From 60ee751e919036b380a8442591149dc3386cc2f7 Mon Sep 17 00:00:00 2001
From: Bertrand Benjamin <benjamin.bertrand@opytex.org>
Date: Wed, 20 Oct 2021 15:31:14 +0200
Subject: [PATCH] Fix: add special case to add typing

Sometimes, typing/add.py tried to build MOpolynomial with only one
coefficient.
---
 mapytex/calculus/core/MO/monomial.py   |  2 +-
 mapytex/calculus/core/MO/polynomial.py | 13 +++++-
 mapytex/calculus/core/typing/add.py    | 61 +++++++++++++++++++++++++-
 3 files changed, 72 insertions(+), 4 deletions(-)

diff --git a/mapytex/calculus/core/MO/monomial.py b/mapytex/calculus/core/MO/monomial.py
index 32cfdfd..00edc40 100644
--- a/mapytex/calculus/core/MO/monomial.py
+++ b/mapytex/calculus/core/MO/monomial.py
@@ -132,7 +132,7 @@ class MOstrPower(Molecule):
 
 class MOMonomial(Molecule):
 
-    """ Monomial math object"""
+    """ Monomial math object : ax^n"""
 
     MAINOP = "*"
 
diff --git a/mapytex/calculus/core/MO/polynomial.py b/mapytex/calculus/core/MO/polynomial.py
index 73005c4..ced79eb 100644
--- a/mapytex/calculus/core/MO/polynomial.py
+++ b/mapytex/calculus/core/MO/polynomial.py
@@ -18,7 +18,7 @@ __all__ = ["MOpolynomial"]
 
 class MOpolynomial(Molecule):
 
-    """ MO polynomial"""
+    """ MO polynomial: ax^n + ... + z (can't be a monomial)"""
 
     MAINOP = "+"
 
@@ -39,6 +39,14 @@ class MOpolynomial(Molecule):
         <MOpolynomial 4x^3 + 1>
         >>> MOpolynomial('x', {0: 1, 3: 1})
         <MOpolynomial x^3 + 1>
+        >>> MOpolynomial('x', [0, 0, 3])
+        Traceback (most recent call last):
+        ...
+        TypeError: A MOpolynomial can't be monomial it has to have more than one coefficient.
+        >>> MOpolynomial('x', {3: 1})
+        Traceback (most recent call last):
+        ...
+        TypeError: A MOpolynomial can't be monomial it has to have more than one coefficient.
 
         """
         _variable = MO.factory(variable)
@@ -58,6 +66,9 @@ class MOpolynomial(Molecule):
             raise TypeError("Coefs needs to be a dictionnary or a list")
         self._coefs = _coefs
 
+        if len(self._coefs) == 1:
+            raise TypeError("A MOpolynomial can't be monomial it has to have more than one coefficient.")
+
         monomials = OrderedDict()
         for deg in sorted(self._coefs.keys()):
             coef = self._coefs[deg]
diff --git a/mapytex/calculus/core/typing/add.py b/mapytex/calculus/core/typing/add.py
index 6daa038..d7c1717 100644
--- a/mapytex/calculus/core/typing/add.py
+++ b/mapytex/calculus/core/typing/add.py
@@ -11,11 +11,11 @@ Add MO with typing
 """
 
 from multipledispatch import Dispatcher
-from ..tree import Tree
-from ..MO import MO, MOnumber, MOstr
+from ..MO import MOnumber, MOstr
 from ..MO.monomial import MOstrPower, MOMonomial
 from ..MO.polynomial import MOpolynomial
 from ..MO.fraction import MOFraction
+from ..compute.filters import special_case
 
 add_doc = """ Add MOs
 
@@ -27,8 +27,26 @@ add_doc = """ Add MOs
 
 add = Dispatcher("add", doc=add_doc)
 
+def add_filter(left, right):
+    """ Special cases for add MO (adding 0) 
+
+    :param left: MO
+    :param right: MO
+    :returns: MO if it is a special case, nothing other wise
+    """
+    try:
+        if left == 0:
+            return right
+    except TypeError:
+        pass
+    try:
+        if right == 0:
+            return left
+    except TypeError:
+        pass
 
 @add.register((MOnumber, MOFraction), MOstr)
+@special_case(add_filter)
 def moscalar_mostr(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -39,11 +57,15 @@ def moscalar_mostr(left, right):
     >>> a = MOFraction(1, 5)
     >>> add(a, b)
     <MOpolynomial x + 1 / 5>
+    >>> a = MOnumber(0)
+    >>> add(a, b)
+    <MOstr x>
     """
     return MOpolynomial(right, [left, 1])
 
 
 @add.register(MOstr, (MOnumber, MOFraction))
+@special_case(add_filter)
 def mostr_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -54,11 +76,15 @@ def mostr_moscalar(left, right):
     >>> b = MOFraction(1, 5)
     >>> add(a, b)
     <MOpolynomial x + 1 / 5>
+    >>> b = MOnumber(0)
+    >>> add(a, b)
+    <MOstr x>
     """
     return MOpolynomial(left, [right, 1])
 
 
 @add.register((MOnumber, MOFraction), MOstrPower)
+@special_case(add_filter)
 def moscalar_mostrpower(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -74,6 +100,7 @@ def moscalar_mostrpower(left, right):
 
 
 @add.register(MOstrPower, (MOnumber, MOFraction))
+@special_case(add_filter)
 def mostrpower_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -89,6 +116,7 @@ def mostrpower_moscalar(left, right):
 
 
 @add.register((MOnumber, MOFraction), MOMonomial)
+@special_case(add_filter)
 def moscalar_momonomial(left, right):
     """ add a scalar with a MOMonomial to create a MOpolynomial
 
