Merge lp:~zorba-coders/zorba/bug-1055608-node-kinds-for-roundtrip into lp:zorba

[Till Westmann]

use XDM node kinds in encode-for-roundtrip

use XDM node kinds in encode-for-roundtrip

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-09-27T02-17-43.713Z/log.html

[Zorba Build Bot (zorba-buildbot)]

The attempt to merge lp:~zorba-coders/zorba/bug-1055608-node-kinds-for-roundtrip into lp:zorba failed. Below is the output from the failed tests.

CMake Error at /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake:274 (message):
  Validation queue job
  bug-1055608-node-kinds-for-roundtrip-2012-09-27T02-17-43.713Z is finished.
  The final status was:

  3 tests did not succeed - changes not commited.

Error in read script: /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-09-27T03-36-39.765Z/log.html

[Zorba Build Bot (zorba-buildbot)]

Validation queue job bug-1055608-node-kinds-for-roundtrip-2012-09-27T03-36-39.765Z is finished. The final status was:

All tests succeeded!

[Zorba Build Bot (zorba-buildbot)]

Voting does not meet specified criteria. Required: Approve > 1, Disapprove < 1, Needs Fixing < 1, Pending < 1. Got: 2 Pending.

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-09-27T05-41-43.261Z/log.html

[Zorba Build Bot (zorba-buildbot)]

Validation queue job bug-1055608-node-kinds-for-roundtrip-2012-09-27T05-41-43.261Z is finished. The final status was:

All tests succeeded!

[Zorba Build Bot (zorba-buildbot)]

Voting does not meet specified criteria. Required: Approve > 1, Disapprove < 1, Needs Fixing < 1, Pending < 1. Got: 2 Pending.

[Matthias Brantner (matthias-brantner)]

review: Approve

[Ghislain Fourny (gislenius)]

Looks good, but there is a typo :-) (s/instauction/instruction).

review: Approve

[Till Westmann (tillw)]

> Looks good, but there is a typo :-) (s/instauction/instruction).

fixed. Thanks!

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-10-01T16-23-54.914Z/log.html

[Zorba Build Bot (zorba-buildbot)]

The attempt to merge lp:~zorba-coders/zorba/bug-1055608-node-kinds-for-roundtrip into lp:zorba failed. Below is the output from the failed tests.

CMake Error at /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake:274 (message):
  Validation queue job
  bug-1055608-node-kinds-for-roundtrip-2012-10-01T16-23-54.914Z is finished.
  The final status was:

  1 tests did not succeed - changes not commited.

Error in read script: /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-10-01T17-12-56.025Z/log.html

[Zorba Build Bot (zorba-buildbot)]

The attempt to merge lp:~zorba-coders/zorba/bug-1055608-node-kinds-for-roundtrip into lp:zorba failed. Below is the output from the failed tests.

CMake Error at /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake:274 (message):
  Validation queue job
  bug-1055608-node-kinds-for-roundtrip-2012-10-01T17-12-56.025Z is finished.
  The final status was:

  1 tests did not succeed - changes not commited.

Error in read script: /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-10-01T21-33-01.981Z/log.html

[Zorba Build Bot (zorba-buildbot)]

The attempt to merge lp:~zorba-coders/zorba/bug-1055608-node-kinds-for-roundtrip into lp:zorba failed. Below is the output from the failed tests.

CMake Error at /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake:274 (message):
  Validation queue job
  bug-1055608-node-kinds-for-roundtrip-2012-10-01T21-33-01.981Z is finished.
  The final status was:

  1 tests did not succeed - changes not commited.

Error in read script: /home/ceej/zo/testing/zorbatest/tester/TarmacLander.cmake

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-10-01T22-14-52.682Z/log.html

[Zorba Build Bot (zorba-buildbot)]

Validation queue starting for merge proposal.
Log at: http://zorbatest.lambda.nu:8080/remotequeue/bug-1055608-node-kinds-for-roundtrip-2012-10-02T11-24-30.174Z/log.html

[Zorba Build Bot (zorba-buildbot)]

Validation queue job bug-1055608-node-kinds-for-roundtrip-2012-10-02T11-24-30.174Z is finished. The final status was:

All tests succeeded!

