From d977e71fe11186d1a22b2508233aedd4e9f2d324 Mon Sep 17 00:00:00 2001
From: "David I. Lehn" <dlehn@digitalbazaar.com>
Date: Wed, 28 Aug 2019 17:17:19 -0400
Subject: [PATCH 1/9] Support list of lists.

---
 CHANGELOG.md                     |  3 +++
 lib/compact.js                   | 32 +++++++++++++++++++++++--------
 lib/expand.js                    | 12 ++----------
 lib/fromRdf.js                   | 33 ++++++++++++++++----------------
 lib/nodeMap.js                   | 27 +++++++++++++++++++++++---
 lib/toRdf.js                     |  3 +++
 lib/util.js                      |  9 ++++++++-
 tests/test-common.js             | 28 ---------------------------
 tests/webidl/JsonLdProcessor.idl |  2 --
 9 files changed, 81 insertions(+), 68 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dd1ec40e..4ffead86 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # jsonld ChangeLog
 
+### Added
+- Support list of lists.
+
 ## 1.6.2 - 2019-05-21
 
 ### Fixed
diff --git a/lib/compact.js b/lib/compact.js
index 9603bd12..78aad528 100644
--- a/lib/compact.js
+++ b/lib/compact.js
@@ -138,6 +138,22 @@ api.compact = ({
       return rval;
     }
 
+    // if expanded property is @list and we're contained within a list
+    // container, recursively compact this item to an array
+    if(_isList(element)) {
+      const container = _getContextValue(
+        activeCtx, activeProperty, '@container') || [];
+      if(container.includes('@list')) {
+        return api.compact({
+          activeCtx,
+          activeProperty,
+          element: element['@list'],
+          options,
+          compactionMap
+        });
+      }
+    }
+
     // FIXME: avoid misuse of active property as an expanded property?
     const insideReverse = (activeProperty === '@reverse');
 
@@ -399,14 +415,14 @@ api.compact = ({
                 relativeTo: {vocab: true}
               })] = expandedItem['@index'];
             }
-          } else if(nestResult.hasOwnProperty(itemActiveProperty)) {
-            // can't use @list container for more than 1 list
-            throw new JsonLdError(
-              'JSON-LD compact error; property has a "@list" @container ' +
-              'rule but there is more than a single @list that matches ' +
-              'the compacted term in the document. Compaction might mix ' +
-              'unwanted items into the list.',
-              'jsonld.SyntaxError', {code: 'compaction to list of lists'});
+          // FIXME
+          //} else if(nestResult.hasOwnProperty(itemActiveProperty)) {
+          } else {
+            _addValue(nestResult, itemActiveProperty, compactedItem, {
+              valueIsArray: true,
+              allowDuplicate: true
+            });
+            continue;
           }
         }
 
diff --git a/lib/expand.js b/lib/expand.js
index 74e466f0..994debaf 100644
--- a/lib/expand.js
+++ b/lib/expand.js
@@ -122,11 +122,8 @@ api.expand = ({
         insideIndex,
         typeScopedContext
       });
-      if(insideList && (_isArray(e) || _isList(e))) {
-        // lists of lists are illegal
-        throw new JsonLdError(
-          'Invalid JSON-LD syntax; lists of lists are not permitted.',
-          'jsonld.SyntaxError', {code: 'list of lists'});
+      if(insideList && _isArray(e)) {
+        e = {'@list': e};
       }
 
       if(e === null) {
@@ -672,11 +669,6 @@ function _expandObject({
           insideList: isList,
           expansionMap
         });
-        if(isList && _isList(expandedValue)) {
-          throw new JsonLdError(
-            'Invalid JSON-LD syntax; lists of lists are not permitted.',
-            'jsonld.SyntaxError', {code: 'list of lists'});
-        }
       } else {
         // recursively expand value with key as new active property
         expandedValue = api.expand({
diff --git a/lib/fromRdf.js b/lib/fromRdf.js
index dca067ec..286ef5e6 100644
--- a/lib/fromRdf.js
+++ b/lib/fromRdf.js
@@ -225,22 +225,23 @@ api.fromRDF = async (
       }
 
