add LayoutLeft mapping and Integer trait#14
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oliverlee
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Mar 18, 2026
oliverlee
commented
Mar 18, 2026
Add `LayoutLeft` and `LayoutLeftMapping` implementing column-major (Fortran-order) index mapping, where stride in dimension `k` is the product of extents in dimensions `0..k` (exclusive prefix product, forward order). Extract `exclusive_product_scan` to replace the ad-hoc `extents_to_strides_layout_right` function. The new implementation is generic over an `Integer` bound and parameterized by a `Direction` type tag (`Forward`/`Reverse`), dispatching to either `core::array::from_fn` or `array_from_fn_rev` to avoid an in-place reversal. `LayoutLeft` uses `Forward` and `LayoutRight` uses `Reverse`. Extract `inner_product` as a standalone helper used by both mappings in `to_memory_index`, replacing the inline `zip(...).map(...).sum()`. Add an `Integer` trait alias over `num_integer::Integer + NumAssign + Copy + Sum + Product` to give a coherent numeric concept for array dimension arithmetic, excluding floating point via `Eq` (through `num_integer::Integer`) while keeping the bound concise at call sites. Add `num-integer` and `num-traits` to crate universe.
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Add
LayoutLeftandLayoutLeftMappingimplementing column-major (Fortran-order)index mapping, where stride in dimension
kis the product of extents in dimensions0..k(exclusive prefix product, forward order).Extract
exclusive_product_scanto replace the ad-hocextents_to_strides_layout_rightfunction. The new implementation is generic over an
Integerbound and parameterizedby a
Directiontype tag (Forward/Reverse), dispatching to eithercore::array::from_fnor
array_from_fn_revto avoid an in-place reversal.LayoutLeftusesForwardandLayoutRightusesReverse.Extract
inner_productas a standalone helper used by both mappings into_memory_index, replacing the inlinezip(...).map(...).sum().Add an
Integertrait alias overnum_integer::Integer + NumAssign + Copy + Sum + Productto give a coherent numeric concept for array dimension arithmetic, excluding floating
point via
Eq(throughnum_integer::Integer) while keeping the bound concise atcall sites.
Add
num-integerandnum-traitsto crate universe.