Some performance optimization with shallowCopy

private/dom.nim

@@ -60,7 +60,7 @@ proc composeNode(s: var YamlStream, tagLib: TagLibrary,
         of yamlScalar:
             result.tag = tagLib.uri(start.scalarTag)
             result.kind = yScalar
-            result.content = start.scalarContent
+            shallowCopy(result.content, start.scalarContent)
             if start.scalarAnchor != yAnchorNone:
                 assert(not c.refs.hasKey(start.scalarAnchor))
                 c.refs[start.scalarAnchor] = cast[pointer](result)

private/json.nim

@@ -61,7 +61,7 @@ proc jsonFromScalar(content: string, tag: TagId): JsonNode
             result.kind = JNull
         else:
             result.kind = JString
-            result.str = content
+            shallowCopy(result.str, content)
     except ValueError:
         var e = newException(YamlConstructionError,
                              "Cannot parse numeric value")

private/streams.nim

@@ -11,7 +11,13 @@ proc initYamlStream*(backend: iterator(): YamlStreamEvent): YamlStream =
 proc next*(s: var YamlStream): YamlStreamEvent =
     if s.peeked:
         s.peeked = false
-        result = s.cached
+        if s.cached.kind == yamlScalar:
+            # performance optimization
+            result = YamlStreamEvent(kind: yamlScalar,
+                                     scalarTag: s.cached.scalarTag,
+                                     scalarAnchor: s.cached.scalarAnchor)
+            shallowCopy(result.scalarContent, s.cached.scalarContent)
+        else: result = s.cached
     else:
         try:
             result = s.backend()