converters from/to XmlNode (#229)

* converters from/to XmlNode

* fix: text and verbatim from VNode to xmlnode

* Update karax/xdom.nim

* Update karax/xdom.nim

* change converters to procs

Co-authored-by: untoreh <francesco.giannelli@yahoo.it>
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

karax/xdom.nim

@@ -0,0 +1,39 @@
+import std/[xmltree, htmlparser, strtabs, strutils]
+import ./vdom
+
+proc toXmlNode*(el: VNode): XmlNode =
+  case el.kind
+  of VNodeKind.verbatim:
+    parseHtml($el)
+  of VNodeKind.text:
+    newText(el.text)
+  else:
+    let xAttrs = @[].toXmlAttributes
+    for k, v in el.attrs:
+      xAttrs[k] = v
+    var kids: seq[XmlNode]
+    if el.len > 0:
+      for k in el:
+        kids.add k.toXmlNode
+    newXmlTree($el.kind, kids, attributes = xAttrs)
+
+proc toVNode*(el: XmlNode): VNode =
+  try:
+    case el.kind
+    of xnElement:
+      let kind = parseEnum[VNodeKind](el.tag)
+      var vnAttrs: seq[(string, string)]
+      if not el.attrs.isnil:
+        for k, v in el.attrs:
+          vnAttrs.add (k, v)
+      var kids: seq[VNode]
+      if el.len > 0:
+        for k in el:
+          kids.add k.toVNode
+      tree(kind, vnAttrs, kids)
+    of xnText:
+      vn($el)
+    else:
+      verbatim($el)
+  except ValueError: # karax doesn't support the node tag
+    verbatim($el)

tests/tester.nim

@@ -37,6 +37,7 @@ proc main =
   exec("nim js examples/carousel/carousel.nim")
   exec("nim js -d:nodejs -r tests/difftest.nim")
   exec("nim c tests/nativehtmlgen.nim")
+  exec("nim c tests/xmlNodeConversionTests.nim")
 
   for test in os.walkFiles("examples/*.nim"):
     exec("nim js " & test)

tests/xmlNodeConversionTests.nim

@@ -0,0 +1,19 @@
+import std/xmltree
+import "../karax"/[vdom, xdom]
+
+let xn = newXmlTree("div", @[], attributes = [("a", "b")].toXmlAttributes)
+let vn = tree(tdiv, attrs = (@[("a", "b"), ("c", "d")]))
+vn.add newVNode(a)
+vn[0].add vn("bbb")
+vn.add verbatim("<app>abc</app>")
+xn.add newXmlTree("i", @[], attributes = [("a", "b")].toXmlAttributes)
+
+let vnX = vn.toXmlNode
+
+doassert vnX[0].len == 1 and vnX[1][0].kind == xnText
+doassert $vnX[1].tag == "app"
+doassert $vnX == """<div c="d" a="b">
+  <a>bbb</a>
+  <app>abc</app>
+</div>"""
+doassert $xn.toVNode == """<div a="b"><i a="b"></i></div>"""