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use crate::{App, AppError, Plugin};
use bevy_utils::{tracing::debug, tracing::warn, TypeIdMap};
use std::any::TypeId;
/// Combines multiple [`Plugin`]s into a single unit.
pub trait PluginGroup: Sized {
/// Configures the [`Plugin`]s that are to be added.
fn build(self) -> PluginGroupBuilder;
/// Configures a name for the [`PluginGroup`] which is primarily used for debugging.
fn name() -> String {
std::any::type_name::<Self>().to_string()
}
/// Sets the value of the given [`Plugin`], if it exists
fn set<T: Plugin>(self, plugin: T) -> PluginGroupBuilder {
self.build().set(plugin)
}
}
struct PluginEntry {
plugin: Box<dyn Plugin>,
enabled: bool,
}
impl PluginGroup for PluginGroupBuilder {
fn build(self) -> PluginGroupBuilder {
self
}
}
/// Facilitates the creation and configuration of a [`PluginGroup`].
/// Provides a build ordering to ensure that [`Plugin`]s which produce/require a [`Resource`](bevy_ecs::system::Resource)
/// are built before/after dependent/depending [`Plugin`]s. [`Plugin`]s inside the group
/// can be disabled, enabled or reordered.
pub struct PluginGroupBuilder {
group_name: String,
plugins: TypeIdMap<PluginEntry>,
order: Vec<TypeId>,
}
impl PluginGroupBuilder {
/// Start a new builder for the [`PluginGroup`].
pub fn start<PG: PluginGroup>() -> Self {
Self {
group_name: PG::name(),
plugins: Default::default(),
order: Default::default(),
}
}
/// Finds the index of a target [`Plugin`]. Panics if the target's [`TypeId`] is not found.
fn index_of<Target: Plugin>(&self) -> usize {
let index = self
.order
.iter()
.position(|&ty| ty == TypeId::of::<Target>());
match index {
Some(i) => i,
None => panic!(
"Plugin does not exist in group: {}.",
std::any::type_name::<Target>()
),
}
}
// Insert the new plugin as enabled, and removes its previous ordering if it was
// already present
fn upsert_plugin_state<T: Plugin>(&mut self, plugin: T, added_at_index: usize) {
self.upsert_plugin_entry_state(
TypeId::of::<T>(),
PluginEntry {
plugin: Box::new(plugin),
enabled: true,
},
added_at_index,
);
}
// Insert the new plugin entry as enabled, and removes its previous ordering if it was
// already present
fn upsert_plugin_entry_state(
&mut self,
key: TypeId,
plugin: PluginEntry,
added_at_index: usize,
) {
if let Some(entry) = self.plugins.insert(key, plugin) {
if entry.enabled {
warn!(
"You are replacing plugin '{}' that was not disabled.",
entry.plugin.name()
);
}
if let Some(to_remove) = self
.order
.iter()
.enumerate()
.find(|(i, ty)| *i != added_at_index && **ty == key)
.map(|(i, _)| i)
{
self.order.remove(to_remove);
}
}
}
/// Sets the value of the given [`Plugin`], if it exists.
///
/// # Panics
///
/// Panics if the [`Plugin`] does not exist.
pub fn set<T: Plugin>(mut self, plugin: T) -> Self {
let entry = self.plugins.get_mut(&TypeId::of::<T>()).unwrap_or_else(|| {
panic!(
"{} does not exist in this PluginGroup",
std::any::type_name::<T>(),
)
});
entry.plugin = Box::new(plugin);
self
}
/// Adds the plugin [`Plugin`] at the end of this [`PluginGroupBuilder`]. If the plugin was
/// already in the group, it is removed from its previous place.
// This is not confusing, clippy!
#[allow(clippy::should_implement_trait)]
pub fn add<T: Plugin>(mut self, plugin: T) -> Self {
let target_index = self.order.len();
self.order.push(TypeId::of::<T>());
self.upsert_plugin_state(plugin, target_index);
self
}
/// Adds a [`PluginGroup`] at the end of this [`PluginGroupBuilder`]. If the plugin was
/// already in the group, it is removed from its previous place.
pub fn add_group(mut self, group: impl PluginGroup) -> Self {
let Self {
mut plugins, order, ..
} = group.build();
for plugin_id in order {
self.upsert_plugin_entry_state(
plugin_id,
plugins.remove(&plugin_id).unwrap(),
self.order.len(),
);
self.order.push(plugin_id);
}
self
}
/// Adds a [`Plugin`] in this [`PluginGroupBuilder`] before the plugin of type `Target`.
/// If the plugin was already the group, it is removed from its previous place. There must
/// be a plugin of type `Target` in the group or it will panic.
pub fn add_before<Target: Plugin, T: Plugin>(mut self, plugin: T) -> Self {
let target_index = self.index_of::<Target>();
self.order.insert(target_index, TypeId::of::<T>());
self.upsert_plugin_state(plugin, target_index);
self
}
/// Adds a [`Plugin`] in this [`PluginGroupBuilder`] after the plugin of type `Target`.
