
+impl Engine {
+    /// The maximum levels of function calls allowed for a script.
+    ///
+    /// Always returns [`usize::MAX`] under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_call_levels(&self) -> usize {
+        usize::MAX
+    }
+    /// The maximum number of operations allowed for a script to run (0 for unlimited).
+    ///
+    /// Always returns zero under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_operations(&self) -> u64 {
+        0
+    }
+    /// The maximum number of imported [modules][crate::Module] allowed for a script.
+    ///
+    /// Always returns [`usize::MAX`] under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_modules(&self) -> usize {
+        usize::MAX
+    }
+    /// The depth limit for expressions (0 for unlimited).
+    ///
+    /// Always returns zero under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_expr_depth(&self) -> usize {
+        0
+    }
+    /// The depth limit for expressions in functions (0 for unlimited).
+    ///
+    /// Always returns zero under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_function_expr_depth(&self) -> usize {
+        0
+    }
+    /// The maximum length of [strings][crate::ImmutableString] (0 for unlimited).
+    ///
+    /// Always returns zero under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_string_size(&self) -> usize {
+        0
+    }
+    /// The maximum length of [arrays][crate::Array] (0 for unlimited).
+    ///
+    /// Always returns zero under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_array_size(&self) -> usize {
+        0
+    }
+    /// The maximum size of [object maps][crate::Map] (0 for unlimited).
+    ///
+    /// Always returns zero under `unchecked`.
+    #[inline(always)]
+    #[must_use]
+    pub const fn max_map_size(&self) -> usize {
+        0
+    }
+}

src/api/mod.rs

@@ -19,9 +19,21 @@ pub mod options;
 pub mod optimize;
 
 pub mod limits;
+pub mod limits_unchecked;
 
 pub mod events;
 
+pub mod type_names;
+
+pub mod custom_syntax;
+
+pub mod build_type;
+
+#[cfg(feature = "metadata")]
+pub mod definitions;
+
+pub mod deprecated;
+
 use crate::{Dynamic, Engine, Identifier};
 
 #[cfg(feature = "no_std")]
@@ -156,7 +168,7 @@ impl Engine {
             Some(token) if token.is_standard_keyword() => {
                 if !self
                     .disabled_symbols
-                    .as_ref()
+                    .as_deref()
                     .map_or(false, |m| m.contains(token.literal_syntax()))
                 {
                     return Err(format!("'{keyword}' is a reserved keyword"));
@@ -166,7 +178,7 @@ impl Engine {
             Some(token) if token.is_standard_symbol() => {
                 if !self
                     .disabled_symbols
-                    .as_ref()
+                    .as_deref()
                     .map_or(false, |m| m.contains(token.literal_syntax()))
                 {
                     return Err(format!("'{keyword}' is a reserved operator"));
@@ -176,7 +188,7 @@ impl Engine {
             Some(token)
                 if !self
                     .disabled_symbols
-                    .as_ref()
+                    .as_deref()
                     .map_or(false, |m| m.contains(token.literal_syntax())) =>
             {
                 return Err(format!("'{keyword}' is a reserved symbol"))
@@ -212,82 +224,3 @@ impl Engine {
         self
     }
 }
-
-#[cfg(feature = "unchecked")]
-impl Engine {
-    /// The maximum levels of function calls allowed for a script.
-    ///
-    /// Always returns [`usize::MAX`] under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_call_levels(&self) -> usize {
-        usize::MAX
-    }
-    /// The maximum number of operations allowed for a script to run (0 for unlimited).
-    ///
-    /// Always returns zero under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_operations(&self) -> u64 {
-        0
-    }
-    /// The maximum number of imported [modules][crate::Module] allowed for a script.
-    ///
-    /// Always returns [`usize::MAX`] under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_modules(&self) -> usize {
-        usize::MAX
-    }
-    /// The depth limit for expressions (0 for unlimited).
-    ///
-    /// Always returns zero under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_expr_depth(&self) -> usize {
-        0
-    }
-    /// The depth limit for expressions in functions (0 for unlimited).
-    ///
-    /// Always returns zero under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_function_expr_depth(&self) -> usize {
-        0
-    }
-    /// The maximum length of [strings][crate::ImmutableString] (0 for unlimited).
-    ///
-    /// Always returns zero under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_string_size(&self) -> usize {
-        0
-    }
-    /// The maximum length of [arrays][crate::Array] (0 for unlimited).
-    ///
-    /// Always returns zero under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_array_size(&self) -> usize {
-        0
-    }
-    /// The maximum size of [object maps][crate::Map] (0 for unlimited).
-    ///
-    /// Always returns zero under `unchecked`.
-    #[inline(always)]
-    #[must_use]
-    pub const fn max_map_size(&self) -> usize {
-        0
-    }
-}
-
-pub mod type_names;
-
-pub mod custom_syntax;
-
-pub mod build_type;
-
-#[cfg(feature = "metadata")]
-pub mod definitions;
-
-pub mod deprecated;

src/api/optimize.rs

@@ -57,7 +57,7 @@ impl Engine {
             #[cfg(not(feature = "no_function"))]
             ast.shared_lib()
                 .iter_fn()
-                .map(|f| f.func.get_script_fn_def().expect("`ScriptFnDef").clone())
+                .map(|f| f.func.get_script_fn_def().cloned().expect("`ScriptFnDef"))
                 .collect(),
             optimization_level,
         );

src/ast/expr.rs

@@ -1,9 +1,9 @@
 //! Module defining script expressions.
 
-use super::{ASTFlags, ASTNode, Ident, Stmt, StmtBlock};
+use super::{ASTFlags, ASTNode, Ident, Namespace, Stmt, StmtBlock};
 use crate::engine::{KEYWORD_FN_PTR, OP_EXCLUSIVE_RANGE, OP_INCLUSIVE_RANGE};
 use crate::func::hashing::ALT_ZERO_HASH;
-use crate::tokenizer::Token;
+use crate::tokenizer::{Token, NO_TOKEN};
 use crate::types::dynamic::Union;
 use crate::{
     calc_fn_hash, Dynamic, FnPtr, Identifier, ImmutableString, Position, SmartString, StaticVec,
@@ -197,8 +197,7 @@ impl FnCallHashes {
 #[derive(Clone, Hash)]
 pub struct FnCallExpr {
     /// Namespace of the function, if any.
-    #[cfg(not(feature = "no_module"))]
+    pub namespace: Namespace,
-    pub namespace: super::Namespace,
     /// Function name.
     pub name: ImmutableString,
     /// Pre-calculated hashes.
@@ -208,7 +207,7 @@ pub struct FnCallExpr {
     /// Does this function call capture the parent scope?
     pub capture_parent_scope: bool,
     /// Is this function call a native operator?
-    /// Otherwise set to [`Token::NonToken`].
+    /// Otherwise set to [`Token::NONE`].
     pub op_token: Token,
 }
 
@@ -217,14 +216,13 @@ impl fmt::Debug for FnCallExpr {
     #[inline(never)]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let mut ff = f.debug_struct("FnCallExpr");
-        #[cfg(not(feature = "no_module"))]
         if !self.namespace.is_empty() {
             ff.field("namespace", &self.namespace);
         }
         ff.field("hash", &self.hashes)
             .field("name", &self.name)
             .field("args", &self.args);
-        if self.op_token != Token::NonToken {
+        if self.op_token != NO_TOKEN {
             ff.field("op_token", &self.op_token);
         }
         if self.capture_parent_scope {
@@ -241,10 +239,7 @@ impl FnCallExpr {
     #[inline(always)]
     #[must_use]
     pub fn is_qualified(&self) -> bool {
-        #[cfg(not(feature = "no_module"))]
+        !self.namespace.is_empty()
-        return !self.namespace.is_empty();
-        #[cfg(feature = "no_module")]
-        return false;
     }
     /// Convert this into an [`Expr::FnCall`].
     #[inline(always)]
@@ -304,9 +299,7 @@ pub enum Expr {
     /// majority of cases (unless there are more than 255 variables defined!).
     /// This is to avoid reading a pointer redirection during each variable access.
     Variable(
-        #[cfg(not(feature = "no_module"))]
+        Box<(Option<NonZeroUsize>, Namespace, u64, ImmutableString)>,
-        Box<(Option<NonZeroUsize>, super::Namespace, u64, ImmutableString)>,
-        #[cfg(feature = "no_module")] Box<(Option<NonZeroUsize>, [(); 0], u64, ImmutableString)>,
         Option<NonZeroU8>,
         Position,
     ),
@@ -584,13 +577,12 @@ impl Expr {
 
             Union::FnPtr(f, ..) if !f.is_curried() => Self::FnCall(
                 FnCallExpr {
-                    #[cfg(not(feature = "no_module"))]
+                    namespace: Namespace::NONE,
-                    namespace: super::Namespace::NONE,
                     name: KEYWORD_FN_PTR.into(),
                     hashes: calc_fn_hash(None, f.fn_name(), 1).into(),
                     args: once(Self::StringConstant(f.fn_name().into(), pos)).collect(),
                     capture_parent_scope: false,
-                    op_token: Token::NonToken,
+                    op_token: NO_TOKEN,
                 }
                 .into(),
                 pos,

src/ast/mod.rs

@@ -5,6 +5,7 @@ pub mod expr;
 pub mod flags;
 pub mod ident;
 pub mod namespace;
+pub mod namespace_none;
 pub mod script_fn;
 pub mod stmt;
 
