From 2551037b6522b92cf472543b239091349fe03334 Mon Sep 17 00:00:00 2001
From: Bertrand Benjamin <benjamin.bertrand@opytex.org>
Date: Mon, 17 Dec 2018 14:54:48 +0100
Subject: [PATCH] Fix(Core): Tree.from_str allow - in front of parenthesis

---
 mapytex/calculus/core/compute/minus.py | 80 ++++++++++++++++++++++++--
 mapytex/calculus/core/tree.py          | 12 +++-
 2 files changed, 86 insertions(+), 6 deletions(-)

diff --git a/mapytex/calculus/core/compute/minus.py b/mapytex/calculus/core/compute/minus.py
index 8378c2e..27abbf6 100644
--- a/mapytex/calculus/core/compute/minus.py
+++ b/mapytex/calculus/core/compute/minus.py
@@ -11,9 +11,12 @@ Minus MO: take the opposit
 """
 
 from multipledispatch import Dispatcher
-from ..MO.mo import MO, MOnumber
-from ..MO.fraction import MOFraction
 from .exceptions import MinusError
+from ..MO.mo import MO, MOnumber, MOstr
+from ..MO.fraction import MOFraction
+from ..MO.monomial import MOstrPower, MOMonomial
+from ..MO.polynomial import MOpolynomial
+from ..tree import Tree
 
 minus_doc = """ Opposite of a MO
 
@@ -26,7 +29,7 @@ minus_doc = """ Opposite of a MO
 minus = Dispatcher("minus", doc=minus_doc)
 
 @minus.register(type(None), MOnumber)
-def monumber(left, right):
+def monumber(_, right):
     """
 
     >>> a = MOnumber(4)
@@ -37,7 +40,7 @@ def monumber(left, right):
     return MO.factory(- right.value)
 
 @minus.register(type(None), MOFraction)
-def mofraction(left, right):
+def mofraction(_, right):
     """ 4 differents cases
 
     Either fraction , numerator or denominator is negative
@@ -91,6 +94,75 @@ def mofraction(left, right):
 
     return MOFraction(right._numerator, right._denominator, True)
 
+@minus.register(type(None), MOstr)
+def mostr(_, right):
+    """ Opposite of 'x' is '-x'
+
+    :example:
+    >>> x = MOstr("x")
+    >>> print(minus(None, x))
+    *
+     > -1
+     > x
+    """
+    return MOMonomial(-1, right)
+
+@minus.register(type(None), MOstrPower)
+def mostrpower(_, right):
+    """ Opposite of 'x^n' is '-x^n'
+
+    :example:
+    >>> x2 = MOstrPower("x", 2)
+    >>> print(minus(None, x2))
+    *
+     > -1
+     > ^
+     | > x
+     | > 2
+    """
+    return MOMonomial(-1, right.variable, right.power)
+
+@minus.register(type(None), MOMonomial)
+def momonomial(_, right):
+    """ Opposite of 'ax^n' is '-ax^n'
+
+    :example:
+    >>> tx2 = MOMonomial(3, "x", 2)
+    >>> print(minus(None, tx2))
+    *
+     > -3
+     > ^
+     | > x
+     | > 2
+    """
+    try:
+        return MOMonomial(-right.coefficient.value, right.variable, right.power)
+    except TypeError:
+        coef = Tree("-", None, right.coefficient)
+        return Tree("*", coef, right.strpower)
+
+@minus.register(type(None), MOpolynomial)
+def mopolynomial(_, right):
+    """ Opposite of a polynomial
+
+    :example:
+    >>> P = MOpolynomial('x', [1, -2, 3])
+    >>> print(minus(None, P))
+    +
+     > *
+     | > -3
+     | > ^
+     | | > x
+     | | > 2
+     > +
+     | > *
+     | | > 2
+     | | > x
+     | > -1
+    """
+    neg_coefs = {p: -c.value for (p, c) in right.coefficients.items()}
+    return MOpolynomial(right.variable, neg_coefs)
+
 # -----------------------------
 # Reglages pour 'vim'
 # vim:set autoindent expandtab tabstop=4 shiftwidth=4:
diff --git a/mapytex/calculus/core/tree.py b/mapytex/calculus/core/tree.py
index 0d2abc6..ba82ea9 100644
--- a/mapytex/calculus/core/tree.py
+++ b/mapytex/calculus/core/tree.py
@@ -20,7 +20,7 @@ from .operator import OPERATORS, is_operator
 __all__ = ["Tree", "MutableTree"]
 
 
-class Tree(object):
+class Tree():
 
     """
     Binary tree
@@ -219,6 +219,15 @@ class Tree(object):
         Traceback (most recent call last):
             ...
         TypeError: Tree can't have empty node or leaf
+        >>> t = MutableTree("-", None, 1)
+        >>> print(t)
+        -
+         > None
+         > 1
+        >>> print(Tree.from_any_tree(t))
+        -
+         > None
+         > 1
         >>> tl = LeafTree("/", 1, 4)
         >>> t2 = MutableTree("*", tl, 3)
         >>> t = Tree.from_any_tree(t2)
@@ -233,7 +242,6 @@ class Tree(object):
         right_value = tree.right_value
 
         if node is None or \
-                left_value is None or \
                 right_value is None:
                     raise TypeError("Tree can't have empty node or leaf")