Data commit

Task/Ternary-logic/Python/ternary-logic.py

@@ -0,0 +1,129 @@
+class Trit(int):
+    def __new__(cls, value):
+        if value == 'TRUE':
+            value = 1
+        elif value == 'FALSE':
+            value = 0
+        elif value == 'MAYBE':
+            value = -1
+        return super(Trit, cls).__new__(cls, value // (abs(value) or 1))
+
+    def __repr__(self):
+        if self > 0:
+            return 'TRUE'
+        elif self == 0:
+            return 'FALSE'
+        return 'MAYBE'
+
+    def __str__(self):
+        return repr(self)
+
+    def __bool__(self):
+        if self > 0:
+            return True
+        elif self == 0:
+            return False
+        else:
+            raise ValueError("invalid literal for bool(): '%s'" % self)
+
+    def __or__(self, other):
+        if isinstance(other, Trit):
+            return _ttable[(self, other)][1]
+        else:
+            try:
+                return _ttable[(self, Trit(bool(other)))][1]
+            except:
+                return NotImplemented
+
+    def __ror__(self, other):
+        if isinstance(other, Trit):
+            return _ttable[(self, other)][1]
+        else:
+            try:
+                return _ttable[(self, Trit(bool(other)))][1]
+            except:
+                return NotImplemented
+
+    def __and__(self, other):
+        if isinstance(other, Trit):
+            return _ttable[(self, other)][0]
+        else:
+            try:
+                return _ttable[(self, Trit(bool(other)))][0]
+            except:
+                return NotImplemented
+
+    def __rand__(self, other):
+        if isinstance(other, Trit):
+            return _ttable[(self, other)][0]
+        else:
+            try:
+                return _ttable[(self, Trit(bool(other)))][0]
+            except:
+                return NotImplemented
+
+    def __xor__(self, other):
+        if isinstance(other, Trit):
+            return _ttable[(self, other)][2]
+        else:
+            try:
+                return _ttable[(self, Trit(bool(other)))][2]
+            except:
+                return NotImplemented
+
+    def __rxor__(self, other):
+        if isinstance(other, Trit):
+            return _ttable[(self, other)][2]
+        else:
+            try:
+                return _ttable[(self, Trit(bool(other)))][2]
+            except:
+                return NotImplemented
+
+    def __invert__(self):
+        return _ttable[self]
+
+    def __getattr__(self, name):
+        if name in ('_n', 'flip'):
+            # So you can do x._n == x.flip; the inverse of x
+            # In Python 'not' is strictly boolean so we can't write `not x`
+            # Same applies to keywords 'and' and 'or'.
+            return _ttable[self]
+        else:
+            raise AttributeError
+
+
+
+TRUE, FALSE, MAYBE = Trit(1), Trit(0), Trit(-1)
+
+_ttable = {
+    #    A: -> flip_A
+         TRUE: FALSE,
+        FALSE:  TRUE,
+        MAYBE: MAYBE,
+    #     (A, B): -> (A_and_B, A_or_B, A_xor_B)
+        (MAYBE, MAYBE): (MAYBE, MAYBE, MAYBE),
+        (MAYBE, FALSE): (FALSE, MAYBE, MAYBE),
+        (MAYBE,  TRUE): (MAYBE,  TRUE, MAYBE),
+        (FALSE, MAYBE): (FALSE, MAYBE, MAYBE),
+        (FALSE, FALSE): (FALSE, FALSE, FALSE),
+        (FALSE,  TRUE): (FALSE,  TRUE,  TRUE),
+        ( TRUE, MAYBE): (MAYBE,  TRUE, MAYBE),
+        ( TRUE, FALSE): (FALSE,  TRUE,  TRUE),
+        ( TRUE,  TRUE): ( TRUE,  TRUE, FALSE),
+    }
+
+
+values = ('FALSE', 'TRUE ', 'MAYBE')
+
+print("\nTrit logical inverse, '~'")
+for a in values:
+    expr = '~%s' % a
+    print('  %s = %s' % (expr, eval(expr)))
+
+for op, ophelp in (('&', 'and'), ('|', 'or'), ('^', 'exclusive-or')):
+    print("\nTrit logical %s, '%s'" % (ophelp, op))
+    for a in values:
+        for b in values:
+            expr = '%s %s %s' % (a, op, b)
+            print('  %s = %s' % (expr, eval(expr)))