Add 'shf/' from commit 'b6c5a95b664aeb861d7b33ffc9eefe447ba99dd7'

git-subtree-dir: shf
git-subtree-mainline: 401408448f
git-subtree-split: b6c5a95b66

shf/fcore/cursor-dfa/vi-l-dfa.sml

@@ -0,0 +1,53 @@
+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