Make module_resolver optional and remove NullModuleResolver.

Cargo.toml

@@ -20,7 +20,7 @@ categories = [ "no-std", "embedded", "parser-implementations" ]
 num-traits = { version = "0.2.11", default-features = false }
 
 [features]
-#default = ["no_stdlib", "no_function", "no_index", "no_object", "no_float", "only_i32", "unchecked", "no_optimize", "sync"]
+#default = ["no_stdlib", "no_function", "no_index", "no_object", "no_module", "no_float", "only_i32", "unchecked", "no_optimize", "sync"]
 default = []
 unchecked = []      # unchecked arithmetic
 no_index = []       # no arrays and indexing

README.md

@@ -2118,13 +2118,16 @@ Built-in module resolvers are grouped under the `rhai::module_resolvers` module
 | ---------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `FileModuleResolver`   | The default module resolution service, not available under the [`no_std`] feature. Loads a script file (based off the current directory) with `.rhai` extension.<br/>The base directory can be changed via the `FileModuleResolver::new_with_path()` constructor function. |
 | `StaticModuleResolver` | Loads modules that are statically added. This can be used when the [`no_std`] feature is turned on.                                                                                                                                                                        |
-| `NullModuleResolver`   | The default module resolution service under the [`no_std`] feature. Always returns an `EvalAltResult::ErrorModuleNotFound` error.                                                                                                                                          |
 
 An [`Engine`]'s module resolver is set via a call to `set_module_resolver`:
 
 ```rust
-// Use the 'NullModuleResolver'
+// Use the 'StaticModuleResolver'
-engine.set_module_resolver(rhai::module_resolvers::NullModuleResolver::new());
+let resolver = rhai::module_resolvers::StaticModuleResolver::new();
+engine.set_module_resolver(Some(resolver));
+
+// Effectively disable 'import' statements by setting module resolver to 'None'
+engine.set_module_resolver(None);
 ```
 
 Script optimization

examples/repl.rs

@@ -1,4 +1,4 @@
-use rhai::{Dynamic, Engine, EvalAltResult, Map, Scope, AST, INT};
+use rhai::{Dynamic, Engine, EvalAltResult, Scope, AST, INT};
 
 #[cfg(not(feature = "no_optimize"))]
 use rhai::OptimizationLevel;
@@ -163,6 +163,7 @@ fn main() {
         }
 
         // Throw away all the statements, leaving only the functions
+        #[cfg(not(feature = "no_function"))]
         main_ast.retain_functions();
     }
 }

src/engine.rs

@@ -262,7 +262,7 @@ pub struct Engine {
     pub(crate) type_iterators: HashMap<TypeId, Box<IteratorFn>>,
 
     /// A module resolution service.
-    pub(crate) module_resolver: Box<dyn ModuleResolver>,
+    pub(crate) module_resolver: Option<Box<dyn ModuleResolver>>,
 
     /// A hashmap mapping type names to pretty-print names.
     pub(crate) type_names: HashMap<String, String>,
@@ -300,9 +300,9 @@ impl Default for Engine {
 
             #[cfg(not(feature = "no_module"))]
             #[cfg(not(feature = "no_std"))]
-            module_resolver: Box::new(resolvers::FileModuleResolver::new()),
+            module_resolver: Some(Box::new(resolvers::FileModuleResolver::new())),
             #[cfg(any(feature = "no_std", feature = "no_module"))]
-            module_resolver: Box::new(resolvers::NullModuleResolver::new()),
+            module_resolver: None,
 
