Add renderRstToJson in docutils

lib/packages/docutils/rstast.nim

@@ -286,3 +286,28 @@ proc renderRstToRst*(n: PRstNode, result: var string) =
   var d: TRenderContext
   renderRstToRst(d, n, result)
 
+proc renderRstToJson*(node: PRstNode): string =
+  ## Writes the given RST node as JSON that is in the form
+  ## :: code-block
+  ##   {
+  ##     "kind":string node.kind,
+  ##     "text":optional string node.text,
+  ##     "level":optional int node.level,
+  ##     "sons":optional node array
+  ##   }
+  result = ""
+  result.add("{\"kind\":\"" & $ node.kind & "\",")
+  if node.text != Nil:
+    # XXX Json spec requires control charecters be escaped as \uXXXX,
+    # strutils.escape writes them as \uXX
+    result.add("\"text\":" & node.text.escape & ",")
+  result.add("\"level\":" & $ node.level)
+  if node.sons == nil or len(node.sons) == 0:
+    result.add("}")
+  else:
+    result.add(",\"sons\":[")
+    for i, son in node.sons:
+      result.add(renderRstToJson(son))
+      if i < len(node.sons) - 1:
+        result.add(",")
+    result.add("]}")