Make 'read' and 'append' easier to override for user-defined types

The 'rlp.inspect' output have been improved.

.gitignore

@@ -2,6 +2,7 @@
 *
 !*.*
 !*/
+*.exe
 
 nimcache/
 

rlp.nim

@@ -267,19 +267,19 @@ proc listLen*(self: Rlp): int =
   for elem in rlp:
     inc result
 
-proc read*(rlp: var Rlp, T: type string): string =
+proc readImpl(rlp: var Rlp, T: type string): string =
   result = rlp.toString
   rlp.skipElem
 
-proc read*(rlp: var Rlp, T: type Integer): Integer =
+proc readImpl(rlp: var Rlp, T: type Integer): Integer =
   result = rlp.toInt(T)
   rlp.skipElem
 
-proc read*(rlp: var Rlp, T: typedesc[enum]): T =
+proc readImpl(rlp: var Rlp, T: typedesc[enum]): T =
   result = type(result)(rlp.toInt(int))
   rlp.skipElem
 
-proc read*[R, E](rlp: var Rlp, T: type array[R, E]): T =
+proc readImpl[R, E](rlp: var Rlp, T: type array[R, E]): T =
   mixin read
 
   when E is (byte or char):
@@ -306,7 +306,7 @@ proc read*[R, E](rlp: var Rlp, T: type array[R, E]): T =
       result[i] = rlp.read(E)
       inc i
 
-proc read*[E](rlp: var Rlp, T: type seq[E]): T =
+proc readImpl[E](rlp: var Rlp, T: type seq[E]): T =
   mixin read
 
   when E is (byte or char):
@@ -323,10 +323,10 @@ proc read*[E](rlp: var Rlp, T: type seq[E]): T =
     for elem in rlp:
       result.add rlp.read(E)
 
-proc read*[E](rlp: var Rlp, T: type openarray[E]): seq[E] =
+proc readImpl[E](rlp: var Rlp, T: type openarray[E]): seq[E] =
-  result = read(rlp, seq[E])
+  result = readImpl(rlp, seq[E])
 
-proc read*(rlp: var Rlp, T: typedesc[object|tuple],
+proc readImpl(rlp: var Rlp, T: typedesc[object|tuple],
               wrappedInList = wrapObjectsInList): T =
   mixin enumerateRlpFields, read
 
@@ -356,14 +356,19 @@ proc toNodes*(self: var Rlp): RlpNode =
     result.bytes = toBytes()
     position = currentElemEnd()
 
+# We define a single `read` template with a pretty low specifity
+# score in order to facilitate easier overloading with user types:
+template read*(rlp: var Rlp, T: typedesc): auto =
+  readImpl(rlp, T)
+
 proc decode*(bytes: openarray[byte]): RlpNode =
   var
     bytesCopy = @bytes
     rlp = rlpFromBytes(bytesCopy.toRange())
   return rlp.toNodes
 
-
 template decode*(bytes: BytesRange, T: typedesc): untyped =
+  mixin read
   var rlp = rlpFromBytes bytes
   rlp.read(T)
 
@@ -374,6 +379,13 @@ template decode*(bytes: openarray[byte], T: typedesc): T =
 proc append*(writer: var RlpWriter; rlp: Rlp) =
   append(writer, rlp.rawData)
 
+proc isPrintable(s: string): bool =
+  for c in s:
+    if ord(c) < 32 or ord(c) >= 128:
+      return false
+
+  return true
+
 proc inspectAux(self: var Rlp, depth: int, output: var string) =
   if not hasData():
     return
@@ -388,9 +400,17 @@ proc inspectAux(self: var Rlp, depth: int, output: var string) =
     output.add "byte "
     output.add $bytes[position]
   elif self.isBlob:
+    let str = self.toString
+    if str.isPrintable:
       output.add '"'
-    output.add self.toString
+      output.add str
       output.add '"'
+    else:
+      output.add "blob(" & $str.len & ") ["
+      for c in str:
+        output.add $ord(c)
+        output.add ","
+      output[^1] = ']'
   else:
     output.add "{\n"
     for subitem in self:

rlp/object_serialization.nim

@@ -15,3 +15,8 @@ macro rlpFields*(T: typedesc, fields: varargs[untyped]): untyped =
   result = quote do:
     template enumerateRlpFields*(`ins`: `T`, `op`: untyped) {.inject.} =
       `body`
+
+template rlpInline* {.pragma.}
+  ## This can be specified on a record field in order to avoid the
+  ## default behavior of wrapping the record in a RLP list.
+

rlp/writer.nim

@@ -126,7 +126,7 @@ proc startList*(self; listSize: int) =
   else:
     pendingLists.add((listSize, output.len))
 