=== modified file 'src/runtime/json/jsoniq_functions_impl.cpp'
--- src/runtime/json/jsoniq_functions_impl.cpp	2012-09-24 17:11:12 +0000
+++ src/runtime/json/jsoniq_functions_impl.cpp	2012-10-01 16:22:23 +0000
@@ -1,12 +1,12 @@
 /*
  * Copyright 2006-2008 The FLWOR Foundation.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -67,6 +67,72 @@
 const char * OPTIONS_KEY_PREFIX = "prefix";
 const char * OPTIONS_KEY_SER_PARAMS = "serialization-parameters";
 
+const char * SEQTYPE_ANYNODE  = "node()";
+const char * SEQTYPE_COMMENT  = "comment()";
+const char * SEQTYPE_DOCUMENT = "document-node()";
+const char * SEQTYPE_ELEMENT  = "element()";
+const char * SEQTYPE_PROCINST = "processing-instruction()";
+const char * SEQTYPE_TEXT     = "text()";
+
+const char * kind2str(const store::NodeKind& aKind)
+{
+  // we do not support attibutes and namespaces as they cannot be serialized
+  switch (aKind)
+  {
+  case store::StoreConsts::anyNode:      return SEQTYPE_ANYNODE;
+  case store::StoreConsts::commentNode:  return SEQTYPE_COMMENT;
+  case store::StoreConsts::documentNode: return SEQTYPE_DOCUMENT;
+  case store::StoreConsts::elementNode:  return SEQTYPE_ELEMENT;
+  case store::StoreConsts::piNode:       return SEQTYPE_PROCINST;
+  case store::StoreConsts::textNode:     return SEQTYPE_TEXT;
+  default: return "";
+  }
+}
+
+bool str2kind(const zstring& aString, store::NodeKind& aKind)
+{
+  switch(aString.at(0))
+  {
+  case 'c':
+    if (aString == SEQTYPE_COMMENT)
+    {
+      aKind = store::StoreConsts::commentNode;
+      return true;
+    }
+    break;
+  case 'd':
+    if (aString == SEQTYPE_DOCUMENT)
+    {
+      aKind = store::StoreConsts::documentNode;
+      return true;
+    }
+    break;
+  case 'e':
+  case 'n': // "node()" maps to element for backwards compatibility
+    if (aString == SEQTYPE_ELEMENT || aString == SEQTYPE_ANYNODE)
+    {
+      aKind = store::StoreConsts::elementNode;
+      return true;
+    }
+    break;
+  case 'p':
+    if (aString == SEQTYPE_PROCINST)
+    {
+      aKind = store::StoreConsts::piNode;
+      return true;
+    }
+    break;
+  case 't':
+    if (aString == SEQTYPE_TEXT)
+    {
+      aKind = store::StoreConsts::textNode;
+      return true;
+    }
+    break;
+  }
+  return false;
+}
+
 /*******************************************************************************
   json:decode-from-roundtrip($items as json-item()*,
                              $options as object()) as structured-item()*
@@ -97,6 +163,82 @@
   }
 }
 
+void
+JSONDecodeFromRoundtripIterator::extractChildOfKind(
+  const store::Item_t& aParent,
+  const store::NodeKind& aKind,
+  store::Item_t& aChild)
+{
+  store::Iterator_t lIt = aParent->getChildren();
+  bool lFound = false;
+  lIt->open();
+  while (! lFound && lIt->next(aChild))
+  {
+    lFound = aChild->getNodeKind() == aKind;
+  }
+  lIt->close();
+  ZORBA_ASSERT(lFound);
+}
+
+bool
+JSONDecodeFromRoundtripIterator::decodeNode(
+  const store::Item_t& aSerializedNode,
+  const store::NodeKind& aKind,
+  store::Item_t& aResult) const
+{
+  store::LoadProperties lProperties;
+  lProperties.setStoreDocument(false);
+  store::Item_t lDoc;
+  zstring lXmlString;
+  switch (aKind)
+  {
+  case store::StoreConsts::commentNode:
+  case store::StoreConsts::piNode:
+  case store::StoreConsts::textNode:
+    {
+      // we have to wrap these 3 node kinds, so we cannot care about streams
+      aSerializedNode->getStringValue2(lXmlString);
+      lXmlString = "<a>" + lXmlString + "</a>";
+      std::istringstream lStream(lXmlString.c_str());
+      lDoc = GENV.getStore().loadDocument("", "", lStream, lProperties);
+    }
+    break;
+  default:
+    if (aSerializedNode->isStreamable())
+    {
+      lDoc = GENV.getStore().loadDocument(
+            "", "", aSerializedNode->getStream(), lProperties);
+    }
+    else
+    {
+      aSerializedNode->getStringValue2(lXmlString);
+      std::istringstream lStream(lXmlString.c_str());
+      lDoc = GENV.getStore().loadDocument("", "", lStream, lProperties);
+    }
+    break;
+  }
+  if (aKind == store::StoreConsts::documentNode)
+  {
+    aResult = lDoc;
+  }
+  else
+  {
+    store::Item_t lRootElem;
+    extractChildOfKind(lDoc, store::StoreConsts::elementNode, lRootElem);
+    if (aKind == store::StoreConsts::elementNode)
+    {
+      // if we needed an element we're done
+      aResult = lRootElem;
+    }
+    else
+    {
+      // otherwise we have to pass through the wrapper that we've created
+      extractChildOfKind(lRootElem, aKind, aResult);
+    }
+  }
+  return true;
+}
+
 bool
 JSONDecodeFromRoundtripIterator::decodeXDM(
   const store::Item_t& anObj,
@@ -125,32 +267,10 @@
 
