fix(engine): prevent ignored mouse button input when main loop is slow

1 files changed, 46 insertions, 0 deletions

diff --git a/engine/src/util.rs b/engine/src/util.rs
index a8ee893..bd69734 100644
--- a/engine/src/util.rs
+++ b/engine/src/util.rs
@@ -21,6 +21,15 @@ impl<Key: Ord, Value> MapVec<Key, Value>
             .insert_at_part_pt_by_key((key, value), |(a_key, _)| a_key);
     }
 
+    pub fn insert_mut(&mut self, key: Key, value: Value) -> &mut Value
+    {
+        let insert_index = self
+            .inner
+            .partition_point(|(other_key, _other_value)| other_key <= &key);
+
+        &mut self.inner.insert_mut(insert_index, (key, value)).1
+    }
+
     pub fn remove(&mut self, key: Key) -> Option<Value>
     {
         let index = self
@@ -61,6 +70,21 @@ impl<Key: Ord, Value> MapVec<Key, Value>
         Some(value)
     }
 
+    pub fn entry(&mut self, key: Key) -> MapVecEntry<'_, Key, Value>
+    {
+        let index = self
+            .inner
+            .binary_search_by_key(&&key, |(a_key, _)| a_key)
+            .ok();
+
+        MapVecEntry { map: self, key, index }
+    }
+
+    pub fn iter_mut(&mut self) -> impl Iterator<Item = (&mut Key, &mut Value)>
+    {
+        self.inner.iter_mut().map(|(key, value)| (key, value))
+    }
+
     pub fn values(&self) -> impl Iterator<Item = &Value>
     {
         self.inner.iter().map(|(_, value)| value)
@@ -89,6 +113,28 @@ impl<Key: Ord, Value> Default for MapVec<Key, Value>
     }
 }
 
+pub struct MapVecEntry<'map, Key: Ord, Value>
+{
+    map: &'map mut MapVec<Key, Value>,
+    key: Key,
+    index: Option<usize>,
+}
+
+impl<'map, Key: Ord, Value> MapVecEntry<'map, Key, Value>
+{
+    pub fn or_insert_with(self, func: impl FnOnce() -> Value) -> &'map mut Value
+    {
+        match self.index {
+            Some(index) => {
+                let (_, value) = unsafe { self.map.inner.get_unchecked_mut(index) };
+
+                value
+            }
+            None => self.map.insert_mut(self.key, func()),
+        }
+    }
+}
+
 pub trait OptionExt<T>
 {
     /// Substitute for the currently experimental function