       // the list is nested in another list
-      if(property === RDF_FIRST) {
-        // empty list
-        if(node['@id'] === RDF_NIL) {
-          // can't convert rdf:nil to a @list object because it would
-          // result in a list of lists which isn't supported
-          continue;
-        }
-
-        // preserve list head
-        if(RDF_REST in graphObject[head['@id']]) {
-          head = graphObject[head['@id']][RDF_REST][0];
-        }
-
-        list.pop();
-        listNodes.pop();
-      }
+      // FIXME
+      //if(property === RDF_FIRST) {
+      //  // empty list
+      //  if(node['@id'] === RDF_NIL) {
+      //    // can't convert rdf:nil to a @list object because it would
+      //    // result in a list of lists which isn't supported
+      //    continue;
+      //  }
+
+      //  // preserve list head
+      //  if(RDF_REST in graphObject[head['@id']]) {
+      //    head = graphObject[head['@id']][RDF_REST][0];
+      //  }
+
+      //  list.pop();
+      //  listNodes.pop();
+      //}
 
       // transform list into @list object
       delete head['@id'];
diff --git a/lib/nodeMap.js b/lib/nodeMap.js
index e71c28dc..bae62e5a 100644
--- a/lib/nodeMap.js
+++ b/lib/nodeMap.js
@@ -74,6 +74,11 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
       list.push(input);
     }
     return;
+  } else if(graphTypes.isList(input)) {
+    if(list) {
+      list.push(input);
+    }
+    return;
   }
 
   // Note: At this point, input must be a subject.
@@ -190,14 +195,30 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
           subject, property, {'@id': id},
           {propertyIsArray: true, allowDuplicate: false});
         api.createNodeMap(o, graphs, graph, issuer, id);
+      } else if(graphTypes.isValue(o)) {
+        //if('@type' in o) {
+        //  o['@type'] = o['@type'][0];
+        //}
+        if(!list) {
+          util.addValue(
+            subject, property, o,
+            {propertyIsArray: true, allowDuplicate: false});
+        } else {
+          list['@list'] = o;
+        }
       } else if(graphTypes.isList(o)) {
         // handle @list
+        // XXX
         const _list = [];
         api.createNodeMap(o['@list'], graphs, graph, issuer, name, _list);
         o = {'@list': _list};
-        util.addValue(
-          subject, property, o,
-          {propertyIsArray: true, allowDuplicate: false});
+        if(!list) {
+          util.addValue(
+            subject, property, o,
+            {propertyIsArray: true, allowDuplicate: false});
+        } else {
+          list['@list'] = o;
+        }
       } else {
         // handle @value
         api.createNodeMap(o, graphs, graph, issuer, name);
diff --git a/lib/toRdf.js b/lib/toRdf.js
index f062ee28..be1b48d4 100644
--- a/lib/toRdf.js
+++ b/lib/toRdf.js
@@ -241,6 +241,9 @@ function _objectToRDF(item) {
       object.value = value;
       object.datatype.value = datatype || XSD_STRING;
     }
+  } else if(graphTypes.isList(item)) {
+    //_listToRDF(item, issuer, subject, predicate, dataset, graphTerm);
+    _listToRDF(item['@list'], issuer, subject, predicate, dataset, graphTerm);
   } else {
     // convert string/node object to RDF
     const id = types.isObject(item) ? item['@id'] : item;
diff --git a/lib/util.js b/lib/util.js
index a41e6e7b..2b9b482a 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -249,6 +249,8 @@ api.hasValue = (subject, property, value) => {
  * @param [options] the options to use:
  *        [propertyIsArray] true if the property is always an array, false
  *          if not (default: false).
+ *        [valueIsArray] true if the value to be added should be preserved as
+ *          an array (lists) (default: false).
  *        [allowDuplicate] true to allow duplicates, false not to (uses a
  *          simple shallow comparison of subject ID or value) (default: true).
  */
@@ -257,11 +259,16 @@ api.addValue = (subject, property, value, options) => {
   if(!('propertyIsArray' in options)) {
     options.propertyIsArray = false;
   }
+  if(!('valueIsArray' in options)) {
+    options.valueIsArray = false;
+  }
   if(!('allowDuplicate' in options)) {
     options.allowDuplicate = true;
   }
 
