bevy/crates/bevy_app/src/app_builder.rs

use crate::{
    app::{App, AppExit},
    event::Events,
    plugin::Plugin,
    stage, startup_stage, PluginGroup, PluginGroupBuilder,
};
use bevy_ecs::{FromResources, IntoSystem, Resources, System, World};
use bevy_utils::tracing::debug;

/// Configure [App]s using the builder pattern
pub struct AppBuilder {
    pub app: App,
}

impl Default for AppBuilder {
    fn default() -> Self {
        let mut app_builder = AppBuilder {
            app: App::default(),
        };

        app_builder.add_default_stages();
        app_builder.add_event::<AppExit>();
        app_builder
    }
}

impl AppBuilder {
    pub fn empty() -> AppBuilder {
        AppBuilder {
            app: App::default(),
        }
    }

    pub fn resources(&self) -> &Resources {
        &self.app.resources
    }

    pub fn resources_mut(&mut self) -> &mut Resources {
        &mut self.app.resources
    }

    pub fn run(&mut self) {
        let app = std::mem::take(&mut self.app);
        app.run();
    }

    pub fn set_world(&mut self, world: World) -> &mut Self {
        self.app.world = world;
        self
    }

    pub fn add_stage(&mut self, stage_name: &'static str) -> &mut Self {
        self.app.schedule.add_stage(stage_name);
        self
    }

    pub fn add_stage_after(&mut self, target: &'static str, stage_name: &'static str) -> &mut Self {
        self.app.schedule.add_stage_after(target, stage_name);
        self
    }

    pub fn add_stage_before(
        &mut self,
        target: &'static str,
        stage_name: &'static str,
    ) -> &mut Self {
        self.app.schedule.add_stage_before(target, stage_name);
        self
    }

    pub fn add_startup_stage(&mut self, stage_name: &'static str) -> &mut Self {
        self.app.startup_schedule.add_stage(stage_name);
        self
    }

    pub fn add_startup_stage_after(
        &mut self,
        target: &'static str,
        stage_name: &'static str,
    ) -> &mut Self {
        self.app
            .startup_schedule
            .add_stage_after(target, stage_name);
        self
    }

    pub fn add_startup_stage_before(
        &mut self,
        target: &'static str,
        stage_name: &'static str,
    ) -> &mut Self {
        self.app
            .startup_schedule
            .add_stage_before(target, stage_name);
        self
    }

    pub fn add_system(&mut self, system: Box<dyn System>) -> &mut Self {
        self.add_system_to_stage(stage::UPDATE, system)
    }

    pub fn add_systems(&mut self, systems: Vec<Box<dyn System>>) -> &mut Self {
        self.add_systems_to_stage(stage::UPDATE, systems)
    }

    pub fn init_system(
        &mut self,
        build: impl FnMut(&mut Resources) -> Box<dyn System>,
    ) -> &mut Self {
        self.init_system_to_stage(stage::UPDATE, build)
    }

    pub fn init_system_to_stage(
        &mut self,
        stage: &'static str,
        mut build: impl FnMut(&mut Resources) -> Box<dyn System>,
    ) -> &mut Self {
        let system = build(&mut self.app.resources);
        self.add_system_to_stage(stage, system)
    }

    pub fn add_startup_system_to_stage(
        &mut self,
        stage_name: &'static str,
        system: Box<dyn System>,
    ) -> &mut Self {
        self.app
            .startup_schedule
            .add_system_to_stage(stage_name, system);
        self
    }

    pub fn add_startup_systems_to_stage(
        &mut self,
        stage_name: &'static str,
        systems: Vec<Box<dyn System>>,
    ) -> &mut Self {
        for system in systems {
            self.app
                .startup_schedule
                .add_system_to_stage(stage_name, system);
        }
        self
    }

    pub fn add_startup_system(&mut self, system: Box<dyn System>) -> &mut Self {
        self.app
            .startup_schedule
            .add_system_to_stage(startup_stage::STARTUP, system);
        self
    }

    pub fn add_startup_systems(&mut self, systems: Vec<Box<dyn System>>) -> &mut Self {
        self.add_startup_systems_to_stage(startup_stage::STARTUP, systems)
    }

