gecko-dev/xpcom/ds/Atom.py
Cameron McCormack be0a66bcfb Bug 1483121 - Generate static atom hash in StaticAtoms.py. r=njn,emilio
Summary: Depends On D3286

Reviewers: njn!, emilio!

Tags: #secure-revision

Bug #: 1483121

Differential Revision: https://phabricator.services.mozilla.com/D3295
2018-08-15 15:52:42 +10:00

55 lines
1.5 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)
class PseudoElementAtom(Atom):
def __init__(self, ident, string):
Atom.__init__(self, ident, string, ty="nsICSSPseudoElement")
class AnonBoxAtom(Atom):
def __init__(self, ident, string):
Atom.__init__(self, ident, string, ty="nsICSSAnonBoxPseudo")
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