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fix asymptotic behavior of resize functions

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Simon Cruanes 2021-10-21 11:07:11 -04:00
parent e6e07ba4da
commit 2c2fa5d008
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GPG key ID: 4AC01D0849AA62B6
1 changed files with 32 additions and 29 deletions
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53
src/core/CCVector.ml
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@ -138,9 +138,11 @@ let grow_with_ v ~filler:x =
Use a doubling-size strategy so that calling many times [ensure] will
behave well *)
let ensure_assuming_not_empty_ v ~size =
if size > Sys.max_array_length
then invalid_arg "vec.ensure: size too big"
else (
if size > Sys.max_array_length then (
invalid_arg "vec.ensure: size too big"
) else if size < Array.length v.vec then (
() (* nothing to do *)
) else (
let n = ref (max 8 (Array.length v.vec)) in
while !n < size do n := min Sys.max_array_length (2* !n) done;
resize_ v !n v.vec.(0)
@ -203,19 +205,17 @@ let push v x =
let resize_with v f size =
if size<0 then invalid_arg "Vec.resize_with";
let new_vec =
if size >= Array.length v.vec then
let new_vec = Array.make size (f 0) in
Array.blit v.vec 0 new_vec 0 v.size;
new_vec
else
v.vec
in
for i = v.size to size - 1 do
Array.unsafe_set new_vec i (f i)
done;
if Array.length v.vec = 0 then (
let new_vec = Array.init size f in
v.vec <- new_vec;
v.size <- size
) else (
ensure_assuming_not_empty_ v size;
for i = v.size to size - 1 do
Array.unsafe_set v.vec i (f i)
done;
v.size <- size
)
(*$T
let v = make 1 0 in resize_with v (fun i -> i) 5; to_list v = [0;1;2;3;4]
@ -230,19 +230,17 @@ let resize_with v f size =
let resize_with_init v ~init size =
if size<0 then invalid_arg "Vec.resize_with_init";
let new_vec =
if size >= Array.length v.vec then
let new_vec = Array.make size init in
Array.blit v.vec 0 new_vec 0 v.size;
new_vec
else
v.vec
in
if Array.length v.vec = 0 then (
let vec = Array.make size init in
v.vec <- vec;
v.size <- size;
) else (
ensure_assuming_not_empty_ v size;
for i = v.size to size - 1 do
Array.unsafe_set new_vec i init
Array.unsafe_set v.vec i init
done;
v.vec <- new_vec;
v.size <- size
v.size <- size;
)
(*$T
let v = make 1 0 in resize_with_init v ~init:1 5; to_list v = [0;1;1;1;1]
@ -256,6 +254,11 @@ let resize_with_init v ~init size =
let v = make 5 0 in resize_with_init v ~init:1 5; List.length (to_list v) = 5
*)
(* test for asymptotic behavior *)
(*$T
let v =make 1 0 in for i=0 to 100_000 do resize_with_init v ~init:10 i; done; true
*)
(** Add all elements of b to a *)
let append a b =
if array_is_empty_ a then (