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amend error in cursor.sml's 'getCursorColumn' function, where we may need to check tail of string to start convert cursorIdx to relative strIdx

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This commit is contained in:
Humza Shahid
2024-10-19 23:04:26 +01:00
parent e0f44fc8ea
commit 47f4d452fe
3 changed files with 597 additions and 38 deletions
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98
fcore/cursor.sml
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@@ -213,6 +213,44 @@ struct
end
| (_, _) => distanceFromLine
fun helpGetCursorColumnBranch (strIdx, strHd, lnHd, leftStrings, leftLines) =
if String.sub (strHd, strIdx) = #"\n" then
(* If we are at newline, column is 0 *)
0
else if Vector.length lnHd = 1 then
(* check if the one line idx in the vector
* is before the strIdx *)
let
val lineIdx = Vector.sub (lnHd, 0)
in
if lineIdx < strIdx then strIdx - lineIdx
else helpGetCursorColumn (strIdx, leftStrings, leftLines)
end
else if Vector.length lnHd > 1 then
let
(* check if strIdx is inside line vector,
* and perform binary search if so *)
val low = Vector.sub (lnHd, 0)
in
if low < strIdx then
(* strIdx is less than low, so use bin search
* to find lineIdx that is lower than strIdx *)
let
val lineIdx = binSearch (strIdx - 1, lnHd)
(* linebreakPos = index of linebreak before strIdx *)
val linebreakPos = Vector.sub (lnHd, lineIdx)
in
strIdx - linebreakPos - 1
end
else
(* line before strIdx must be in leftStrings/lines *)
helpGetCursorColumn (strIdx, leftStrings, leftLines)
end
else
(* lnHd has length of 0, so most recent
* line break must be in leftStrings/lines *)
helpGetCursorColumn (strIdx, leftStrings, leftLines)
(* Prerequisite: lineGap is moved to cursorIdx *)
fun getCursorColumn (lineGap: LineGap.t, cursorIdx) =
let
@@ -221,47 +259,35 @@ struct
lineGap
in
case (rightStrings, rightLines) of
(strHd :: _, lnHd :: _) =>
(strHd :: strTl, lnHd :: lnTl) =>
let
(* convert absolute cursorIdx to idx relative to hd string *)
val strIdx = cursorIdx - bufferIdx
in
if String.sub (strHd, strIdx) = #"\n" then
(* If we are at newline, column is 0 *)
0
else if Vector.length lnHd = 1 then
(* check if the one line idx in the vector
* is before the strIdx *)
let
val lineIdx = Vector.sub (lnHd, 0)
in
if lineIdx < strIdx then strIdx - lineIdx
else helpGetCursorColumn (strIdx, leftStrings, leftLines)
end
else if Vector.length lnHd > 1 then
let
(* check if strIdx is inside line vector,
* and perform binary search if so *)
val low = Vector.sub (lnHd, 0)
in
if low < strIdx then
(* strIdx is less than low, so use bin search
* to find lineIdx that is lower than strIdx *)
let
val lineIdx = binSearch (strIdx - 1, lnHd)
(* linebreakPos = index of linebreak before strIdx *)
val linebreakPos = Vector.sub (lnHd, lineIdx)
in
strIdx - linebreakPos - 1
end
else
(* line before strIdx must be in leftStrings/lines *)
helpGetCursorColumn (strIdx, leftStrings, leftLines)
end
if strIdx < String.size strHd then
(* strIdx is in this string *)
helpGetCursorColumnBranch
(strIdx, strHd, lnHd, leftStrings, leftLines)
else
(* lnHd has length of 0, so most recent
* line break must be in leftStrings/lines *)
helpGetCursorColumn (strIdx, leftStrings, leftLines)
(* strIdx must be in the strTl *)
(case (strTl, lnTl) of
(nestStrHd :: nestStrTl, nestLnHd :: nestLnTl) =>
let
val strIdx = strIdx - String.size strHd
val leftStrings = strHd :: leftStrings
val leftLines = lnHd :: leftLines
in
helpGetCursorColumnBranch
(strIdx, nestStrHd, nestLnHd, leftStrings, leftLines)
end
| (_, _) =>
helpGetCursorColumnBranch
( String.size strHd - 1
, strHd
, lnHd
, leftStrings
, leftLines
))
end
| (_, _) => helpGetCursorColumn (0, leftStrings, leftLines)
end