-  if(types.isArray(value)) {
+  if(options.valueIsArray) {
+    subject[property] = value;
+  } else if(types.isArray(value)) {
     if(value.length === 0 && options.propertyIsArray &&
       !subject.hasOwnProperty(property)) {
       subject[property] = [];
diff --git a/tests/test-common.js b/tests/test-common.js
index fc7c3946..1a5b455e 100644
--- a/tests/test-common.js
+++ b/tests/test-common.js
@@ -37,12 +37,6 @@ const TEST_TYPES = {
       specVersion: ['json-ld-1.0'],
       // FIXME
       idRegex: [
-        // list of lists
-        /compact-manifest.jsonld#tli01$/,
-        /compact-manifest.jsonld#tli02$/,
-        /compact-manifest.jsonld#tli03$/,
-        /compact-manifest.jsonld#tli04$/,
-        /compact-manifest.jsonld#tli05$/,
         // terms
         /compact-manifest.jsonld#tp001$/,
         // rel iri
@@ -110,17 +104,6 @@ const TEST_TYPES = {
     skip: {
       // FIXME
       idRegex: [
-        // list of lists
-        /expand-manifest.jsonld#tli01$/,
-        /expand-manifest.jsonld#tli02$/,
-        /expand-manifest.jsonld#tli03$/,
-        /expand-manifest.jsonld#tli04$/,
-        /expand-manifest.jsonld#tli05$/,
-        /expand-manifest.jsonld#tli06$/,
-        /expand-manifest.jsonld#tli07$/,
-        /expand-manifest.jsonld#tli08$/,
-        /expand-manifest.jsonld#tli09$/,
-        /expand-manifest.jsonld#tli10$/,
         // mode
         /expand-manifest.jsonld#tp001$/,
         /expand-manifest.jsonld#tp002$/,
@@ -252,10 +235,6 @@ const TEST_TYPES = {
     skip: {
       // FIXME
       idRegex: [
-        // list of lists
-        /flatten-manifest.jsonld#tli01$/,
-        /flatten-manifest.jsonld#tli02$/,
-        /flatten-manifest.jsonld#tli03$/,
         // html
         /html-manifest.jsonld#tf001$/,
         /html-manifest.jsonld#tf002$/,
@@ -333,10 +312,6 @@ const TEST_TYPES = {
     skip: {
       // FIXME
       idRegex: [
-        // list of lists
-        /fromRdf-manifest.jsonld#tli01$/,
-        /fromRdf-manifest.jsonld#tli02$/,
-        /fromRdf-manifest.jsonld#tli03$/,
         // JSON literals
         /fromRdf-manifest.jsonld#tjs01$/,
         /fromRdf-manifest.jsonld#tjs02$/,
@@ -366,9 +341,6 @@ const TEST_TYPES = {
     skip: {
       // FIXME
       idRegex: [
-        // list of lists
-        /toRdf-manifest.jsonld#tli01$/,
-        /toRdf-manifest.jsonld#tli02$/,
         // blank node properties
         /toRdf-manifest.jsonld#t0118$/,
         // well formed
diff --git a/tests/webidl/JsonLdProcessor.idl b/tests/webidl/JsonLdProcessor.idl
index 31cac3a8..5f0906f5 100644
--- a/tests/webidl/JsonLdProcessor.idl
+++ b/tests/webidl/JsonLdProcessor.idl
@@ -37,7 +37,6 @@ dictionary JsonLdError {
 
 enum JsonLdErrorCode {
     "colliding keywords",
-    "compaction to list of lists",
     "conflicting indexes",
     "cyclic IRI mapping",
     "invalid @id value",
@@ -70,7 +69,6 @@ enum JsonLdErrorCode {
     "invalid value object value",
     "invalid vocab mapping",
     "keyword redefinition",
-    "list of lists",
     "loading document failed",
     "loading remote context failed",
     "multiple context link headers",

From 29e167e723484984df99cb8a0f968390b31b6885 Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Thu, 29 Aug 2019 15:15:47 -0700
Subject: [PATCH 2/9] Add skip version to test runner to not run json-ld-1.0
 tests.

