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use std::hash::{Hash, Hasher};
use crate::{
binding_model::{self},
FastIndexMap,
};
/// Where a given BGL came from.
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum Origin {
/// The bind group layout was created by the user and is present in the BGL resource pool.
Pool,
/// The bind group layout was derived and is not present in the BGL resource pool.
Derived,
}
/// A HashMap-like structure that stores a BindGroupLayouts [`wgt::BindGroupLayoutEntry`]s.
///
/// It is hashable, so bind group layouts can be deduplicated.
#[derive(Debug, Default, Clone, Eq)]
pub struct EntryMap {
/// We use a IndexMap here so that we can sort the entries by their binding index,
/// guaranteeing that the hash of equivalent layouts will be the same.
inner: FastIndexMap<u32, wgt::BindGroupLayoutEntry>,
/// We keep track of whether the map is sorted or not, so that we can assert that
/// it is sorted, so that PartialEq and Hash will be stable.
///
/// We only need sorted if it is used in a Hash or PartialEq, so we never need
/// to actively sort it.
sorted: bool,
}
impl PartialEq for EntryMap {
fn eq(&self, other: &Self) -> bool {
self.assert_sorted();
other.assert_sorted();
self.inner == other.inner
}
}
impl Hash for EntryMap {
fn hash<H: Hasher>(&self, state: &mut H) {
self.assert_sorted();
// We don't need to hash the keys, since they are just extracted from the values.
//
// We know this is stable and will match the behavior of PartialEq as we ensure
// that the array is sorted.
for entry in self.inner.values() {
entry.hash(state);
}
}
}
impl EntryMap {
fn assert_sorted(&self) {
assert!(self.sorted);
}
/// Create a new [`EntryMap`] from a slice of [`wgt::BindGroupLayoutEntry`]s.
///
/// Errors if there are duplicate bindings or if any binding index is greater than
/// the device's limits.
pub fn from_entries(
device_limits: &wgt::Limits,
entries: &[wgt::BindGroupLayoutEntry],
) -> Result<Self, binding_model::CreateBindGroupLayoutError> {
let mut inner = FastIndexMap::with_capacity_and_hasher(entries.len(), Default::default());
for entry in entries {
if entry.binding >= device_limits.max_bindings_per_bind_group {
return Err(
binding_model::CreateBindGroupLayoutError::InvalidBindingIndex {
binding: entry.binding,
maximum: device_limits.max_bindings_per_bind_group,
},
);
}
if inner.insert(entry.binding, *entry).is_some() {
return Err(binding_model::CreateBindGroupLayoutError::ConflictBinding(
entry.binding,
));
}
}
inner.sort_unstable_keys();
Ok(Self {
inner,
sorted: true,
})
}
/// Get the count of [`wgt::BindGroupLayoutEntry`]s in this map.
pub fn len(&self) -> usize {
self.inner.len()
}
/// Get the [`wgt::BindGroupLayoutEntry`] for the given binding index.
pub fn get(&self, binding: u32) -> Option<&wgt::BindGroupLayoutEntry> {
self.inner.get(&binding)
}
/// Iterator over all the binding indices in this map.
pub fn indices(&self) -> impl ExactSizeIterator<Item = u32> + '_ {
self.inner.keys().copied()
}
/// Iterator over all the [`wgt::BindGroupLayoutEntry`]s in this map.
pub fn values(&self) -> impl ExactSizeIterator<Item = &wgt::BindGroupLayoutEntry> + '_ {
self.inner.values()
}
pub fn iter(&self) -> impl ExactSizeIterator<Item = (&u32, &wgt::BindGroupLayoutEntry)> + '_ {
self.inner.iter()
}
pub fn is_empty(&self) -> bool {
self.inner.is_empty()
}
pub fn contains_key(&self, key: u32) -> bool {
self.inner.contains_key(&key)
}
pub fn entry(&mut self, key: u32) -> indexmap::map::Entry<'_, u32, wgt::BindGroupLayoutEntry> {
self.sorted = false;
self.inner.entry(key)
}
pub fn sort(&mut self) {
self.inner.sort_unstable_keys();
self.sorted = true;
}
}