@@ -16,6 +17,8 @@ pub use flags::{ASTFlags, FnAccess};
 pub use ident::Ident;
 #[cfg(not(feature = "no_module"))]
 pub use namespace::Namespace;
+#[cfg(feature = "no_module")]
+pub use namespace_none::Namespace;
 #[cfg(not(feature = "no_module"))]
 #[cfg(not(feature = "no_function"))]
 pub use script_fn::EncapsulatedEnviron;

src/ast/namespace_none.rs

@@ -0,0 +1,22 @@
+//! Namespace reference type.
+#![cfg(feature = "no_module")]
+
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+
+/// _(internals)_ A chain of [module][crate::Module] names to namespace-qualify a variable or function call.
+/// Exported under the `internals` feature only.
+///
+/// Not available under `no_module`.
+#[derive(Debug, Clone, Eq, PartialEq, Default, Hash)]
+pub struct Namespace;
+
+impl Namespace {
+    /// Constant for no namespace.
+    pub const NONE: Self = Self;
+
+    #[inline(always)]
+    pub const fn is_empty(&self) -> bool {
+        true
+    }
+}

src/ast/script_fn.rs

@@ -16,7 +16,6 @@ use std::{fmt, hash::Hash};
 ///
 /// Not available under `no_module` or `no_function`.
 #[cfg(not(feature = "no_module"))]
-#[cfg(not(feature = "no_function"))]
 #[derive(Debug, Clone)]
 pub struct EncapsulatedEnviron {
     /// Functions defined within the same [`AST`][crate::AST].
@@ -35,7 +34,6 @@ pub struct ScriptFnDef {
     pub body: StmtBlock,
     /// Encapsulated AST environment, if any.
     #[cfg(not(feature = "no_module"))]
-    #[cfg(not(feature = "no_function"))]
     pub environ: Option<crate::Shared<EncapsulatedEnviron>>,
     /// Function name.
     pub name: ImmutableString,

src/ast/stmt.rs

@@ -2,7 +2,8 @@
 
 use super::{ASTFlags, ASTNode, BinaryExpr, Expr, FnCallExpr, Ident};
 use crate::engine::KEYWORD_EVAL;
-use crate::tokenizer::{Span, Token};
+use crate::tokenizer::Token;
+use crate::types::Span;
 use crate::{calc_fn_hash, Position, StaticVec, INT};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;

src/eval/chaining.rs

@@ -5,7 +5,7 @@ use super::{Caches, GlobalRuntimeState, Target};
 use crate::ast::{ASTFlags, Expr, OpAssignment};
 use crate::config::hashing::SusLock;
 use crate::engine::{FN_IDX_GET, FN_IDX_SET};
-use crate::tokenizer::Token;
+use crate::tokenizer::NO_TOKEN;
 use crate::types::{dynamic::Union, RestoreOnDrop};
 use crate::{
     calc_fn_hash, Dynamic, Engine, FnArgsVec, Position, RhaiResult, RhaiResultOf, Scope, ERR,
@@ -72,17 +72,11 @@ impl Engine {
         global.level += 1;
         let global = &mut *RestoreOnDrop::lock(global, move |g| g.level = orig_level);
 
-        self.exec_native_fn_call(
+        let hash = hash_idx().0;
-            global,
+        let args = &mut [target, idx];
-            caches,
+
-            FN_IDX_GET,
+        self.exec_native_fn_call(global, caches, FN_IDX_GET, NO_TOKEN, hash, args, true, pos)
-            Token::NonToken,
+            .map(|(r, ..)| r)
-            hash_idx().0,
-            &mut [target, idx],
-            true,
-            pos,
-        )
-        .map(|(r, ..)| r)
     }
 
     /// Call a set indexer.
@@ -101,15 +95,11 @@ impl Engine {
         global.level += 1;
         let global = &mut *RestoreOnDrop::lock(global, move |g| g.level = orig_level);
 
+        let hash = hash_idx().1;
+        let args = &mut [target, idx, new_val];
+
         self.exec_native_fn_call(
-            global,
+            global, caches, FN_IDX_SET, NO_TOKEN, hash, args, is_ref_mut, pos,
-            caches,
-            FN_IDX_SET,
-            Token::NonToken,
-            hash_idx().1,
-            &mut [target, idx, new_val],
-            is_ref_mut,
-            pos,
         )
     }
 
@@ -766,15 +756,10 @@ impl Engine {
 
                         if op_info.is_op_assignment() {
                             let args = &mut [target.as_mut()];
+
                             let (mut orig_val, ..) = self
                                 .exec_native_fn_call(
-                                    global,
+                                    global, caches, getter, NO_TOKEN, *hash_get, args, is_ref_mut,
-                                    caches,
-                                    getter,
-                                    Token::NonToken,
-                                    *hash_get,
-                                    args,
-                                    is_ref_mut,
                                     *pos,
                                 )
                                 .or_else(|err| match *err {
@@ -807,15 +792,9 @@ impl Engine {
                         }
 
                         let args = &mut [target.as_mut(), &mut new_val];
+
                         self.exec_native_fn_call(
-                            global,
+                            global, caches, setter, NO_TOKEN, *hash_set, args, is_ref_mut, *pos,
-                            caches,
-                            setter,
-                            Token::NonToken,
-                            *hash_set,
-                            args,
-                            is_ref_mut,
-                            *pos,
                         )
                         .or_else(|err| match *err {
                             // Try an indexer if property does not exist
@@ -840,15 +819,9 @@ impl Engine {
 
                         let ((getter, hash_get), _, name) = &**x;
                         let args = &mut [target.as_mut()];
+
                         self.exec_native_fn_call(
-                            global,
+                            global, caches, getter, NO_TOKEN, *hash_get, args, is_ref_mut, *pos,
-                            caches,
-                            getter,
-                            Token::NonToken,
-                            *hash_get,
-                            args,
-                            is_ref_mut,
-                            *pos,
                         )
                         .map_or_else(
                             |err| match *err {
@@ -938,20 +911,13 @@ impl Engine {
                                 self.run_debugger(global, caches, scope, this_ptr, _node)?;
 
                                 let ((getter, hash_get), (setter, hash_set), name) = &**p;
-                                let mut arg_values = [target.as_mut(), &mut Dynamic::UNIT.clone()];
+                                let args = &mut [target.as_mut()];
-                                let args = &mut arg_values[..1];
 
                                 // Assume getters are always pure
                                 let (mut val, ..) = self
                                     .exec_native_fn_call(
-                                        global,
+                                        global, caches, getter, NO_TOKEN, *hash_get, args,
-                                        caches,
+                                        is_ref_mut, pos,
-                                        getter,
-                                        Token::NonToken,
-                                        *hash_get,
-                                        args,
-                                        is_ref_mut,
-                                        pos,
                                     )
                                     .or_else(|err| match *err {
                                         // Try an indexer if property does not exist
@@ -981,19 +947,13 @@ impl Engine {
                                 // Feed the value back via a setter just in case it has been updated
                                 if may_be_changed {
                                     // 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 [target.as_mut(), val.as_mut()];
-                                    let args = &mut arg_values;
+
                                     // The return value is thrown away and not used.
                                     let _ = self
                                         .exec_native_fn_call(
-                                            global,
+                                            global, caches, setter, NO_TOKEN, *hash_set, args,
-                                            caches,
+                                            is_ref_mut, pos,
-                                            setter,
-                                            Token::NonToken,
-                                            *hash_set,
-                                            args,
-                                            is_ref_mut,
-                                            pos,
                                         )
                                         .or_else(|err| match *err {
                                             // Try an indexer if property does not exist

src/eval/debugger.rs

@@ -508,11 +508,10 @@ impl Engine {
         node: ASTNode<'a>,
         event: DebuggerEvent,
     ) -> Result<Option<DebuggerStatus>, Box<crate::EvalAltResult>> {
-        let src = global.source_raw().cloned();
-        let src = src.as_ref().map(|s| s.as_str());
-        let context = crate::EvalContext::new(self, global, caches, scope, this_ptr);
-
         if let Some(ref x) = self.debugger_interface {
+            let src = global.source_raw().cloned();
+            let src = src.as_ref().map(|s| s.as_str());
+            let context = EvalContext::new(self, global, caches, scope, this_ptr);
             let (.., ref on_debugger) = **x;
 
             let command = on_debugger(context, event, node, src, node.position())?;

src/eval/eval_context.rs

@@ -7,7 +7,6 @@ use std::prelude::v1::*;
 