---
 tests/test-common.js | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tests/test-common.js b/tests/test-common.js
index 1a5b455e..8913ec40 100644
--- a/tests/test-common.js
+++ b/tests/test-common.js
@@ -102,6 +102,9 @@ const TEST_TYPES = {
   },
   'jld:ExpandTest': {
     skip: {
+      // skip tests where behavior changed for a 1.1 processor
+      // see JSON-LD 1.0 Errata
+      specVersion: ['json-ld-1.0'],
       // FIXME
       idRegex: [
         // mode
@@ -233,6 +236,9 @@ const TEST_TYPES = {
   },
   'jld:FlattenTest': {
     skip: {
+      // skip tests where behavior changed for a 1.1 processor
+      // see JSON-LD 1.0 Errata
+      specVersion: ['json-ld-1.0'],
       // FIXME
       idRegex: [
         // html
@@ -259,6 +265,9 @@ const TEST_TYPES = {
   },
   'jld:FrameTest': {
     skip: {
+      // skip tests where behavior changed for a 1.1 processor
+      // see JSON-LD 1.0 Errata
+      specVersion: ['json-ld-1.0'],
       // FIXME
       idRegex: [
         // ex
@@ -310,6 +319,9 @@ const TEST_TYPES = {
   },
   'jld:FromRDFTest': {
     skip: {
+      // skip tests where behavior changed for a 1.1 processor
+      // see JSON-LD 1.0 Errata
+      specVersion: ['json-ld-1.0'],
       // FIXME
       idRegex: [
         // JSON literals
@@ -339,6 +351,9 @@ const TEST_TYPES = {
   },
   'jld:ToRDFTest': {
     skip: {
+      // skip tests where behavior changed for a 1.1 processor
+      // see JSON-LD 1.0 Errata
+      specVersion: ['json-ld-1.0'],
       // FIXME
       idRegex: [
         // blank node properties

From cf2ab04be4d6ab2bd3c0f28ca255b17cc899b07f Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Thu, 29 Aug 2019 15:16:47 -0700
Subject: [PATCH 3/9] Modernize for loops and variable declarations in nodeMap.

---
 lib/nodeMap.js | 28 ++++++++++------------------
 1 file changed, 10 insertions(+), 18 deletions(-)

