109 lines
4.0 KiB
Standard ML
109 lines
4.0 KiB
Standard ML
structure Buffer =
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struct
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(* builds text from a string with char-wrap.
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* char-wrap is a similar concept to word-wrap,
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* but it breaks on character in the middle of a word.
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* Todo:
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* - Let caller know which termination case was reached.
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* Did we reach the end of the string or did we exhaust the screen space?
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* - Possibly add visual horizontal indentation when char-wrap occurs
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* on an indented line *)
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fun buildTextString
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( pos, str, acc, posX, posY, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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) =
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if pos < String.size str then
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case String.sub (str, pos) of
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#" " =>
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(* if space, then proceed forward one char
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* without adding to acc *)
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buildTextString
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( pos + 1, str, acc, posX + 25, posY, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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| #"\t" =>
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(* if tab, proceed forward one char,
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* and jump visually forwards three chars *)
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buildTextString
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( pos + 1, str, acc, posX + 75, posY, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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| #"\n" =>
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(* if \n, move down vertically, and move to start horizontally
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* assuming we have not exceeded the window's height.
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* If we have exceeded the window's height, just return acc. *)
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if posY + 25 < windowHeight then
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buildTextString
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( pos + 1, str, acc, startX, posY + 25, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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else
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acc
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| #"\r" =>
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(* same as \n, except we also check if we are in a \r\n pair,
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* and proceed two characters forward if so *)
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if posY + 25 < windowHeight then
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if
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pos < String.size str - 1
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andalso String.sub (str, pos + 1) = #"\n"
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then
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buildTextString
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( pos + 2, str, acc, startX, posY + 25, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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else
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buildTextString
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( pos + 1, str, acc, startX, posY + 25, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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else
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acc
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| chr =>
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(* for any other character, add it to acc if there is space,
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* and proceed forward one character in the string *)
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let
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val chrFun = Vector.sub (CozetteAscii.asciiTable, Char.ord chr)
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in
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if posX + 25 < windowWidth then
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(* if there is horizontal space, place char on the right *)
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let
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val chrVec = chrFun
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(posX, posY, 25.0, 25.0, fWindowWidth, fWindowHeight, r, g, b)
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val acc = chrVec :: acc
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in
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buildTextString
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( pos + 1, str, acc, posX + 25, posY, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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end
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else if posY + 25 < windowHeight then
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(* if there is vertical space, place char down below at startX *)
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let
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val chrVec = chrFun
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( startX, posY + 25, 25.0, 25.0
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, fWindowWidth, fWindowHeight
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, r, g, b
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)
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val acc = chrVec :: acc
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in
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buildTextString
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( pos + 1, str, acc, startX + 25, posY + 25, startX
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, windowWidth, windowHeight, fWindowWidth, fWindowHeight
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, r, g, b
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)
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end
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else
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(* if no space horizontally or vertically, just return *)
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acc
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end
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else
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acc
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end
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