Source file view.ml
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type layout = C_contiguous | Strided
type t = {
shape : int array;
strides : int array;
offset : int;
mask : (int * int) array option;
layout : layout;
}
let prod arr = Array.fold_left ( * ) 1 arr
let compute_strides shape =
let n = Array.length shape in
if n = 0 then [||]
else
let strides = Array.make n 0 in
strides.(n - 1) <- (if shape.(n - 1) = 0 then 0 else 1);
for i = n - 2 downto 0 do
strides.(i) <-
(if shape.(i) = 0 then 0 else strides.(i + 1) * max 1 shape.(i + 1))
done;
strides
let canonicalize_strides shape strides =
Array.mapi (fun i s -> if shape.(i) = 1 then 0 else s) strides
let shape v = v.shape
let strides v = v.strides
let stride axis v =
if axis < 0 then
Error.invalid ~op:"stride" ~what:"axis"
~reason:(Printf.sprintf "%d < 0" axis)
()
else if axis >= Array.length v.strides then
Error.axis_out_of_bounds ~op:"stride" ~axis ~ndim:(Array.length v.strides)
();
let stride = Array.unsafe_get v.strides axis in
stride
let offset v = v.offset
let mask v = v.mask
let is_c_contiguous v = v.layout = C_contiguous
let dim axis v =
if axis < 0 then
Error.invalid ~op:"dim" ~what:"axis"
~reason:(Printf.sprintf "%d < 0" axis)
()
else if axis >= Array.length v.shape then
Error.axis_out_of_bounds ~op:"dim" ~axis ~ndim:(Array.length v.shape) ();
let dim = Array.unsafe_get v.shape axis in
dim
let ndim v = Array.length v.shape
let numel v =
let n = Array.length v.shape in
if n = 0 then 1 else Array.fold_left ( * ) 1 v.shape
let create ?(offset = 0) ?strides ?mask shape_arr =
let is_zero_size = Array.exists (( = ) 0) shape_arr in
let current_shape =
if is_zero_size then Array.map (fun s -> max s 0) shape_arr else shape_arr
in
let current_strides =
match strides with
| Some s -> canonicalize_strides current_shape s
| None -> compute_strides current_shape
in
let current_offset = if is_zero_size then 0 else offset in
let current_mask =
if is_zero_size then None
else
match mask with
| Some m
when Array.for_all2 (fun (b, e) s -> b = 0 && e = s) m current_shape ->
None
| _ -> mask
in
let new_layout =
if
current_offset = 0 && current_mask = None
&& current_strides = compute_strides current_shape
then C_contiguous
else Strided
in
{
shape = current_shape;
strides = current_strides;
offset = current_offset;
mask = current_mask;
layout = new_layout;
}
let linear_index view indices =
if Array.length indices <> Array.length view.shape then
Error.invalid ~op:"linear_index" ~what:"indices"
~reason:
(Printf.sprintf "rank mismatch: %d vs %d" (Array.length indices)
(Array.length view.shape))
();
let physical_offset = ref view.offset in
Array.iteri
(fun i idx ->
physical_offset := !physical_offset + (idx * view.strides.(i)))
indices;
!physical_offset
let is_valid view indices =
match view.mask with
| None -> true
| Some mask_array ->
if Array.length indices <> Array.length mask_array then false
else
Array.for_all2
(fun idx (b, e) -> idx >= b && idx < e)
indices mask_array
let expand view new_shape =
if Array.length new_shape <> Array.length view.shape then
Error.invalid ~op:"expand" ~what:"shape dimensions"
~reason:
(Printf.sprintf "rank mismatch: %d vs %d" (Array.length new_shape)
(Array.length view.shape))
();
if Array.exists (( = ) 0) view.shape then create new_shape
else
let strides =
Array.mapi
(fun i ns ->
let s = view.shape.(i) in
if s = ns then view.strides.(i)
else if s = 1 then 0
else
(Error.cannot ~op:"expand" ~what:"expand"
~from:(Printf.sprintf "dimension %d (size %d)" i s)
~to_:(Printf.sprintf "size %d" ns)
~reason:"can only expand singleton dimensions")
())
new_shape
in
let mask =
match view.mask with
| None -> None
| Some m ->
Some
(Array.mapi
(fun i (b, e) ->
if view.shape.(i) = 1 && new_shape.(i) <> 1 then
if b = 0 && e = 1 then (0, new_shape.(i))
else
Error.invalid ~op:"expand"
~what:"masked singleton dimension"
~reason:
(Printf.sprintf
"bounds [%d,%d] incompatible with expansion" b e)
()
else (b, e))
m)
in
create ~offset:view.offset ?mask ~strides new_shape
let permute view axes =
let n = ndim view in
if Array.length axes <> n then
