Decorator for computing special cases

mapytex/calculus/core/compute/divide.py

@@ -15,7 +15,7 @@ from ..tree import Tree
 from ..MO.mo import MO, MOnumber
 from ..MO.fraction import MOFraction
 from .exceptions import DivideError
-from .type_filter import args_are
+from .filters import special_case
 
 divide_doc = """ Dividing MOs
 
@@ -27,7 +27,42 @@ divide_doc = """ Dividing MOs
 
 divide = Dispatcher("divide", doc=divide_doc)
 
+def divide_filter(left, right):
+    """ Automatic divide on MO
+
+    >>> a = MOnumber(4)
+    >>> b = MOnumber(1)
+    >>> divide(a, b)
+    <MOnumber 4>
+    >>> a = MOnumber(0)
+    >>> b = MOnumber(1)
+    >>> divide(a, b)
+    <MOnumber 0>
+    >>> a = MOnumber(4)
+    >>> b = MOnumber(0)
+    >>> divide(a, b)
+    Traceback (most recent call last):
+        ...
+    mapytex.calculus.core.compute.exceptions.DivideError: Division by zero
+    """
+    try:
+        if left == 0:
+            return left
+    except TypeError:
+        pass
+    try:
+        if right == 1:
+            return left
+    except TypeError:
+        pass
+    try:
+        if right == 0:
+            raise DivideError("Division by zero")
+    except TypeError:
+        pass
+
 @divide.register(MOnumber, MOnumber)
+@special_case(divide_filter)
 def monumber_monumber(left, right):
     """ Divide 2 monumbers and return a MOFraction
 
@@ -39,6 +74,7 @@ def monumber_monumber(left, right):
     return MOFraction(left, right)
 
 @divide.register(MOnumber, MOFraction)
+@special_case(divide_filter)
 def monumber_mofraction(left, right):
     """ Divide a monumber and a mofraction by inverting MOFraction
 
@@ -63,6 +99,7 @@ def monumber_mofraction(left, right):
     return Tree("*", left, right.inverse())
 
 @divide.register(MOFraction, MOnumber)
+@special_case(divide_filter)
 def mofraction_monumber(left, right):
     """ Divide a monumber and a mofraction by inverting MOnumber
 
@@ -82,6 +119,7 @@ def mofraction_monumber(left, right):
     return Tree("*", left, right_fraction)
 
 @divide.register(MOFraction, MOFraction)
+@special_case(divide_filter)
 def mofraction_mofraction(left, right):
     """ Divide two mofractions by inverting right MOFraction
 
@@ -99,37 +137,6 @@ def mofraction_mofraction(left, right):
     """
     return Tree("*", left, right.inverse())
 
-#def divide(left, right):
-#    """ Perform the addition of left and right
-#
-#    :param left: left MO
-#    :param right: right MO
-#    :returns: Tree or MO
-#
-#    >>> a = MOnumber(4)
-#    >>> b = MOnumber(6)
-#    >>> divide(a, b)
-#    <MOFraction 4 / 6>
-#    >>> b = MOnumber(0)
-#    >>> divide(a, b)
-#    Traceback (most recent call last):
-#        ...
-#    mapytex.calculus.core.compute.exceptions.DivideError: Division by zero
-#
-#    """
-#    try:
-#        right.value
-#    except AttributeError:
-#        pass
-#    else:
-#        if right.value == 0:
-#            raise DivideError("Division by zero")
-#
-#    if right.value == 1:
-#        return left
-#
-#    return MULFUNCTIONS[(type(left), type(right))](left, right)
-
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