             type_names: Default::default(),
 
@@ -438,13 +438,7 @@ impl Engine {
             packages: Default::default(),
             functions: HashMap::with_capacity(FUNCTIONS_COUNT / 2),
             type_iterators: Default::default(),
-
+            module_resolver: None,
-            #[cfg(not(feature = "no_module"))]
-            #[cfg(not(feature = "no_std"))]
-            module_resolver: Box::new(resolvers::FileModuleResolver::new()),
-            #[cfg(any(feature = "no_std", feature = "no_module"))]
-            module_resolver: Box::new(resolvers::NullModuleResolver::new()),
-
             type_names: Default::default(),
             print: Box::new(|_| {}),
             debug: Box::new(|_| {}),
@@ -491,8 +485,8 @@ impl Engine {
     ///
     /// Not available under the `no_module` feature.
     #[cfg(not(feature = "no_module"))]
-    pub fn set_module_resolver(&mut self, resolver: impl ModuleResolver + 'static) {
+    pub fn set_module_resolver(&mut self, resolver: Option<impl ModuleResolver + 'static>) {
-        self.module_resolver = Box::new(resolver);
+        self.module_resolver = resolver.map(|f| Box::new(f) as Box<dyn ModuleResolver>);
     }
 
     /// Universal method for calling functions either registered with the `Engine` or written in Rhai.
@@ -1264,8 +1258,7 @@ impl Engine {
                         let hash = calc_fn_hash(fn_name, args.iter().map(|a| a.type_id()));
 
                         match module.get_qualified_fn(fn_name, hash, modules, *pos) {
-                            Ok(func) => func(&mut args, *pos)
+                            Ok(func) => func(&mut args, *pos),
-                                .map_err(|err| EvalAltResult::set_position(err, *pos)),
                             Err(_) if def_val.is_some() => Ok(def_val.as_deref().unwrap().clone()),
                             Err(err) => Err(err),
                         }
@@ -1530,15 +1523,19 @@ impl Engine {
                     .eval_expr(scope, state, fn_lib, expr, level)?
                     .try_cast::<String>()
                 {
-                    let module = self
+                    if let Some(resolver) = self.module_resolver.as_ref() {
-                        .module_resolver
+                        let module = resolver.resolve(self, &path, expr.position())?;
-                        .resolve(self, &path)
-                        .map_err(|err| EvalAltResult::set_position(err, expr.position()))?;
 
-                    // TODO - avoid copying module name in inner block?
+                        // TODO - avoid copying module name in inner block?
-                    let mod_name = name.as_ref().clone();
+                        let mod_name = name.as_ref().clone();
-                    scope.push_module(mod_name, module);
+                        scope.push_module(mod_name, module);
-                    Ok(Default::default())
+                        Ok(Default::default())
+                    } else {
+                        Err(Box::new(EvalAltResult::ErrorModuleNotFound(
+                            path,
+                            expr.position(),
+                        )))
+                    }
                 } else {
                     Err(Box::new(EvalAltResult::ErrorImportExpr(expr.position())))
                 }

src/module.rs

@@ -5,21 +5,35 @@ use crate::calc_fn_hash;
 use crate::engine::{Engine, FnAny, FnCallArgs, FunctionsLib};
 use crate::parser::FnDef;
 use crate::result::EvalAltResult;
-use crate::scope::{EntryType as ScopeEntryType, Scope};
+use crate::scope::{Entry as ScopeEntry, EntryType as ScopeEntryType, Scope};
 use crate::token::Position;
 use crate::token::Token;
 use crate::utils::StaticVec;
 
 use crate::stdlib::{
-    any::TypeId, collections::HashMap, fmt, iter::empty, mem, rc::Rc, string::String, sync::Arc,
+    any::TypeId,
+    collections::HashMap,
+    fmt, mem,
+    ops::{Deref, DerefMut},
+    rc::Rc,
+    string::String,
+    sync::Arc,
 };
 
 /// A trait that encapsulates a module resolution service.
 pub trait ModuleResolver {
     /// Resolve a module based on a path string.
-    fn resolve(&self, engine: &Engine, path: &str) -> Result<Module, Box<EvalAltResult>>;
+    fn resolve(
+        &self,
+        engine: &Engine,
+        path: &str,
+        pos: Position,
+    ) -> Result<Module, Box<EvalAltResult>>;
 }
 
+/// Return type of module-level Rust function.
+type FuncReturn<T> = Result<T, Box<EvalAltResult>>;
+
 /// An imported module, which may contain variables, sub-modules,
 /// external Rust functions, and script-defined functions.
 ///
@@ -158,7 +172,6 @@ impl Module {
 
