rpc-router 0.2.0

//! rpc-router Notes:
//! - Currently, this is mostly copy of the `extensions.rs` from the `http@1.1.0` crate.
//! - Only visible to `crate::resource` and encapsulated within `RpcResponses`.
//! - Subject to future changes. Ideally, it should be a type map.
//! - Presently, added a `_..` prefix to all unused functions.
//! - Decisions on what to retain or discard will be made later.

use std::any::{Any, TypeId};
use std::collections::HashMap;
use std::fmt;
use std::hash::{BuildHasherDefault, Hasher};

type AnyMap = HashMap<TypeId, Box<dyn AnyClone + Send + Sync>, BuildHasherDefault<IdHasher>>;

// With TypeIds as keys, there's no need to hash them. They are already hashes
// themselves, coming from the compiler. The IdHasher just holds the u64 of
// the TypeId, and then returns it, instead of doing any bit fiddling.
#[derive(Default)]
struct IdHasher(u64);

impl Hasher for IdHasher {
	fn write(&mut self, _: &[u8]) {
		unreachable!("TypeId calls write_u64");
	}

	#[inline]
	fn write_u64(&mut self, id: u64) {
		self.0 = id;
	}

	#[inline]
	fn finish(&self) -> u64 {
		self.0
	}
}

/// A type map of protocol extensions.
///
/// `Extensions` can be used by `Request` and `Response` to store
/// extra data derived from the underlying protocol.
#[derive(Clone, Default)]
pub(crate) struct ResourcesInner {
	// If extensions are never used, no need to carry around an empty HashMap.
	// That's 3 words. Instead, this is only 1 word.
	map: Option<Box<AnyMap>>,
}

// Note: Cherry picked functions from `extensions.rs` that is used in this code base.
//       The rest are prefixed with `_` for now.
impl ResourcesInner {
	/// Insert a type into this `Extensions`.
	///
	/// If a extension of this type already existed, it will
	/// be returned.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// assert!(ext.insert(5i32).is_none());
	/// assert!(ext.insert(4u8).is_none());
	/// assert_eq!(ext.insert(9i32), Some(5i32));
	/// ```
	pub fn insert<T: Clone + Send + Sync + 'static>(&mut self, val: T) -> Option<T> {
		self.map
			.get_or_insert_with(Box::default)
			.insert(TypeId::of::<T>(), Box::new(val))
			.and_then(|boxed| boxed.into_any().downcast().ok().map(|boxed| *boxed))
	}

	/// Get a reference to a type previously inserted on this `Extensions`.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// assert!(ext.get::<i32>().is_none());
	/// ext.insert(5i32);
	///
	/// assert_eq!(ext.get::<i32>(), Some(&5i32));
	/// ```
	pub fn get<T: Send + Sync + 'static>(&self) -> Option<&T> {
		self.map
			.as_ref()
			.and_then(|map| map.get(&TypeId::of::<T>()))
			.and_then(|boxed| (**boxed).as_any().downcast_ref())
	}

	/// Extends `self` with another `Extensions`.
	///
	/// If an instance of a specific type exists in both, the one in `self` is overwritten with the
	/// one from `other`.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext_a = Extensions::new();
	/// ext_a.insert(8u8);
	/// ext_a.insert(16u16);
	///
	/// let mut ext_b = Extensions::new();
	/// ext_b.insert(4u8);
	/// ext_b.insert("hello");
	///
	/// ext_a.extend(ext_b);
	/// assert_eq!(ext_a.len(), 3);
	/// assert_eq!(ext_a.get::<u8>(), Some(&4u8));
	/// assert_eq!(ext_a.get::<u16>(), Some(&16u16));
	/// assert_eq!(ext_a.get::<&'static str>().copied(), Some("hello"));
	/// ```
	pub fn extend(&mut self, other: Self) {
		if let Some(other) = other.map {
			if let Some(map) = &mut self.map {
				map.extend(*other);
			} else {
				self.map = Some(other);
			}
		}
	}

	/// Check whether the extension set is empty or not.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// assert!(ext.is_empty());
	/// ext.insert(5i32);
	/// assert!(!ext.is_empty());
	/// ```
	#[inline]
	pub fn is_empty(&self) -> bool {
		self.map.as_ref().is_none_or(|map| map.is_empty())
	}
}

// Note: Usued code for now (from `extensions.rs`, keep until refactor)
#[allow(unused)] // For early development.
impl ResourcesInner {
	/// Create an empty `Extensions`.
	#[inline]
	fn _new() -> ResourcesInner {
		ResourcesInner { map: None }
	}

	/// Get a mutable reference to a type previously inserted on this `Extensions`.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// ext.insert(String::from("Hello"));
	/// ext.get_mut::<String>().unwrap().push_str(" World");
	///
	/// assert_eq!(ext.get::<String>().unwrap(), "Hello World");
	/// ```
	fn get_mut<T: Send + Sync + 'static>(&mut self) -> Option<&mut T> {
		self.map
			.as_mut()
			.and_then(|map| map.get_mut(&TypeId::of::<T>()))
			.and_then(|boxed| (**boxed).as_any_mut().downcast_mut())
	}

