added hashCode and equals for FunctionalExpression

Author: andreacalia

src/java/org/tensorics/core/functional/expressions/FunctionalExpression.java

@@ -38,4 +38,35 @@ public FuncN<R> function() {
         return func;
     }
 
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((children == null) ? 0 : children.hashCode());
+        result = prime * result + ((func == null) ? 0 : func.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        FunctionalExpression<?> other = (FunctionalExpression<?>) obj;
+        if (children == null) {
+            if (other.children != null)
+                return false;
+        } else if (!children.equals(other.children))
+            return false;
+        if (func == null) {
+            if (other.func != null)
+                return false;
+        } else if (!func.equals(other.func))
+            return false;
+        return true;
+    }
+
 }