optimize and document
parent
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@ -1,15 +1,27 @@
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module Constraint exposing (Model, focusOn, init, positions, unfocus, updateAttachments)
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module Constraint exposing (Model, focusOn, init, positions, unfocus, updateIdealPositions)
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import Dict exposing (Dict)
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{-| Lay out comments according to these constraints:
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1. if there is a focused comment, it must be at it's ideal position
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2. comments may not overlap
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3. comments should be as close as possible to their ideal position (but the
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first comment in an otherwise-overlapping sequence should be at it's ideal position)
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Notably missing here: the ability to add new comments. That's just not something
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that we need to solve for yet. Once we do, it should not be too hard to add
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(recalculate the `comments` ordering with respect to the new height and ideal
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position data, and re-solve.)
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-}
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type Model
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= Model
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{ -- comment ID to comment height
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heights : Dict Int Float
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-- comment ID to ideal position
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, attachments : Dict Int Float
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{ -- comment ID to dimensions. This needs to be sorted by idealPosition
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-- since this algorithm will be walking the data that way several
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-- times.
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comments : List ( Int, { height : Float, idealPosition : Float } )
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-- comment ID to actual position
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, positions : Dict Int Float
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@ -24,14 +36,23 @@ type Model
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init :
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{ heights : Dict Int Float
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, attachments : Dict Int Float
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, idealPositions : Dict Int Float
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, margin : Float
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}
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-> Model
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init { heights, attachments, margin } =
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init { heights, idealPositions, margin } =
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Model
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{ heights = heights
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, attachments = attachments
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{ comments =
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-- take the intersection of the heights and ideal positions. Gotta have both for a comment to do this algorithm!
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Dict.merge
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(\_ _ result -> result)
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(\key height idealPosition -> Dict.insert key { height = height, idealPosition = idealPosition })
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(\_ _ result -> result)
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heights
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idealPositions
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Dict.empty
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|> Dict.toList
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|> List.sortBy (\( _, { idealPosition } ) -> idealPosition)
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, positions = Dict.empty
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, margin = margin
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, focus = Nothing
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@ -53,16 +74,9 @@ solveWithoutFocus (Model guts) =
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Model
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{ guts
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| positions =
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guts.attachments
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|> Dict.toList
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|> List.sortBy Tuple.second
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guts.comments
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|> List.foldl
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(\( id, idealPosition ) ( finalPositions, progressLine ) ->
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let
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height =
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Dict.get id guts.heights
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|> Maybe.withDefault 0
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in
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(\( id, { idealPosition, height } ) ( finalPositions, progressLine ) ->
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if idealPosition >= progressLine then
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( Dict.insert id idealPosition finalPositions
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, idealPosition + height + guts.margin
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@ -87,20 +101,13 @@ solveWithFocus (Model guts) =
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solveWithoutFocus (Model guts)
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( goUp, goDown ) =
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newGuts.attachments
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|> Dict.toList
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|> List.sortBy Tuple.second
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-- == 0 is a trick to get the compiler to generate
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-- more efficient code. Will not always be needed!
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|> splitAtReversing (\( curId, _ ) -> curId - id == 0)
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-- == 0 is a trick to get the compiler to generate
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-- more efficient code. Will not always be needed!
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splitAtReversing (\( curId, _ ) -> curId - id == 0) newGuts.comments
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( downwardPositions, _ ) =
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List.foldl
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(\( curId, idealPosition ) ( finalPositions, progressLine ) ->
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let
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height =
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Dict.get curId newGuts.heights |> Maybe.withDefault 0
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in
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(\( curId, { height, idealPosition } ) ( finalPositions, progressLine ) ->
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if idealPosition >= progressLine then
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( Dict.insert curId idealPosition finalPositions
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, idealPosition + height + newGuts.margin
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@ -116,11 +123,8 @@ solveWithFocus (Model guts) =
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( downwardAndUpwardPositions, _ ) =
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List.foldl
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(\( curId, idealPosition ) ( finalPositions, progressLine ) ->
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(\( curId, { height, idealPosition } ) ( finalPositions, progressLine ) ->
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let
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height =
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Dict.get curId newGuts.heights |> Maybe.withDefault 0
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currentPosition =
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Dict.get curId newGuts.positions |> Maybe.withDefault idealPosition
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in
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@ -140,8 +144,8 @@ solveWithFocus (Model guts) =
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)
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( downwardPositions
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, case goDown of
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( _, start ) :: _ ->
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start
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( _, { idealPosition } ) :: _ ->
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idealPosition
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_ ->
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-- infinity
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@ -155,13 +159,21 @@ solveWithFocus (Model guts) =
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solveWithFocus (Model guts)
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updateAttachments : Dict Int Float -> Model -> Model
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updateAttachments attachments (Model guts) =
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if attachments == guts.attachments then
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Model guts
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else
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Model { guts | attachments = attachments } |> solve
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updateIdealPositions : Dict Int Float -> Model -> Model
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updateIdealPositions attachments (Model guts) =
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Model
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{ guts
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| comments =
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guts.comments
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|> List.filterMap
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(\( id, metrics ) ->
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Maybe.map
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(\newIdealPosition -> ( id, { metrics | idealPosition = newIdealPosition } ))
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(Dict.get id attachments)
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)
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|> List.sortBy (\( _, { idealPosition } ) -> idealPosition)
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}
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|> solve
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focusOn : Int -> Model -> Model
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@ -97,7 +97,7 @@ update msg model =
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( { model
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| commentPositions =
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Maybe.map
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(Constraint.updateAttachments (finalAttachments attachments))
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(Constraint.updateIdealPositions (idealPositionsFor attachments))
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model.commentPositions
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}
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, Cmd.none
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@ -109,7 +109,7 @@ update msg model =
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Just <|
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Constraint.init
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{ heights = Dict.fromList commentHeights
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, attachments = finalAttachments attachments
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, idealPositions = idealPositionsFor attachments
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, margin = 10
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}
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}
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@ -133,8 +133,8 @@ update msg model =
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)
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finalAttachments : List ( Int, Float ) -> Dict Int Float
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finalAttachments =
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idealPositionsFor : List ( Int, Float ) -> Dict Int Float
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idealPositionsFor =
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List.foldl
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(\( commentId, top ) soFar ->
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Dict.update commentId
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Reference in New Issue