   zstring lTypeNameString;
   lTypeValueItem->getStringValue2(lTypeNameString);
-  if (lTypeNameString == "node()")
+  store::NodeKind lNodeKind;
+  if (str2kind(lTypeNameString, lNodeKind))
   {
-    store::LoadProperties lProperties;
-    lProperties.setStoreDocument(false);
-    store::Item_t lDoc;
-    if (lValueValueItem->isStreamable())
-    {
-      lDoc = GENV.getStore().loadDocument(
-            "", "", lValueValueItem->getStream(), lProperties);
-    }
-    else
-    {
-      zstring lXmlString;
-      lValueValueItem->getStringValue2(lXmlString);
-      std::istringstream lStream(lXmlString.c_str());
-      lDoc = GENV.getStore().loadDocument("", "", lStream, lProperties);
-    }
-    store::Iterator_t lIt = lDoc->getChildren();
-    bool lFound = false;
-    lIt->open();
-    while (! lFound && lIt->next(aResult))
-    {
-       lFound = aResult->getNodeKind() == store::StoreConsts::elementNode;
-    }
-    lIt->close();
-    ZORBA_ASSERT(lFound);
+    return decodeNode(lValueValueItem, lNodeKind, aResult);
   }
   else
   {
@@ -184,8 +304,8 @@
                                 &lTmpNsCtx,
                                 loc);
     }
+    return true;
   }
-  return true;
 }
 
 bool
@@ -478,23 +598,12 @@
     store::Item_t& aResult,
     JSONEncodeForRoundtripIteratorState* aState) const
 {
-  if (aNode->getNodeKind() != store::StoreConsts::elementNode)
-  {
-    // this is a temporary solution until we decide if/how we encode
-    // node kinds
-    RAISE_ERROR(
-      zerr::ZXQP0004_NOT_IMPLEMENTED,
-      loc,
-      ERROR_PARAMS(store::StoreConsts::toString(aNode->getNodeKind()))
-    );
-  }
-
   std::vector<store::Item_t> names(2);
   std::vector<store::Item_t> values(2);
 
   {
     zstring typeKey = aState->thePrefix + TYPE_KEY;
-    zstring typeValue = "node()";
+    zstring typeValue = kind2str(aNode->getNodeKind());
     GENV_ITEMFACTORY->createString(names.at(0), typeKey);
     GENV_ITEMFACTORY->createString(values.at(0), typeValue);
   }

=== modified file 'src/runtime/json/pregenerated/jsoniq_functions.h'
--- src/runtime/json/pregenerated/jsoniq_functions.h	2012-09-24 09:17:44 +0000
+++ src/runtime/json/pregenerated/jsoniq_functions.h	2012-10-01 16:22:23 +0000
@@ -72,6 +72,8 @@
   virtual ~JSONDecodeFromRoundtripIterator();
 
 public:
+  static void extractChildOfKind(const store::Item_t& aParent, const store::NodeKind& aKind, store::Item_t& aChild);
+  bool decodeNode(const store::Item_t& aSerializedNode, const store::NodeKind& aKind, store::Item_t& aResult) const;
   bool decodeXDM(const store::Item_t& anObj, store::Item_t& aResult, JSONDecodeFromRoundtripIteratorState* aState) const;
   bool decodeObject(const store::Item_t& anObj, store::Item_t& aResult, JSONDecodeFromRoundtripIteratorState* aState) const;
   bool decodeArray(const store::Item_t& anArray, store::Item_t& aResult, JSONDecodeFromRoundtripIteratorState* aState) const;

