Logical position tracking not reflected properly.

[ixchow]

Using xfers to set the logical position of a carrier and then knitting in such a way that it would be trapped is not reflected in the current visualizer. (See example in textiles-lab/knitout#5 )

[ixchow]

Slightly shorter test case:

;!knitout-2
;;Carriers: 1 2 3 4 5 6 7 8 9 10

in 1
knit + f1 1
knit + f2 1
knit + f3 1

in 2
knit + f1 2
knit + f2 2
knit + f3 2

xfer f3 b3
rack -1
xfer b3 f2

knit - f2 2
knit - f1 2
knit + f1 2
knit + f2 2
knit + f3 2

drop f1
drop f2
drop f3

Carrier 1's logical position should follow the xfer but it does not.

Output:

Expected:

(possibly with slightly more elegant handling in terms of vertical space)

[ixchow]

Useful context for a fix:

• Carriers currently store their front-bed-relative positions as c.after = {d: direction, n: needle}.
• The bringCarriers routine moves carriers along the front bed. A fix will likely result in more bringCarriers calls being made.

A possible fix would be to store the logical position of each carrier as c.logical = {d: direction, n:needle} and emit a bringCarriers after split or rack to fix any carriers whose .logical and .after don't match (.logical will need to be mapped to the front bed before this comparison).

(NOTE: after is always a front bed position, so rack will probably trigger lots of wig-wags in carriers referenced to a back-bed stitch.)