diff --git a/lib/nodeMap.js b/lib/nodeMap.js
index bae62e5a..b7ababb7 100644
--- a/lib/nodeMap.js
+++ b/lib/nodeMap.js
@@ -47,8 +47,8 @@ api.createMergedNodeMap = (input, options) => {
 api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
   // recurse through array
   if(types.isArray(input)) {
-    for(let i = 0; i < input.length; ++i) {
-      api.createNodeMap(input[i], graphs, graph, issuer, undefined, list);
+    for(const node of input) {
+      api.createNodeMap(node, graphs, graph, issuer, undefined, list);
     }
     return;
   }
@@ -64,7 +64,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
   // add values to list
   if(graphTypes.isValue(input)) {
     if('@type' in input) {
-      let type = input['@type'];
+      const type = input['@type'];
       // rename @type blank node
       if(type.indexOf('_:') === 0) {
         input['@type'] = type = issuer.getId(type);
@@ -86,8 +86,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
   // spec requires @type to be named first, so assign names early
   if('@type' in input) {
     const types = input['@type'];
-    for(let i = 0; i < types.length; ++i) {
-      const type = types[i];
+    for(const type of types) {
       if(type.indexOf('_:') === 0) {
         issuer.getId(type);
       }
@@ -110,9 +109,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
   const subject = subjects[name] = subjects[name] || {};
   subject['@id'] = name;
   const properties = Object.keys(input).sort();
-  for(let pi = 0; pi < properties.length; ++pi) {
-    let property = properties[pi];
-
+  for(const property of properties) {
     // skip @id
     if(property === '@id') {
       continue;
@@ -124,8 +121,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
       const reverseMap = input['@reverse'];
       for(const reverseProperty in reverseMap) {
         const items = reverseMap[reverseProperty];
-        for(let ii = 0; ii < items.length; ++ii) {
-          const item = items[ii];
+        for(const item of items) {
           let itemName = item['@id'];
           if(graphTypes.isBlankNode(item)) {
             itemName = issuer.getId(itemName);
@@ -176,9 +172,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
       util.addValue(subject, property, [], {propertyIsArray: true});
       continue;
     }
-    for(let oi = 0; oi < objects.length; ++oi) {
-      let o = objects[oi];
-
+    for(var o of objects) {
       if(property === '@type') {
         // rename @type blank nodes
         o = (o.indexOf('_:') === 0) ? issuer.getId(o) : o;
@@ -270,8 +264,7 @@ api.mergeNodeMaps = graphs => {
   // add all non-default graphs to default graph
   const defaultGraph = graphs['@default'];
   const graphNames = Object.keys(graphs).sort();
-  for(let i = 0; i < graphNames.length; ++i) {
-    const graphName = graphNames[i];
+  for(const graphName of graphNames) {
     if(graphName === '@default') {
       continue;
     }
@@ -286,9 +279,8 @@ api.mergeNodeMaps = graphs => {
       subject['@graph'] = [];
     }
     const graph = subject['@graph'];
-    const ids = Object.keys(nodeMap).sort();
-    for(let ii = 0; ii < ids.length; ++ii) {
-      const node = nodeMap[ids[ii]];
+    for(const id of Object.keys(nodeMap).sort()) {
+      const node = nodeMap[id];
       // only add full subjects
       if(!graphTypes.isSubjectReference(node)) {
         graph.push(node);

From 669c0165f4fd6f0968332d73f0a50521d6f3ff64 Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Thu, 29 Aug 2019 17:41:12 -0700
Subject: [PATCH 4/9] Fix nodeMap support for lists and reimplement toRdf lists
 to work from _objectToRDF.

---
 lib/nodeMap.js |  31 +++++---------
 lib/toRdf.js   | 107 ++++++++++++++++++++++++++-----------------------
 2 files changed, 68 insertions(+), 70 deletions(-)

diff --git a/lib/nodeMap.js b/lib/nodeMap.js
index b7ababb7..d32aaf63 100644
--- a/lib/nodeMap.js
+++ b/lib/nodeMap.js
@@ -74,10 +74,10 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
       list.push(input);
     }
     return;
-  } else if(graphTypes.isList(input)) {
-    if(list) {
-      list.push(input);
-    }
+  } else if(list && graphTypes.isList(input)) {
+    const _list = [];
+    api.createNodeMap(input['@list'], graphs, graph, issuer, name, _list);
+    list.push({'@list': _list});
     return;
   }
 