         #[cfg(not(feature = "sync"))]
         self.functions.insert(hash, Rc::new(func));
-
         #[cfg(feature = "sync")]
         self.functions.insert(hash, Arc::new(func));
 
@@ -171,14 +184,16 @@ impl Module {
     pub fn set_fn_0<T: Into<Dynamic>>(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn() -> Result<T, Box<EvalAltResult>> + 'static,
+        #[cfg(not(feature = "sync"))] func: impl Fn() -> FuncReturn<T> + 'static,
-        #[cfg(feature = "sync")] func: impl Fn() -> Result<T, Box<EvalAltResult>>
+        #[cfg(feature = "sync")] func: impl Fn() -> FuncReturn<T> + Send + Sync + 'static,
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |_: &mut FnCallArgs, _: Position| func().map(|v| v.into());
+        let f = move |_: &mut FnCallArgs, pos| {
-        self.set_fn(fn_name, &[], Box::new(f))
+            func()
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
+        };
+        let arg_types = &[];
+        self.set_fn(fn_name, arg_types, Box::new(f))
     }
 
     /// Set a Rust function taking one parameter into the module, returning a hash key.
@@ -187,16 +202,16 @@ impl Module {
     pub fn set_fn_1<A: Variant + Clone, T: Into<Dynamic>>(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn(A) -> Result<T, Box<EvalAltResult>> + 'static,
+        #[cfg(not(feature = "sync"))] func: impl Fn(A) -> FuncReturn<T> + 'static,
-        #[cfg(feature = "sync")] func: impl Fn(A) -> Result<T, Box<EvalAltResult>>
+        #[cfg(feature = "sync")] func: impl Fn(A) -> FuncReturn<T> + Send + Sync + 'static,
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |args: &mut FnCallArgs, _: Position| {
+        let f = move |args: &mut FnCallArgs, pos| {
-            func(mem::take(args[0]).cast::<A>()).map(|v| v.into())
+            func(mem::take(args[0]).cast::<A>())
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
         };
-        self.set_fn(fn_name, &[TypeId::of::<A>()], Box::new(f))
+        let arg_types = &[TypeId::of::<A>()];
+        self.set_fn(fn_name, arg_types, Box::new(f))
     }
 
     /// Set a Rust function taking one mutable parameter into the module, returning a hash key.
@@ -205,16 +220,16 @@ impl Module {
     pub fn set_fn_1_mut<A: Variant + Clone, T: Into<Dynamic>>(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A) -> Result<T, Box<EvalAltResult>> + 'static,
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A) -> FuncReturn<T> + 'static,
-        #[cfg(feature = "sync")] func: impl Fn(&mut A) -> Result<T, Box<EvalAltResult>>
+        #[cfg(feature = "sync")] func: impl Fn(&mut A) -> FuncReturn<T> + Send + Sync + 'static,
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |args: &mut FnCallArgs, _: Position| {
+        let f = move |args: &mut FnCallArgs, pos| {
-            func(args[0].downcast_mut::<A>().unwrap()).map(|v| v.into())
+            func(args[0].downcast_mut::<A>().unwrap())
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
         };
-        self.set_fn(fn_name, &[TypeId::of::<A>()], Box::new(f))
+        let arg_types = &[TypeId::of::<A>()];
+        self.set_fn(fn_name, arg_types, Box::new(f))
     }
 
     /// Set a Rust function taking two parameters into the module, returning a hash key.
@@ -223,23 +238,19 @@ impl Module {
     pub fn set_fn_2<A: Variant + Clone, B: Variant + Clone, T: Into<Dynamic>>(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn(A, B) -> Result<T, Box<EvalAltResult>> + 'static,
+        #[cfg(not(feature = "sync"))] func: impl Fn(A, B) -> FuncReturn<T> + 'static,
-        #[cfg(feature = "sync")] func: impl Fn(A, B) -> Result<T, Box<EvalAltResult>>
+        #[cfg(feature = "sync")] func: impl Fn(A, B) -> FuncReturn<T> + Send + Sync + 'static,
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |args: &mut FnCallArgs, _: Position| {
+        let f = move |args: &mut FnCallArgs, pos| {
             let a = mem::take(args[0]).cast::<A>();
             let b = mem::take(args[1]).cast::<B>();
 
