Given an $x$-monotone curve xcv and an enumeration ce that specifies either the minimum or the maximum end of the curve, determines the location of the curve end along the $y$-dimension.

The variable xcv identifies the parametric curve $C(t) = (X(t),Y(t))$ defined over an open or half-open interval with endpoints $0$ and $1$. The enumeration ce identifies an open end $d \in\{0,1\}$ of $C$. Formally, determines whether $\lim_{t \rightarrow d} Y(t)$ evaluates to $b_b$, $b_t$, or a value in between, where $b_b$ and $b_t$ are the $y$-coordinates of the bottom and top boundaries of the parameter space, respectively. Returns ARR_BOTTOM_BOUNDARY, ARR_TOP_BOUNDARY, or ARR_INTERIOR, accordingly.

Postcondition

If ArrTraits::Bottom_side_category is not convertible to Arr_open_side_tag then the result is not ARR_BOTTOM_BOUNDARY.

If ArrTraits::Top_side_category is not convertible to Arr_open_side_tag then the result is not ARR_TOP_BOUNDARY.