Humza Shahid
6b91d64fc3
git-subtree-dir: shf git-subtree-mainline:401408448fgit-subtree-split:b6c5a95b66
54 lines
1.6 KiB
Standard ML
54 lines
1.6 KiB
Standard ML
structure ViLDfa =
|
|
struct
|
|
val startState: Word8.word = 0w0
|
|
val newlineState: Word8.word = 0w1
|
|
val chrState: Word8.word = 0w2
|
|
val newlineAfterCHrState: Word8.word = 0w3
|
|
|
|
fun makeStart i =
|
|
if Char.chr i = #"\n" then newlineState else chrState
|
|
|
|
fun makeChr i =
|
|
if Char.chr i = #"\n" then newlineAfterCHrState else chrState
|
|
|
|
val startTable = Vector.tabulate (255, makeStart)
|
|
val newlineTable = startTable
|
|
val chrTable = Vector.tabulate (255, makeChr)
|
|
val newlineAfterCHrTable = startTable
|
|
|
|
val tables = #[startTable, newlineTable, chrTable, newlineAfterCHrTable]
|
|
|
|
fun next (currentState, chr) =
|
|
let val table = Vector.sub (tables, Word8.toInt currentState)
|
|
in Vector.sub (table, Char.ord chr)
|
|
end
|
|
|
|
structure ViL =
|
|
MakeNextDfaLoop
|
|
(struct
|
|
val startState = startState
|
|
|
|
fun loop (idx, absIdx, str, tl, currentState, counter) =
|
|
if idx = String.size str then
|
|
case tl of
|
|
str :: tl => loop (0, absIdx, str, tl, currentState, counter)
|
|
| [] => absIdx
|
|
else
|
|
let
|
|
val chr = String.sub (str, idx)
|
|
val newState = next (currentState, chr)
|
|
in
|
|
if newState = newlineAfterCHrState then
|
|
loop (idx + 1, absIdx + 1, str, tl, newState, counter)
|
|
else if counter - 1 = ~1 then
|
|
absIdx
|
|
else
|
|
loop (idx + 1, absIdx + 1, str, tl, newState, counter - 1)
|
|
end
|
|
|
|
val fStart = loop
|
|
end)
|
|
|
|
val next = ViL.next
|
|
end
|