Serialization: Support enum types

README.md

@@ -212,8 +212,7 @@ Output:
    - Add type hints for more scalar types
  * Serialization:
    - Support for more standard library types
-   - Support for enum types
-   - Support polymorphism (requires ref and ptr types)
+   - Support polymorphism
    - Support variant objects
    - Support transient fields (i.e. fields that will not be (de-)serialized on
      objects and tuples)

test/serializing.nim

@@ -7,6 +7,9 @@ type
         i: int32
         b: bool
     
+    TrafficLight = enum
+        tlGreen, tlYellow, tlRed
+    
     Person = object
         firstname, surname: string
         age: int32
@@ -89,6 +92,25 @@ suite "Serialization":
         assertStringEqual "%YAML 1.2\n--- \n- [1, 2, 3]\n- [4, 5]\n- [6]",
                           output.data
     
+    test "Serialization: Load Enum":
+        let input = newStringStream("- tlRed\n- tlGreen\n- tlYellow")
+        var
+            result: seq[TrafficLight]
+            parser = newYamlParser(tagLib)
+            events = parser.parse(input)
+        construct(events, result)
+        assert result.len == 3
+        assert result[0] == tlRed
+        assert result[1] == tlGreen
+        assert result[2] == tlYellow
+    
+    test "Serialization: Serialize Enum":
+        let input = @[tlRed, tlGreen, tlYellow]
+        var output = newStringStream()
+        dump(input, output, psBlockOnly, tsNone)
+        assertStringEqual "%YAML 1.2\n--- \n- tlRed\n- tlGreen\n- tlYellow",
+                          output.data
+    
     test "Serialization: Load Tuple":
         let input = newStringStream("str: value\ni: 42\nb: true")
         var

yaml/serialization.nim

@@ -605,7 +605,7 @@ proc serializeObject*[K, V](value: Table[K, V], ts: TagStyle,
                 yield event
         yield YamlStreamEvent(kind: yamlEndMap)
 
-template yamlTag*(T: typedesc[object]): expr =
+template yamlTag*(T: typedesc[object|enum]): expr =
     var uri = when compiles(yamlTagId(T)): yamlTagId(T) else:
             "!nim:custom:" & T.name
     try:
@@ -663,6 +663,27 @@ proc serializeObject*[O: object|tuple](value: O, ts: TagStyle,
                 yield event
         yield endMapEvent()
 
+proc constructObject*[O: enum](s: YamlStream, c: ConstructionContext,
+                               result: var O)
+        {.raises: [YamlConstructionError, YamlConstructionStreamError].} =
+    let e = s()
+    assert(not finished(s))
+    if e.kind != yamlScalar:
+        raise newException(YamlConstructionError, "Expected scalar, got " &
+                           $e.kind)
+    try: result = parseEnum[O](e.scalarContent)
+    except ValueError:
+        var ex = newException(YamlConstructionError, "Cannot parse '" &
+                e.scalarContent & "' as " & type(O).name)
+        ex.parent = getCurrentException()
+        raise ex
+
+proc serializeObject*[O: enum](value: O, ts: TagStyle,
+                               c: SerializationContext):
+        YamlStream {.raises: [].} =
+    result = iterator(): YamlStreamEvent =
+        yield scalarEvent($value, presentTag(O, ts), yAnchorNone)
+
 proc yamlTag*[O](T: typedesc[ref O]): TagId {.inline, raises: [].} = yamlTag(O)
 
 proc constructObject*[O](s: YamlStream, c: ConstructionContext,