mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-10-08 19:04:45 +00:00
6ca25ecbe6
And thus massively speed up ascii-case-insensitive atom comparisons when both atoms are lowercase (which is the common case by far). This removes almost all the slow selector-matching in this page, and it seems an easier fix than storing the lowercased version of all class-names in quirks mode in elements and selectors... Differential Revision: https://phabricator.services.mozilla.com/D10945 --HG-- extra : moz-landing-system : lando
65 lines
1.9 KiB
Python
65 lines
1.9 KiB
Python
# 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/.
|
|
|
|
|
|
class Atom():
|
|
def __init__(self, ident, string, ty="nsStaticAtom"):
|
|
self.ident = ident
|
|
self.string = string
|
|
self.ty = ty
|
|
self.atom_type = self.__class__.__name__
|
|
self.hash = hash_string(string)
|
|
self.is_ascii_lowercase = is_ascii_lowercase(string)
|
|
|
|
|
|
class PseudoElementAtom(Atom):
|
|
def __init__(self, ident, string):
|
|
Atom.__init__(self, ident, string, ty="nsCSSPseudoElementStaticAtom")
|
|
|
|
|
|
class AnonBoxAtom(Atom):
|
|
def __init__(self, ident, string):
|
|
Atom.__init__(self, ident, string, ty="nsCSSAnonBoxPseudoStaticAtom")
|
|
|
|
|
|
class NonInheritingAnonBoxAtom(AnonBoxAtom):
|
|
def __init__(self, ident, string):
|
|
AnonBoxAtom.__init__(self, ident, string)
|
|
|
|
|
|
class InheritingAnonBoxAtom(AnonBoxAtom):
|
|
def __init__(self, ident, string):
|
|
AnonBoxAtom.__init__(self, ident, string)
|
|
|
|
|
|
GOLDEN_RATIO_U32 = 0x9E3779B9
|
|
|
|
|
|
def rotate_left_5(value):
|
|
return ((value << 5) | (value >> 27)) & 0xFFFFFFFF
|
|
|
|
|
|
def wrapping_multiply(x, y):
|
|
return (x * y) & 0xFFFFFFFF
|
|
|
|
|
|
# Calculate the precomputed hash of the static atom. This is a port of
|
|
# mozilla::HashString(const char16_t*), which is what we use for atomizing
|
|
# strings. An assertion in nsAtomTable::RegisterStaticAtoms ensures that
|
|
# the value we compute here matches what HashString() would produce.
|
|
def hash_string(s):
|
|
h = 0
|
|
for c in s:
|
|
h = wrapping_multiply(GOLDEN_RATIO_U32, rotate_left_5(h) ^ ord(c))
|
|
return h
|
|
|
|
|
|
# Returns true if lowercasing this string in an ascii-case-insensitive way
|
|
# would leave the string unchanged.
|
|
def is_ascii_lowercase(s):
|
|
for c in s:
|
|
if c >= 'A' and c <= 'Z':
|
|
return False
|
|
return True
|