From 65432330c468d3923a40ade26771bce6eb8cdcf6 Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Sun, 25 Oct 2020 00:39:47 +0800
Subject: [PATCH] Add Module::fill_with.

---
 RELEASES.md       |   9 ++++
 src/module/mod.rs | 120 +++++++++++++++++++++++-----------------------
 2 files changed, 69 insertions(+), 60 deletions(-)

diff --git a/RELEASES.md b/RELEASES.md
index c9c1d81e..17e19f7d 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -2,6 +2,15 @@ Rhai Release Notes
 ==================
 
 
+Version 0.19.4
+==============
+
+New features
+------------
+
+* `Module::fill_with` to poly-fill a module with another.
+
+
 Version 0.19.3
 ==============
 
diff --git a/src/module/mod.rs b/src/module/mod.rs
index 4c2b3780..66dcf988 100644
--- a/src/module/mod.rs
+++ b/src/module/mod.rs
@@ -1125,18 +1125,10 @@ impl Module {
     /// The other module is consumed to merge into this module.
     #[inline]
     pub fn combine(&mut self, other: Self) -> &mut Self {
-        if !other.modules.is_empty() {
-            self.modules.extend(other.modules.into_iter());
-        }
-        if !other.variables.is_empty() {
-            self.variables.extend(other.variables.into_iter());
-        }
-        if !other.functions.is_empty() {
-            self.functions.extend(other.functions.into_iter());
-        }
-        if !other.type_iterators.is_empty() {
-            self.type_iterators.extend(other.type_iterators.into_iter());
-        }
+        self.modules.extend(other.modules.into_iter());
+        self.variables.extend(other.variables.into_iter());
+        self.functions.extend(other.functions.into_iter());
+        self.type_iterators.extend(other.type_iterators.into_iter());
         self.all_functions.clear();
         self.all_variables.clear();
         self.indexed = false;
@@ -1148,20 +1140,38 @@ impl Module {
     /// Sub-modules are flattened onto the root module, with higher level overriding lower level.
     #[inline]
     pub fn combine_flatten(&mut self, other: Self) -> &mut Self {
-        if !other.modules.is_empty() {
-            other.modules.into_iter().for_each(|(_, m)| {
-                self.combine_flatten(m);
-            });
-        }
-        if !other.variables.is_empty() {
-            self.variables.extend(other.variables.into_iter());
-        }
-        if !other.functions.is_empty() {
-            self.functions.extend(other.functions.into_iter());
-        }
-        if !other.type_iterators.is_empty() {
-            self.type_iterators.extend(other.type_iterators.into_iter());
-        }
+        other.modules.into_iter().for_each(|(_, m)| {
+            self.combine_flatten(m);
+        });
+        self.variables.extend(other.variables.into_iter());
+        self.functions.extend(other.functions.into_iter());
+        self.type_iterators.extend(other.type_iterators.into_iter());
+        self.all_functions.clear();
+        self.all_variables.clear();
+        self.indexed = false;
+        self
+    }
+
+    /// Poly-fill this module with another module.
+    /// Only items not existing in this module are added.
+    #[inline]
+    pub fn fill_with(&mut self, other: &Self) -> &mut Self {
+        other.modules.iter().for_each(|(k, v)| {
+            if !self.modules.contains_key(k) {
+                self.modules.insert(k.clone(), v.clone());
+            }
+        });
+        other.variables.iter().for_each(|(k, v)| {
+            if !self.variables.contains_key(k) {
+                self.variables.insert(k.clone(), v.clone());
+            }
+        });
+        other.functions.iter().for_each(|(&k, v)| {
+            self.functions.entry(k).or_insert_with(|| v.clone());
+        });
+        other.type_iterators.iter().for_each(|(&k, &v)| {
+            self.type_iterators.entry(k).or_insert(v);
+        });
         self.all_functions.clear();
         self.all_variables.clear();
         self.indexed = false;
@@ -1181,42 +1191,32 @@ impl Module {
         mut _filter: &mut impl FnMut(FnAccess, &str, usize) -> bool,
     ) -> &mut Self {
         #[cfg(not(feature = "no_function"))]
-        if !other.modules.is_empty() {
-            other.modules.iter().for_each(|(k, v)| {
-                let mut m = Self::new();
-                m.merge_filtered(v, _filter);
-                self.modules.insert(k.clone(), m);
-            });
-        }
+        other.modules.iter().for_each(|(k, v)| {
+            let mut m = Self::new();
+            m.merge_filtered(v, _filter);
+            self.modules.insert(k.clone(), m);
+        });
         #[cfg(feature = "no_function")]
-        if !other.modules.is_empty() {
-            self.modules
-                .extend(other.modules.iter().map(|(k, v)| (k.clone(), v.clone())));
-        }
-        if !other.variables.is_empty() {
-            self.variables
-                .extend(other.variables.iter().map(|(k, v)| (k.clone(), v.clone())));
-        }
-        if !other.functions.is_empty() {
-            self.functions.extend(
-                other
-                    .functions
-                    .iter()
-                    .filter(|(_, (_, _, _, _, v))| match v {
-                        #[cfg(not(feature = "no_function"))]
-                        CallableFunction::Script(f) => {
-                            _filter(f.access, f.name.as_str(), f.params.len())
-                        }
-                        _ => true,
-                    })
-                    .map(|(&k, v)| (k, v.clone())),
-            );
-        }
+        self.modules
+            .extend(other.modules.iter().map(|(k, v)| (k.clone(), v.clone())));
 
-        if !other.type_iterators.is_empty() {
-            self.type_iterators
-                .extend(other.type_iterators.iter().map(|(&k, v)| (k, v.clone())));
-        }
+        self.variables
+            .extend(other.variables.iter().map(|(k, v)| (k.clone(), v.clone())));
+        self.functions.extend(
+            other
+                .functions
+                .iter()
+                .filter(|(_, (_, _, _, _, v))| match v {
+                    #[cfg(not(feature = "no_function"))]
+                    CallableFunction::Script(f) => {
+                        _filter(f.access, f.name.as_str(), f.params.len())
+                    }
+                    _ => true,
+                })
+                .map(|(&k, v)| (k, v.clone())),
+        );
+
+        self.type_iterators.extend(other.type_iterators.iter());
         self.all_functions.clear();
         self.all_variables.clear();
         self.indexed = false;