-            func(a, b).map(|v| v.into())
+            func(a, b)
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
         };
-        self.set_fn(
+        let arg_types = &[TypeId::of::<A>(), TypeId::of::<B>()];
-            fn_name,
+        self.set_fn(fn_name, arg_types, Box::new(f))
-            &[TypeId::of::<A>(), TypeId::of::<B>()],
-            Box::new(f),
-        )
     }
 
     /// Set a Rust function taking two parameters (the first one mutable) into the module,
@@ -249,24 +260,19 @@ impl Module {
     pub fn set_fn_2_mut<A: Variant + Clone, B: Variant + Clone, T: Into<Dynamic>>(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B) -> Result<T, Box<EvalAltResult>>
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B) -> FuncReturn<T> + 'static,
-            + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(&mut A, B) -> FuncReturn<T> + Send + Sync + 'static,
-        #[cfg(feature = "sync")] func: impl Fn(&mut A, B) -> Result<T, Box<EvalAltResult>>
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |args: &mut FnCallArgs, _: Position| {
+        let f = move |args: &mut FnCallArgs, pos| {
             let b = mem::take(args[1]).cast::<B>();
             let a = args[0].downcast_mut::<A>().unwrap();
 
-            func(a, b).map(|v| v.into())
+            func(a, b)
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
         };
-        self.set_fn(
+        let arg_types = &[TypeId::of::<A>(), TypeId::of::<B>()];
-            fn_name,
+        self.set_fn(fn_name, arg_types, Box::new(f))
-            &[TypeId::of::<A>(), TypeId::of::<B>()],
-            Box::new(f),
-        )
     }
 
     /// Set a Rust function taking three parameters into the module, returning a hash key.
@@ -280,24 +286,20 @@ impl Module {
     >(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn(A, B, C) -> Result<T, Box<EvalAltResult>> + 'static,
+        #[cfg(not(feature = "sync"))] func: impl Fn(A, B, C) -> FuncReturn<T> + 'static,
-        #[cfg(feature = "sync")] func: impl Fn(A, B, C) -> Result<T, Box<EvalAltResult>>
+        #[cfg(feature = "sync")] func: impl Fn(A, B, C) -> FuncReturn<T> + Send + Sync + 'static,
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |args: &mut FnCallArgs, _: Position| {
+        let f = move |args: &mut FnCallArgs, pos| {
             let a = mem::take(args[0]).cast::<A>();
             let b = mem::take(args[1]).cast::<B>();
             let c = mem::take(args[2]).cast::<C>();
 
-            func(a, b, c).map(|v| v.into())
+            func(a, b, c)
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
         };
-        self.set_fn(
+        let arg_types = &[TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()];
-            fn_name,
+        self.set_fn(fn_name, arg_types, Box::new(f))
-            &[TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()],
-            Box::new(f),
-        )
     }
 
     /// Set a Rust function taking three parameters (the first one mutable) into the module,
@@ -312,25 +314,20 @@ impl Module {
     >(
         &mut self,
         fn_name: &str,
-        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B, C) -> Result<T, Box<EvalAltResult>>
+        #[cfg(not(feature = "sync"))] func: impl Fn(&mut A, B, C) -> FuncReturn<T> + 'static,
-            + 'static,
+        #[cfg(feature = "sync")] func: impl Fn(&mut A, B, C) -> FuncReturn<T> + Send + Sync + 'static,
-        #[cfg(feature = "sync")] func: impl Fn(&mut A, B, C) -> Result<T, Box<EvalAltResult>>
-            + Send
-            + Sync
-            + 'static,
     ) -> u64 {
-        let f = move |args: &mut FnCallArgs, _: Position| {
+        let f = move |args: &mut FnCallArgs, pos| {
             let b = mem::take(args[1]).cast::<B>();
             let c = mem::take(args[2]).cast::<C>();
             let a = args[0].downcast_mut::<A>().unwrap();
 