 /// Context of a script evaluation process.
 #[derive(Debug)]
-#[allow(dead_code)]
 pub struct EvalContext<'a, 's, 'ps, 'g, 'c, 't> {
     /// The current [`Engine`].
     engine: &'a Engine,

src/eval/stmt.rs

@@ -6,13 +6,26 @@ use crate::ast::{
     ASTFlags, BinaryExpr, Expr, Ident, OpAssignment, Stmt, SwitchCasesCollection, TryCatchBlock,
 };
 use crate::func::{get_builtin_op_assignment_fn, get_hasher};
-use crate::types::dynamic::AccessMode;
+use crate::types::dynamic::{AccessMode, Union};
 use crate::types::RestoreOnDrop;
 use crate::{Dynamic, Engine, RhaiResult, RhaiResultOf, Scope, ERR, INT};
 use std::hash::{Hash, Hasher};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 
+impl Dynamic {
+    /// If the value is a string, intern it.
+    #[inline(always)]
+    fn intern_string(self, engine: &Engine) -> Self {
+        match self.0 {
+            Union::Str(..) => engine
+                .get_interned_string(self.into_immutable_string().expect("`ImmutableString`"))
+                .into(),
+            _ => self,
+        }
+    }
+}
+
 impl Engine {
     /// Evaluate a statements block.
     pub(crate) fn eval_stmt_block(
@@ -169,14 +182,13 @@ impl Engine {
             self.check_data_size(&*args[0], root.position())?;
         } else {
             // Normal assignment
-
+            match target {
-            // If value is a string, intern it
+                // Lock it again just in case it is shared
-            if new_val.is_string() {
+                Target::RefMut(_) | Target::TempValue(_) => {
-                let value = new_val.into_immutable_string().expect("`ImmutableString`");
+                    *target.write_lock::<Dynamic>().unwrap() = new_val
-                new_val = self.get_interned_string(value).into();
+                }
+                _ => **target = new_val,
             }
-
-            *target.write_lock::<Dynamic>().unwrap() = new_val;
         }
 
         target.propagate_changed_value(op_info.pos)
@@ -224,14 +236,13 @@ impl Engine {
 
                 let mut target = self.search_namespace(global, caches, scope, this_ptr, lhs)?;
 
+                let is_temp_result = !target.is_ref();
                 let var_name = x.3.as_str();
 
                 #[cfg(not(feature = "no_closure"))]
                 // Also handle case where target is a `Dynamic` shared value
                 // (returned by a variable resolver, for example)
-                let is_temp_result = !target.is_ref() && !target.is_shared();
+                let is_temp_result = is_temp_result && !target.is_shared();
-                #[cfg(feature = "no_closure")]
-                let is_temp_result = !target.is_ref();
 
                 // Cannot assign to temp result from expression
                 if is_temp_result {
@@ -251,36 +262,31 @@ impl Engine {
 
             #[cfg(any(not(feature = "no_index"), not(feature = "no_object")))]
             {
-                let mut rhs_val = self
+                let rhs_val = self
                     .eval_expr(global, caches, scope, this_ptr, rhs)?
-                    .flatten();
+                    .flatten()
-
+                    .intern_string(self);
-                // If value is a string, intern it
-                if rhs_val.is_string() {
-                    let value = rhs_val.into_immutable_string().expect("`ImmutableString`");
-                    rhs_val = self.get_interned_string(value).into();
-                }
 
                 let _new_val = Some((rhs_val, op_info));
 
-                // Must be either `var[index] op= val` or `var.prop op= val`
+                // Must be either `var[index] op= val` or `var.prop op= val`.
-                match lhs {
+                // The return value of any op-assignment (should be `()`) is thrown away and not used.
-                    // name op= rhs (handled above)
+                let _ =
-                    Expr::Variable(..) => {
+                    match lhs {
-                        unreachable!("Expr::Variable case is already handled")
+                        // name op= rhs (handled above)
-                    }
+                        Expr::Variable(..) => {
-                    // idx_lhs[idx_expr] op= rhs
+                            unreachable!("Expr::Variable case is already handled")
-                    #[cfg(not(feature = "no_index"))]
+                        }
-                    Expr::Index(..) => {
+                        // idx_lhs[idx_expr] op= rhs
-                        self.eval_dot_index_chain(global, caches, scope, this_ptr, lhs, _new_val)
+                        #[cfg(not(feature = "no_index"))]
-                    }
+                        Expr::Index(..) => self
-                    // dot_lhs.dot_rhs op= rhs
+                            .eval_dot_index_chain(global, caches, scope, this_ptr, lhs, _new_val),
-                    #[cfg(not(feature = "no_object"))]
+                        // dot_lhs.dot_rhs op= rhs
-                    Expr::Dot(..) => {
+                        #[cfg(not(feature = "no_object"))]
-                        self.eval_dot_index_chain(global, caches, scope, this_ptr, lhs, _new_val)
+                        Expr::Dot(..) => self
-                    }
+                            .eval_dot_index_chain(global, caches, scope, this_ptr, lhs, _new_val),
-                    _ => unreachable!("cannot assign to expression: {:?}", lhs),
+                        _ => unreachable!("cannot assign to expression: {:?}", lhs),
-                }?;
+                    }?;
 
                 return Ok(Dynamic::UNIT);
             }
@@ -723,7 +729,8 @@ impl Engine {
                 // Evaluate initial value
                 let mut value = self
                     .eval_expr(global, caches, scope, this_ptr, expr)?
-                    .flatten();
+                    .flatten()
+                    .intern_string(self);
 
                 let _alias = if !rewind_scope {
                     // Put global constants into global module

src/eval/target.rs

@@ -89,9 +89,9 @@ pub enum Target<'a> {
     #[cfg(not(feature = "no_closure"))]
     SharedValue {
         /// Lock guard to the shared [`Dynamic`].
-        source: crate::types::dynamic::DynamicWriteLock<'a, Dynamic>,
+        guard: crate::types::dynamic::DynamicWriteLock<'a, Dynamic>,
-        /// Copy of the value.
+        /// Copy of the shared value.
-        value: Dynamic,
+        shared_value: Dynamic,
     },
     /// The target is a temporary [`Dynamic`] value (i.e. its mutation can cause no side effects).
     TempValue(Dynamic),
@@ -178,21 +178,21 @@ impl<'a> Target<'a> {
         }
     }
     /// Is the [`Target`] a shared value?
-    #[cfg(not(feature = "no_closure"))]
     #[inline]
     #[must_use]
     pub fn is_shared(&self) -> bool {
-        match self {
+        #[cfg(not(feature = "no_closure"))]
+        return match self {
             Self::RefMut(r) => r.is_shared(),
-            #[cfg(not(feature = "no_closure"))]
             Self::SharedValue { .. } => true,
             Self::TempValue(value) => value.is_shared(),
-            #[cfg(not(feature = "no_index"))]
             Self::Bit { .. }
             | Self::BitField { .. }
             | Self::BlobByte { .. }
             | Self::StringChar { .. } => false,
-        }
+        };
+        #[cfg(feature = "no_closure")]
+        return false;
     }
     /// Get the value of the [`Target`] as a [`Dynamic`], cloning a referenced value if necessary.
     #[inline]
@@ -200,7 +200,7 @@ impl<'a> Target<'a> {
         match self {
             Self::RefMut(r) => r.clone(), // Referenced value is cloned
             #[cfg(not(feature = "no_closure"))]
-            Self::SharedValue { value, .. } => value, // Original shared value is simply taken
+            Self::SharedValue { shared_value, .. } => shared_value, // Original shared value is simply taken
             Self::TempValue(value) => value, // Owned value is simply taken
             #[cfg(not(feature = "no_index"))]
             Self::Bit { value, .. } => value, // boolean is taken
@@ -227,7 +227,7 @@ impl<'a> Target<'a> {
         match self {
             Self::RefMut(r) => Self::TempValue(r.clone()),
             #[cfg(not(feature = "no_closure"))]
-            Self::SharedValue { value, .. } => Self::TempValue(value),
+            Self::SharedValue { shared_value, .. } => Self::TempValue(shared_value),
             _ => self,
         }
     }
@@ -239,7 +239,7 @@ impl<'a> Target<'a> {
         match self {
             Self::RefMut(r) => r,
             #[cfg(not(feature = "no_closure"))]
-            Self::SharedValue { source, .. } => source,
+            Self::SharedValue { guard, .. } => guard,
             Self::TempValue(value) => value,
             #[cfg(not(feature = "no_index"))]
             Self::Bit { source, .. } => source,
@@ -365,9 +365,12 @@ impl<'a> From<&'a mut Dynamic> for Target<'a> {
         #[cfg(not(feature = "no_closure"))]
         if value.is_shared() {
             // Cloning is cheap for a shared value
-            let val = value.clone();
+            let shared_value = value.clone();
-            let source = value.write_lock::<Dynamic>().expect("`Dynamic`");
+            let guard = value.write_lock::<Dynamic>().expect("`Dynamic`");
-            return Self::SharedValue { source, value: val };
+            return Self::SharedValue {
+                guard,
+                shared_value,
+            };
         }
 
         Self::RefMut(value)
@@ -382,7 +385,7 @@ impl Deref for Target<'_> {
         match self {
             Self::RefMut(r) => r,
             #[cfg(not(feature = "no_closure"))]
-            Self::SharedValue { source, .. } => source,
+            Self::SharedValue { guard, .. } => guard,
             Self::TempValue(ref value) => value,
             #[cfg(not(feature = "no_index"))]
             Self::Bit { ref value, .. }
@@ -415,7 +418,7 @@ impl DerefMut for Target<'_> {
         match self {
             Self::RefMut(r) => r,
             #[cfg(not(feature = "no_closure"))]
-            Self::SharedValue { source, .. } => &mut *source,
+            Self::SharedValue { guard, .. } => &mut *guard,
             Self::TempValue(ref mut value) => value,
             #[cfg(not(feature = "no_index"))]
             Self::Bit { ref mut value, .. }

src/func/call.rs

@@ -8,7 +8,7 @@ use crate::engine::{
     KEYWORD_IS_DEF_VAR, KEYWORD_PRINT, KEYWORD_TYPE_OF,
 };
 use crate::eval::{Caches, FnResolutionCacheEntry, GlobalRuntimeState};
-use crate::tokenizer::{is_valid_function_name, Token};
+use crate::tokenizer::{is_valid_function_name, Token, NO_TOKEN};
 use crate::types::RestoreOnDrop;
 use crate::{
     calc_fn_hash, calc_fn_hash_full, Dynamic, Engine, FnArgsVec, FnPtr, ImmutableString,
@@ -272,7 +272,7 @@ impl Engine {
 