@@ -109,7 +109,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
   const subject = subjects[name] = subjects[name] || {};
   subject['@id'] = name;
   const properties = Object.keys(input).sort();
-  for(const property of properties) {
+  for(let property of properties) {
     // skip @id
     if(property === '@id') {
       continue;
@@ -193,26 +193,17 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
         //if('@type' in o) {
         //  o['@type'] = o['@type'][0];
         //}
-        if(!list) {
-          util.addValue(
-            subject, property, o,
-            {propertyIsArray: true, allowDuplicate: false});
-        } else {
-          list['@list'] = o;
-        }
+        util.addValue(
+          subject, property, o,
+          {propertyIsArray: true, allowDuplicate: false});
       } else if(graphTypes.isList(o)) {
         // handle @list
-        // XXX
         const _list = [];
         api.createNodeMap(o['@list'], graphs, graph, issuer, name, _list);
         o = {'@list': _list};
-        if(!list) {
-          util.addValue(
-            subject, property, o,
-            {propertyIsArray: true, allowDuplicate: false});
-        } else {
-          list['@list'] = o;
-        }
+        util.addValue(
+          subject, property, o,
+          {propertyIsArray: true, allowDuplicate: false});
       } else {
         // handle @value
         api.createNodeMap(o, graphs, graph, issuer, name);
diff --git a/lib/toRdf.js b/lib/toRdf.js
index be1b48d4..1e821123 100644
--- a/lib/toRdf.js
+++ b/lib/toRdf.js
@@ -85,8 +85,7 @@ api.toRDF = (input, options) => {
  */
 function _graphToRDF(dataset, graph, graphTerm, issuer, options) {
   const ids = Object.keys(graph).sort();
-  for(let i = 0; i < ids.length; ++i) {
-    const id = ids[i];
+  for(const id of ids) {
     const node = graph[id];
     const properties = Object.keys(node).sort();
     for(let property of properties) {
@@ -126,22 +125,16 @@ function _graphToRDF(dataset, graph, graphTerm, issuer, options) {
           continue;
         }
 
-        // convert @list to triples
-        if(graphTypes.isList(item)) {
-          _listToRDF(
-            item['@list'], issuer, subject, predicate, dataset, graphTerm);
-        } else {
-          // convert value or node object to triple
-          const object = _objectToRDF(item);
-          // skip null objects (they are relative IRIs)
-          if(object) {
-            dataset.push({
-              subject,
-              predicate,
-              object,
-              graph: graphTerm
-            });
-          }
+        // convert list, value or node object to triple
+        const object = _objectToRDF(item, issuer, dataset, graphTerm);
+        // skip null objects (they are relative IRIs)
+        if(object) {
+          dataset.push({
+            subject,
+            predicate,
+            object,
+            graph: graphTerm
+          });
         }
       }
     }
@@ -154,59 +147,72 @@ function _graphToRDF(dataset, graph, graphTerm, issuer, options) {
  *
  * @param list the @list value.
  * @param issuer a IdentifierIssuer for assigning blank node names.
- * @param subject the subject for the head of the list.
- * @param predicate the predicate for the head of the list.
  * @param dataset the array of quads to append to.
  * @param graphTerm the graph term for each quad.
+ *
+ * @return the head of the list.
  */
-function _listToRDF(list, issuer, subject, predicate, dataset, graphTerm) {
+function _listToRDF(list, issuer, dataset, graphTerm) {
   const first = {termType: 'NamedNode', value: RDF_FIRST};
   const rest = {termType: 'NamedNode', value: RDF_REST};
   const nil = {termType: 'NamedNode', value: RDF_NIL};
 
+  const last = list.pop();
+  // Result is the head of the list
+  const result = last ? {termType: 'BlankNode', value: issuer.getId()} : nil;
+  var subject = result;
+
   for(const item of list) {
-    const blankNode = {termType: 'BlankNode', value: issuer.getId()};
+    const object = _objectToRDF(item, issuer, dataset, graphTerm);
+    const next = {termType: 'BlankNode', value: issuer.getId()};
     dataset.push({
       subject,
-      predicate,
-      object: blankNode,
+      predicate: first,
+      object: object,
       graph: graphTerm
     });
+    dataset.push({
+      subject,
+      predicate: rest,
+      object: next,
+      graph: graphTerm
+    });
+    subject = next;
+  }
 
-    subject = blankNode;
-    predicate = first;
-    const object = _objectToRDF(item);
-
-    // skip null objects (they are relative IRIs)
-    if(object) {
-      dataset.push({
-        subject,
-        predicate,
-        object,
-        graph: graphTerm
-      });
-    }
-
-    predicate = rest;
+  // Tail of list
+  if(last) {
+    const object = _objectToRDF(last, issuer, dataset, graphTerm);
+    dataset.push({
+      subject,
+      predicate: first,
+      object: object,
+      graph: graphTerm
+    });
+    dataset.push({
+      subject,
+      predicate: rest,
+      object: nil,
+      graph: graphTerm
+    });
   }
 
