Serialization for sets

json_serialization/reader.nim

@@ -108,6 +108,19 @@ proc allocPtr[T](p: var ptr T) =
 proc allocPtr[T](p: var ref T) =
   p = new(T)
 
+iterator readArray*(r: var JsonReader, ElemType: typedesc): ElemType =
+  mixin readValue
+
+  r.skipToken tkBracketLe
+  if r.lexer.tok != tkBracketRi:
+    while true:
+      var res: ElemType
+      readValue(r, res)
+      yield res
+      if r.lexer.tok != tkComma: break
+      r.lexer.next()
+  r.skipToken tkBracketRi
+
 proc readValue*(r: var JsonReader, value: var auto) =
   mixin readValue
 

json_serialization/std/sets.nim

@@ -0,0 +1,15 @@
+import stew/shims/sets, ../../json_serialization/[reader, writer, lexer]
+export sets
+
+type
+  SetType = OrderedSet | HashSet | set
+
+proc writeValue*(writer: var JsonWriter, value: SetType) =
+  writer.writeIterable value
+
+proc readValue*(reader: var JsonReader, value: var SetType) =
+  type ElemType = type(value.items)
+  value = init SetType
+  for elem in readArray(reader, ElemType):
+    value.incl elem
+

json_serialization/writer.nim

@@ -92,7 +92,7 @@ template endRecordField*(w: var JsonWriter) =
   endRecord(w)
   w.state = AfterField
 
-proc writeArray[T](w: var JsonWriter, elements: openarray[T]) =
+proc writeIterable*(w: var JsonWriter, collection: auto) =
   mixin writeValue
 
   append '['
@@ -102,8 +102,9 @@ proc writeArray[T](w: var JsonWriter, elements: openarray[T]) =
     w.nestingLevel += 2
     indent()
 
-  for i, e in elements:
-    if i != 0:
+  var first = true
+  for e in collection:
+    if not first:
       append ','
       if w.hasPrettyOutput:
         append '\n'
@@ -111,6 +112,7 @@ proc writeArray[T](w: var JsonWriter, elements: openarray[T]) =
 
     w.state = RecordExpected
     w.writeValue(e)
+    first = false
 
   if w.hasPrettyOutput:
     append '\n'
@@ -119,6 +121,9 @@ proc writeArray[T](w: var JsonWriter, elements: openarray[T]) =
 
   append ']'
 
+proc writeArray[T](w: var JsonWriter, elements: openarray[T]) =
+  writeIterable(w, elements)
+
 proc writeValue*(w: var JsonWriter, value: auto) =
   template addChar(c) =
     append c

tests/test_serialization.nim

@@ -2,7 +2,7 @@ import
   strutils, unittest,
   serialization/testing/generic_suite,
   ../json_serialization, ./utils,
-  ../json_serialization/std/options
+  ../json_serialization/std/[options, sets]
 
 type
   Meter = distinct int
@@ -138,3 +138,14 @@ suite "toJson tests":
     Json.roundtripTest h1, """{"r":null,"o":{"x":1,"y":"2","distance":3}}"""
     Json.roundtripTest h2, """{"r":{"x":1,"y":"2","distance":3},"o":null}"""
 
+  test "Set types":
+    type HoldsSet = object
+      a: int
+      s: HashSet[string]
+
+    var s1 = toSet([1, 2, 3, 1, 4, 2])
+    var s2 = HoldsSet(a: 100, s: toSet(["a", "b", "c"]))
+
+    Json.roundtripTest s1
+    Json.roundtripTest s2
+