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implement core operations

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This commit is contained in:
Humza Shahid
2023-11-13 03:16:56 +00:00
parent 2d00d67a7e
commit 49204dd3f1
1 changed files with 100 additions and 8 deletions
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108
rope.sml
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@@ -180,14 +180,14 @@ fun ins cur_index string rope =
end
| _ => raise Empty
fun ins index string rope =
fun insert index string rope =
let
val rope = ins index string rope
in
root rope
end
fun sub_internal start_idx end_idx acc rope =
fun sub start_idx end_idx acc rope =
case rope of
N0 str =>
let
@@ -221,7 +221,7 @@ fun sub_internal start_idx end_idx acc rope =
end
end
| N1 t =>
sub_internal start_idx end_idx acc t
sub start_idx end_idx acc t
| N2(l, lm, _, r) =>
let
val starts_before = lm > start_idx
@@ -230,13 +230,13 @@ fun sub_internal start_idx end_idx acc rope =
val ends_after = lm < end_idx
in
if starts_before andalso ends_before then
sub_internal start_idx end_idx acc l
sub start_idx end_idx acc l
else if starts_after andalso ends_after then
let
val next_start = start_idx - lm
val next_end = end_idx - lm
in
sub_internal next_start next_end acc r
sub next_start next_end acc r
end
else
let
@@ -244,17 +244,109 @@ fun sub_internal start_idx end_idx acc rope =
val next_end = end_idx - lm
val sub_acc = sub next_start next_end acc r
in
sub_internal start_idx end_idx sub_acc l
sub start_idx end_idx sub_acc l
end
end
| _ => raise Empty
fun sub start length rope =
fun substring start length rope =
let
val finish = start + length
val lst = sub_internal start finish [] rope
val lst = sub start finish [] rope
in
String.concat lst
end
fun del start_idx end_idx rope =
case rope of
N0 str =>
let
val str_size = String.size str
val before_start = start_idx <= 0
val after_end = end_idx >= str_size
val after_start = start_idx >= 0
val before_end = end_idx <= str_size
in
if before_start andalso after_end then
(N0 "", false)
else if after_start andalso before_end then
let
val str1 = String.substring(str, 0, start_idx)
val del_len = str_size - end_idx
val str2 = String.substring(str, start_idx, del_len)
val new_len = str_size - del_len
in
if new_len <= target_length then
(N0(str1 ^ str2), false)
else
(L2(str1, str2), true)
end
else if after_start andalso after_end then
let
val str = String.substring(str, 0, start_idx)
in
(N0 str, false)
end
else
let
val len = str_size - end_idx
val str = String.substring(str, end_idx, len)
in
(N0 str, false)
end
end
| N1 t =>
let
val (t, did_ins) = del start_idx end_idx t
val t = if did_ins then n1 t else t
in
(t, did_ins)
end
| N2(l, lm, rm, r) =>
let
val start_is_less = lm > start_idx
val end_is_less = lm > end_idx
val start_is_more = lm < start_idx
val end_is_more = lm < end_idx
in
if start_is_less andalso end_is_less then
let
val (l, did_ins) = del start_idx end_idx l
in
case did_ins of
false =>
(N2(l, size l, rm, r), false)
| true =>
(ins_n2_left l r, true)
end
else if start_is_more andalso end_is_more then
let
val next_start = start_idx - lm
val next_end = end_idx - lm
val (r, did_ins) = del next_start next_end r
in
case did_ins of
false =>
(N2(l, lm, size r, r), false)
| true =>
(ins_n2_right l r, true)
end
else
let
val (l, did_ins_l) = del start_idx end_idx l
val r_start = start_idx - lm
val r_end = end_idx - lm
val (r, did_ins_r) = del r_start r_end r
in
if did_ins_l then
(ins_n2_left l r, true)
else if did_ins_r then
(ins_n2_right l r, true)
else
(N2(l, size l, size r, r), false)
end
end
| _ => raise Empty