Restore plugins code.

src/fn_native.rs

@@ -1,6 +1,7 @@
 use crate::any::Dynamic;
 use crate::engine::Engine;
 use crate::parser::ScriptFnDef;
+use crate::plugin::PluginFunction;
 use crate::result::EvalAltResult;
 use crate::utils::ImmutableString;
 
@@ -96,6 +97,11 @@ pub type FnAny =
 /// A standard function that gets an iterator from a type.
 pub type IteratorFn = fn(Dynamic) -> Box<dyn Iterator<Item = Dynamic>>;
 
+#[cfg(feature = "sync")]
+pub type SharedPluginFunction = Arc<dyn PluginFunction + Send + Sync>;
+#[cfg(not(feature = "sync"))]
+pub type SharedPluginFunction = Rc<dyn PluginFunction>;
+
 /// A standard callback function.
 #[cfg(not(feature = "sync"))]
 pub type Callback<T, R> = Box<dyn Fn(&T) -> R + 'static>;
@@ -113,6 +119,8 @@ pub enum CallableFunction {
     Method(Shared<FnAny>),
     /// An iterator function.
     Iterator(IteratorFn),
+    /// A plugin-defined function,
+    Plugin(SharedPluginFunction),
     /// A script-defined function.
     Script(Shared<ScriptFnDef>),
 }
@@ -123,6 +131,7 @@ impl fmt::Debug for CallableFunction {
             Self::Pure(_) => write!(f, "NativePureFunction"),
             Self::Method(_) => write!(f, "NativeMethod"),
             Self::Iterator(_) => write!(f, "NativeIterator"),
+            Self::Plugin(_) => write!(f, "PluginFunction"),
             Self::Script(fn_def) => fmt::Debug::fmt(fn_def, f),
         }
     }
@@ -134,6 +143,7 @@ impl fmt::Display for CallableFunction {
             Self::Pure(_) => write!(f, "NativePureFunction"),
             Self::Method(_) => write!(f, "NativeMethod"),
             Self::Iterator(_) => write!(f, "NativeIterator"),
+            Self::Plugin(_) => write!(f, "PluginFunction"),
             CallableFunction::Script(s) => fmt::Display::fmt(s, f),
         }
     }
@@ -144,28 +154,35 @@ impl CallableFunction {
     pub fn is_pure(&self) -> bool {
         match self {
             Self::Pure(_) => true,
-            Self::Method(_) | Self::Iterator(_) | Self::Script(_) => false,
+            Self::Method(_) | Self::Iterator(_) | Self::Script(_) | Self::Plugin(_) => false,
         }
     }
     /// Is this a native Rust method function?
     pub fn is_method(&self) -> bool {
         match self {
             Self::Method(_) => true,
-            Self::Pure(_) | Self::Iterator(_) | Self::Script(_) => false,
+            Self::Pure(_) | Self::Iterator(_) | Self::Script(_) | Self::Plugin(_) => false,
         }
     }
     /// Is this an iterator function?
     pub fn is_iter(&self) -> bool {
         match self {
             Self::Iterator(_) => true,
-            Self::Pure(_) | Self::Method(_) | Self::Script(_) => false,
+            Self::Pure(_) | Self::Method(_) | Self::Script(_) | Self::Plugin(_) => false,
         }
     }
     /// Is this a Rhai-scripted function?
     pub fn is_script(&self) -> bool {
         match self {
             Self::Script(_) => true,
-            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => false,
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) | Self::Plugin(_) => false,
+        }
+    }
+    /// Is this a plugin-defined function?
+    pub fn is_plugin_fn(&self) -> bool {
+        match self {
+            Self::Plugin(_) => true,
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) | Self::Script(_) => false,
         }
     }
     /// Get a reference to a native Rust function.
@@ -176,7 +193,7 @@ impl CallableFunction {
     pub fn get_native_fn(&self) -> &FnAny {
         match self {
             Self::Pure(f) | Self::Method(f) => f.as_ref(),
-            Self::Iterator(_) | Self::Script(_) => unreachable!(),
+            Self::Iterator(_) | Self::Script(_) | Self::Plugin(_) => unreachable!(),
         }
     }
     /// Get a shared reference to a script-defined function definition.
@@ -186,7 +203,7 @@ impl CallableFunction {
     /// Panics if the `CallableFunction` is not `Script`.
     pub fn get_shared_fn_def(&self) -> Shared<ScriptFnDef> {
         match self {
-            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => unreachable!(),
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) | Self::Plugin(_) => unreachable!(),
             Self::Script(f) => f.clone(),
         }
     }
@@ -197,7 +214,7 @@ impl CallableFunction {
     /// Panics if the `CallableFunction` is not `Script`.
     pub fn get_fn_def(&self) -> &ScriptFnDef {
         match self {
-            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) => unreachable!(),
+            Self::Pure(_) | Self::Method(_) | Self::Iterator(_) | Self::Plugin(_) => unreachable!(),
             Self::Script(f) => f,
         }
     }
@@ -209,7 +226,18 @@ impl CallableFunction {
     pub fn get_iter_fn(&self) -> IteratorFn {
         match self {
             Self::Iterator(f) => *f,
-            Self::Pure(_) | Self::Method(_) | Self::Script(_) => unreachable!(),
+            Self::Pure(_) | Self::Method(_) | Self::Script(_) | Self::Plugin(_) => unreachable!(),
+        }
+    }
+    /// Get a reference to a plugin function.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `CallableFunction` is not `Plugin`.
+    pub fn get_plugin_fn<'s>(&'s self) -> SharedPluginFunction {
+        match self {
+            Self::Plugin(f) => f.clone(),
+            Self::Pure(_) | Self::Method(_) | Self::Script(_) | Self::Iterator(_) => unreachable!(),
         }
     }
     /// Create a new `CallableFunction::Pure`.
@@ -220,6 +248,18 @@ impl CallableFunction {
     pub fn from_method(func: Box<FnAny>) -> Self {
         Self::Method(func.into())
     }
+
+    #[cfg(feature = "sync")]
+    /// Create a new `CallableFunction::Plugin`.
+    pub fn from_plugin(plugin: impl PluginFunction + 'static + Send + Sync) -> Self {
+        Self::Plugin(Arc::new(plugin))
+    }
+
+    #[cfg(not(feature = "sync"))]
+    /// Create a new `CallableFunction::Plugin`.
+    pub fn from_plugin(plugin: impl PluginFunction + 'static) -> Self {
+        Self::Plugin(Rc::new(plugin))
+    }
 }
 
 impl From<IteratorFn> for CallableFunction {