move to fixed-size arrays instead of sequences

colors.nim

@@ -0,0 +1,139 @@
+import strutils
+
+
+type
+  Color* = enum
+    cRed, cGreen, cBlue, cYellow, cPurple
+
+  ColorStack* = object
+    pieces: array[5, int8]
+    last: int8
+
+
+proc init*(s: var ColorStack) =
+  for i in 0..4:
+    s.pieces[i] = -1
+  s.last = -1
+
+
+proc `[]`*(s: ColorStack, i: Natural): Color =
+  if i > s.last:
+    raise newException(IndexDefect, "index " & $i & " is out of bounds.")
+  result = Color(s.pieces[i])
+
+
+proc `[]`*(s: ColorStack, i: BackwardsIndex): Color =
+  if s.last == -1:
+    raise newException(IndexDefect, "index out of bounds, the container is empty.") # matching stdlib again
+  result = Color(s.pieces[s.last - int8(i) + 1])
+
+
+proc `[]=`*(s: var ColorStack, i: Natural, v: Color) =
+  if i > s.last:
+    raise newException(IndexDefect, "index " & $i & " is out of bounds.")
+  s.pieces[i] = int8(v)
+
+
+proc `$`*(s: ColorStack): string =
+  result.add("St@[")
+  for i in 0 .. s.last:
+    let c = Color(s.pieces[i])
+    result.add($c)
+    if i < s.last:
+      result.add(", ")
+  result.add("]")
+
+
+proc high*(s: ColorStack): int8 =
+  result = s.last
+
+
+proc low*(s: ColorStack): int8 =
+  result = case s.last
+  of -1: 0 # a bit weird but it's how the stdlib seq works
+  else: s.last
+
+
+proc len*(s: ColorStack): int8 =
+  result = s.last + 1
+
+
+iterator items*(s: ColorStack): Color =
+  for i in 0 .. s.last:
+    yield Color(s[i])
+
+
+iterator asInt*(s: ColorStack): int8 =
+  for i in 0 .. s.last:
+    yield s.pieces[i] # no conversion, should speed up hashing? maybe
+
+
+iterator pairs*(s: ColorStack): auto =
+  var count = 0
+  for c in s:
+    yield (count, c)
+    inc count
+
+
+proc add*(s: var ColorStack, c: Color) =
+  let i = s.last + 1
+  s.pieces[i] = int8(c) # will raise exception if out of bounds
+  s.last = i
+
+
+proc insert*(s: var ColorStack, c: Color, idx: Natural = 0) =
+  for i in countdown(s.last, int8(idx)):
+    swap(s.pieces[i], s.pieces[i + 1]) # will also raise exception if out of bounds
+  s.pieces[idx] = int8(c)
+  inc s.last
+
+
+proc delete*(s: var ColorStack, idx: Natural) =
+  if idx > s.last:
+    raise newException(IndexDefect, "index " & $idx & " is out of bounds.")
+  s.pieces[idx] = -1
+  dec s.last
+  for i in int8(idx) .. s.last:
+    swap(s.pieces[i], s.pieces[i + 1])
+
+
+proc find(s: ColorStack, c: Color): int8 =
+  let needle = int(c)
+  for i, v in s.pieces:
+    if v == needle:
+      return i
+  return -1
+
+
+proc moveSubstack*(src, dst: var ColorStack; start: Natural) =
+  var count = 0 # have to track this separately apparently
+  for idx in (int8(start) .. src.last):
+    swap(src.pieces[idx], dst.pieces[dst.last + 1 + count])
+    inc count
+  dst.last += int8(count)
+  src.last -= int8(count)
+
+
+proc moveSubstackPre*(src, dst: var ColorStack; start: Natural) =
+  let ssLen = src.last - start + 1 # length of substack
+  for i in countdown(dst.last, 0):
+    swap(dst.pieces[i], dst.pieces[i + ssLen])
+
+  var count = 0
+  for i in start .. src.last:
+    swap(src.pieces[i], dst.pieces[count])
+    inc count
+
+  dst.last += int8(ssLen)
+  src.last -= int8(ssLen)
+
+
+proc display(s: ColorStack) =
+  var p: seq[string]
+  for i in s.pieces:
+    if i == -1:
+      p.add("none")
+    else:
+      p.add($Color(i))
+  echo "pieces: @[", p.join(", "), "], last: ", s.last
+  echo "len: ", s.len, "\n"

combinators.nim

@@ -12,23 +12,24 @@ iterator allPermutations*[T](x: seq[T]): seq[T] =
     yield workingCopy
 