-  dataset.push({
-    subject,
-    predicate,
-    object: nil,
-    graph: graphTerm
-  });
+  return result;
 }
 
 /**
- * Converts a JSON-LD value object to an RDF literal or a JSON-LD string or
- * node object to an RDF resource.
+ * Converts a JSON-LD value object to an RDF literal or a JSON-LD string,
+ * node object to an RDF resource,
+ * or adds a list.
  *
  * @param item the JSON-LD value or node object.
+ * @param issuer a IdentifierIssuer for assigning blank node names.
+ * @param dataset the dataset to append RDF quads to.
+ * @param graphTerm the graph term for each quad.
  *
  * @return the RDF literal or RDF resource.
  */
-function _objectToRDF(item) {
+function _objectToRDF(item, issuer, dataset, graphTerm) {
   const object = {};
 
   // convert value object to RDF
@@ -242,8 +248,9 @@ function _objectToRDF(item) {
       object.datatype.value = datatype || XSD_STRING;
     }
   } else if(graphTypes.isList(item)) {
-    //_listToRDF(item, issuer, subject, predicate, dataset, graphTerm);
-    _listToRDF(item['@list'], issuer, subject, predicate, dataset, graphTerm);
+    const _list = _listToRDF(item['@list'], issuer, dataset, graphTerm);
+    object.termType = _list.termType;
+    object.value = _list.value;
   } else {
     // convert string/node object to RDF
     const id = types.isObject(item) ? item['@id'] : item;

From 0743093c448a4fa656982216ce0e0f60ce62e4d6 Mon Sep 17 00:00:00 2001
From: "David I. Lehn" <dlehn@digitalbazaar.com>
Date: Fri, 30 Aug 2019 12:25:17 -0400
Subject: [PATCH 5/9] Fix linting issues.

---
 lib/nodeMap.js | 4 ++--
 lib/toRdf.js   | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/nodeMap.js b/lib/nodeMap.js
index d32aaf63..e0999303 100644
--- a/lib/nodeMap.js
+++ b/lib/nodeMap.js
@@ -64,7 +64,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
   // add values to list
   if(graphTypes.isValue(input)) {
     if('@type' in input) {
-      const type = input['@type'];
+      let type = input['@type'];
       // rename @type blank node
       if(type.indexOf('_:') === 0) {
         input['@type'] = type = issuer.getId(type);
@@ -172,7 +172,7 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
       util.addValue(subject, property, [], {propertyIsArray: true});
       continue;
     }
-    for(var o of objects) {
+    for(let o of objects) {
       if(property === '@type') {
         // rename @type blank nodes
         o = (o.indexOf('_:') === 0) ? issuer.getId(o) : o;
diff --git a/lib/toRdf.js b/lib/toRdf.js
index 1e821123..1745e11d 100644
--- a/lib/toRdf.js
+++ b/lib/toRdf.js
@@ -160,7 +160,7 @@ function _listToRDF(list, issuer, dataset, graphTerm) {
   const last = list.pop();
   // Result is the head of the list
   const result = last ? {termType: 'BlankNode', value: issuer.getId()} : nil;
-  var subject = result;
+  let subject = result;
 
   for(const item of list) {
     const object = _objectToRDF(item, issuer, dataset, graphTerm);
@@ -168,7 +168,7 @@ function _listToRDF(list, issuer, dataset, graphTerm) {
     dataset.push({
       subject,
       predicate: first,
-      object: object,
+      object,
       graph: graphTerm
     });
     dataset.push({
@@ -186,7 +186,7 @@ function _listToRDF(list, issuer, dataset, graphTerm) {
     dataset.push({
       subject,
       predicate: first,
-      object: object,
+      object,
       graph: graphTerm
     });
     dataset.push({

From 7538c0b144ffe591170a437a655f0a8e9070f77c Mon Sep 17 00:00:00 2001
From: "David I. Lehn" <dlehn@digitalbazaar.com>
Date: Fri, 30 Aug 2019 12:57:23 -0400
Subject: [PATCH 6/9] Fix style.

