From 082e6468f701a19f0e58cc09b0095961da3b67ca Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89milie=20Feral?= <emilie.feral@numworks.com>
Date: Fri, 6 Oct 2017 17:06:46 +0200
Subject: [PATCH] [poincare] In power: (a^b)^c = a^(b+c) if a > 0 or c is
 integer

Change-Id: Iad7b559de5e15972a54e322bca832d78596abf53
---
 poincare/include/poincare/power.h |  2 +-
 poincare/src/power.cpp            | 25 +++++++++++++++++--------
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/poincare/include/poincare/power.h b/poincare/include/poincare/power.h
index 84a1137f9..043e3c3f6 100644
--- a/poincare/include/poincare/power.h
+++ b/poincare/include/poincare/power.h
@@ -34,7 +34,7 @@ private:
   int compareToSameTypeExpression(const Expression * e) const override;
   /* Simplification */
   void immediateSimplify() override;
-  void simplifyPowerPower(Power * p, Rational * r);
+  void simplifyPowerPower(Power * p, Expression * r);
   void simplifyPowerMultiplication(Multiplication * m, Rational * r);
   void simplifyRationalRationalPower(Rational * a, Rational * b);
   static Expression * CreateSimplifiedIntegerRationalPower(Integer i, Rational * r);
diff --git a/poincare/src/power.cpp b/poincare/src/power.cpp
index f712ce132..89638ee71 100644
--- a/poincare/src/power.cpp
+++ b/poincare/src/power.cpp
@@ -160,10 +160,6 @@ void Power::immediateSimplify() {
         Rational r = Rational::Power(*(e), b->numerator());
         replaceWith(new Rational(r),true);
         return;
-      } else if (operand(0)->type() == Type::Power) {
-        Power * e = static_cast<Power *>((Expression *)operand(0));
-        simplifyPowerPower(e, b);
-        return;
       } else if (operand(0)->type() == Type::Multiplication) {
         Multiplication * e = static_cast<Multiplication *>((Expression *)operand(0));
         simplifyPowerMultiplication(e, b);
@@ -176,14 +172,27 @@ void Power::immediateSimplify() {
       return;
     }
   }
-  // TODO: (a^b)^c -> a^(b+c) if a > 0
+  // (a^b)^c -> a^(b+c) if a > 0 or c is integer
+  if (operand(0)->type() == Type::Power) {
+     Power * p = static_cast<Power *>((Expression *)operand(0));
+     // Check is a > 0 or c is Integer
+     if (p->operand(0)->isPositive() ||
+         (operand(1)->type() == Type::Rational && static_cast<Rational *>((Expression *)operand(1))->denominator().isOne())) {
+       simplifyPowerPower(p, const_cast<Expression *>(operand(1)));
+       return;
+     }
+  }
   // TODO: (a*b)^c -> |a|^c*(sign(a)*b)^c
 }
 
-void Power::simplifyPowerPower(Power * p, Rational * r) {
-  const Expression * multOperands[2] = {const_cast<Expression *>(p->operand(1)), r};
+void Power::simplifyPowerPower(Power * p, Expression * e) {
+  Expression * p0 = const_cast<Expression *>(p->operand(0));
+  Expression * p1 = const_cast<Expression *>(p->operand(1));
+  p->detachOperands();
+  const Expression * multOperands[2] = {p1, e};
   Multiplication * m = new Multiplication(multOperands, 2, false);
-  replaceOperand(r, m, false);
+  replaceOperand(e, m, false);
+  replaceOperand(p, p0, true);
   m->immediateSimplify();
   immediateSimplify();
 }