                         // Try to find a built-in version
                         let builtin = args.and_then(|args| match op_token {
-                            Token::NonToken => None,
+                            Token::NONE => None,
                             token if token.is_op_assignment() => {
                                 let (first_arg, rest_args) = args.split_first().unwrap();
 
@@ -639,15 +639,7 @@ impl Engine {
             let local_entry = &mut None;
 
             if let Some(FnResolutionCacheEntry { func, ref source }) = self
-                .resolve_fn(
+                .resolve_fn(global, caches, local_entry, NO_TOKEN, hash, None, false)
-                    global,
-                    caches,
-                    local_entry,
-                    Token::NonToken,
-                    hash,
-                    None,
-                    false,
-                )
                 .cloned()
             {
                 // Script function call
@@ -791,7 +783,7 @@ impl Engine {
                     caches,
                     None,
                     fn_name,
-                    Token::NonToken,
+                    NO_TOKEN,
                     new_hash,
                     &mut args,
                     false,
@@ -845,7 +837,7 @@ impl Engine {
                     caches,
                     None,
                     &fn_name,
-                    Token::NonToken,
+                    NO_TOKEN,
                     new_hash,
                     &mut args,
                     is_ref_mut,
@@ -944,7 +936,7 @@ impl Engine {
                     caches,
                     None,
                     fn_name,
-                    Token::NonToken,
+                    NO_TOKEN,
                     hash,
                     &mut args,
                     is_ref_mut,
@@ -986,7 +978,7 @@ impl Engine {
         let redirected; // Handle call() - Redirect function call
 
         match name {
-            _ if op_token != Token::NonToken => (),
+            _ if op_token != NO_TOKEN => (),
 
             // Handle call()
             KEYWORD_FN_PTR_CALL if total_args >= 1 => {
@@ -1217,12 +1209,7 @@ impl Engine {
 
                 self.track_operation(global, first_expr.position())?;
 
-                #[cfg(not(feature = "no_closure"))]
+                if target.is_shared() || target.is_temp_value() {
-                let target_is_shared = target.is_shared();
-                #[cfg(feature = "no_closure")]
-                let target_is_shared = false;
-
-                if target_is_shared || target.is_temp_value() {
                     arg_values.insert(0, target.take_or_clone().flatten());
                 } else {
                     // Turn it into a method call only if the object is not shared and not a simple value
@@ -1500,7 +1487,7 @@ impl Engine {
         let op_token = op_token.clone();
 
         // Short-circuit native binary operator call if under Fast Operators mode
-        if op_token != Token::NonToken && self.fast_operators() && args.len() == 2 {
+        if op_token != NO_TOKEN && self.fast_operators() && args.len() == 2 {
             let mut lhs = self
                 .get_arg_value(global, caches, scope, this_ptr, &args[0])?
                 .0

src/func/native.rs

@@ -4,7 +4,7 @@ use super::call::FnCallArgs;
 use crate::ast::FnCallHashes;
 use crate::eval::{Caches, GlobalRuntimeState};
 use crate::plugin::PluginFunction;
-use crate::tokenizer::{is_valid_function_name, Token, TokenizeState};
+use crate::tokenizer::{is_valid_function_name, Token, TokenizeState, NO_TOKEN};
 use crate::types::dynamic::Variant;
 use crate::{
     calc_fn_hash, reify, Dynamic, Engine, EvalContext, FuncArgs, Position, RhaiResult,
@@ -424,7 +424,7 @@ impl<'a> NativeCallContext<'a> {
         let caches = &mut Caches::new();
 
         let fn_name = fn_name.as_ref();
-        let op_token = Token::lookup_symbol_from_syntax(fn_name).unwrap_or(Token::NonToken);
+        let op_token = Token::lookup_symbol_from_syntax(fn_name).unwrap_or(NO_TOKEN);
         let args_len = args.len();
 
         global.level += 1;

src/lib.rs

@@ -207,9 +207,9 @@ pub use engine::{Engine, OP_CONTAINS, OP_EQUALS};
 pub use eval::EvalContext;
 pub use func::{NativeCallContext, RegisterNativeFunction};
 pub use module::{FnNamespace, Module};
-pub use tokenizer::Position;
 #[cfg(not(feature = "no_time"))]
 pub use types::Instant;
+pub use types::Position;
 pub use types::{
     Dynamic, EvalAltResult, FnPtr, ImmutableString, LexError, ParseError, ParseErrorType, Scope,
 };
@@ -311,12 +311,12 @@ pub use types::dynamic::{AccessMode, DynamicReadLock, DynamicWriteLock, Variant}
 pub use types::FloatWrapper;
 
 #[cfg(feature = "internals")]
-pub use types::StringsInterner;
+pub use types::{Span, StringsInterner};
 
 #[cfg(feature = "internals")]
 pub use tokenizer::{
     get_next_token, is_valid_function_name, is_valid_identifier, parse_string_literal, InputStream,
-    MultiInputsStream, Span, Token, TokenIterator, TokenizeState, TokenizerControl,
+    MultiInputsStream, Token, TokenIterator, TokenizeState, TokenizerControl,
     TokenizerControlBlock,
 };
 

src/optimizer.rs

@@ -69,14 +69,15 @@ impl<'a> OptimizerState<'a> {
     #[inline(always)]
     pub fn new(
         engine: &'a Engine,
-        #[cfg(not(feature = "no_function"))] lib: &'a [crate::SharedModule],
+        lib: &'a [crate::SharedModule],
         optimization_level: OptimizationLevel,
     ) -> Self {
         let mut _global = GlobalRuntimeState::new(engine);
+        let _lib = lib;
 
         #[cfg(not(feature = "no_function"))]
         {
-            _global.lib = lib.iter().cloned().collect();
+            _global.lib = _lib.iter().cloned().collect();
         }
 
         Self {
@@ -986,7 +987,7 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, _chaining: bool) {
         // ``
         Expr::InterpolatedString(x, pos) if x.is_empty() => {
             state.set_dirty();
-            *expr = Expr::StringConstant(state.engine.get_interned_string(""), *pos);
+            *expr = Expr::StringConstant(state.engine.const_empty_string(), *pos);
         }
         // `... ${const} ...`
         Expr::InterpolatedString(..) if expr.is_constant() => {
@@ -1117,7 +1118,7 @@ fn optimize_expr(expr: &mut Expr, state: &mut OptimizerState, _chaining: bool) {
                     return;
                 }
                 // Overloaded operators can override built-in.
-                _ if x.args.len() == 2 && x.op_token != Token::NonToken && (state.engine.fast_operators() || !state.engine.has_native_fn_override(x.hashes.native(), &arg_types)) => {
+                _ if x.args.len() == 2 && x.op_token != Token::NONE && (state.engine.fast_operators() || !state.engine.has_native_fn_override(x.hashes.native(), &arg_types)) => {
                     if let Some(result) = get_builtin_binary_op_fn(x.op_token.clone(), &arg_values[0], &arg_values[1])
                         .and_then(|f| {
                             let context = (state.engine, x.name.as_str(),None, &state.global, *pos).into();
@@ -1265,7 +1266,7 @@ impl Engine {
         &self,
         statements: StmtBlockContainer,
         scope: &Scope,
-        #[cfg(not(feature = "no_function"))] lib: &[crate::SharedModule],
+        lib: &[crate::SharedModule],
         optimization_level: OptimizationLevel,
     ) -> StmtBlockContainer {
         let mut statements = statements;
@@ -1277,12 +1278,7 @@ impl Engine {
         }
 
         // Set up the state
-        let mut state = OptimizerState::new(
+        let mut state = OptimizerState::new(self, lib, optimization_level);
-            self,
-            #[cfg(not(feature = "no_function"))]
-            lib,
-            optimization_level,
-        );
 
         // Add constants from global modules
         for (name, value) in self.global_modules.iter().rev().flat_map(|m| m.iter_var()) {
@@ -1355,19 +1351,17 @@ impl Engine {
 
             module.into()
         };
+        #[cfg(feature = "no_function")]
+        let lib: crate::Shared<_> = crate::Module::new().into();
 
         statements.shrink_to_fit();
 