	/// Get a mutable reference to a type, inserting `value` if not already present on this
	/// `Extensions`.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// *ext.get_or_insert(1i32) += 2;
	///
	/// assert_eq!(*ext.get::<i32>().unwrap(), 3);
	/// ```
	fn get_or_insert<T: Clone + Send + Sync + 'static>(&mut self, value: T) -> &mut T {
		self.get_or_insert_with(|| value)
	}

	/// Get a mutable reference to a type, inserting the value created by `f` if not already present
	/// on this `Extensions`.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// *ext.get_or_insert_with(|| 1i32) += 2;
	///
	/// assert_eq!(*ext.get::<i32>().unwrap(), 3);
	/// ```
	fn get_or_insert_with<T: Clone + Send + Sync + 'static, F: FnOnce() -> T>(&mut self, f: F) -> &mut T {
		let out = self
			.map
			.get_or_insert_with(Box::default)
			.entry(TypeId::of::<T>())
			.or_insert_with(|| Box::new(f()));
		(**out).as_any_mut().downcast_mut().unwrap()
	}

	/// Get a mutable reference to a type, inserting the type's default value if not already present
	/// on this `Extensions`.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// *ext.get_or_insert_default::<i32>() += 2;
	///
	/// assert_eq!(*ext.get::<i32>().unwrap(), 2);
	/// ```
	fn get_or_insert_default<T: Default + Clone + Send + Sync + 'static>(&mut self) -> &mut T {
		self.get_or_insert_with(T::default)
	}

	/// Remove a type from this `Extensions`.
	///
	/// If a extension of this type existed, it will be returned.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// ext.insert(5i32);
	/// assert_eq!(ext.remove::<i32>(), Some(5i32));
	/// assert!(ext.get::<i32>().is_none());
	/// ```
	fn remove<T: Send + Sync + 'static>(&mut self) -> Option<T> {
		self.map
			.as_mut()
			.and_then(|map| map.remove(&TypeId::of::<T>()))
			.and_then(|boxed| boxed.into_any().downcast().ok().map(|boxed| *boxed))
	}

	/// Clear the `Extensions` of all inserted extensions.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// ext.insert(5i32);
	/// ext.clear();
	///
	/// assert!(ext.get::<i32>().is_none());
	/// ```
	#[inline]
	fn clear(&mut self) {
		if let Some(ref mut map) = self.map {
			map.clear();
		}
	}

	/// Get the numer of extensions available.
	///
	/// # Example
	///
	/// ```
	/// # use http::Extensions;
	/// let mut ext = Extensions::new();
	/// assert_eq!(ext.len(), 0);
	/// ext.insert(5i32);
	/// assert_eq!(ext.len(), 1);
	/// ```
	#[inline]
	pub fn len(&self) -> usize {
		self.map.as_ref().map_or(0, |map| map.len())
	}
}

impl fmt::Debug for ResourcesInner {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		f.debug_struct("Extensions").finish()
	}
}

trait AnyClone: Any {
	fn clone_box(&self) -> Box<dyn AnyClone + Send + Sync>;
	fn as_any(&self) -> &dyn Any;
	fn as_any_mut(&mut self) -> &mut dyn Any;
	fn into_any(self: Box<Self>) -> Box<dyn Any>;
}

impl<T: Clone + Send + Sync + 'static> AnyClone for T {
	fn clone_box(&self) -> Box<dyn AnyClone + Send + Sync> {
		Box::new(self.clone())
	}

	fn as_any(&self) -> &dyn Any {
		self
	}

	fn as_any_mut(&mut self) -> &mut dyn Any {
		self
	}

	fn into_any(self: Box<Self>) -> Box<dyn Any> {
		self
	}
}

impl Clone for Box<dyn AnyClone + Send + Sync> {
	fn clone(&self) -> Self {
		(**self).clone_box()
	}
}

#[test]
fn test_extensions() {
	#[derive(Clone, Debug, PartialEq)]
	struct MyType(i32);

	let mut extensions = ResourcesInner::_new();

	extensions.insert(5i32);
	extensions.insert(MyType(10));

	assert_eq!(extensions.get(), Some(&5i32));
	assert_eq!(extensions.get_mut(), Some(&mut 5i32));

	let ext2 = extensions.clone();

	assert_eq!(extensions.remove::<i32>(), Some(5i32));
	assert!(extensions.get::<i32>().is_none());

	// clone still has it
	assert_eq!(ext2.get(), Some(&5i32));
	assert_eq!(ext2.get(), Some(&MyType(10)));

	assert_eq!(extensions.get::<bool>(), None);
	assert_eq!(extensions.get(), Some(&MyType(10)));
}