    pub fn init_startup_system(
        &mut self,
        build: impl FnMut(&mut Resources) -> Box<dyn System>,
    ) -> &mut Self {
        self.init_startup_system_to_stage(startup_stage::STARTUP, build)
    }

    pub fn init_startup_system_to_stage(
        &mut self,
        stage: &'static str,
        mut build: impl FnMut(&mut Resources) -> Box<dyn System>,
    ) -> &mut Self {
        let system = build(&mut self.app.resources);
        self.add_startup_system_to_stage(stage, system)
    }

    pub fn add_default_stages(&mut self) -> &mut Self {
        self.add_startup_stage(startup_stage::PRE_STARTUP)
            .add_startup_stage(startup_stage::STARTUP)
            .add_startup_stage(startup_stage::POST_STARTUP)
            .add_stage(stage::FIRST)
            .add_stage(stage::PRE_EVENT)
            .add_stage(stage::EVENT)
            .add_stage(stage::PRE_UPDATE)
            .add_stage(stage::UPDATE)
            .add_stage(stage::POST_UPDATE)
            .add_stage(stage::LAST)
    }

    pub fn add_system_to_stage(
        &mut self,
        stage_name: &'static str,
        system: Box<dyn System>,
    ) -> &mut Self {
        self.app.schedule.add_system_to_stage(stage_name, system);
        self
    }

    pub fn add_system_to_stage_front(
        &mut self,
        stage_name: &'static str,
        system: Box<dyn System>,
    ) -> &mut Self {
        self.app
            .schedule
            .add_system_to_stage_front(stage_name, system);
        self
    }

    pub fn add_systems_to_stage(
        &mut self,
        stage_name: &'static str,
        systems: Vec<Box<dyn System>>,
    ) -> &mut Self {
        for system in systems {
            self.app.schedule.add_system_to_stage(stage_name, system);
        }
        self
    }

    pub fn add_event<T>(&mut self) -> &mut Self
    where
        T: Send + Sync + 'static,
    {
        self.add_resource(Events::<T>::default())
            .add_system_to_stage(stage::EVENT, Events::<T>::update_system.system())
    }

    /// Adds a resource to the current [App] and overwrites any resource previously added of the same type.
    pub fn add_resource<T>(&mut self, resource: T) -> &mut Self
    where
        T: Send + Sync + 'static,
    {
        self.app.resources.insert(resource);
        self
    }

    pub fn add_thread_local_resource<T>(&mut self, resource: T) -> &mut Self
    where
        T: 'static,
    {
        self.app.resources.insert_thread_local(resource);
        self
    }

    pub fn init_resource<R>(&mut self) -> &mut Self
    where
        R: FromResources + Send + Sync + 'static,
    {
        let resource = R::from_resources(&self.app.resources);
        self.app.resources.insert(resource);

        self
    }

    pub fn init_thread_local_resource<R>(&mut self) -> &mut Self
    where
        R: FromResources + 'static,
    {
        let resource = R::from_resources(&self.app.resources);
        self.app.resources.insert_thread_local(resource);

        self
    }

    pub fn set_runner(&mut self, run_fn: impl Fn(App) + 'static) -> &mut Self {
        self.app.runner = Box::new(run_fn);
        self
    }

    pub fn add_plugin<T>(&mut self, plugin: T) -> &mut Self
    where
        T: Plugin,
    {
        debug!("added plugin: {}", plugin.name());
        plugin.build(self);
        self
    }

    pub fn add_plugins<T: PluginGroup>(&mut self, mut group: T) -> &mut Self {
        let mut plugin_group_builder = PluginGroupBuilder::default();
        group.build(&mut plugin_group_builder);
        plugin_group_builder.finish(self);
        self
    }

    pub fn add_plugins_with<T, F>(&mut self, mut group: T, func: F) -> &mut Self
    where
        T: PluginGroup,
        F: FnOnce(&mut PluginGroupBuilder) -> &mut PluginGroupBuilder,
    {
        let mut plugin_group_builder = PluginGroupBuilder::default();
        group.build(&mut plugin_group_builder);
        func(&mut plugin_group_builder);
        plugin_group_builder.finish(self);
        self
    }
}