From fa8beb6bb2a8fde045b6e71b8f9373a1922a9f8b Mon Sep 17 00:00:00 2001
From: Bertrand Benjamin <benjamin.bertrand@opytex.org>
Date: Mon, 15 Jul 2019 11:14:48 +0200
Subject: [PATCH] Feat: Polynomial can be evaluated

---
 mapytex/calculus/API/tokens/polynomial.py | 34 +++++++++++++++++++----
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/mapytex/calculus/API/tokens/polynomial.py b/mapytex/calculus/API/tokens/polynomial.py
index 4252e7e..e765a5e 100644
--- a/mapytex/calculus/API/tokens/polynomial.py
+++ b/mapytex/calculus/API/tokens/polynomial.py
@@ -10,8 +10,11 @@
 Tokens representing polynomials functions 
 
 """
+from ..expression import Expression
+from functools import partial
 from .token import Token
 from ...core.MO import MO
+from ...core.MO.atoms import moify
 
 __all__ = ["Polynomial", "Quadratic", "Linear"]
 
@@ -24,6 +27,7 @@ class Polynomial(Token):
     >>> from ...core.MO.polynomial import MOpolynomial
     >>> P = Polynomial(MOpolynomial('x', [1, 2, 3]))
     >>> P
+    <Polynomial 3x^2 + 2x + 1>
     """
 
     def __init__(self, a, name="", ancestor=None):
@@ -61,9 +65,21 @@ class Polynomial(Token):
         :examples:
         >>> from ...core.MO.polynomial import MOpolynomial
         >>> P = Polynomial(MOpolynomial('x', [1, 2, 3]))
-        >>> P(2)
+        >>> for s in P(2).explain():
+        ...     print(s)
+        3 * 2^2 + 2 * 2 + 1
+        3 * 4 + 4 + 1
+        12 + 5
+        17
         """
-        pass
+        tree = self._mo.tree
+        variable = (set(tree.get_leafs(extract_variable)) - {None}).pop()
+
+        dest = moify(value)
+        replace_var = partial(replace, origin=variable, dest=dest)
+        tree = tree.map_on_leaf(replace_var)
+
+        return Expression(tree).simplify()
 
 
 class Linear(Polynomial):
@@ -101,10 +117,16 @@ def extract_variable(leaf):
         return None
 
 def replace(leaf, origin, dest):
-    # map_on_leaf sur leaf?
-    if leaf == origin:
-        return dest
-    return leaf
+    """ Recursively replace origin to dest in leaf """
+    try:
+        leaf.tree
+    except AttributeError:
+        if leaf == origin:
+            return dest
+        return leaf
+
+    replace_var = partial(replace, origin=origin, dest=dest)
+    return leaf.tree.map_on_leaf(replace_var)
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