 
-iterator allDigits*(lo, hi, size: int): seq[int] =
+iterator allDigits*(lo, hi, size: Natural): seq[int] =
-  # we use uninitialized since we will initialize it below, but not necessarily with 0s
+  if size > 0: # otherwise we get an infinite loop
-  var digits = newSeqUninitialized[int](size)
+    # we use uninitialized since we will initialize it below, but not necessarily with 0s
-  for i in 0 .. digits.high:
+    var digits = newSeqUninitialized[int](size)
-    digits[i] = lo
+    for i in 0 .. digits.high:
+      digits[i] = lo
 
-  var complete = false
+    var complete = false
-  while not complete:
+    while not complete:
-    yield digits
+      yield digits
-    for i in countdown(digits.high, 0):
+      for i in countdown(digits.high, 0):
-      if digits[i] < hi:
+        if digits[i] < hi:
-        inc digits[i]
+          inc digits[i]
-        break
+          break
-      elif i == 0: # since this is the last digit to be incremented, we must be done
+        elif i == 0: # since this is the last digit to be incremented, we must be done
-        complete = true
+          complete = true
-      else:
+        else:
-        digits[i] = lo
+          digits[i] = lo
 
 
 iterator possibleFutures*[C](dice: seq[C]): seq[tuple[color: C, value: int]] =

main.nim

@@ -1,46 +1,44 @@
 import math, hashes, options, tables, sequtils, sets, sugar
-import combinators
+import combinators, colors
-
-
-type
-  Color = enum
-    cRed, cGreen, cBlue, cYellow, cPurple
-
-  Tile = enum
-    tBackward = -1,
-    tForward = 1
-
-  Square = object
-    camels: seq[Color]
-    tile: Option[Tile]
-
-  Die = tuple[color: Color, value: int]
-
-  ScoreSet = array[Color, int]
-
-  LegResults = tuple[scores: ScoreSet, endStates: HashSet[Board]]
-
-  Board = object
-    squares: array[1..16, Square]
-    camels: array[Color, range[1..16]]
-    diceRolled: array[Color, bool]
-    leader: Option[Color]
-    gameOver: bool
 
 
 const allDice = @[cRed, cGreen, cBlue, cYellow, cPurple]
 
 
-proc update(scores: var ScoreSet, toAdd: ScoreSet) =
+type
+  Die* = tuple[color: Color, value: int]
+
+  Tile* = enum
+    tBackward = -1,
+    tForward = 1
+
+  Square* = object
+    camels: ColorStack
+    tile: Option[Tile]
+
+  Board* = object
+    squares: array[1..16, Square]
+    camels: array[Color, range[1..16]]
+    diceRolled: array[Color, bool]
+    leader: Option[Color]
+    gameOver: bool
+    initialized: bool
+
+  ScoreSet* = array[Color, int]
+
+  LegResults* = tuple[scores: ScoreSet, endStates: HashSet[Board]]
+
+
+proc update*(scores: var ScoreSet, toAdd: ScoreSet) =
   for i, s in toAdd:
     scores[i] += s
 
 
-proc `[]`[T](b: var Board, idx: T): var Square =
+proc `[]`*[T](b: var Board, idx: T): var Square =
   b.squares[idx]
 