=== modified file 'src/runtime/spec/json/jsoniq_functions.xml'
--- src/runtime/spec/json/jsoniq_functions.xml	2012-09-21 19:01:00 +0000
+++ src/runtime/spec/json/jsoniq_functions.xml	2012-10-01 16:22:23 +0000
@@ -40,6 +40,18 @@
     <zorba:member type="zstring" name="thePrefix" brief=""/>
   </zorba:state>
 
+  <zorba:method static="true" name="extractChildOfKind" return="void">
+    <zorba:param type="const store::Item_t&amp;" name="aParent"/>
+    <zorba:param type="const store::NodeKind&amp;" name="aKind"/>
+    <zorba:param type="store::Item_t&amp;" name="aChild"/>
+  </zorba:method>
+
+  <zorba:method const="true" name="decodeNode" return="bool">
+    <zorba:param type="const store::Item_t&amp;" name="aSerializedNode"/>
+    <zorba:param type="const store::NodeKind&amp;" name="aKind"/>
+    <zorba:param type="store::Item_t&amp;" name="aResult"/>
+  </zorba:method>
+
   <zorba:method const="true" name="decodeXDM" return="bool">
     <zorba:param type="const store::Item_t&amp;" name="anObj"/>
     <zorba:param type="store::Item_t&amp;" name="aResult"/>

=== modified file 'test/rbkt/ExpQueryResults/zorba/jsoniq/jn_accumulate.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/jn_accumulate.xml.res	2012-09-15 01:17:21 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/jn_accumulate.xml.res	2012-10-01 16:22:23 +0000
@@ -1,1 +1,1 @@
-{ "n1" : { "type" : "node()", "value" : "<node>10</node>" }, "n2" : { "type" : "node()", "value" : "<node>20</node>" } }
+{ "n1" : { "type" : "element()", "value" : "<node>10</node>" }, "n2" : { "type" : "element()", "value" : "<node>20</node>" } }

=== modified file 'test/rbkt/ExpQueryResults/zorba/jsoniq/obj_constr_02.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/obj_constr_02.xml.res	2012-09-20 04:54:07 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/obj_constr_02.xml.res	2012-10-01 16:22:23 +0000
@@ -1,1 +1,1 @@
-{ "n1" : { "type" : "node()", "value" : "<node>10</node>" }, "n2" : { "type" : "node()", "value" : "<node>20</node>" } }
+{ "n1" : { "type" : "element()", "value" : "<node>10</node>" }, "n2" : { "type" : "element()", "value" : "<node>20</node>" } }

=== modified file 'test/rbkt/ExpQueryResults/zorba/jsoniq/obj_constr_04.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/obj_constr_04.xml.res	2012-09-20 04:54:07 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/obj_constr_04.xml.res	2012-10-01 16:22:23 +0000
@@ -1,1 +1,1 @@
-{ "n1" : [ { "type" : "node()", "value" : "<node>10</node>" }, 1 ], "n2" : { "type" : "node()", "value" : "<node>20</node>" } }
+{ "n1" : [ { "type" : "element()", "value" : "<node>10</node>" }, 1 ], "n2" : { "type" : "element()", "value" : "<node>20</node>" } }

=== modified file 'test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_03.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_03.xml.res	2012-09-13 21:35:10 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_03.xml.res	2012-10-01 16:22:23 +0000
@@ -1,1 +1,1 @@
-{ "serialized XML" : { "Q{http://jsoniq.org/roundtrip}type" : "node()", "Q{http://jsoniq.org/roundtrip}value" : "<para>\n         A pair named \"[$prefix]value\" (where [$prefix] is replaced with the\n         value of the parameter $prefix) and whose value is a serialization\n         of the XML node according to the XML output method and with the\n         serialization parameters specified by $param.\n         </para>" } }
\ No newline at end of file
+{ "serialized XML" : { "Q{http://jsoniq.org/roundtrip}type" : "element()", "Q{http://jsoniq.org/roundtrip}value" : "<para>\n         A pair named \"[$prefix]value\" (where [$prefix] is replaced with the\n         value of the parameter $prefix) and whose value is a serialization\n         of the XML node according to the XML output method and with the\n         serialization parameters specified by $param.\n         </para>" } }