-            func(a, b, c).map(|v| v.into())
+            func(a, b, c)
+                .map(|v| v.into())
+                .map_err(|err| EvalAltResult::set_position(err, pos))
         };
-        self.set_fn(
+        let arg_types = &[TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()];
-            fn_name,
+        self.set_fn(fn_name, arg_types, Box::new(f))
-            &[TypeId::of::<A>(), TypeId::of::<B>(), TypeId::of::<C>()],
-            Box::new(f),
-        )
     }
 
     /// Get a Rust function.
@@ -388,22 +385,40 @@ impl Module {
     }
 }
 
+/// Re-export module resolvers.
 pub mod resolvers {
-    use super::*;
+    pub use super::file::FileModuleResolver;
+    pub use super::stat::StaticModuleResolver;
+}
 
-    #[cfg(not(feature = "no_std"))]
+/// Script file-based module resolver.
+#[cfg(not(feature = "no_std"))]
+mod file {
+    use super::*;
     use crate::stdlib::path::PathBuf;
 
-    /// A module resolution service that loads module script files (assumed `.rhai` extension).
+    /// A module resolution service that loads module script files from the file system.
-    #[cfg(not(feature = "no_std"))]
+    ///
-    #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
+    /// The `new_with_path` and `new_with_path_and_extension` constructor functions
-    pub struct FileModuleResolver(PathBuf);
+    /// allow specification of a base directory with module path used as a relative path offset
+    /// to the base directory. The script file is then forced to be in a specified extension
+    /// (default `.rhai`).
+    #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Default)]
+    pub struct FileModuleResolver {
+        path: PathBuf,
+        extension: String,
+    }
 
-    #[cfg(not(feature = "no_std"))]
     impl FileModuleResolver {
         /// Create a new `FileModuleResolver` with a specific base path.
         pub fn new_with_path(path: PathBuf) -> Self {
-            Self(path)
+            Self::new_with_path_and_extension(path, "rhai".to_string())
+        }
+        /// Create a new `FileModuleResolver` with a specific base path and file extension.
+        ///
+        /// The default extension is `.rhai`.
+        pub fn new_with_path_and_extension(path: PathBuf, extension: String) -> Self {
+            Self { path, extension }
         }
         /// Create a new `FileModuleResolver` with the current directory as base path.
         pub fn new() -> Self {
@@ -411,54 +426,63 @@ pub mod resolvers {
         }
     }
 
-    #[cfg(not(feature = "no_std"))]
-    impl Default for FileModuleResolver {
-        fn default() -> Self {
-            Self::new_with_path(".".into())
-        }
-    }
-
-    #[cfg(not(feature = "no_std"))]
     impl ModuleResolver for FileModuleResolver {
-        fn resolve(&self, engine: &Engine, path: &str) -> Result<Module, Box<EvalAltResult>> {
+        fn resolve(
-            // Load the script file (attaching `.rhai`)
+            &self,
-            let mut file_path = self.0.clone();
+            engine: &Engine,
+            path: &str,
+            pos: Position,
+        ) -> Result<Module, Box<EvalAltResult>> {
+            // Construct the script file path
+            let mut file_path = self.path.clone();
             file_path.push(path);
-            file_path.set_extension("rhai");
+            file_path.set_extension(&self.extension); // Force extension
 
             // Compile it
-            let ast = engine.compile_file(file_path)?;
+            let ast = engine
+                .compile_file(file_path)
+                .map_err(|err| EvalAltResult::set_position(err, pos))?;
 
             // Use new scope
             let mut scope = Scope::new();
 
             // Run the script
-            engine.eval_ast_with_scope_raw(&mut scope, &ast)?;
+            engine
+                .eval_ast_with_scope_raw(&mut scope, &ast)
+                .map_err(|err| EvalAltResult::set_position(err, pos))?;
 
             // Create new module
             let mut module = Module::new();
 
