servo/components/style/gecko_string_cache/mod.rs
2017-05-08 21:33:58 +10:00

360 lines
9.2 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/. */
#![allow(unsafe_code)]
//! A drop-in replacement for string_cache, but backed by Gecko `nsIAtom`s.
use gecko_bindings::bindings::Gecko_AddRefAtom;
use gecko_bindings::bindings::Gecko_Atomize;
use gecko_bindings::bindings::Gecko_Atomize16;
use gecko_bindings::bindings::Gecko_ReleaseAtom;
use gecko_bindings::structs::nsIAtom;
use nsstring::nsAString;
use precomputed_hash::PrecomputedHash;
use std::ascii::AsciiExt;
use std::borrow::{Cow, Borrow};
use std::char::{self, DecodeUtf16};
use std::fmt::{self, Write};
use std::hash::{Hash, Hasher};
use std::iter::Cloned;
use std::mem;
use std::ops::Deref;
use std::slice;
#[macro_use]
#[allow(improper_ctypes, non_camel_case_types, missing_docs)]
pub mod atom_macro {
include!(concat!(env!("OUT_DIR"), "/gecko/atom_macro.rs"));
}
#[macro_use]
pub mod namespace;
pub use self::namespace::{Namespace, WeakNamespace};
macro_rules! local_name {
($s: tt) => { atom!($s) }
}
/// A strong reference to a Gecko atom.
#[derive(PartialEq, Eq)]
pub struct Atom(*mut WeakAtom);
/// An atom *without* a strong reference.
///
/// Only usable as `&'a WeakAtom`,
/// where `'a` is the lifetime of something that holds a strong reference to that atom.
pub struct WeakAtom(nsIAtom);
/// A BorrowedAtom for Gecko is just a weak reference to a `nsIAtom`, that
/// hasn't been bumped.
pub type BorrowedAtom<'a> = &'a WeakAtom;
impl Deref for Atom {
type Target = WeakAtom;
#[inline]
fn deref(&self) -> &WeakAtom {
unsafe {
&*self.0
}
}
}
impl PrecomputedHash for Atom {
#[inline]
fn precomputed_hash(&self) -> u32 {
self.get_hash()
}
}
impl Borrow<WeakAtom> for Atom {
#[inline]
fn borrow(&self) -> &WeakAtom {
self
}
}
impl Eq for WeakAtom {}
impl PartialEq for WeakAtom {
#[inline]
fn eq(&self, other: &Self) -> bool {
let weak: *const WeakAtom = self;
let other: *const WeakAtom = other;
weak == other
}
}
unsafe impl Send for Atom {}
unsafe impl Sync for Atom {}
unsafe impl Sync for WeakAtom {}
impl WeakAtom {
/// Construct a `WeakAtom` from a raw `nsIAtom`.
#[inline]
pub unsafe fn new<'a>(atom: *mut nsIAtom) -> &'a mut Self {
&mut *(atom as *mut WeakAtom)
}
/// Clone this atom, bumping the refcount if the atom is not static.
#[inline]
pub fn clone(&self) -> Atom {
Atom::from(self.as_ptr())
}
/// Get the atom hash.
#[inline]
pub fn get_hash(&self) -> u32 {
self.0.mHash
}
/// Get the atom as a slice of utf-16 chars.
#[inline]
pub fn as_slice(&self) -> &[u16] {
unsafe {
slice::from_raw_parts((*self.as_ptr()).mString, self.len() as usize)
}
}
// NOTE: don't expose this, since it's slow, and easy to be misused.
fn chars(&self) -> DecodeUtf16<Cloned<slice::Iter<u16>>> {
char::decode_utf16(self.as_slice().iter().cloned())
}
/// Execute `cb` with the string that this atom represents.
///
/// Find alternatives to this function when possible, please, since it's
/// pretty slow.
pub fn with_str<F, Output>(&self, cb: F) -> Output
where F: FnOnce(&str) -> Output
{
// FIXME(bholley): We should measure whether it makes more sense to
// cache the UTF-8 version in the Gecko atom table somehow.
let owned = self.to_string();
cb(&owned)
}
/// Convert this Atom into a string, decoding the UTF-16 bytes.
///
/// Find alternatives to this function when possible, please, since it's
/// pretty slow.
#[inline]
pub fn to_string(&self) -> String {
String::from_utf16(self.as_slice()).unwrap()
}
/// Returns whether this atom is static.
#[inline]
pub fn is_static(&self) -> bool {
// FIXME(emilio): re-introduce bitfield accessors:
//
// https://github.com/servo/rust-bindgen/issues/519
unsafe {
((*self.as_ptr())._bitfield_1 & (0x80000000 as u32)) != 0
}
}
/// Returns the length of the atom string.
#[inline]
pub fn len(&self) -> u32 {
// FIXME(emilio): re-introduce bitfield accessors:
//
// https://github.com/servo/rust-bindgen/issues/519
unsafe {
(*self.as_ptr())._bitfield_1 & 0x7FFFFFFF
}
}
/// Returns whether this atom is the empty string.
