Name component with fast comparisons (#1109)

Name component with fast comparisons

crates/bevy_core/Cargo.toml

@@ -20,4 +20,4 @@ bevy_ecs = { path = "../bevy_ecs", version = "0.4.0" }
 bevy_math = { path = "../bevy_math", version = "0.4.0" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.4.0", features = ["bevy"] }
 bevy_tasks = { path = "../bevy_tasks", version = "0.4.0" }
-bevy_utils = { path = "../bevy_utils", version = "0.4.0" }
+bevy_utils = { path = "../bevy_utils", version = "0.4.0" }

crates/bevy_core/src/lib.rs

@@ -1,6 +1,7 @@
 mod bytes;
 mod float_ord;
 mod label;
+mod name;
 mod task_pool_options;
 mod time;
 
@@ -11,6 +12,7 @@ use bevy_reflect::RegisterTypeBuilder;
 pub use bytes::*;
 pub use float_ord::*;
 pub use label::*;
+pub use name::*;
 pub use task_pool_options::DefaultTaskPoolOptions;
 pub use time::*;
 
@@ -36,6 +38,7 @@ impl Plugin for CorePlugin {
             .init_resource::<EntityLabels>()
             .init_resource::<FixedTimesteps>()
             .register_type::<Option<String>>()
+            .register_type::<Name>()
             .register_type::<Labels>()
             .register_type::<Range<f32>>()
             .register_type::<Timer>()

crates/bevy_core/src/name.rs

@@ -0,0 +1,96 @@
+use bevy_reflect::{Reflect, ReflectComponent};
+use bevy_utils::AHasher;
+use std::{
+    hash::{Hash, Hasher},
+    ops::Deref,
+};
+
+/// Component used to identify a 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,
+}
+
+impl Default for Name {
+    fn default() -> Self {
+        Name::new("".to_string())
+    }
+}
+
+impl Name {
+    pub fn new(name: String) -> Self {
+        let mut name = Name { name, hash: 0 };
+        name.update_hash();
+        name
+    }
+
+    #[inline(always)]
+    pub fn set(&mut self, name: String) {
+        *self = Name::new(name);
+    }
+
+    #[inline(always)]
+    pub fn mutate<F: FnOnce(&mut String)>(&mut self, f: F) {
+        f(&mut self.name);
+        self.update_hash();
+    }
+
+    #[inline(always)]
+    pub fn as_str(&self) -> &str {
+        self.name.as_str()
+    }
+
+    fn update_hash(&mut self) {
+        let mut hasher = AHasher::default();
+        self.name.hash(&mut hasher);
+        self.hash = hasher.finish();
+    }
+}
+
+impl From<&str> for Name {
+    #[inline(always)]
+    fn from(name: &str) -> Self {
+        Name::new(name.to_owned())
+    }
+}
+
+impl Hash for Name {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.name.hash(state);
+    }
+}
+
+impl PartialEq for Name {
+    fn eq(&self, other: &Self) -> bool {
+        if self.hash != other.hash {
+            // Makes the common case of two strings not been equal very fast
+            return false;
+        }
+
+        self.name.eq(&other.name)
+    }
+}
+
+impl Eq for Name {}
+
+impl PartialOrd for Name {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        self.name.partial_cmp(&other.name)
+    }
+}
+
+impl Ord for Name {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        self.name.cmp(&other.name)
+    }
+}
+
+impl Deref for Name {
+    type Target = String;
+
+    fn deref(&self) -> &Self::Target {
+        &self.name
+    }
+}