         AST::new(
             match optimization_level {
                 OptimizationLevel::None => statements,
-                OptimizationLevel::Simple | OptimizationLevel::Full => self.optimize_top_level(
+                OptimizationLevel::Simple | OptimizationLevel::Full => {
-                    statements,
+                    self.optimize_top_level(statements, scope, &[lib.clone()], optimization_level)
-                    scope,
+                }
-                    #[cfg(not(feature = "no_function"))]
-                    &[lib.clone()],
-                    optimization_level,
-                ),
             },
             #[cfg(not(feature = "no_function"))]
             lib,

src/parser.rs

@@ -4,7 +4,7 @@ use crate::api::events::VarDefInfo;
 use crate::api::options::LangOptions;
 use crate::ast::{
     ASTFlags, BinaryExpr, CaseBlocksList, ConditionalExpr, Expr, FnCallExpr, FnCallHashes, Ident,
-    OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlock, StmtBlockContainer,
+    Namespace, OpAssignment, RangeCase, ScriptFnDef, Stmt, StmtBlock, StmtBlockContainer,
     SwitchCasesCollection, TryCatchBlock,
 };
 use crate::engine::{Precedence, KEYWORD_THIS, OP_CONTAINS};
@@ -12,14 +12,14 @@ use crate::eval::{Caches, GlobalRuntimeState};
 use crate::func::{hashing::get_hasher, StraightHashMap};
 use crate::tokenizer::{
     is_keyword_function, is_valid_function_name, is_valid_identifier, Token, TokenStream,
-    TokenizerControl,
+    TokenizerControl, NO_TOKEN,
 };
 use crate::types::dynamic::AccessMode;
 use crate::types::StringsInterner;
 use crate::{
-    calc_fn_hash, Dynamic, Engine, EvalAltResult, EvalContext, ExclusiveRange, FnArgsVec,
+    calc_fn_hash, Dynamic, Engine, EvalAltResult, EvalContext, ExclusiveRange, Identifier,
-    Identifier, ImmutableString, InclusiveRange, LexError, OptimizationLevel, ParseError, Position,
+    ImmutableString, InclusiveRange, LexError, OptimizationLevel, ParseError, Position, Scope,
-    Scope, Shared, SmartString, StaticVec, AST, INT, PERR,
+    Shared, SmartString, StaticVec, AST, INT, PERR,
 };
 use bitflags::bitflags;
 #[cfg(feature = "no_std")]
@@ -63,7 +63,7 @@ pub struct ParseState<'e, 's> {
     pub block_stack_len: usize,
     /// Tracks a list of external variables (variables that are not explicitly declared in the scope).
     #[cfg(not(feature = "no_closure"))]
-    pub external_vars: Option<Box<FnArgsVec<Ident>>>,
+    pub external_vars: Option<Box<crate::FnArgsVec<Ident>>>,
     /// An indicator that disables variable capturing into externals one single time
     /// up until the nearest consumed Identifier token.
     /// If set to false the next call to [`access_var`][ParseState::access_var] will not capture the variable.
@@ -557,7 +557,7 @@ impl Engine {
         id: ImmutableString,
         no_args: bool,
         capture_parent_scope: bool,
-        #[cfg(not(feature = "no_module"))] namespace: crate::ast::Namespace,
+        namespace: Namespace,
         settings: ParseSettings,
     ) -> ParseResult<Expr> {
         let (token, token_pos) = if no_args {
@@ -566,8 +566,7 @@ impl Engine {
             input.peek().expect(NEVER_ENDS)
         };
 
-        #[cfg(not(feature = "no_module"))]
+        let mut _namespace = namespace;
-        let mut namespace = namespace;
         let mut args = StaticVec::new_const();
 
         match token {
@@ -588,17 +587,16 @@ impl Engine {
                 }
 
                 #[cfg(not(feature = "no_module"))]
-                let hash = if namespace.is_empty() {
+                let hash = if _namespace.is_empty() {
                     calc_fn_hash(None, &id, 0)
                 } else {
-                    let root = namespace.root();
+                    let root = _namespace.root();
                     let index = state.find_module(root);
+                    let is_global = false;
 
                     #[cfg(not(feature = "no_function"))]
                     #[cfg(not(feature = "no_module"))]
-                    let is_global = root == crate::engine::KEYWORD_GLOBAL;
+                    let is_global = is_global || root == crate::engine::KEYWORD_GLOBAL;
-                    #[cfg(any(feature = "no_function", feature = "no_module"))]
-                    let is_global = false;
 
                     if settings.has_option(LangOptions::STRICT_VAR)
                         && index.is_none()
@@ -615,13 +613,13 @@ impl Engine {
                             .map_or(false, |m| m.contains_key(root))
                     {
                         return Err(
-                            PERR::ModuleUndefined(root.into()).into_err(namespace.position())
+                            PERR::ModuleUndefined(root.into()).into_err(_namespace.position())
                         );
                     }
 
-                    namespace.set_index(index);
+                    _namespace.set_index(index);
 
-                    crate::calc_fn_hash(namespace.iter().map(Ident::as_str), &id, 0)
+                    calc_fn_hash(_namespace.iter().map(Ident::as_str), &id, 0)
                 };
                 #[cfg(feature = "no_module")]
                 let hash = calc_fn_hash(None, &id, 0);
@@ -637,9 +635,8 @@ impl Engine {
                 return Ok(FnCallExpr {
                     name: state.get_interned_string(id),
                     capture_parent_scope,
-                    op_token: Token::NonToken,
+                    op_token: NO_TOKEN,
-                    #[cfg(not(feature = "no_module"))]
+                    namespace: _namespace,
-                    namespace,
                     hashes,
                     args,
                 }
@@ -664,10 +661,10 @@ impl Engine {
                     eat_token(input, Token::RightParen);
 
                     #[cfg(not(feature = "no_module"))]
-                    let hash = if namespace.is_empty() {
+                    let hash = if _namespace.is_empty() {
                         calc_fn_hash(None, &id, args.len())
                     } else {
-                        let root = namespace.root();
+                        let root = _namespace.root();
                         let index = state.find_module(root);
 
                         #[cfg(not(feature = "no_function"))]
@@ -691,13 +688,13 @@ impl Engine {
                                 .map_or(false, |m| m.contains_key(root))
                         {
                             return Err(
-                                PERR::ModuleUndefined(root.into()).into_err(namespace.position())
+                                PERR::ModuleUndefined(root.into()).into_err(_namespace.position())
                             );
                         }
 
-                        namespace.set_index(index);
+                        _namespace.set_index(index);
 
-                        crate::calc_fn_hash(namespace.iter().map(Ident::as_str), &id, args.len())
+                        calc_fn_hash(_namespace.iter().map(Ident::as_str), &id, args.len())
                     };
                     #[cfg(feature = "no_module")]
                     let hash = calc_fn_hash(None, &id, args.len());
@@ -713,9 +710,8 @@ impl Engine {
                     return Ok(FnCallExpr {
                         name: state.get_interned_string(id),
                         capture_parent_scope,
-                        op_token: Token::NonToken,
+                        op_token: NO_TOKEN,
-                        #[cfg(not(feature = "no_module"))]
+                        namespace: _namespace,
-                        namespace,
                         hashes,
                         args,
                     }
@@ -1592,10 +1588,7 @@ impl Engine {
 
             // Identifier
             Token::Identifier(..) => {
-                #[cfg(not(feature = "no_module"))]
+                let ns = Namespace::NONE;
-                let ns = crate::ast::Namespace::NONE;
-                #[cfg(feature = "no_module")]
-                let ns = [];
 
                 let s = match input.next().expect(NEVER_ENDS) {
                     (Token::Identifier(s), ..) => s,
@@ -1657,10 +1650,7 @@ impl Engine {
 
             // Reserved keyword or symbol
             Token::Reserved(..) => {
-                #[cfg(not(feature = "no_module"))]
+                let ns = Namespace::NONE;
-                let ns = crate::ast::Namespace::NONE;
-                #[cfg(feature = "no_module")]
-                let ns = [];
 
                 let s = match input.next().expect(NEVER_ENDS) {
                     (Token::Reserved(s), ..) => s,
@@ -1763,35 +1753,18 @@ impl Engine {
 
                     let no_args = input.next().expect(NEVER_ENDS).0 == Token::Unit;
 
-                    let (.., _ns, _, name) = *x;
+                    let (.., ns, _, name) = *x;
                     settings.pos = pos;
-                    self.parse_fn_call(
+                    let settings = settings.level_up()?;
-                        input,
+                    self.parse_fn_call(input, state, lib, name, no_args, true, ns, settings)?
-                        state,
-                        lib,
-                        name,
-                        no_args,
-                        true,
-                        #[cfg(not(feature = "no_module"))]
-                        _ns,
-                        settings.level_up()?,
-                    )?
                 }
                 // Function call
                 (Expr::Variable(x, .., pos), t @ (Token::LeftParen | Token::Unit)) => {
-                    let (.., _ns, _, name) = *x;
+                    let (.., ns, _, name) = *x;
+                    let no_args = t == Token::Unit;
                     settings.pos = pos;
-                    self.parse_fn_call(
+                    let settings = settings.level_up()?;
-                        input,
+                    self.parse_fn_call(input, state, lib, name, no_args, false, ns, settings)?
-                        state,
-                        lib,
-                        name,
-                        t == Token::Unit,
-                        false,
-                        #[cfg(not(feature = "no_module"))]
-                        _ns,
-                        settings.level_up()?,
-                    )?
                 }
                 // module access
                 #[cfg(not(feature = "no_module"))]
@@ -1959,8 +1932,7 @@ impl Engine {
                         args.shrink_to_fit();
 
                         Ok(FnCallExpr {
-                            #[cfg(not(feature = "no_module"))]
+                            namespace: Namespace::NONE,
-                            namespace: Default::default(),
                             name: state.get_interned_string("-"),
                             hashes: FnCallHashes::from_native(calc_fn_hash(None, "-", 1)),
                             args,
@@ -1988,8 +1960,7 @@ impl Engine {
                         args.shrink_to_fit();
 
                         Ok(FnCallExpr {
-                            #[cfg(not(feature = "no_module"))]
+                            namespace: Namespace::NONE,
-                            namespace: Default::default(),
                             name: state.get_interned_string("+"),
                             hashes: FnCallHashes::from_native(calc_fn_hash(None, "+", 1)),
                             args,
@@ -2010,8 +1981,7 @@ impl Engine {
                 args.shrink_to_fit();
 
