Added jester-based YAML parsing webservice

* Added server/server.nim
 * Fixed a problem in presenter that made it crash when
   outputting a root map to JSON

config.nims

@@ -34,3 +34,7 @@ task bench, "Benchmarking":
 task clean, "Remove all generated files":
     exec "rm -f yaml.html libyaml.* test/tests test/parsing test/lexing"
     setCommand "nop"
+
+task server, "Compile server daemon":
+    --d:release
+    setCommand "c", "server/server"

private/presenter.nim

@@ -323,7 +323,7 @@ proc present*(s: YamlStream, target: Stream, tagLib: YamlTagLibrary,
             of ypsCanonical:
                 nextState = dFlowExplicitMapStart
             of ypsJson:
-                if levels[levels.high] in
+                if levels.len > 0 and levels[levels.high] in
                         [dFlowImplicitMapStart, dFlowImplicitMapValue]:
                     raise newException(YamlPresenterJsonError,
                             "Cannot have map as map key in JSON output!")

server/server.nim

@@ -0,0 +1,48 @@
+#            NimYAML - YAML implementation in Nim
+#        (c) Copyright 2015 Felix Krause
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+
+import jester, asyncdispatch, json, streams
+import yaml
+
+routes:
+    get "/":
+        headers["Content-Type"] = "text/plain"
+        resp "I am a friendly NimYAML parser webservice."
+    post "/":
+        var style: YamlPresentationStyle
+        case @"style"
+        of "minimal": style = ypsMinimal
+        of "canonical": style = ypsCanonical
+        of "default": style = ypsDefault
+        of "json": style = ypsJson
+        of "blocks": style = ypsBlockOnly
+        var
+            output = newStringStream()
+            resultNode = newJObject()
+        headers["Access-Control-Allow-Origin"] = "flyx.github.io"
+        try:
+            try:
+                transform(newStringStream(@"input"), output, style)
+                resultNode["code"] = %0
+                resultNode["output"] = %output.data
+            except YamlParserError:
+                let e = (ref YamlParserError)(getCurrentException())
+                resultNode["code"] = %1
+                resultNode["line"] = %e.line
+                resultNode["column"] = %e.column
+                resultNode["message"] = %e.msg
+                resultNode["detail"] = %e.lineContent
+            except YamlPresenterJsonError:
+                let e = (ref YamlPresenterJsonError)(getCurrentException())
+                resultNode["code"] = %2
+                resultNode["message"] = %e.msg
+            headers["Content-Type"] = "application/json"
+            resp resultNode.pretty
+        except:
+            status = Http500
+            resp getCurrentException().repr
+
+runForever()