=== modified file 'test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_04.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_04.xml.res	2012-09-13 21:40:53 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_04.xml.res	2012-10-01 16:22:23 +0000
@@ -1,1 +1,1 @@
-{ "serialized XML" : { "pre-type" : "node()", "pre-value" : "<a>\n  <b>text<c>more text</c>\n  </b>\n</a>" } }
\ No newline at end of file
+{ "serialized XML" : { "pre-type" : "element()", "pre-value" : "<a>\n  <b>text<c>more text</c>\n  </b>\n</a>" } }

=== added file 'test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_10.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_10.xml.res	1970-01-01 00:00:00 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/encode_10.xml.res	2012-10-01 16:22:23 +0000
@@ -0,0 +1,1 @@
+{ "comment" : { "Q{http://jsoniq.org/roundtrip}type" : "comment()", "Q{http://jsoniq.org/roundtrip}value" : "<!--a comment-->" }, "document" : { "Q{http://jsoniq.org/roundtrip}type" : "document-node()", "Q{http://jsoniq.org/roundtrip}value" : "<a/>" }, "pi" : { "Q{http://jsoniq.org/roundtrip}type" : "processing-instruction()", "Q{http://jsoniq.org/roundtrip}value" : "<?target an instruction?>" }, "text" : { "Q{http://jsoniq.org/roundtrip}type" : "text()", "Q{http://jsoniq.org/roundtrip}value" : "some text" } }

=== modified file 'test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/roundtrip_03.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/roundtrip_03.xml.res	2012-09-20 17:44:15 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/roundtrip_03.xml.res	2012-10-01 16:22:23 +0000
@@ -1,1 +1,1 @@
-{ "foo" : { "Q{http://jsoniq.org/roundtrip}type" : "node()", "Q{http://jsoniq.org/roundtrip}value" : "<a id=\"bar\"/>" } }
+{ "foo" : { "Q{http://jsoniq.org/roundtrip}type" : "element()", "Q{http://jsoniq.org/roundtrip}value" : "<a id=\"bar\"/>" } }

=== added file 'test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/roundtrip_06.xml.res'
--- test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/roundtrip_06.xml.res	1970-01-01 00:00:00 +0000
+++ test/rbkt/ExpQueryResults/zorba/jsoniq/roundtrip/roundtrip_06.xml.res	2012-10-01 16:22:23 +0000
@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+true true true true

=== added file 'test/rbkt/Queries/zorba/jsoniq/roundtrip/encode_10.xq'
--- test/rbkt/Queries/zorba/jsoniq/roundtrip/encode_10.xq	1970-01-01 00:00:00 +0000
+++ test/rbkt/Queries/zorba/jsoniq/roundtrip/encode_10.xq	2012-10-01 16:22:23 +0000
@@ -0,0 +1,8 @@
+jn:encode-for-roundtrip(
+  {
+    'comment' : comment { "a comment" },
+    'document' : document { <a/> },
+    'pi' : processing-instruction target { "an instruction" },
+    'text' : text { "some text" }
+  }
+)

=== added file 'test/rbkt/Queries/zorba/jsoniq/roundtrip/roundtrip_06.xq'
--- test/rbkt/Queries/zorba/jsoniq/roundtrip/roundtrip_06.xq	1970-01-01 00:00:00 +0000
+++ test/rbkt/Queries/zorba/jsoniq/roundtrip/roundtrip_06.xq	2012-10-01 16:22:23 +0000
@@ -0,0 +1,15 @@
+let $enc := jn:encode-for-roundtrip(
+    {
+      'comment' : comment { "a comment" },
+      'document' : document { <a/> } ,
+      'pi' : processing-instruction target { "an instruction" },
+      'text' : text { "some text" }
+    }
+  )
+let $dec := jn:decode-from-roundtrip($enc)
+return (
+  $dec("comment") instance of comment(),
+  $dec("document") instance of document-node(),
+  $dec("pi") instance of processing-instruction(),
+  $dec("text") instance of text()
+)