/// If the plugin was already the group, it is removed from its previous place. There must
/// be a plugin of type `Target` in the group or it will panic.
pub fn add_after<Target: Plugin, T: Plugin>(mut self, plugin: T) -> Self {
let target_index = self.index_of::<Target>() + 1;
self.order.insert(target_index, TypeId::of::<T>());
self.upsert_plugin_state(plugin, target_index);
self
}
/// Enables a [`Plugin`].
///
/// [`Plugin`]s within a [`PluginGroup`] are enabled by default. This function is used to
/// opt back in to a [`Plugin`] after [disabling](Self::disable) it. If there are no plugins
/// of type `T` in this group, it will panic.
pub fn enable<T: Plugin>(mut self) -> Self {
let plugin_entry = self
.plugins
.get_mut(&TypeId::of::<T>())
.expect("Cannot enable a plugin that does not exist.");
plugin_entry.enabled = true;
self
}
/// Disables a [`Plugin`], preventing it from being added to the [`App`] with the rest of the
/// [`PluginGroup`]. The disabled [`Plugin`] keeps its place in the [`PluginGroup`], so it can
/// still be used for ordering with [`add_before`](Self::add_before) or
/// [`add_after`](Self::add_after), or it can be [re-enabled](Self::enable). If there are no
/// plugins of type `T` in this group, it will panic.
pub fn disable<T: Plugin>(mut self) -> Self {
let plugin_entry = self
.plugins
.get_mut(&TypeId::of::<T>())
.expect("Cannot disable a plugin that does not exist.");
plugin_entry.enabled = false;
self
}
/// Consumes the [`PluginGroupBuilder`] and [builds](Plugin::build) the contained [`Plugin`]s
/// in the order specified.
///
/// # Panics
///
/// Panics if one of the plugin in the group was already added to the application.
#[track_caller]
pub fn finish(mut self, app: &mut App) {
for ty in &self.order {
if let Some(entry) = self.plugins.remove(ty) {
if entry.enabled {
debug!("added plugin: {}", entry.plugin.name());
if let Err(AppError::DuplicatePlugin { plugin_name }) =
app.add_boxed_plugin(entry.plugin)
{
panic!(
"Error adding plugin {} in group {}: plugin was already added in application",
plugin_name,
self.group_name
);
}
}
}
}
}
}
/// A plugin group which doesn't do anything. Useful for examples:
/// ```
/// # use bevy_app::prelude::*;
/// use bevy_app::NoopPluginGroup as MinimalPlugins;
///
/// fn main(){
/// App::new().add_plugins(MinimalPlugins).run();
/// }
/// ```
#[doc(hidden)]
pub struct NoopPluginGroup;
impl PluginGroup for NoopPluginGroup {
fn build(self) -> PluginGroupBuilder {
PluginGroupBuilder::start::<Self>()
}
}
#[cfg(test)]
mod tests {
use super::PluginGroupBuilder;
use crate::{App, NoopPluginGroup, Plugin};
struct PluginA;
impl Plugin for PluginA {
fn build(&self, _: &mut App) {}
}
struct PluginB;
impl Plugin for PluginB {
fn build(&self, _: &mut App) {}
}
struct PluginC;
impl Plugin for PluginC {
fn build(&self, _: &mut App) {}
}
#[test]
fn basic_ordering() {
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB)
.add(PluginC);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginB>(),
std::any::TypeId::of::<PluginC>(),
]
);
}
#[test]
fn add_after() {
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB)
.add_after::<PluginA, PluginC>(PluginC);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginC>(),
std::any::TypeId::of::<PluginB>(),
]
);
}
#[test]
fn add_before() {
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB)
.add_before::<PluginB, PluginC>(PluginC);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginC>(),
std::any::TypeId::of::<PluginB>(),
]
);
}
#[test]
fn readd() {
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB)
.add(PluginC)
.add(PluginB);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginC>(),
std::any::TypeId::of::<PluginB>(),
]
);
}
#[test]
fn readd_after() {
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB)
.add(PluginC)
.add_after::<PluginA, PluginC>(PluginC);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginC>(),
std::any::TypeId::of::<PluginB>(),
]
);
}
#[test]
fn readd_before() {
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB)
.add(PluginC)
.add_before::<PluginB, PluginC>(PluginC);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginC>(),
std::any::TypeId::of::<PluginB>(),
]
);
}
#[test]
fn add_basic_subgroup() {
let group_a = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginB);
let group_b = PluginGroupBuilder::start::<NoopPluginGroup>()
.add_group(group_a)
.add(PluginC);
assert_eq!(
group_b.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginB>(),
std::any::TypeId::of::<PluginC>(),
]
);
}
#[test]
fn add_conflicting_subgroup() {
let group_a = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginA)
.add(PluginC);
let group_b = PluginGroupBuilder::start::<NoopPluginGroup>()
.add(PluginB)
.add(PluginC);
let group = PluginGroupBuilder::start::<NoopPluginGroup>()
.add_group(group_a)
.add_group(group_b);
assert_eq!(
group.order,
vec![
std::any::TypeId::of::<PluginA>(),
std::any::TypeId::of::<PluginB>(),
std::any::TypeId::of::<PluginC>(),
]
);
}
}