                 Ok(FnCallExpr {
-                    #[cfg(not(feature = "no_module"))]
+                    namespace: Namespace::NONE,
-                    namespace: Default::default(),
                     name: state.get_interned_string("!"),
                     hashes: FnCallHashes::from_native(calc_fn_hash(None, "!", 1)),
                     args,
@@ -2062,7 +2032,7 @@ impl Engine {
             }
         }
 
-        let op_info = if op != Token::NonToken {
+        let op_info = if op != NO_TOKEN {
             OpAssignment::new_op_assignment_from_token(op, op_pos)
         } else {
             OpAssignment::new_assignment(op_pos)
@@ -2143,7 +2113,7 @@ impl Engine {
     ) -> ParseResult<Stmt> {
         let (op, pos) = match input.peek().expect(NEVER_ENDS) {
             // var = ...
-            (Token::Equals, ..) => (Token::NonToken, eat_token(input, Token::Equals)),
+            (Token::Equals, ..) => (NO_TOKEN, eat_token(input, Token::Equals)),
             // var op= ...
             (token, ..) if token.is_op_assignment() => {
                 input.next().map(|(op, pos)| (op, pos)).expect(NEVER_ENDS)
@@ -2389,7 +2359,7 @@ impl Engine {
             let hash = calc_fn_hash(None, &op, 2);
             let is_valid_script_function = is_valid_function_name(&op);
             let operator_token = if is_valid_script_function {
-                Token::NonToken
+                NO_TOKEN
             } else {
                 op_token.clone()
             };
@@ -2400,8 +2370,7 @@ impl Engine {
             args.shrink_to_fit();
 
             let mut op_base = FnCallExpr {
-                #[cfg(not(feature = "no_module"))]
+                namespace: Namespace::NONE,
-                namespace: Default::default(),
                 name: state.get_interned_string(&op),
                 hashes: FnCallHashes::from_native(hash),
                 args,
@@ -2539,10 +2508,7 @@ impl Engine {
                     let (name, pos) = parse_var_name(input)?;
                     let name = state.get_interned_string(name);
 
-                    #[cfg(not(feature = "no_module"))]
+                    let ns = Namespace::NONE;
-                    let ns = crate::ast::Namespace::NONE;
-                    #[cfg(feature = "no_module")]
-                    let ns = [];
 
                     segments.push(name.clone());
                     tokens.push(state.get_interned_string(CUSTOM_SYNTAX_MARKER_IDENT));
@@ -3632,7 +3598,7 @@ impl Engine {
         }
         .into();
 
-        let mut params: FnArgsVec<_> = params.into_iter().map(|(p, ..)| p).collect();
+        let mut params: crate::FnArgsVec<_> = params.into_iter().map(|(p, ..)| p).collect();
         params.shrink_to_fit();
 
         Ok(ScriptFnDef {
@@ -3660,7 +3626,7 @@ impl Engine {
         parent: &mut ParseState,
         lib: &FnLib,
         fn_expr: Expr,
-        externals: FnArgsVec<Ident>,
+        externals: crate::FnArgsVec<Ident>,
         pos: Position,
     ) -> Expr {
         // If there are no captured variables, no need to curry
@@ -3684,8 +3650,7 @@ impl Engine {
         }));
 
         let expr = FnCallExpr {
-            #[cfg(not(feature = "no_module"))]
+            namespace: Namespace::NONE,
-            namespace: Default::default(),
             name: state.get_interned_string(crate::engine::KEYWORD_FN_PTR_CURRY),
             hashes: FnCallHashes::from_native(calc_fn_hash(
                 None,
@@ -3693,7 +3658,7 @@ impl Engine {
                 num_externals + 1,
             )),
             args,
-            op_token: Token::NonToken,
+            op_token: NO_TOKEN,
             capture_parent_scope: false,
         }
         .into_fn_call_expr(pos);
@@ -3708,7 +3673,7 @@ impl Engine {
                     let (index, _) = parent.access_var(&name, lib, pos);
                     (name, index, pos)
                 })
-                .collect::<FnArgsVec<_>>()
+                .collect::<crate::FnArgsVec<_>>()
                 .into(),
         ));
         statements.push(Stmt::Expr(expr.into()));
@@ -3779,20 +3744,20 @@ impl Engine {
         // so extract them into a list.
         #[cfg(not(feature = "no_closure"))]
         let (mut params, externals) = if let Some(ref external_vars) = state.external_vars {
-            let externals: FnArgsVec<_> = external_vars.iter().cloned().collect();
+            let externals: crate::FnArgsVec<_> = external_vars.iter().cloned().collect();
 
-            let mut params = FnArgsVec::with_capacity(params_list.len() + externals.len());
+            let mut params = crate::FnArgsVec::with_capacity(params_list.len() + externals.len());
             params.extend(externals.iter().map(|Ident { name, .. }| name.clone()));
 
             (params, externals)
         } else {
             (
-                FnArgsVec::with_capacity(params_list.len()),
+                crate::FnArgsVec::with_capacity(params_list.len()),
-                FnArgsVec::new_const(),
+                crate::FnArgsVec::new_const(),
             )
         };
         #[cfg(feature = "no_closure")]
-        let mut params = FnArgsVec::with_capacity(params_list.len());
+        let mut params = crate::FnArgsVec::with_capacity(params_list.len());
 
         params.append(&mut params_list);
 

src/tokenizer.rs

@@ -5,7 +5,7 @@ use crate::engine::{
     KEYWORD_FN_PTR_CURRY, KEYWORD_IS_DEF_VAR, KEYWORD_PRINT, KEYWORD_THIS, KEYWORD_TYPE_OF,
 };
 use crate::func::native::OnParseTokenCallback;
-use crate::{Engine, Identifier, LexError, SmartString, StaticVec, INT, UNSIGNED_INT};
+use crate::{Engine, Identifier, LexError, Position, SmartString, StaticVec, INT, UNSIGNED_INT};
 #[cfg(feature = "no_std")]
 use std::prelude::v1::*;
 use std::{
@@ -13,7 +13,6 @@ use std::{
     char, fmt,
     iter::{FusedIterator, Peekable},
     num::NonZeroUsize,
-    ops::{Add, AddAssign},
     rc::Rc,
     str::{Chars, FromStr},
 };
@@ -50,326 +49,12 @@ type LERR = LexError;
 /// Separator character for numbers.
 const NUMBER_SEPARATOR: char = '_';
 
+/// No token.
+pub const NO_TOKEN: Token = Token::NONE;
+
 /// A stream of tokens.
 pub type TokenStream<'a> = Peekable<TokenIterator<'a>>;
 
