Update functions to use the clone interface.

Change-Id: I6b4d6be5b1d963bc7d97851432e40844d3619d8d

poincare/src/function.cpp

@@ -1,6 +1,19 @@
+extern "C" {
+#include <stdlib.h>
+}
 #include <poincare/function.h>
 #include "layout/function_layout.h"
 
+Function::Function(Expression * arg, char* function_name, bool clone_operands) {
+  m_arg = (Expression *)malloc(sizeof(Expression));
+  m_function_name = function_name;
+  if (clone_operands) {
+    m_arg = arg->clone();
+  } else {
+    m_arg = arg;
+  }
+}
+
 Function::~Function() {
   delete m_arg;
 }
@@ -8,3 +21,15 @@ Function::~Function() {
 ExpressionLayout * Function::createLayout(ExpressionLayout * parent) {
   return new FunctionLayout(parent, m_function_name, m_arg);
 }
+
+Expression * Function::operand(int i) {
+  if (i==0) {
+    return m_arg;
+  } else {
+    return nullptr;
+  }
+}
+
+int Function::numberOfOperands() {
+  return 1;
+}