improve code to move rightwards in cursor.sml (making it clearer with comments), and improve code to draw cursor at newline in text=builder.sml
This commit is contained in:
122
fcore/cursor.sml
122
fcore/cursor.sml
@@ -1,58 +1,72 @@
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structure Cursor =
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struct
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(* todo: viL does not handle \r\n pair right now
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* but this is not a priority so it's okay *)
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local
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fun helpVilLf (hd, strIdx, bufferIdx, cursorIdx, tl) =
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(* if we are in \n,
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* move cursor to character after newline
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* if possible *)
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if strIdx < String.size hd - 3 then
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(* we know it is safe to move cursorIdx by 2
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* if strIdx + 2 is before or at the end of the string. *)
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cursorIdx + 2
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else
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(* we have to check the tl to see if it is not empty
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* so we know it is safe to move. *)
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case tl of
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_ :: _ =>
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(* not empty, so we can increment by 2 *)
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cursorIdx + 2
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| [] =>
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(* empty, so return end of string which is \n *)
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bufferIdx + String.size hd - 1
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in
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(* Prerequisite: lineGap is moved to requested idx first
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* todo: check if we are in a \r\n pair, but this is not a priority *)
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fun viL (lineGap: LineGap.t, cursorIdx) =
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let
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val {rightStrings, idx = bufferIdx, ...} = lineGap
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in
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case rightStrings of
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hd :: tl =>
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let
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(* convert absolute cursorIdx to idx relative to hd string *)
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val strIdx = cursorIdx - bufferIdx
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in
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if strIdx < String.size hd - 2 then
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(case String.sub (hd, strIdx + 1) of
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#"\n" => helpVilLf (hd, strIdx, bufferIdx, cursorIdx, tl)
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(* Prerequisite: lineGap is moved to requested idx first
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* todo: check if we are in a \r\n pair, but this is not a priority *)
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fun viL (lineGap: LineGap.t, cursorIdx) =
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let
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val {rightStrings, idx = bufferIdx, ...} = lineGap
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in
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case rightStrings of
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hd :: tl =>
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let
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(* convert absolute cursorIdx to idx relative to hd string *)
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val strIdx = cursorIdx - bufferIdx
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in
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if strIdx + 1 < String.size hd then
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(* if there is at least one character after this idx *)
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let
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val nextChr = String.sub (hd, strIdx + 1)
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in
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(case nextChr of
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#"\n" =>
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if strIdx + 2 < String.size hd then
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(* if there are at least two chars after strIdx *)
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cursorIdx + 2
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else
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(* only one char after strIdx which is \n
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* if there is a string at the tl, can increment by 2 *)
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(case tl of
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_ :: _ => cursorIdx + 2
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| [] => cursorIdx + 1)
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| _ => cursorIdx + 1)
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else
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(case tl of
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tlhd :: tltl =>
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(* if there is another string after current head, we can increment cursorIdx
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* however, first we need to check if next char is \n. *)
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(case String.sub (tlhd, 0) of
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#"\n" => helpVilLf (tlhd, 0, bufferIdx, cursorIdx, tltl)
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| _ => cursorIdx + 1)
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| _ =>
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(* if there is no string after current head, return original cursorIdx *)
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cursorIdx)
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end
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| [] =>
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(* return original cursorIdx if there is nothing to the right *)
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cursorIdx
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end
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end
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end
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else
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(* no chars after this idx; have to check tl *)
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(case tl of
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tlhd :: tltl =>
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(* if there is another string after current head, we can increment cursorIdx
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* however, first we need to check if next char is \n. *)
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let
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val nextChr = String.sub (tlhd, 0)
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in
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(case nextChr of
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#"\n" =>
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if String.size tlhd > 2 then
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(* if there is at least one character after \n
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* then increment cursorIdx by 2 *)
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cursorIdx + 2
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else
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(* this string only contains \n
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* but there is a small possibility tltl
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* contains another string.
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* If it does, we can increment cursorIdx by 2,
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* moving past newline.
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* If not, increment cursorIdx by 1,
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* landing on newline. *)
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(case tltl of
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tltlhd :: _ => cursorIdx + 2
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| [] => cursorIdx + 1)
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| _ =>
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(* next char is not newline,
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* so we can just increment by 1 *)
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cursorIdx + 1)
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end
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| [] =>
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(* if there is no string after current head, return original cursorIdx *)
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cursorIdx)
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end
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| [] =>
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(* return original cursorIdx if there is nothing to the right *)
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cursorIdx
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end
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end
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@@ -326,15 +326,25 @@ struct
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else
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(* in cursor position, so build cursorAcc
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* and call AfterCursor function *)
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let
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val cursorAcc = buildCursor (posX, posY, fWindowWidth, fWindowHeight, r, g ,b)
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in
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buildTextStringAfterCursor
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( pos + 1, str, acc, startX, posY + ySpace, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b, tl, cursorAcc
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)
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end
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if pos = String.size str - 1 andalso tl = [] then
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(* if we are at end of lineGap, we want to build cursorAcc
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* at different coordinates than usual *)
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let
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val cursorAcc =
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buildCursor (startX, posY + ySpace, fWindowWidth, fWindowHeight, r, g, b)
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in
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accToDrawMsg (acc, cursorAcc)
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end
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else
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let
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val cursorAcc = buildCursor (posX, posY, fWindowWidth, fWindowHeight, r, g ,b)
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in
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buildTextStringAfterCursor
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( pos + 1, str, acc, startX, posY + ySpace, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b, tl, cursorAcc
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)
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end
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else
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accToDrawMsg (acc, cursorAcc)
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| #"\r" =>
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