#[inline]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Returns the atom as a mutable pointer.
#[inline]
pub fn as_ptr(&self) -> *mut nsIAtom {
let const_ptr: *const nsIAtom = &self.0;
const_ptr as *mut nsIAtom
}
}
impl fmt::Debug for WeakAtom {
fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
write!(w, "Gecko WeakAtom({:p}, {})", self, self)
}
}
impl fmt::Display for WeakAtom {
fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
for c in self.chars() {
try!(w.write_char(c.unwrap_or(char::REPLACEMENT_CHARACTER)))
}
Ok(())
}
}
impl Atom {
/// Execute a callback with the atom represented by `ptr`.
pub unsafe fn with<F, R: 'static>(ptr: *mut nsIAtom, callback: &mut F) -> R where F: FnMut(&Atom) -> R {
let atom = Atom(WeakAtom::new(ptr));
let ret = callback(&atom);
mem::forget(atom);
ret
}
/// Creates an atom from an static atom pointer without checking in release
/// builds.
///
/// Right now it's only used by the atom macro, and ideally it should keep
/// that way, now we have sugar for is_static, creating atoms using
/// Atom::from should involve almost no overhead.
#[inline]
unsafe fn from_static(ptr: *mut nsIAtom) -> Self {
let atom = Atom(ptr as *mut WeakAtom);
debug_assert!(atom.is_static(),
"Called from_static for a non-static atom!");
atom
}
/// Creates an atom from a dynamic atom pointer that has already had AddRef
/// called on it.
#[inline]
pub unsafe fn from_addrefed(ptr: *mut nsIAtom) -> Self {
debug_assert!(!ptr.is_null());
unsafe {
Atom(WeakAtom::new(ptr))
}
}
/// Convert this atom into an addrefed nsIAtom pointer.
#[inline]
pub fn into_addrefed(self) -> *mut nsIAtom {
let ptr = self.as_ptr();
mem::forget(self);
ptr
}
/// Return whether two atoms are ASCII-case-insensitive matches
pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool {
let a = self.as_slice();
let b = other.as_slice();
a.len() == b.len() && a.iter().zip(b).all(|(&a16, &b16)| {
if a16 <= 0x7F && b16 <= 0x7F {
(a16 as u8).eq_ignore_ascii_case(&(b16 as u8))
} else {
a16 == b16
}
})
}
/// Return whether this atom is an ASCII-case-insensitive match for the given string
pub fn eq_str_ignore_ascii_case(&self, other: &str) -> bool {
self.chars().map(|r| r.map(|c: char| c.to_ascii_lowercase()))
.eq(other.chars().map(|c: char| Ok(c.to_ascii_lowercase())))
}
}
impl Hash for Atom {
fn hash<H>(&self, state: &mut H) where H: Hasher {
state.write_u32(self.get_hash());
}
}
impl Hash for WeakAtom {
fn hash<H>(&self, state: &mut H) where H: Hasher {
state.write_u32(self.get_hash());
}
}
impl Clone for Atom {
#[inline(always)]
fn clone(&self) -> Atom {
Atom::from(self.as_ptr())
}
}
impl Drop for Atom {
#[inline]
fn drop(&mut self) {
if !self.is_static() {
unsafe {
Gecko_ReleaseAtom(self.as_ptr());
}
}
}
}
impl Default for Atom {
#[inline]
fn default() -> Self {
atom!("")
}
}
impl fmt::Debug for Atom {
fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
write!(w, "Gecko Atom({:p}, {})", self.0, self)
}
}
impl fmt::Display for Atom {
fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
unsafe {
(&*self.0).fmt(w)
}
}
}
impl<'a> From<&'a str> for Atom {
#[inline]
fn from(string: &str) -> Atom {
debug_assert!(string.len() <= u32::max_value() as usize);
unsafe {
Atom(WeakAtom::new(
Gecko_Atomize(string.as_ptr() as *const _, string.len() as u32)
))
}
}
}
impl<'a> From<&'a nsAString> for Atom {
#[inline]
fn from(string: &nsAString) -> Atom {
unsafe {
Atom(WeakAtom::new(
Gecko_Atomize16(string)
))
}
}
}
impl<'a> From<Cow<'a, str>> for Atom {
#[inline]
fn from(string: Cow<'a, str>) -> Atom {
Atom::from(&*string)
}
}
impl From<String> for Atom {
#[inline]
fn from(string: String) -> Atom {
Atom::from(&*string)
}
}
impl From<*mut nsIAtom> for Atom {
#[inline]
fn from(ptr: *mut nsIAtom) -> Atom {
debug_assert!(!ptr.is_null());
unsafe {
let ret = Atom(WeakAtom::new(ptr));
if !ret.is_static() {
Gecko_AddRefAtom(ptr);
}
ret
}
}
}