@@ -99,11 +127,17 @@ def moscalar_momonomial(left, right):
     >>> a = MOFraction(1, 5)
     >>> add(a, b)
     <MOpolynomial 3x^4 + 1 / 5>
+
+    >>> a = MOnumber(0)
+    >>> b = MOMonomial(2, 'x', 4)
+    >>> add(a, b)
+    <MOMonomial 2x^4>
     """
     return MOpolynomial(right.variable, {right.power: right.coefficient, 0: left})
 
 
 @add.register(MOMonomial, (MOnumber, MOFraction))
+@special_case(add_filter)
 def momonial_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -115,11 +149,17 @@ def momonial_moscalar(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^4 + 1 / 5>
 
+    >>> a = MOMonomial(2, 'x', 4)
+    >>> b = MOnumber(0)
+    >>> add(a, b)
+    <MOMonomial 2x^4>
+
     """
     return MOpolynomial(left.variable, {0: right, left.power: left.coefficient})
 
 
 @add.register((MOnumber, MOFraction), MOpolynomial)
+@special_case(add_filter)
 def moscalar_mopolynomial(left, right):
     """ add a scalar with a MOpolynomial to create a MOpolynomial
 
@@ -143,6 +183,7 @@ def moscalar_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, (MOnumber, MOFraction))
+@special_case(add_filter)
 def mopolynomial_moscalar(left, right):
     """ add a scalar with a MOpolynomial to create a MOpolynomial
 
@@ -164,6 +205,7 @@ def mopolynomial_moscalar(left, right):
 
 
 @add.register(MOstr, MOstr)
+@special_case(add_filter)
 def mostr_mostr(left, right):
     """ add 2 mostr
 
@@ -178,6 +220,7 @@ def mostr_mostr(left, right):
 
 
 @add.register(MOstr, MOstrPower)
+@special_case(add_filter)
 def mostr_mostrpower(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -195,6 +238,7 @@ def mostr_mostrpower(left, right):
 
 
 @add.register(MOstrPower, MOstr)
+@special_case(add_filter)
 def mostrpower_mostr(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
@@ -212,6 +256,7 @@ def mostrpower_mostr(left, right):
 
 
 @add.register(MOstrPower, MOstrPower)
+@special_case(add_filter)
 def mostrpower_mostrpower(left, right):
     """ add 2 mostrpower
 
@@ -231,6 +276,7 @@ def mostrpower_mostrpower(left, right):
 
 
 @add.register(MOstr, MOpolynomial)
+@special_case(add_filter)
 def mostr_mopolynomial(left, right):
     """ add a str with a MOpolynomial to create a MOpolynomial
 
@@ -249,6 +295,7 @@ def mostr_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, MOstr)
+@special_case(add_filter)
 def mopolynomial_mostr(left, right):
     """ add a str with a MOpolynomial to create a MOpolynomial
 
@@ -266,6 +313,7 @@ def mopolynomial_mostr(left, right):
 
 
 @add.register(MOstrPower, MOpolynomial)
+@special_case(add_filter)
 def mostrpower_mopolynomial(left, right):
     """ add a strPower with a MOpolynomial to create a MOpolynomial
 
@@ -284,6 +332,7 @@ def mostrpower_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, MOstrPower)
+@special_case(add_filter)
 def mopolynomial_mostrpower(left, right):
     """ add a strPower with a MOpolynomial to create a MOpolynomial
 
@@ -301,6 +350,7 @@ def mopolynomial_mostrpower(left, right):
 
 
 @add.register(MOMonomial, MOpolynomial)
+@special_case(add_filter)
 def momonomial_mopolynomial(left, right):
     """ add a Monomial with a MOpolynomial to create a MOpolynomial
 
@@ -319,6 +369,7 @@ def momonomial_mopolynomial(left, right):
 
 
 @add.register(MOpolynomial, MOMonomial)
+@special_case(add_filter)
 def mopolynomial_momonomial(left, right):
     """ add a Monomial with a MOpolynomial to create a MOpolynomial
 
@@ -336,6 +387,7 @@ def mopolynomial_momonomial(left, right):
 
 
 @add.register(MOpolynomial, MOpolynomial)
+@special_case(add_filter)
 def mopolynomial_mopolynomial(left, right):
     """ add a polynomial with a MOpolynomial to create a MOpolynomial
 
@@ -355,6 +407,7 @@ def mopolynomial_mopolynomial(left, right):
 
 
 @add.register(MOstr, MOMonomial)
+@special_case(add_filter)
 def mostr_monomial(left, right):
     """ add a mostr with a MOMonomial to create a MOpolynomial
 
@@ -370,6 +423,7 @@ def mostr_monomial(left, right):
 
 
 @add.register(MOMonomial, MOstr)
+@special_case(add_filter)
 def monomial_mostr(left, right):
     """ add a mostr with a MOMonomial to create a MOpolynomial
 
@@ -385,6 +439,7 @@ def monomial_mostr(left, right):
 
 
 @add.register(MOstrPower, MOMonomial)
+@special_case(add_filter)
 def mostrpower_monomial(left, right):
     """ add a mostrPower with a MOMonomial to create a MOpolynomial
 
@@ -402,6 +457,7 @@ def mostrpower_monomial(left, right):
 
 
 @add.register(MOMonomial, MOstrPower)
+@special_case(add_filter)
 def monomial_mostrpower(left, right):
     """ add a mostrPower with a MOMonomial to create a MOpolynomial
 
@@ -419,6 +475,7 @@ def monomial_mostrpower(left, right):
 
 
 @add.register(MOMonomial, MOMonomial)
+@special_case(add_filter)
 def monomial_momonomial(left, right):
     """ add a moMonomial with a MOMonomial to create a MOpolynomial