Implementing bitcode.

src/bitcode/intbitset.py

@@ -0,0 +1,194 @@
+# Copyright (c) nexB Inc. and others. All rights reserved.
+# ahocode is a trademark of nexB Inc.
+# SPDX-License-Identifier: Apache-2.0
+# See http://www.apache.org/licenses/LICENSE-2.0 for the license text.
+# See https://github.com/nexB/ahocode for support or download.
+# See https://aboutcode.org for more information about nexB OSS projects.
+
+CFG_INTBITSET_ENABLE_SANITY_CHECKS = True
+
+
+class intbitset:
+    def __init__(self, rhs=None, preallocate=-1, trailing_bits=0, sanity_checks=CFG_INTBITSET_ENABLE_SANITY_CHECKS,
+                 no_allocate=0):
+        self.bitset = 0
+
+        if isinstance(rhs, int):
+            self.bitset = rhs
+        elif isinstance(rhs, intbitset):
+            self.bitset = rhs.bitset
+        elif isinstance(rhs, (list, set, frozenset)):
+            for value in rhs:
+                self.add(value)
+
+        self.preallocate = preallocate
+        self.trailing_bits = trailing_bits
+        self.sanity_checks = sanity_checks
+        self.no_allocate = no_allocate
+
+    def add(self, value):
+        """
+        Add an element to a set.
+                This has no effect if the element is already present.
+        """
+        if value < 0:
+            raise ValueError("Value can't be negative")
+        self.bitset |= 1 << value
+
+    def clear(self):
+        self.bitset = 0
+
+    def copy(self):
+        """ Return a shallow copy of a set. """
+        new = intbitset()
+        intbitset.bitset = self.bitset
+        return new
+
+    def difference(self, other):
+        """ Return a new intbitset with elements from the intbitset that are not in the others. """
+        new = intbitset()
+        new.bitset = (self.bitset ^ other.bitset) & self.bitset
+        return new
+
+    def difference_update(self, other):
+        """ Update the intbitset, removing elements found in others. """
+        self.bitset &= (self.bitset ^ other.bitset)
+
+    def discard(self, value):
+        """
+        Remove an element from a intbitset if it is a member.
+                If the element is not a member, do nothing.
+        """
+        self.bitset &= ~(1 << value)
+
+    def isdisjoint(self, other):
+        """ Return True if two intbitsets have a null intersection. """
+        return self.intersection(*[other]).bitset == 0
+
+    def issuperset(self, other):
+        """ Report whether this set contains another set. """
+        return (self.bitset & other.bitset) == other.bitset
+
+    def issubset(self, other):
+        """ Report whether another set contains this set. """
+        return (self.bitset & other.bitset) == self.bitset
+
+    def remove(self, key):
+        """
+        Remove an element from a set; it must be a member.
+                If the element is not a member, raise a KeyError.
+        """
+        initial_bitset = self.bitset
+        self.discard(key)
+        if initial_bitset != self.bitset:
+            raise KeyError(f"{key} not in bitset")
+
+    def strbits(self):
+        """
+        Return a string of 0s and 1s representing the content in memory
+                of the intbitset.
+        """
+        return bin(self.bitset)[2:]
+
+    def symmetric_difference(self, other):
+        """
+        Return the symmetric difference of two sets as a new set.
+                (i.e. all elements that are in exactly one of the sets.)
+        """
+        new = intbitset()
+        new.bitset = other.bitset ^ self.bitset
+        return new
+
+    def symmetric_difference_update(self, other):
+        """ Update an intbitset with the symmetric difference of itself and another. """
+        self.bitset ^= other.bitset
+
+    def tolist(self):
+        """
+        Legacy method to retrieve a list of all the elements inside an
+                intbitset.
+        """
+        elements = []
+        for element in self:
+            elements = [element] + elements
+        return elements
+
+    def union(self, *args):
+        """ Return a new intbitset with elements from the intbitset and all others. """
+        new = intbitset()
+        bitset = self.bitset
+        for other in args:
+            bitset |= other.bitset
+        new.bitset = bitset
+        return new
+
+    def union_update(self, *args):  # real signature unknown
+        """ Update the intbitset, adding elements from all others. """
+        for other in args:
+            self.bitset |= other.bitset
+
+    def intersection(self, *args):
+        """ Return a new intbitset with elements common to the intbitset and all others. """
+        new = intbitset()
+        bitset = self.bitset
+        for other in args:
+            bitset &= other.bitset
+        new.bitset = bitset
+        return new
+
+    def intersection_update(self, *args):
+        """ Update the intbitset, keeping only elements found in it and all others. """
+        for other in args:
+            self.bitset &= other.bitset
+
+    def update(self, *args, **kwargs):
+        """ Update the intbitset, adding elements from all others. """
+        pass
+
+    def __and__(self, other):
+        """
+            Return the intersection of two intbitsets as a new set.
+            (i.e. all elements that are in both intbitsets.)
+        """
+        new = intbitset()
+        new.bitset = self.bitset & other.bitset
+        return new
+
+    def __eq__(self, other):
+        """ Return self==value. """
+        return self.bitset == other.bitset
+
+    def __contains__(self, key):
+        """ Return key in self. """
+        key_bit = 1 << key
+        return key_bit & self.bitset == key_bit
+
+    def __len__(self):
+        """ Return len(self). """
+        return len(bin(self.bitset)) - 2
+
+    def __iter__(self):
+        """ Implement iter(self). """
+        bits = bin(self.bitset)[2:]
+        size = len(bits)
+        for bit in bits:
+            if bit == "1":
+                yield size
+            size -= 1
+
+    def __hash__(self):
+        return self.bitset
+
+    def __str__(self):
+        binary = bin(self.bitset)[2:]
+        n = len(binary)
+        ans = "intbitset(["
+        for char in binary:
+            if char == "1":
+                ans += str(n - 1)
+                if n > 0:
+                    ans += ", "
+            n -= 1
+        ans = ans.rstrip(', ')
+        ans += "])"
+        return ans