add scary-looking-but-safe dynamic downcast for a component_mut accessor

This commit is contained in:
lifning 2021-10-17 21:46:12 -07:00
parent 26ff040136
commit 268f1b4ff8
2 changed files with 30 additions and 8 deletions

View File

@ -1,5 +1,6 @@
use crate::prelude::*;
use ferretro_base::retro::ffi::*;
use std::any::{Any, TypeId};
use std::os::raw::c_uint;
use std::path::{PathBuf, Path};
use std::pin::Pin;
@ -9,7 +10,8 @@ pub struct RetroComponentBase {
retro: LibretroWrapper,
libretro_path: PathBuf,
// TODO: control when things get added to this with lifetime constraints defined by implementers
components: Vec<Box<dyn RetroComponent>>,
components: Vec<Pin<Box<dyn RetroComponent>>>,
component_ptrs: Vec<(TypeId, *mut ())>,
// replaying env calls for late-added components
cached_rom_path: Option<PathBuf>,
@ -25,6 +27,9 @@ pub struct RetroComponentBase {
cached_geometry: Option<GameGeometry>,
}
#[derive(Copy, Clone, Debug)]
pub struct RetroComponentId(usize);
// TODO: replace with std::ops::ControlFlow when it becomes stable
pub enum ControlFlow {
Continue,
@ -35,7 +40,7 @@ pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
#[rustfmt::skip]
#[allow(unused_variables)]
pub trait RetroComponent: RetroCallbacks {
pub trait RetroComponent: RetroCallbacks + Any {
fn pre_init(&mut self, retro: &mut LibretroWrapper) -> Result<()> { Ok(()) }
fn post_init(&mut self, retro: &mut LibretroWrapper) -> Result<()> { Ok(()) }
fn pre_load_game(&mut self, retro: &mut LibretroWrapper, rom: &Path) -> Result<()> { Ok(()) }
@ -55,6 +60,7 @@ impl RetroComponentBase {
retro,
libretro_path: core_path.as_ref().to_path_buf(),
components: Vec::new(),
component_ptrs: Vec::new(),
cached_rom_path: None,
cached_pixel_format: None,
cached_input_descriptors: None,
@ -87,11 +93,13 @@ impl RetroComponentBase {
Ok(())
}
pub fn register_component<T>(&mut self, comp: T) -> Option<()> // TODO: Result
where T: RetroComponent
pub fn register_component<T>(&mut self, comp: T) -> Result<RetroComponentId>
where T: RetroComponent + Any
{
// TODO: match comp.schedule { BeforeInit, BeforeLoad, BeforeFirstRun, Anytime }
let mut comp = Box::new(comp);
let comp_type = comp.type_id();
let mut comp = Box::pin(comp);
let comp_ptr = comp.as_mut().get_mut() as *mut T;
if let Some(cached) = &self.cached_pixel_format {
if let Some(false) = comp.set_pixel_format(*cached) {
// TODO: error, and propagate this pattern downward
@ -126,12 +134,26 @@ impl RetroComponentBase {
}
if let Some(cached) = &self.cached_rom_path {
comp.post_load_game(&mut self.retro, &cached);
comp.post_load_game(&mut self.retro, &cached)?;
}
self.components.push(comp);
self.component_ptrs.push((comp_type, comp_ptr as *mut ()));
Some(())
Ok(RetroComponentId(self.components.len() - 1))
}
pub fn component_mut<T: RetroComponent>(&mut self, id: RetroComponentId) -> Result<&mut T> {
let (comp_type, comp_ptr) = self.component_ptrs.get(id.0)
.ok_or_else(|| format!("Invalid ID given to component_mut: {:?}", id))?;
if *comp_type == TypeId::of::<T>() {
Ok(unsafe { &mut *(*comp_ptr as *mut T) })
} else {
Err(format!(
"Invalid downcast for {:?}: {:?} != {:?}",
id, comp_type, TypeId::of::<T>()
).into())
}
}
pub fn load_game(&mut self, rom: impl AsRef<Path>) -> Result<()> {

View File

@ -2,7 +2,7 @@ pub mod provided;
pub mod base;
pub mod prelude {
pub use crate::base::{RetroComponent, RetroComponentBase};
pub use crate::base::{RetroComponent, RetroComponentBase, RetroComponentId};
pub use ferretro_base::retro::constants::*;
pub use ferretro_base::retro::wrapped_types::*;
pub use ferretro_base::retro::wrapper::{RetroCallbacks, LibretroWrapper, LibretroWrapperAccess};