make lengths a tuple

eth/rlp/hash_writer.nim

@@ -4,13 +4,13 @@ import
   nimcrypto/keccak,
   stew/[arraybuf, shims/macros],
   ./priv/defs,
-  utils
+  utils,
+  length_writer
 
 type
   RlpHashWriter* = object
     keccak: keccak.keccak256
-    listLengths*: seq[int]
-    prefixLengths*: seq[int]
+    lengths*: seq[tuple[listLen, prefixLen: int]]
     listCount: int
     bigEndianBuf: array[8, byte]
 
@@ -61,8 +61,8 @@ proc startList*(self: var RlpHashWriter, listSize: int) =
     self.writeCount(0, LIST_START_MARKER)
   else:
     let 
-      prefixLen = self.prefixLengths[self.listCount]
-      listLen = self.listLengths[self.listCount]
+      prefixLen = self.lengths[self.listCount].prefixLen
+      listLen = self.lengths[self.listCount].listLen
 
     self.listCount += 1
 
@@ -74,13 +74,14 @@ proc startList*(self: var RlpHashWriter, listSize: int) =
       
       self.updateBigEndian(uint64(listLen), listLenBytes)
 
+func initHashWriter*(tracker: var RlpLengthTracker): RlpHashWriter =
+  result.lengths = move(tracker.lengths)
+
 template finish*(self: var RlpHashWriter): MDigest[self.keccak.bits] =
-  self.listLengths.setLen(0)
-  self.prefixLengths.setLen(0)
+  self.lengths.setLen(0)
   self.keccak.finish()
 
 func clear*(w: var RlpHashWriter) =
   # Prepare writer for reuse
-  w.listLengths.setLen(0)
-  w.prefixLengths.setLen(0)
+  w.lengths.setLen(0)
 

eth/rlp/length_writer.nim

@@ -7,8 +7,7 @@ import
 
 type
   RlpLengthTracker* = object
-    prefixLengths*: seq[int]
-    listLengths*: seq[int]
+    lengths*: seq[tuple[listLen, prefixLen: int]]
     pendingLists: seq[tuple[idx, remainingItems, startLen: int]]
     listCount: int
     totalLength*: int
@@ -29,8 +28,7 @@ proc maybeClosePendingLists(self: var RlpLengthTracker) =
                       else: int(uint64(listLen).bytesNeeded) + 1
 
       # save the list lengths and prefix lengths
-      self.listLengths[listIdx] = listLen
-      self.prefixLengths[listIdx] = prefixLen
+      self.lengths[listIdx] = (listLen, prefixLen)
 
       # close the list by deleting
       self.pendingLists.setLen(lastIdx)
@@ -51,9 +49,8 @@ proc startList*(self: var RlpLengthTracker, listSize: int) =
     # open a list
     self.pendingLists.add((self.listCount, listSize, self.totalLength))
     self.listCount += 1
-    if self.listCount == self.listLengths.len:
-      self.listLengths.setLen(self.listLengths.len + LIST_LENGTH)
-      self.prefixLengths.setLen(self.prefixLengths.len + LIST_LENGTH)
+    if self.listCount == self.lengths.len:
+      self.lengths.setLen(self.lengths.len + LIST_LENGTH)
 
 func lengthCount(count: int): int {.inline.} =
   return if count < THRESHOLD_LIST_LEN: 1 
@@ -76,10 +73,7 @@ func writeInt*(self: var RlpLengthTracker, i: SomeUnsignedInt) =
 func initLengthTracker*(): RlpLengthTracker =
   # we preset the lengths since we want to skip using add method for
   # these lists
-  result.prefixLengths = newSeqOfCap[int](LIST_LENGTH)
-  result.prefixLengths.setLen(LIST_LENGTH)
-  result.listLengths = newSeqOfCap[int](LIST_LENGTH)
-  result.listLengths.setLen(LIST_LENGTH)
+  result.lengths = newSeq[(int, int)](LIST_LENGTH)
 
 template finish*(self: RlpLengthTracker): int =
   doAssert self.pendingLists.len == 0, 
@@ -89,5 +83,4 @@ template finish*(self: RlpLengthTracker): int =
 func clear*(w: var RlpLengthTracker) =
   # Prepare writer for reuse
   w.pendingLists.setLen(0)
-  w.prefixLengths.setLen(0)
-  w.listLengths.setLen(0)
+  w.lengths.setLen(0)

eth/rlp/two_pass_writer.nim

@@ -3,14 +3,14 @@ import
   pkg/results,
   stew/[arraybuf, assign2, shims/macros],
   ./priv/defs,
-  utils
+  utils,
+  length_writer
 
 type
   RlpTwoPassWriter* = object
     pendingLists*: seq[tuple[remainingItems, startPos, prefixLen: int]]
     output*: seq[byte]
-    prefixLengths*: seq[int]
-    listLengths*: seq[int]
+    lengths*: seq[tuple[listLen, prefixLen: int]]
     fillLevel: int
     listCount: int
 
@@ -61,8 +61,8 @@ proc startList*(self: var RlpTwoPassWriter, listSize: int) =
     self.writeCount(0, LIST_START_MARKER)
   else:
     let 
-      prefixLen = self.prefixLengths[self.listCount]
-      listLen = self.listLengths[self.listCount]
+      prefixLen = self.lengths[self.listCount].prefixLen
+      listLen = self.lengths[self.listCount].listLen
 
     self.listCount += 1
 
@@ -76,22 +76,19 @@ proc startList*(self: var RlpTwoPassWriter, listSize: int) =
       self.output.writeBigEndian(uint64(listLen), self.fillLevel - 1,
         listLenBytes)
 
-func initTwoPassWriter*(length: int): RlpTwoPassWriter =
+func initTwoPassWriter*(tracker: var RlpLengthTracker): RlpTwoPassWriter =
   result.fillLevel = 0
   result.listCount = 0
-  result.output = newSeqOfCap[byte](length)
-  result.output.setLen(length)
+  result.output = newSeq[byte](tracker.totalLength)
+  result.lengths = move(tracker.lengths)
 
 template finish*(self: RlpTwoPassWriter): seq[byte] =
   doAssert self.pendingLists.len == 0, 
     "Insufficient number of elements written to a started list"
-  self.prefixLengths.setLen(0)
-  self.listLengths.setLen(0)
+  self.lengths.setLen(0)
   self.output
 
 func clear*(w: var RlpTwoPassWriter) =
   # Prepare writer for reuse
   w.pendingLists.setLen(0)
   w.output.setLen(0)
-  w.prefixLengths.setLen(0)
-  w.listLengths.setLen(0)

eth/rlp/writer.nim

@@ -189,9 +189,7 @@ proc encode*[T](v: T): seq[byte] =
   
   tracker.append(v)
 
-  var writer = initTwoPassWriter(tracker.totalLength)
-  writer.prefixLengths = tracker.prefixLengths
-  writer.listLengths = tracker.listLengths
+  var writer = initTwoPassWriter(tracker)
   writer.append(v)
 
   move(writer.finish)
@@ -200,12 +198,10 @@ proc encodeHash*[T](v: T): Hash32 =
   mixin append
 
   var tracker = initLengthTracker()
-  var writer: RlpHashWriter
 
   tracker.append(v)
 
-  writer.prefixLengths = tracker.prefixLengths
-  writer.listLengths = tracker.listLengths
+  var writer = initHashWriter(tracker)
   writer.append(v)
 
   writer.finish.to(Hash32)