Error.invalid ~op:"permute" ~what:"axes array"
~reason:(Printf.sprintf "length %d != ndim %d" (Array.length axes) n)
();
let seen = Array.make n false in
Array.iter
(fun ax ->
if ax < 0 || ax >= n || seen.(ax) then
Error.invalid ~op:"permute"
~what:(Printf.sprintf "axis %d" ax)
~reason:
(if ax < 0 || ax >= n then "out of bounds" else "duplicate axis")
();
seen.(ax) <- true)
axes;
if not (Array.for_all Fun.id seen) then
Error.invalid ~op:"permute" ~what:"axes"
~reason:"do not form a valid permutation" ();
let new_shape =
Array.map (fun i -> view.shape.(axes.(i))) (Array.init n Fun.id)
in
let new_strides =
Array.map (fun i -> view.strides.(axes.(i))) (Array.init n Fun.id)
in
let new_mask =
match view.mask with
| None -> None
| Some m -> Some (Array.map (fun i -> m.(axes.(i))) (Array.init n Fun.id))
in
create ~offset:view.offset ?mask:new_mask ~strides:new_strides new_shape
let reshape view new_shape =
if view.shape = new_shape then view
else
let current_numel = prod view.shape in
let new_numel = prod new_shape in
if current_numel <> new_numel && current_numel <> 0 && new_numel <> 0 then
Error.shape_mismatch ~op:"reshape" ~expected:new_shape ~actual:view.shape
()
else if
Array.exists (( = ) 0) view.shape || Array.exists (( = ) 0) new_shape
then create ~offset:0 new_shape
else if view.mask <> None then
Error.failed ~op:"reshape" ~what:"cannot reshape views with masks"
~hint:"call contiguous() first to create a mask-free copy" ()
else if view.layout = C_contiguous then create ~offset:view.offset new_shape
else if
Array.length new_shape = 0
then
create ~offset:view.offset new_shape
else if Array.for_all (( = ) 0) view.strides then
let new_strides = Array.make (Array.length new_shape) 0 in
create ~offset:view.offset ~strides:new_strides new_shape
else
let old_non_one = Array.to_list view.shape |> List.filter (( <> ) 1) in
let new_non_one = Array.to_list new_shape |> List.filter (( <> ) 1) in
if old_non_one = new_non_one then
let new_strides =
let old_idx = ref 0 in
Array.map
(fun dim ->
if dim = 1 then 0
else (
while
!old_idx < Array.length view.shape
&& view.shape.(!old_idx) = 1
do
incr old_idx
done;
let stride = view.strides.(!old_idx) in
incr old_idx;
stride))
new_shape
in
create ~offset:view.offset ~strides:new_strides new_shape
else
let analyze_reshape old_shape old_strides new_shape =
let try_match old_pos new_pos old_size new_size =
match () with
| _ when old_size = new_size ->
if old_pos + 1 <= Array.length old_shape then
Some [ (old_pos, new_pos, old_size) ]
else None
| _ when old_size < new_size && new_size mod old_size = 0 -> (
let rec accumulate pos acc =
if acc = new_size then
Some
(List.rev
(List.init (pos - old_pos) (fun i -> old_pos + i)))
else if pos >= Array.length old_shape || acc > new_size then
None
else accumulate (pos + 1) (acc * old_shape.(pos))
in
match accumulate (old_pos + 1) old_size with
| Some merged_dims ->
let can_merge =
List.fold_left
(fun (ok, expected_stride) dim ->
if not ok then (false, 0)
else if dim = List.hd merged_dims then
(true, old_strides.(dim))
else
( old_strides.(dim) = expected_stride,
old_strides.(dim) * old_shape.(dim) ))
(true, 0) merged_dims
|> fst
in
if can_merge then Some [ (old_pos, new_pos, new_size) ]
else None
| None -> None)
| _ when new_size < old_size && old_size mod new_size = 0 ->
let factor = old_size / new_size in
if old_strides.(old_pos) = 1 then
Some
[
(old_pos, new_pos, new_size);
(old_pos, new_pos + 1, factor);
]
else None
| _ -> None
in
let rec build_mapping old_idx new_idx mappings =
if
old_idx >= Array.length old_shape
&& new_idx >= Array.length new_shape
then Some (List.rev mappings)
else if
old_idx >= Array.length old_shape
|| new_idx >= Array.length new_shape
then None
else
match
try_match old_idx new_idx old_shape.(old_idx)
new_shape.(new_idx)
with
| Some maps ->
let old_advance =
List.length
(List.filter (fun (o, _, _) -> o = old_idx) maps)
in
let new_advance = List.length maps in
build_mapping (old_idx + old_advance) (new_idx + new_advance)
(maps @ mappings)
| None -> None
in
build_mapping 0 0 []
in
