From 0867dc76a3c50c60f4b6d7e45daecede5c41ca8a Mon Sep 17 00:00:00 2001
From: Nathan Stocks <cleancut@github.com>
Date: Sun, 31 Jan 2021 17:35:23 -0700
Subject: [PATCH] Use Cow<'static, str> in Name (#1308)

* Implement Name { name } as Cow<'static, str>
* Attempt impl Reflect for Cow<'static, str.>
---
 crates/bevy_core/src/name.rs         | 17 +++----
 crates/bevy_reflect/src/impls/std.rs | 67 +++++++++++++++++++++++++++-
 2 files changed, 75 insertions(+), 9 deletions(-)

diff --git a/crates/bevy_core/src/name.rs b/crates/bevy_core/src/name.rs
index b0999773e8..fd2f4d9f78 100644
--- a/crates/bevy_core/src/name.rs
+++ b/crates/bevy_core/src/name.rs
@@ -1,26 +1,27 @@
 use bevy_reflect::{Reflect, ReflectComponent};
 use bevy_utils::AHasher;
 use std::{
+    borrow::Cow,
     hash::{Hash, Hasher},
     ops::Deref,
 };
 
-/// Component used to identify a entity. Stores a hash for faster comparisons
+/// Component used to identify an entity. Stores a hash for faster comparisons
 #[derive(Debug, Clone, Reflect)]
 #[reflect(Component)]
 pub struct Name {
     hash: u64, // TODO: Shouldn't be serialized
-    name: String,
+    name: Cow<'static, str>,
 }
 
 impl Default for Name {
     fn default() -> Self {
-        Name::new("".to_string())
+        Name::new("")
     }
 }
 
 impl Name {
-    pub fn new(name: impl Into<String>) -> Self {
+    pub fn new(name: impl Into<Cow<'static, str>>) -> Self {
         let name = name.into();
         let mut name = Name { name, hash: 0 };
         name.update_hash();
@@ -28,19 +29,19 @@ impl Name {
     }
 
     #[inline(always)]
-    pub fn set(&mut self, name: String) {
+    pub fn set(&mut self, name: impl Into<Cow<'static, str>>) {
         *self = Name::new(name);
     }
 
     #[inline(always)]
     pub fn mutate<F: FnOnce(&mut String)>(&mut self, f: F) {
-        f(&mut self.name);
+        f(self.name.to_mut());
         self.update_hash();
     }
 
     #[inline(always)]
     pub fn as_str(&self) -> &str {
-        self.name.as_str()
+        &self.name
     }
 
     fn update_hash(&mut self) {
@@ -89,7 +90,7 @@ impl Ord for Name {
 }
 
 impl Deref for Name {
-    type Target = String;
+    type Target = Cow<'static, str>;
 
     fn deref(&self) -> &Self::Target {
         &self.name
diff --git a/crates/bevy_reflect/src/impls/std.rs b/crates/bevy_reflect/src/impls/std.rs
index 0af5cead11..feae40b69a 100644
--- a/crates/bevy_reflect/src/impls/std.rs
+++ b/crates/bevy_reflect/src/impls/std.rs
@@ -6,7 +6,12 @@ use crate::{
 use bevy_reflect_derive::impl_reflect_value;
 use bevy_utils::{HashMap, HashSet};
 use serde::{Deserialize, Serialize};
-use std::{any::Any, hash::Hash, ops::Range};
+use std::{
+    any::Any,
+    borrow::Cow,
+    hash::{Hash, Hasher},
+    ops::Range,
+};
 
 impl_reflect_value!(bool(Hash, PartialEq, Serialize, Deserialize));
 impl_reflect_value!(u8(Hash, PartialEq, Serialize, Deserialize));
@@ -199,3 +204,63 @@ impl<K: Reflect + Clone + Eq + Hash, V: Reflect + Clone> Reflect for HashMap<K,
         None
     }
 }
+
+impl Reflect for Cow<'static, str> {
+    fn type_name(&self) -> &str {
+        std::any::type_name::<Self>()
+    }
+
+    fn any(&self) -> &dyn Any {
+        self
+    }
+
+    fn any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+
+    fn apply(&mut self, value: &dyn Reflect) {
+        let value = value.any();
+        if let Some(value) = value.downcast_ref::<Self>() {
+            *self = value.clone();
+        } else {
+            panic!("Value is not a {}.", std::any::type_name::<Self>());
+        }
+    }
+
+    fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>> {
+        *self = value.take()?;
+        Ok(())
+    }
+
+    fn reflect_ref(&self) -> ReflectRef {
+        ReflectRef::Value(self)
+    }
+
+    fn reflect_mut(&mut self) -> ReflectMut {
+        ReflectMut::Value(self)
+    }
+
+    fn clone_value(&self) -> Box<dyn Reflect> {
+        Box::new(self.clone())
+    }
+
+    fn reflect_hash(&self) -> Option<u64> {
+        let mut hasher = crate::ReflectHasher::default();
+        Hash::hash(&std::any::Any::type_id(self), &mut hasher);
+        Hash::hash(self, &mut hasher);
+        Some(hasher.finish())
+    }
+
+    fn reflect_partial_eq(&self, value: &dyn Reflect) -> Option<bool> {
+        let value = value.any();
+        if let Some(value) = value.downcast_ref::<Self>() {
+            Some(std::cmp::PartialEq::eq(self, value))
+        } else {
+            Some(false)
+        }
+    }
+
+    fn serializable(&self) -> Option<Serializable> {
+        Some(Serializable::Borrowed(self))
+    }
+}