-            // Variables left in the scope become module variables
+            scope.into_iter().for_each(
-            for entry in scope.into_iter() {
+                |ScopeEntry {
-                match entry.typ {
+                     name, typ, value, ..
-                    ScopeEntryType::Normal | ScopeEntryType::Constant => {
+                 }| {
-                        module
+                    match typ {
-                            .variables
+                        // Variables left in the scope become module variables
-                            .insert(entry.name.into_owned(), entry.value);
+                        ScopeEntryType::Normal | ScopeEntryType::Constant => {
+                            module.variables.insert(name.into_owned(), value);
+                        }
+                        // Modules left in the scope become sub-modules
+                        ScopeEntryType::Module => {
+                            module
+                                .modules
+                                .insert(name.into_owned(), value.cast::<Module>());
+                        }
                     }
-                    ScopeEntryType::Module => {
+                },
-                        module
+            );
-                            .modules
-                            .insert(entry.name.into_owned(), entry.value.cast::<Module>());
-                    }
-                }
-            }
 
-            module.fn_lib = FunctionsLib::new().merge(ast.fn_lib());
+            module.fn_lib = module.fn_lib.merge(ast.fn_lib());
 
             Ok(module)
         }
     }
+}
+
+/// Static module resolver.
+mod stat {
+    use super::*;
 
     /// A module resolution service that serves modules added into it.
     #[derive(Debug, Clone, Default)]
@@ -469,40 +493,33 @@ pub mod resolvers {
         pub fn new() -> Self {
             Default::default()
         }
-        /// Add a named module.
+    }
-        pub fn add_module(&mut self, name: &str, module: Module) {
+
-            self.0.insert(name.to_string(), module);
+    impl Deref for StaticModuleResolver {
+        type Target = HashMap<String, Module>;
+
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+
+    impl DerefMut for StaticModuleResolver {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.0
         }
     }
 
     impl ModuleResolver for StaticModuleResolver {
-        fn resolve(&self, _: &Engine, path: &str) -> Result<Module, Box<EvalAltResult>> {
+        fn resolve(
-            self.0.get(path).cloned().ok_or_else(|| {
+            &self,
-                Box::new(EvalAltResult::ErrorModuleNotFound(
+            _: &Engine,
-                    path.to_string(),
+            path: &str,
-                    Position::none(),
+            pos: Position,
-                ))
+        ) -> Result<Module, Box<EvalAltResult>> {
-            })
+            self.0
-        }
+                .get(path)
-    }
+                .cloned()
-
+                .ok_or_else(|| Box::new(EvalAltResult::ErrorModuleNotFound(path.to_string(), pos)))
-    /// A module resolution service that always returns a not-found error.
-    #[derive(Debug, Clone, PartialEq, Eq, Copy, Default)]
-    pub struct NullModuleResolver;
-
-    impl NullModuleResolver {
-        /// Create a new `NullModuleResolver`.
-        pub fn new() -> Self {
-            Default::default()
-        }
-    }
-
-    impl ModuleResolver for NullModuleResolver {
-        fn resolve(&self, _: &Engine, path: &str) -> Result<Module, Box<EvalAltResult>> {
-            Err(Box::new(EvalAltResult::ErrorModuleNotFound(
-                path.to_string(),
-                Position::none(),
-            )))
         }
     }
 }

src/parser.rs

@@ -67,13 +67,9 @@ impl AST {
     /// Create a new `AST`.
     pub fn new(statements: Vec<Stmt>, fn_lib: FunctionsLib) -> Self {
         #[cfg(feature = "sync")]
-        {
+        return Self(statements, Arc::new(fn_lib));
-            Self(statements, Arc::new(fn_lib))
-        }
         #[cfg(not(feature = "sync"))]
-        {
+        return Self(statements, Rc::new(fn_lib));
-            Self(statements, Rc::new(fn_lib))
-        }
     }
 
     /// Get the statements.
@@ -148,13 +144,9 @@ impl AST {
         };
 
         #[cfg(feature = "sync")]
-        {
+        return Self(ast, Arc::new(functions.merge(other.1.as_ref())));
-            Self(ast, Arc::new(functions.merge(other.1.as_ref())))
-        }
         #[cfg(not(feature = "sync"))]
-        {
+        return Self(ast, Rc::new(functions.merge(other.1.as_ref())));
-            Self(ast, Rc::new(functions.merge(other.1.as_ref())))
-        }
     }
 
