Include module for desktop build

libs/pyutil/xor/xor.py

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+#  Copyright © 2002-2010 Zooko Wilcox-O'Hearn
+#  This file is part of pyutil; see README.rst for licensing terms.
+
+"""
+What word has three letters and a 'x' in it?
+
+Not that one silly.
+"""
+
+import warnings
+import array, operator
+
+from pyutil.assertutil import precondition
+
+def py_xor(str1, str2):
+    warnings.warn("deprecated", DeprecationWarning)
+    precondition(len(str1) == len(str2), "str1 and str2 are required to be of the same length.", str1=str1, str2=str2)
+
+    if len(str1)%4 == 0:
+        a1 = array.array('i', str1)
+        a2 = array.array('i', str2)
+        for i in range(len(a1)):
+            a2[i] = a2[i]^a1[i]
+    elif len(str1)%2 == 0:
+        a1 = array.array('h', str1)
+        a2 = array.array('h', str2)
+        for i in range(len(a1)):
+            a2[i] = a2[i]^a1[i]
+    else:
+        a1 = array.array('c', str1)
+        a2 = array.array('c', str2)
+        for i in range(len(a1)):
+            a2[i] = chr(ord(a2[i])^ord(a1[i]))
+
+    return a2.tostring()
+
+def py_xor_simple(str1, str2):
+    """
+    Benchmarks show that this is the same speed as py_xor() for small strings
+    and much slower for large strings, so don't use it. --Zooko 2002-04-29
+    """
+    warnings.warn("deprecated", DeprecationWarning)
+    precondition(len(str1) == len(str2), "str1 and str2 are required to be of the same length.", str1=str1, str2=str2)
+
+    return ''.join(map(chr, map(operator.__xor__, map(ord, str1), map(ord, str2))))
+
+# Now make "xor.xor()" be the best xor we've got:
+xor = py_xor
+
+# for unit tests, see pyutil/test/test_xor.py.  For benchmarks, see pyutil/test/bench_xor.py.