-/// A location (line number + character position) in the input script.
-///
-/// # Limitations
-///
-/// In order to keep footprint small, both line number and character position have 16-bit resolution,
-/// meaning they go up to a maximum of 65,535 lines and 65,535 characters per line.
-///
-/// Advancing beyond the maximum line length or maximum number of lines is not an error but has no effect.
-#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
-pub struct Position {
-    /// Line number: 0 = none
-    #[cfg(not(feature = "no_position"))]
-    line: u16,
-    /// Character position: 0 = BOL
-    #[cfg(not(feature = "no_position"))]
-    pos: u16,
-}
-
-impl Position {
-    /// A [`Position`] representing no position.
-    pub const NONE: Self = Self {
-        #[cfg(not(feature = "no_position"))]
-        line: 0,
-        #[cfg(not(feature = "no_position"))]
-        pos: 0,
-    };
-    /// A [`Position`] representing the first position.
-    pub const START: Self = Self {
-        #[cfg(not(feature = "no_position"))]
-        line: 1,
-        #[cfg(not(feature = "no_position"))]
-        pos: 0,
-    };
-
-    /// Create a new [`Position`].
-    ///
-    /// `line` must not be zero.
-    ///
-    /// If `position` is zero, then it is at the beginning of a line.
-    ///
-    /// # Panics
-    ///
-    /// Panics if `line` is zero.
-    #[inline]
-    #[must_use]
-    pub const fn new(line: u16, position: u16) -> Self {
-        assert!(line != 0, "line cannot be zero");
-
-        let _pos = position;
-
-        Self {
-            #[cfg(not(feature = "no_position"))]
-            line,
-            #[cfg(not(feature = "no_position"))]
-            pos: _pos,
-        }
-    }
-    /// Get the line number (1-based), or [`None`] if there is no position.
-    #[inline]
-    #[must_use]
-    pub const fn line(self) -> Option<usize> {
-        #[cfg(not(feature = "no_position"))]
-        return if self.is_none() {
-            None
-        } else {
-            Some(self.line as usize)
-        };
-
-        #[cfg(feature = "no_position")]
-        return None;
-    }
-    /// Get the character position (1-based), or [`None`] if at beginning of a line.
-    #[inline]
-    #[must_use]
-    pub const fn position(self) -> Option<usize> {
-        #[cfg(not(feature = "no_position"))]
-        return if self.is_none() || self.pos == 0 {
-            None
-        } else {
-            Some(self.pos as usize)
-        };
-
-        #[cfg(feature = "no_position")]
-        return None;
-    }
-    /// Advance by one character position.
-    #[inline]
-    pub(crate) fn advance(&mut self) {
-        #[cfg(not(feature = "no_position"))]
-        {
-            assert!(!self.is_none(), "cannot advance Position::none");
-
-            // Advance up to maximum position
-            if self.pos < u16::MAX {
-                self.pos += 1;
-            }
-        }
-    }
-    /// Go backwards by one character position.
-    ///
-    /// # Panics
-    ///
-    /// Panics if already at beginning of a line - cannot rewind to a previous line.
-    #[inline]
-    pub(crate) fn rewind(&mut self) {
-        #[cfg(not(feature = "no_position"))]
-        {
-            assert!(!self.is_none(), "cannot rewind Position::none");
-            assert!(self.pos > 0, "cannot rewind at position 0");
-            self.pos -= 1;
-        }
-    }
-    /// Advance to the next line.
-    #[inline]
-    pub(crate) fn new_line(&mut self) {
-        #[cfg(not(feature = "no_position"))]
-        {
-            assert!(!self.is_none(), "cannot advance Position::none");
-
-            // Advance up to maximum position
-            if self.line < u16::MAX {
-                self.line += 1;
-                self.pos = 0;
-            }
-        }
-    }
-    /// Is this [`Position`] at the beginning of a line?
-    #[inline]
-    #[must_use]
-    pub const fn is_beginning_of_line(self) -> bool {
-        #[cfg(not(feature = "no_position"))]
-        return self.pos == 0 && !self.is_none();
-        #[cfg(feature = "no_position")]
-        return false;
-    }
-    /// Is there no [`Position`]?
-    #[inline]
-    #[must_use]
-    pub const fn is_none(self) -> bool {
-        #[cfg(not(feature = "no_position"))]
-        return self.line == 0 && self.pos == 0;
-        #[cfg(feature = "no_position")]
-        return true;
-    }
-    /// Returns an fallback [`Position`] if it is [`NONE`][Position::NONE]?
-    #[inline]
-    #[must_use]
-    pub const fn or_else(self, pos: Self) -> Self {
-        if self.is_none() {
-            pos
-        } else {
-            self
-        }
-    }
-    /// Print this [`Position`] for debug purposes.
-    #[inline]
-    pub(crate) fn debug_print(self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if !self.is_none() {
-            write!(_f, " @ {:?}", self)?;
-        }
-        Ok(())
-    }
-}
-
-impl Default for Position {
-    #[inline(always)]
-    #[must_use]
-    fn default() -> Self {
-        Self::START
-    }
-}
-
-impl fmt::Display for Position {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.is_none() {
-            write!(f, "none")?;
-        } else {
-            #[cfg(not(feature = "no_position"))]
-            write!(f, "line {}, position {}", self.line, self.pos)?;
-            #[cfg(feature = "no_position")]
-            unreachable!("no position");
-        }
-
-        Ok(())
-    }
-}
-
-impl fmt::Debug for Position {
-    #[cold]
-    #[inline(never)]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.is_none() {
-            f.write_str("none")
-        } else {
-            #[cfg(not(feature = "no_position"))]
-            if self.is_beginning_of_line() {
-                write!(f, "{}", self.line)
-            } else {
-                write!(f, "{}:{}", self.line, self.pos)
-            }
-
-            #[cfg(feature = "no_position")]
-            unreachable!("no position");
-        }
-    }
-}
-
-impl Add for Position {
-    type Output = Self;
-
-    fn add(self, rhs: Self) -> Self::Output {
-        if rhs.is_none() {
-            self
-        } else {
-            #[cfg(not(feature = "no_position"))]
-            return Self {
-                line: self.line + rhs.line - 1,
-                pos: if rhs.is_beginning_of_line() {
-                    self.pos
-                } else {
-                    self.pos + rhs.pos - 1
-                },
-            };
-            #[cfg(feature = "no_position")]
-            unreachable!("no position");
-        }
-    }
-}
-
-impl AddAssign for Position {
-    fn add_assign(&mut self, rhs: Self) {
-        *self = *self + rhs;
-    }
-}
-
-/// _(internals)_ A span consisting of a starting and an ending [positions][Position].
-/// Exported under the `internals` feature only.
-#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
-pub struct Span {
-    /// Starting [position][Position].
-    start: Position,
-    /// Ending [position][Position].
-    end: Position,
-}
-
-impl Default for Span {
-    #[inline(always)]
-    #[must_use]
-    fn default() -> Self {
-        Self::NONE
-    }
-}
-
-impl Span {
-    /// Empty [`Span`].
-    pub const NONE: Self = Self::new(Position::NONE, Position::NONE);
-
-    /// Create a new [`Span`].
-    #[inline(always)]
-    #[must_use]
-    pub const fn new(start: Position, end: Position) -> Self {
-        Self { start, end }
-    }
-    /// Is this [`Span`] non-existent?
-    #[inline]
-    #[must_use]
-    pub const fn is_none(&self) -> bool {
-        self.start.is_none() && self.end.is_none()
-    }
-    /// Get the [`Span`]'s starting [position][Position].
-    #[inline(always)]
-    #[must_use]
-    pub const fn start(&self) -> Position {
-        self.start
-    }
-    /// Get the [`Span`]'s ending [position][Position].
-    #[inline(always)]
-    #[must_use]
-    pub const fn end(&self) -> Position {
-        self.end
-    }
-}
-
-impl fmt::Display for Span {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let _f = f;
-
-        #[cfg(not(feature = "no_position"))]
-        match (self.start(), self.end()) {
-            (Position::NONE, Position::NONE) => write!(_f, "{:?}", Position::NONE),
-            (Position::NONE, end) => write!(_f, "..{:?}", end),
-            (start, Position::NONE) => write!(_f, "{:?}", start),
-            (start, end) if start.line() != end.line() => {
-                write!(_f, "{:?}-{:?}", start, end)
-            }
-            (start, end) => write!(
-                _f,
-                "{}:{}-{}",
-                start.line().unwrap(),
-                start.position().unwrap_or(0),
-                end.position().unwrap_or(0)
-            ),
-        }
-
-        #[cfg(feature = "no_position")]
-        Ok(())
-    }
-}
-
-impl fmt::Debug for Span {
-    #[cold]
-    #[inline(never)]
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(self, f)
-    }
-}
-
 /// _(internals)_ A Rhai language token.
 /// Exported under the `internals` feature only.
 #[derive(Debug, PartialEq, Clone, Hash)]
@@ -587,7 +272,7 @@ pub enum Token {
     /// Used as a placeholder for the end of input.
     EOF,
     /// Placeholder to indicate the lack of a token.
-    NonToken,
+    NONE,
 }
 
 impl fmt::Display for Token {
@@ -613,7 +298,7 @@ impl fmt::Display for Token {
             Comment(s) => f.write_str(s),
 
             EOF => f.write_str("{EOF}"),
-            NonToken => f.write_str("{NONE}"),
+            NONE => f.write_str("{NONE}"),
 
             token => f.write_str(token.literal_syntax()),
         }
@@ -642,7 +327,7 @@ impl Token {
             Custom(..) => false,
             LexError(..) | Comment(..) => false,
 
-            EOF | NonToken => false,
+            EOF | NONE => false,
 
             _ => true,
         }

src/types/mod.rs

@@ -9,6 +9,8 @@ pub mod fn_ptr;
 pub mod immutable_string;
 pub mod interner;
 pub mod parse_error;
+pub mod position;
+pub mod position_none;
 pub mod restore;
 pub mod scope;
 pub mod variant;
@@ -25,6 +27,12 @@ pub use fn_ptr::FnPtr;
 pub use immutable_string::ImmutableString;
 pub use interner::StringsInterner;
 pub use parse_error::{LexError, ParseError, ParseErrorType};
+
+#[cfg(not(feature = "no_position"))]
+pub use position::{Position, Span};
+#[cfg(feature = "no_position")]
+pub use position_none::{Position, Span};
+
 pub use restore::RestoreOnDrop;
 pub use scope::Scope;
 pub use variant::Variant;