match analyze_reshape view.shape view.strides new_shape with
| Some mapping ->
let new_strides = Array.make (Array.length new_shape) 0 in
List.iter
(fun (old_dim, new_dim, _size) ->
new_strides.(new_dim) <- view.strides.(old_dim))
mapping;
create ~offset:view.offset ~strides:new_strides new_shape
| None ->
Error.cannot ~op:"reshape" ~what:"reshape strided view"
~from:(Shape.to_string view.shape)
~to_:(Shape.to_string new_shape)
~reason:
(Printf.sprintf "incompatible strides %s (expected %s)"
(Shape.to_string view.strides)
(Shape.to_string (compute_strides view.shape)))
~hint:
"call contiguous() before reshape to create a C-contiguous copy"
()
let unsafe_resize view arg new_mask_opt =
if Array.length arg <> Array.length view.shape then
Error.invalid ~op:"unsafe_resize" ~what:"argument array"
~reason:
(Printf.sprintf "length %d != ndim %d" (Array.length arg)
(Array.length view.shape))
();
let new_shape = Array.map (fun (a, b) -> b - a) arg in
let new_offset = ref view.offset in
Array.iteri
(fun i (a, _) -> new_offset := !new_offset + (a * view.strides.(i)))
arg;
let final_mask =
let shift_and_combine_mask old_mask_dim_bounds new_mask_dim_bounds
offset_for_dim =
let old_b, old_e = old_mask_dim_bounds in
let new_b, new_e = new_mask_dim_bounds in
let shifted_old_b = max 0 (old_b - offset_for_dim) in
let shifted_old_e = max 0 (old_e - offset_for_dim) in
(max shifted_old_b new_b, min shifted_old_e new_e)
in
match (view.mask, new_mask_opt) with
| None, None -> None
| Some old_m, None ->
Some
(Array.mapi
(fun i (old_b, old_e) ->
let a, _ = arg.(i) in
let new_dim_size = new_shape.(i) in
(max 0 (old_b - a), min new_dim_size (old_e - a)))
old_m)
| None, Some new_m -> Some new_m
| Some old_m, Some new_m ->
Some
(Array.mapi
(fun i (old_b_i, old_e_i) ->
let new_m_b_i, new_m_e_i = new_m.(i) in
let a_i, _ = arg.(i) in
shift_and_combine_mask (old_b_i, old_e_i) (new_m_b_i, new_m_e_i)
a_i)
old_m)
in
create ~offset:!new_offset ?mask:final_mask ~strides:view.strides new_shape
let pad view arg =
if Array.length arg <> Array.length view.shape then
Error.invalid ~op:"pad" ~what:"padding array"
~reason:
(Printf.sprintf "length %d != ndim %d" (Array.length arg)
(Array.length view.shape))
();
if Array.for_all (fun (b, e) -> b = 0 && e = 0) arg then view
else if Array.exists (fun (b, e) -> b < 0 || e < 0) arg then
Error.invalid ~op:"pad" ~what:"padding values"
~reason:"negative values not allowed"
~hint:"use shrink or slice to remove elements" ()
else
let zvarg =
Array.mapi
(fun i s ->
let pad_before, pad_after = arg.(i) in
(-pad_before, s + pad_after))
view.shape
in
let mask_for_pad =
Array.mapi
(fun i s_old ->
let pad_before, _pad_after = arg.(i) in
(pad_before, pad_before + s_old))
view.shape
in
unsafe_resize view zvarg (Some mask_for_pad)
let shrink view arg =
if Array.length arg <> Array.length view.shape then
Error.invalid ~op:"shrink" ~what:"bounds array"
~reason:
(Printf.sprintf "length %d != ndim %d" (Array.length arg)
(Array.length view.shape))
();
if Array.for_all2 (fun (b, e) s -> b = 0 && e = s) arg view.shape then view
else if
Array.exists2
(fun (b, e) s -> b < 0 || e < 0 || b > s || e > s || b >= e)
arg view.shape
then
Error.invalid ~op:"shrink" ~what:"bounds"
~reason:"must be within shape and start < end" ()
else unsafe_resize view arg None
let flip view flip_axes_bools =
if Array.length flip_axes_bools <> Array.length view.shape then
Error.invalid ~op:"flip" ~what:"boolean array"
~reason:
(Printf.sprintf "length %d != ndim %d"
(Array.length flip_axes_bools)
(Array.length view.shape))
();
let new_offset = ref view.offset in
let new_strides = Array.copy view.strides in
let new_mask =
match view.mask with Some m -> Some (Array.copy m) | None -> None
in
Array.iteri
(fun i do_flip ->
if do_flip then
let s_i = view.shape.(i) in
if s_i > 0 then (
new_offset := !new_offset + ((s_i - 1) * view.strides.(i));
new_strides.(i) <- -new_strides.(i);
match new_mask with
| Some m_arr ->
let b, e = m_arr.(i) in
m_arr.(i) <- (s_i - e, s_i - b)
| None -> ()))
flip_axes_bools;
create ~offset:!new_offset ?mask:new_mask ~strides:new_strides view.shape