Add convenient functions and operators for Module and module resolvers.

src/module/resolvers/stat.rs

@@ -3,7 +3,7 @@ use crate::module::{Module, ModuleResolver};
 use crate::result::EvalAltResult;
 use crate::token::Position;
 
-use crate::stdlib::{boxed::Box, collections::HashMap, string::String};
+use crate::stdlib::{boxed::Box, collections::HashMap, ops::AddAssign, string::String};
 
 /// Module resolution service that serves modules added into it.
 ///
@@ -45,9 +45,6 @@ impl StaticModuleResolver {
     pub fn new() -> Self {
         Default::default()
     }
-}
-
-impl StaticModuleResolver {
     /// Add a module keyed by its path.
     pub fn insert<S: Into<String>>(&mut self, path: S, module: Module) {
         self.0.insert(path.into(), module);
@@ -68,6 +65,10 @@ impl StaticModuleResolver {
     pub fn iter_mut(&mut self) -> impl Iterator<Item = (&str, &mut Module)> {
         self.0.iter_mut().map(|(k, v)| (k.as_str(), v))
     }
+    /// Get a mutable iterator of all the modules.
+    pub fn into_iter(self) -> impl Iterator<Item = (String, Module)> {
+        self.0.into_iter()
+    }
     /// Get an iterator of all the module paths.
     pub fn paths(&self) -> impl Iterator<Item = &str> {
         self.0.keys().map(String::as_str)
@@ -84,6 +85,21 @@ impl StaticModuleResolver {
     pub fn clear(&mut self) {
         self.0.clear();
     }
+    /// Is this `StaticModuleResolver` empty?
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+    /// Get the number of modules in this `StaticModuleResolver`.
+    pub fn len(&self) -> usize {
+        self.0.len()
+    }
+    /// Merge another `StaticModuleResolver` into this.
+    /// The other `StaticModuleResolver` is consumed.
+    pub fn merge(&mut self, other: Self) {
+        if !other.is_empty() {
+            self.0.extend(other.0.into_iter());
+        }
+    }
 }
 
 impl ModuleResolver for StaticModuleResolver {
@@ -94,3 +110,9 @@ impl ModuleResolver for StaticModuleResolver {
             .ok_or_else(|| EvalAltResult::ErrorModuleNotFound(path.into(), pos).into())
     }
 }
+
+impl AddAssign<Self> for StaticModuleResolver {
+    fn add_assign(&mut self, rhs: Self) {
+        self.merge(rhs);
+    }
+}