-template appendImpl(self; data, startMarker) =
+template appendBlob(self; data, startMarker) =
   mixin baseAddr
 
   if data.len == 1 and byte(data[0]) < BLOB_START_MARKER:
@@ -142,22 +142,22 @@ template appendImpl(self; data, startMarker) =
 
   maybeClosePendingLists()
 
-proc append*(self; data: string) =
+proc appendImpl(self; data: string) =
-  appendImpl(self, data, BLOB_START_MARKER)
+  appendBlob(self, data, BLOB_START_MARKER)
 
 proc appendBlob(self; data: openarray[byte]) =
-  appendImpl(self, data, BLOB_START_MARKER)
+  appendBlob(self, data, BLOB_START_MARKER)
 
 proc appendBlob(self; data: openarray[char]) =
-  appendImpl(self, data, BLOB_START_MARKER)
+  appendBlob(self, data, BLOB_START_MARKER)
 
 proc appendBytesRange(self; data: BytesRange) =
-  appendImpl(self, data, BLOB_START_MARKER)
+  appendBlob(self, data, BLOB_START_MARKER)
 
-proc append*(self; data: MemRange) =
+proc appendImpl(self; data: MemRange) =
-  appendImpl(self, data, BLOB_START_MARKER)
+  appendBlob(self, data, BLOB_START_MARKER)
 
-proc append*(self; i: Integer) =
+proc appendImpl(self; i: Integer) =
   type IntType = type(i)
 
   if i == IntType(0):
@@ -171,10 +171,10 @@ proc append*(self; i: Integer) =
 
   self.maybeClosePendingLists()
 
-template append*(self; e: enum) =
+template appendImpl(self; e: enum) =
-  append(self, int(e))
+  appendImpl(self, int(e))
 
-proc append*[T](self; listOrBlob: openarray[T]) =
+proc appendImpl[T](self; listOrBlob: openarray[T]) =
   mixin append
 
   # TODO: This append proc should be overloaded by `openarray[byte]` after
@@ -200,7 +200,7 @@ proc appendTupleOrObject(self; data: object|tuple, wrapInList: bool) =
   template op(x) = append(self, x)
   enumerateRlpFields(data, op)
 
-proc append*(self; data: object, wrapInList = wrapObjectsInList) {.inline.} =
+proc appendImpl(self; data: object, wrapInList = wrapObjectsInList) {.inline.} =
   # TODO: This append proc should be overloaded by `BytesRange` after
   # nim bug #7416 is fixed.
   when data is BytesRange:
@@ -208,9 +208,13 @@ proc append*(self; data: object, wrapInList = wrapObjectsInList) {.inline.} =
   else:
     self.appendTupleOrObject(data, wrapInList)
 
-proc append*(self; data: tuple, wrapInList = wrapObjectsInList) {.inline.} =
+proc appendImpl(self; data: tuple, wrapInList = wrapObjectsInList) {.inline.} =
   self.appendTupleOrObject(data, wrapInList)
 
+# We define a single `append` template with a pretty low specifity
+# score in order to facilitate easier overloading with user types:
+template append*[T](self; data: T) = appendImpl(self, data)
+
 proc initRlpList*(listSize: int): RlpWriter =
   result = initRlpWriter()
   startList(result, listSize)
@@ -222,6 +226,7 @@ proc finish*(self): BytesRange =
   result = output.toRange()
 
 proc encode*[T](v: T): BytesRange =
+  mixin append
   var writer = initRlpWriter()
   writer.append(v)
   return writer.finish
@@ -231,10 +236,11 @@ macro encodeList*(args: varargs[untyped]): BytesRange =
     listLen = args.len
     writer = genSym(nskVar, "rlpWriter")
     body = newStmtList()
+    append = bindSym("append", brForceOpen)
 
   for arg in args:
     body.add quote do:
-      append(`writer`, `arg`)
+      `append`(`writer`, `arg`)
 
   result = quote do:
     var `writer` = initRlpList(`listLen`)
@@ -244,6 +250,7 @@ macro encodeList*(args: varargs[untyped]): BytesRange =
 when false:
   # XXX: Currently fails with a malformed AST error on the args.len expression
   template encodeList*(args: varargs[untyped]): BytesRange =
+    mixin append
     var writer = initRlpList(args.len)
     for arg in args:
       writer.append(arg)