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-rw-r--r--xpcom/ds/Atom.py64
1 files changed, 64 insertions, 0 deletions
diff --git a/xpcom/ds/Atom.py b/xpcom/ds/Atom.py
new file mode 100644
index 0000000000..1399ba840a
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+++ b/xpcom/ds/Atom.py
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+# 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