 
-proc hash(b: Board): Hash =
+proc hash*(b: Board): Hash =
   var h: Hash = 0
   # there could be a tile anywhere so we have to check all squares
   for i, sq in b.squares:
@@ -49,11 +47,17 @@ proc hash(b: Board): Hash =
       if sq.tile.isSome:
         h = h !& int(sq.tile.get) * 10 # so it isn't confused with a camel
       else:
-        for c in sq.camels:
+        for c in sq.camels.asInt:
-          h = h !& int(c)
+          h = h !& c
   result = !$h
 
 
+proc init*(b: var Board) =
+  for sq in b.squares.mitems:
+    sq.camels.init
+  b.initialized = true
+
+
 proc display(b: Board, start, stop: int) =
   for i in start..stop:
     let sq = b.squares[i]
@@ -79,6 +83,11 @@ proc setState(b: var Board;
   b.leader = some(leadCamel)
 
 
+proc resetDice(b: var Board) =
+  var d: array[Color, bool]
+  b.diceRolled = d
+
+
 proc advance(b: var Board, die: Die) =
   let
     (color, roll) = die
@@ -96,21 +105,24 @@ proc advance(b: var Board, die: Die) =
     endPos += int(t)
     if t == tBackward: prepend = true
 
-  for i, c in b[startPos].camels:
+  let stackStart = b[startPos].camels.find(color)
-    if c == color:
+  if prepend:
-      let subStack = b[startPos].camels[i .. ^1]
+    b[startPos].camels.moveSubstackPre(b[endPos].camels, stackStart)
-      if prepend:
+    let stackLen = b[startPos].camels.len - stackStart
-        b[endPos].camels.insert(subStack)
+    for i in 0 ..< stackLen:
-      else:
+      # we know how many camels we added to the bottom, so set the position for each of those
-        b[endPos].camels.add(subStack)
+      b.camels[b[endPos].camels[i]] = endPos
-
+  else:
-      b[startPos].camels[i .. ^1] = @[]
+    let dstPrevHigh = b[endPos].camels.high
-      for moved in subStack:
+    b[startPos].camels.moveSubstack(b[endPos].camels, stackStart)
-        b.camels[moved] = endPos
+    # the camels that have moved start immediately after the previous high camel
-      # if we are stacking on or moving past the previous leader
+    for i in (dstPrevHigh + 1) .. b[endPos].camels.high:
-      if endPos >= b.camels[b.leader.get]:
+      b.camels[b[endPos].camels[i]] = endPos
-        b.leader = some(b[endPos].camels[^1])
+  
-      break # breaking the outer loop here, not the inner - but only conditionally! gah!
+  # if we are stacking on or moving past the previous leader
+  if endPos >= b.camels[b.leader.get]:
+    b.leader = some(b[endPos].camels[^1])
+  
   b.diceRolled[color] = true
 
 
@@ -129,14 +141,20 @@ proc projectLeg(b: Board): LegResults =
     inc scores[prediction.leader.get]
     # deduplicate results
     endStates.incl(prediction)
+
   result = (scores, endStates)
 
 
 proc projectOutcomes(b: Board, maxDepth = 1): ScoreSet =
   var outcomeStack = @[ [b].toHashSet ]
   for depth in 1..maxDepth:
+    echo "simulating ", outcomeStack[^1].len, " possible legs."
     var endStates: HashSet[Board]
+
     for o in outcomeStack[^1]:
+      var o = o # make it mutable
+      o.resetDice # o was describina an end-of-leg state, so dice were exhausted
+
       let projection = o.projectLeg
       result.update(projection[0])
       endStates.incl(projection[1])
@@ -147,11 +165,15 @@ proc projectOutcomes(b: Board, maxDepth = 1): ScoreSet =
 
 
 var b: Board
+b.init
 b.display(1, 5)
 
 b.setState({cGreen: 4, cYellow: 3, cPurple: 4, cBlue: 3, cRed: 4}, @[])
 b.display(1, 5)
 
+# b.advance((cRed, 1))
+# b.display(1, 5)
+
 let r = b.projectOutcomes(2)
 let total = r.sum
 for i, c in r: