Humza Shahid
f3a4e15ed5
git-subtree-dir: dotscape git-subtree-mainline:6b91d64fc3git-subtree-split:f306501a68
83 lines
2.7 KiB
Standard ML
83 lines
2.7 KiB
Standard ML
structure Parser =
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struct
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structure T = Tokens
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fun parseItem (tokens, grid) =
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case tokens of
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T.L_BRACE ::
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T.INT x ::
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T.INT y ::
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T.INT ex ::
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T.INT ey ::
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T.INT r :: T.INT g :: T.INT b :: T.INT a :: T.R_BRACE :: tl =>
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let
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val colour = {r = r, g = g, b = b, a = a}
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val grid = ParseGrid.applyItem (grid, x, y, ex, ey, colour)
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in
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SOME (tl, grid)
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end
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| _ => NONE
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(* note to be careful of:
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* - startParseItems returns NONE if there are no items found,
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* because we have not found a single item yet.
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*
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* - loopParseItems returns SOME if there are no items found,
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* because this function is called after we have parsed at least one item.
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* *)
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fun loopParseItems (tokens, grid) =
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case parseItem (tokens, grid) of
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SOME (tokens, grid) => loopParseItems (tokens, grid)
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| NONE => SOME (tokens, grid)
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fun startParseItems (tokens, grid) =
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case parseItem (tokens, grid) of
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SOME (tokens, grid) => loopParseItems (tokens, grid)
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| NONE => NONE
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fun parseLayer (tokens, canvasWidth, canvasHeight, tree, counter) =
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case tokens of
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T.L_BRACKET :: tl =>
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let
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val grid = ParseGrid.make (canvasWidth, canvasHeight)
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in
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case startParseItems (tl, grid) of
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SOME (T.R_BRACKET :: tl, grid) =>
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let val tree = LayerTree.insert (counter, grid, tree)
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in SOME (tl, tree)
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end
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| SOME _ => NONE
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| NONE => NONE
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end
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| _ => NONE
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fun parseLayerLoop (tokens, canvasWidth, canvasHeight, tree, counter) =
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case parseLayer (tokens, canvasWidth, canvasHeight, tree, counter) of
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SOME (tl, tree) =>
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parseLayerLoop (tl, canvasWidth, canvasHeight, tree, counter + 1)
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| NONE => SOME (tokens, tree)
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fun startParseLayer (tokens, canvasWidth, canvasHeight, tree) =
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case parseLayer (tokens, canvasWidth, canvasHeight, tree, 1) of
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SOME (tl, tree) => parseLayerLoop (tl, canvasWidth, canvasHeight, tree, 2)
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| NONE => NONE
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fun parse string =
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case Lexer.scan string of
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SOME tokens =>
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(case tokens of
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T.INT canvasWidth :: T.INT canvasHeight :: T.L_BRACE :: tl =>
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let
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val maxSide = Int.max (canvasWidth, canvasHeight)
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val tree = LayerTree.init maxSide
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in
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case startParseLayer (tl, canvasWidth, canvasHeight, tree) of
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SOME ([T.R_BRACE], tree) =>
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SOME (canvasWidth, canvasHeight, tree)
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| SOME _ => NONE
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| NONE => NONE
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end
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| _ => NONE)
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| NONE => NONE
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end
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