src/types/position.rs

@@ -0,0 +1,269 @@
+#![cfg(not(feature = "no_position"))]
+
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+use std::{
+    fmt,
+    ops::{Add, AddAssign},
+};
+
+/// A location (line number + character position) in the input script.
+///
+/// # Limitations
+///
+/// In order to keep footprint small, both line number and character position have 16-bit resolution,
+/// meaning they go up to a maximum of 65,535 lines and 65,535 characters per line.
+///
+/// Advancing beyond the maximum line length or maximum number of lines is not an error but has no effect.
+#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
+pub struct Position {
+    /// Line number: 0 = none
+    line: u16,
+    /// Character position: 0 = BOL
+    pos: u16,
+}
+
+impl Position {
+    /// A [`Position`] representing no position.
+    pub const NONE: Self = Self { line: 0, pos: 0 };
+    /// A [`Position`] representing the first position.
+    pub const START: Self = Self { line: 1, pos: 0 };
+
+    /// Create a new [`Position`].
+    ///
+    /// `line` must not be zero.
+    ///
+    /// If `position` is zero, then it is at the beginning of a line.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `line` is zero.
+    #[inline]
+    #[must_use]
+    pub const fn new(line: u16, position: u16) -> Self {
+        assert!(line != 0, "line cannot be zero");
+
+        let _pos = position;
+
+        Self { line, pos: _pos }
+    }
+    /// Get the line number (1-based), or [`None`] if there is no position.
+    #[inline]
+    #[must_use]
+    pub const fn line(self) -> Option<usize> {
+        if self.is_none() {
+            None
+        } else {
+            Some(self.line as usize)
+        }
+    }
+    /// Get the character position (1-based), or [`None`] if at beginning of a line.
+    #[inline]
+    #[must_use]
+    pub const fn position(self) -> Option<usize> {
+        if self.is_none() || self.pos == 0 {
+            None
+        } else {
+            Some(self.pos as usize)
+        }
+    }
+    /// Advance by one character position.
+    #[inline]
+    pub(crate) fn advance(&mut self) {
+        assert!(!self.is_none(), "cannot advance Position::none");
+
+        // Advance up to maximum position
+        if self.pos < u16::MAX {
+            self.pos += 1;
+        }
+    }
+    /// Go backwards by one character position.
+    ///
+    /// # Panics
+    ///
+    /// Panics if already at beginning of a line - cannot rewind to a previous line.
+    #[inline]
+    pub(crate) fn rewind(&mut self) {
+        assert!(!self.is_none(), "cannot rewind Position::none");
+        assert!(self.pos > 0, "cannot rewind at position 0");
+        self.pos -= 1;
+    }
+    /// Advance to the next line.
+    #[inline]
+    pub(crate) fn new_line(&mut self) {
+        assert!(!self.is_none(), "cannot advance Position::none");
+
+        // Advance up to maximum position
+        if self.line < u16::MAX {
+            self.line += 1;
+            self.pos = 0;
+        }
+    }
+    /// Is this [`Position`] at the beginning of a line?
+    #[inline]
+    #[must_use]
+    pub const fn is_beginning_of_line(self) -> bool {
+        self.pos == 0 && !self.is_none()
+    }
+    /// Is there no [`Position`]?
+    #[inline]
+    #[must_use]
+    pub const fn is_none(self) -> bool {
+        self.line == 0 && self.pos == 0
+    }
+    /// Returns an fallback [`Position`] if it is [`NONE`][Position::NONE]?
+    #[inline]
+    #[must_use]
+    pub const fn or_else(self, pos: Self) -> Self {
+        if self.is_none() {
+            pos
+        } else {
+            self
+        }
+    }
+    /// Print this [`Position`] for debug purposes.
+    #[inline]
+    pub(crate) fn debug_print(self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if !self.is_none() {
+            write!(_f, " @ {:?}", self)?;
+        }
+        Ok(())
+    }
+}
+
+impl Default for Position {
+    #[inline(always)]
+    #[must_use]
+    fn default() -> Self {
+        Self::START
+    }
+}
+
+impl fmt::Display for Position {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.is_none() {
+            write!(f, "none")
+        } else {
+            write!(f, "line {}, position {}", self.line, self.pos)
+        }
+    }
+}
+
+impl fmt::Debug for Position {
+    #[cold]
+    #[inline(never)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.is_none() {
+            f.write_str("none")
+        } else {
+            if self.is_beginning_of_line() {
+                write!(f, "{}", self.line)
+            } else {
+                write!(f, "{}:{}", self.line, self.pos)
+            }
+        }
+    }
+}
+
+impl Add for Position {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        if rhs.is_none() {
+            self
+        } else {
+            Self {
+                line: self.line + rhs.line - 1,
+                pos: if rhs.is_beginning_of_line() {
+                    self.pos
+                } else {
+                    self.pos + rhs.pos - 1
+                },
+            }
+        }
+    }
+}
+
+impl AddAssign for Position {
+    fn add_assign(&mut self, rhs: Self) {
+        *self = *self + rhs;
+    }
+}
+
+/// _(internals)_ A span consisting of a starting and an ending [positions][Position].
+/// Exported under the `internals` feature only.
+#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
+pub struct Span {
+    /// Starting [position][Position].
+    start: Position,
+    /// Ending [position][Position].
+    end: Position,
+}
+
+impl Default for Span {
+    #[inline(always)]
+    #[must_use]
+    fn default() -> Self {
+        Self::NONE
+    }
+}
+
+impl Span {
+    /// Empty [`Span`].
+    pub const NONE: Self = Self::new(Position::NONE, Position::NONE);
+
+    /// Create a new [`Span`].
+    #[inline(always)]
+    #[must_use]
+    pub const fn new(start: Position, end: Position) -> Self {
+        Self { start, end }
+    }
+    /// Is this [`Span`] non-existent?
+    #[inline]
+    #[must_use]
+    pub const fn is_none(&self) -> bool {
+        self.start.is_none() && self.end.is_none()
+    }
+    /// Get the [`Span`]'s starting [position][Position].
+    #[inline(always)]
+    #[must_use]
+    pub const fn start(&self) -> Position {
+        self.start
+    }
+    /// Get the [`Span`]'s ending [position][Position].
+    #[inline(always)]
+    #[must_use]
+    pub const fn end(&self) -> Position {
+        self.end
+    }
+}
+
+impl fmt::Display for Span {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let _f = f;
+
+        match (self.start(), self.end()) {
+            (Position::NONE, Position::NONE) => write!(_f, "{:?}", Position::NONE),
+            (Position::NONE, end) => write!(_f, "..{:?}", end),
+            (start, Position::NONE) => write!(_f, "{:?}", start),
+            (start, end) if start.line() != end.line() => {
+                write!(_f, "{:?}-{:?}", start, end)
+            }
+            (start, end) => write!(
+                _f,
+                "{}:{}-{}",
+                start.line().unwrap(),
+                start.position().unwrap_or(0),
+                end.position().unwrap_or(0)
+            ),
+        }
+    }
+}
+
+impl fmt::Debug for Span {
+    #[cold]
+    #[inline(never)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self, f)
+    }
+}

src/types/position_none.rs

@@ -0,0 +1,165 @@
+#![cfg(feature = "no_position")]
+#![allow(unused_variables)]
+
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+use std::{
+    fmt,
+    ops::{Add, AddAssign},
+};
+
+/// A location (line number + character position) in the input script.
+#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
+pub struct Position;
+
+impl Position {
+    /// A [`Position`] representing no position.
+    pub const NONE: Self = Self;
+    /// A [`Position`] representing the first position.
+    pub const START: Self = Self;
+
+    /// Create a new [`Position`].
+    #[inline(always)]
+    #[must_use]
+    pub const fn new(line: u16, position: u16) -> Self {
+        Self
+    }
+    /// Get the line number (1-based), or [`None`] if there is no position.
+    #[inline(always)]
+    #[must_use]
+    pub const fn line(self) -> Option<usize> {
+        None
+    }
+    /// Get the character position (1-based), or [`None`] if at beginning of a line.
+    #[inline(always)]
+    #[must_use]
+    pub const fn position(self) -> Option<usize> {
+        None
+    }
+    /// Advance by one character position.
+    #[inline(always)]
+    pub(crate) fn advance(&mut self) {}
+    /// Go backwards by one character position.
+    #[inline(always)]
+    pub(crate) fn rewind(&mut self) {}
+    /// Advance to the next line.
+    #[inline(always)]
+    pub(crate) fn new_line(&mut self) {}
+    /// Is this [`Position`] at the beginning of a line?
+    #[inline(always)]
+    #[must_use]
+    pub const fn is_beginning_of_line(self) -> bool {
+        false
+    }
+    /// Is there no [`Position`]?
+    #[inline(always)]
+    #[must_use]
+    pub const fn is_none(self) -> bool {
+        true
+    }
+    /// Returns an fallback [`Position`] if it is [`NONE`][Position::NONE]?
+    #[inline(always)]
+    #[must_use]
+    pub const fn or_else(self, pos: Self) -> Self {
+        pos
+    }
+    /// Print this [`Position`] for debug purposes.
+    #[inline(always)]
+    pub(crate) fn debug_print(self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        Ok(())
+    }
+}
+
+impl Default for Position {
+    #[inline(always)]
+    #[must_use]
+    fn default() -> Self {
+        Self
+    }
+}
+
+impl fmt::Display for Position {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "none")
+    }
+}
+
+impl fmt::Debug for Position {
+    #[cold]
+    #[inline(always)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("none")
+    }
+}
+
+impl Add for Position {
+    type Output = Self;
+
+    #[inline(always)]
+    fn add(self, rhs: Self) -> Self::Output {
+        Self
+    }
+}
+
+impl AddAssign for Position {
+    #[inline(always)]
+    fn add_assign(&mut self, rhs: Self) {}
+}
+
+/// _(internals)_ A span consisting of a starting and an ending [positions][Position].
+/// Exported under the `internals` feature only.
+#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Clone, Copy)]
+pub struct Span;
+
+impl Default for Span {
+    #[inline(always)]
+    #[must_use]
+    fn default() -> Self {
+        Self
+    }
+}
+
+impl Span {
+    /// Empty [`Span`].
+    pub const NONE: Self = Self;
+
+    /// Create a new [`Span`].
+    #[inline(always)]
+    #[must_use]
+    pub const fn new(start: Position, end: Position) -> Self {
+        Self
+    }
+    /// Is this [`Span`] non-existent?
+    #[inline(always)]
+    #[must_use]
+    pub const fn is_none(&self) -> bool {
+        true
+    }
+    /// Get the [`Span`]'s starting [position][Position].
+    #[inline(always)]
+    #[must_use]
+    pub const fn start(&self) -> Position {
+        Position
+    }
+    /// Get the [`Span`]'s ending [position][Position].
+    #[inline(always)]
+    #[must_use]
+    pub const fn end(&self) -> Position {
+        Position
+    }
+}
+
+impl fmt::Display for Span {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let f = f;
+        write!(f, "{:?}", Position)
+    }
+}
+
+impl fmt::Debug for Span {
+    #[cold]
+    #[inline(always)]
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(self, f)
+    }
+}