--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/service/rfid_pn532/rdf.nim	Sun Apr 21 03:28:21 2019 -0700
@@ -0,0 +1,76 @@
+import algorithm
+import hashes
+import json
+import sequtils
+import sets
+import strformat
+import strutils
+
+import rdf_nodes
+
+type Namespace* = object of RootObj
+  prefix: string
+  
+proc initNamespace*(prefix: string): Namespace =
+  result.prefix = prefix
+
+proc `[]`*(self: Namespace, tail: string): Uri =
+  initUri(self.prefix & tail)
+
+
+type Quad* = tuple[s: Uri, p: Uri, o: RdfNode, g: Uri]
+     
+proc toJsonLd*(quads: HashSet[Quad]): string =
+  var graphs: HashSet[Uri] = toSet[Uri]([])
+  graphs.init()
+  for q in quads:
+    graphs.incl(q.g)
+  var graphUris = toSeq[Uri](graphs.items)
+  graphUris.sort(cmpUri)
+  var graphJson = newJArray()
+  for g in graphUris:
+    var quadsInGraph: seq[JsonNode]
+    for q in quads:
+      if q.g == g:
+        quadsInGraph.add(%* {"@id": $q.s, $q.p: [toJsonLdObject(q.o)]})
+      
+    graphJson.add(%* {"@graph": quadsInGraph, "@id": $g})
+  $graphJson
+    
+
+proc hash*(x: Quad): Hash =
+  hash(1)
+
+type Patch* = object of RootObj
+  addQuads*: HashSet[Quad]
+  delQuads*: HashSet[Quad]
+
+proc toJson*(self: Patch): string =
+  $ %* {"patch" : {"adds": self.addQuads.toJsonLd(),
+                   "deletes": self.delQuads.toJsonLd()}}
+  
+  
+type Graph* = object of RootObj
+  stmts*: HashSet[Quad]
+
+proc len*(self: Graph): int = len(self.stmts)
+  
+proc initGraph*(): Graph =
+  result.stmts.init()
+
+proc applyPatch*(self: var Graph, p: Patch) =
+  self.stmts.excl(p.delQuads)
+  self.stmts.incl(p.addQuads)
+
+proc toNquads*(self: var Graph): string =
+  var lines: seq[string] = @[]
+  for q in self.stmts:
+    lines.add(&"{q.s.toNt()} {q.p.toNt()} {q.o.toNt()} {q.g.toNt()} .\n")
+  return lines.join("")
+
+proc toNtriples*(stmts: openArray[Quad]): string =
+  var lines: seq[string] = @[]
+  for q in stmts:
+    lines.add(&"{q.s.toNt()} {q.p.toNt()} {q.o.toNt()} .\n")
+  return lines.join("")
+