     /// Clear all function definitions in the `AST`.
@@ -1810,7 +1802,6 @@ fn parse_let<'a>(
 }
 
 /// Parse an import statement.
-#[cfg(not(feature = "no_module"))]
 fn parse_import<'a>(
     input: &mut Peekable<TokenIterator<'a>>,
     stack: &mut Stack,
@@ -1941,7 +1932,6 @@ fn parse_stmt<'a>(
         Token::LeftBrace => parse_block(input, stack, breakable, allow_stmt_expr),
 
         // fn ...
-        #[cfg(not(feature = "no_function"))]
         Token::Fn => Err(PERR::WrongFnDefinition.into_err(*pos)),
 
         Token::If => parse_if(input, stack, breakable, allow_stmt_expr),
@@ -2115,14 +2105,11 @@ fn parse_global_level<'a>(
 
     while !input.peek().unwrap().0.is_eof() {
         // Collect all the function definitions
-        #[cfg(not(feature = "no_function"))]
+        if let (Token::Fn, _) = input.peek().unwrap() {
-        {
+            let mut stack = Stack::new();
-            if let (Token::Fn, _) = input.peek().unwrap() {
+            let f = parse_fn(input, &mut stack, true)?;
-                let mut stack = Stack::new();
+            functions.insert(calc_fn_def(&f.name, f.params.len()), f);
-                let f = parse_fn(input, &mut stack, true)?;
+            continue;
-                functions.insert(calc_fn_def(&f.name, f.params.len()), f);
-                continue;
-            }
         }
 
         // Actual statement

src/token.rs

@@ -153,11 +153,9 @@ pub enum Token {
     RightShift,
     SemiColon,
     Colon,
-    #[cfg(not(feature = "no_module"))]
     DoubleColon,
     Comma,
     Period,
-    #[cfg(not(feature = "no_object"))]
     MapStart,
     Equals,
     True,
@@ -182,7 +180,6 @@ pub enum Token {
     XOr,
     Ampersand,
     And,
-    #[cfg(not(feature = "no_function"))]
     Fn,
     Continue,
     Break,
@@ -199,11 +196,8 @@ pub enum Token {
     XOrAssign,
     ModuloAssign,
     PowerOfAssign,
-    #[cfg(not(feature = "no_module"))]
     Import,
-    #[cfg(not(feature = "no_module"))]
     Export,
-    #[cfg(not(feature = "no_module"))]
     As,
     LexError(Box<LexError>),
     EOF,
@@ -238,11 +232,9 @@ impl Token {
                 Divide => "/",
                 SemiColon => ";",
                 Colon => ":",
-                #[cfg(not(feature = "no_module"))]
                 DoubleColon => "::",
                 Comma => ",",
                 Period => ".",
-                #[cfg(not(feature = "no_object"))]
                 MapStart => "#{",
                 Equals => "=",
                 True => "true",
@@ -266,7 +258,6 @@ impl Token {
                 Or => "||",
                 Ampersand => "&",
                 And => "&&",
-                #[cfg(not(feature = "no_function"))]
                 Fn => "fn",
                 Continue => "continue",
                 Break => "break",
@@ -288,11 +279,8 @@ impl Token {
                 ModuloAssign => "%=",
                 PowerOf => "~",
                 PowerOfAssign => "~=",
-                #[cfg(not(feature = "no_module"))]
                 Import => "import",
-                #[cfg(not(feature = "no_module"))]
                 Export => "export",
-                #[cfg(not(feature = "no_module"))]
                 As => "as",
                 EOF => "{EOF}",
                 _ => panic!("operator should be match in outer scope"),

tests/modules.rs

@@ -64,10 +64,10 @@ fn test_module_resolver() -> Result<(), Box<EvalAltResult>> {
     let mut module = Module::new();
     module.set_var("answer", 42 as INT);
 
-    resolver.add_module("hello", module);
+    resolver.insert("hello".to_string(), module);
 
     let mut engine = Engine::new();
-    engine.set_module_resolver(resolver);
+    engine.set_module_resolver(Some(resolver));
 
     assert_eq!(
         engine.eval::<INT>(