servo/components/style/use_counters/mod.rs
2018-11-10 17:47:28 +01:00

88 lines
2.8 KiB
Rust

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
//! Various stuff for CSS property use counters.
use crate::properties::{NonCustomPropertyId, NON_CUSTOM_PROPERTY_ID_COUNT};
#[cfg(feature = "gecko")]
use gecko_bindings::sugar::ownership::{HasBoxFFI, HasFFI, HasSimpleFFI};
use std::cell::Cell;
#[cfg(target_pointer_width = "64")]
const BITS_PER_ENTRY: usize = 64;
#[cfg(target_pointer_width = "32")]
const BITS_PER_ENTRY: usize = 32;
/// One bit per each non-custom CSS property.
#[derive(Default)]
pub struct NonCustomPropertyUseCounters {
storage: [Cell<usize>; (NON_CUSTOM_PROPERTY_ID_COUNT - 1 + BITS_PER_ENTRY) / BITS_PER_ENTRY],
}
impl NonCustomPropertyUseCounters {
/// Returns the bucket a given property belongs in, and the bitmask for that
/// property.
#[inline(always)]
fn bucket_and_pattern(id: NonCustomPropertyId) -> (usize, usize) {
let bit = id.bit();
let bucket = bit / BITS_PER_ENTRY;
let bit_in_bucket = bit % BITS_PER_ENTRY;
(bucket, 1 << bit_in_bucket)
}
/// Record that a given non-custom property ID has been parsed.
#[inline]
pub fn record(&self, id: NonCustomPropertyId) {
let (bucket, pattern) = Self::bucket_and_pattern(id);
let bucket = &self.storage[bucket];
bucket.set(bucket.get() | pattern)
}
/// Returns whether a given non-custom property ID has been recorded
/// earlier.
#[inline]
pub fn recorded(&self, id: NonCustomPropertyId) -> bool {
let (bucket, pattern) = Self::bucket_and_pattern(id);
self.storage[bucket].get() & pattern != 0
}
/// Merge `other` into `self`.
#[inline]
fn merge(&self, other: &Self) {
for (bucket, other_bucket) in self.storage.iter().zip(other.storage.iter()) {
bucket.set(bucket.get() | other_bucket.get())
}
}
}
/// The use-counter data related to a given document we want to store.
#[derive(Default)]
pub struct UseCounters {
/// The counters for non-custom properties that have been parsed in the
/// document's stylesheets.
pub non_custom_properties: NonCustomPropertyUseCounters,
}
impl UseCounters {
/// Merge the use counters.
///
/// Used for parallel parsing, where we parse off-main-thread.
#[inline]
pub fn merge(&self, other: &Self) {
self.non_custom_properties
.merge(&other.non_custom_properties)
}
}
#[cfg(feature = "gecko")]
unsafe impl HasFFI for UseCounters {
type FFIType = ::gecko_bindings::structs::StyleUseCounters;
}
#[cfg(feature = "gecko")]
unsafe impl HasSimpleFFI for UseCounters {}
#[cfg(feature = "gecko")]
unsafe impl HasBoxFFI for UseCounters {}