---
 lib/toRdf.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/toRdf.js b/lib/toRdf.js
index 1745e11d..634cc01d 100644
--- a/lib/toRdf.js
+++ b/lib/toRdf.js
@@ -202,8 +202,7 @@ function _listToRDF(list, issuer, dataset, graphTerm) {
 
 /**
  * Converts a JSON-LD value object to an RDF literal or a JSON-LD string,
- * node object to an RDF resource,
- * or adds a list.
+ * node object to an RDF resource, or adds a list.
  *
  * @param item the JSON-LD value or node object.
  * @param issuer a IdentifierIssuer for assigning blank node names.

From a78f62448b9c988e0e9a7dbb6753ab1999e373c6 Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Fri, 30 Aug 2019 11:17:38 -0700
Subject: [PATCH 7/9] Drop dead code in compact for list of lists.

---
 lib/compact.js | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/compact.js b/lib/compact.js
index 78aad528..7f1e1051 100644
--- a/lib/compact.js
+++ b/lib/compact.js
@@ -415,8 +415,6 @@ api.compact = ({
                 relativeTo: {vocab: true}
               })] = expandedItem['@index'];
             }
-          // FIXME
-          //} else if(nestResult.hasOwnProperty(itemActiveProperty)) {
           } else {
             _addValue(nestResult, itemActiveProperty, compactedItem, {
               valueIsArray: true,

From 8d3daa9d2271f74e8f587e13453c30b997503c84 Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Fri, 30 Aug 2019 11:18:08 -0700
Subject: [PATCH 8/9] Drop dead code in fromRdf for list of lists.

---
 lib/fromRdf.js | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/lib/fromRdf.js b/lib/fromRdf.js
index 286ef5e6..5ce1ed2e 100644
--- a/lib/fromRdf.js
+++ b/lib/fromRdf.js
@@ -224,25 +224,6 @@ api.fromRDF = async (
         }
       }
 
-      // the list is nested in another list
-      // FIXME
-      //if(property === RDF_FIRST) {
-      //  // empty list
-      //  if(node['@id'] === RDF_NIL) {
-      //    // can't convert rdf:nil to a @list object because it would
-      //    // result in a list of lists which isn't supported
-      //    continue;
-      //  }
-
-      //  // preserve list head
-      //  if(RDF_REST in graphObject[head['@id']]) {
-      //    head = graphObject[head['@id']][RDF_REST][0];
-      //  }
-
-      //  list.pop();
-      //  listNodes.pop();
-      //}
-
       // transform list into @list object
       delete head['@id'];
       head['@list'] = list.reverse();

From 67a8b16a7c17b6a007536bb626a81e0a399a281b Mon Sep 17 00:00:00 2001
From: "David I. Lehn" <dlehn@digitalbazaar.com>
Date: Fri, 30 Aug 2019 14:31:29 -0400
Subject: [PATCH 9/9] Remove unused code.

---
 lib/nodeMap.js | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/lib/nodeMap.js b/lib/nodeMap.js
index e0999303..b9e7da2b 100644
--- a/lib/nodeMap.js
+++ b/lib/nodeMap.js
@@ -190,9 +190,6 @@ api.createNodeMap = (input, graphs, graph, issuer, name, list) => {
           {propertyIsArray: true, allowDuplicate: false});
         api.createNodeMap(o, graphs, graph, issuer, id);
       } else if(graphTypes.isValue(o)) {
-        //if('@type' in o) {
-        //  o['@type'] = o['@type'][0];
-        //}
         util.addValue(
           subject, property, o,
           {propertyIsArray: true, allowDuplicate: false});