fix: correctly handle named graphs in lists

* chore: add test cases for named nodes in lists

* chore: add more graph in list test cases

* fix: correctly handle named graphs in lists

Author: jeswr

src/N3Parser.js

@@ -418,9 +418,8 @@ export default class N3Parser {
   }
 
   // ### `_readListItem` reads items from a list
-  _readListItem(token) {
-    let item = null,                      // The item of the list
-        list = null,                      // The list itself
+  _readListItem(token, item = null /* The list item */) {
+    let list = null,                      // The list itself
         next = this._readListItem;        // The next function to execute
     const previousList = this._subject,   // The previous list that contains this list
         stack = this._contextStack,       // The stack of parent contexts
@@ -510,7 +509,7 @@ export default class N3Parser {
       this._graph = null;
       break;
     default:
-      if ((item = this._readEntity(token)) === undefined)
+      if (item === null && (item = this._readEntity(token)) === undefined)
         return;
     }
 
@@ -613,12 +612,20 @@ export default class N3Parser {
     if (token.type !== '}')
       return this._readPunctuation(token);
 
+    const graph = this._graph;
+
     // Store the last quad of the formula
     if (this._subject !== null)
-      this._emit(this._subject, this._predicate, this._object, this._graph);
+      this._emit(this._subject, this._predicate, this._object, graph);
 
     // Restore the parent context containing this formula
     this._restoreContext('formula', token);
+
+    // If the formula was in a list context, continue reading the list
+    if (this._contextStack.length > 0 && this._contextStack[this._contextStack.length - 1].type === 'list') {
+      return this._readListItem(token, graph);
+    }
+
     // If the formula was the subject, continue reading the predicate.
     // If the formula was the object, read punctuation.
     return this._object === null ? this._readPredicate : this._getContextEndReader();

test/N3Parser-test.js

@@ -1864,6 +1864,48 @@ describe('Parser', () => {
       shouldParse(parser, '@forSome <x>. <x> <x> <x>.',
                   ['_:b0', '_:b0', '_:b0']));
 
+    describe('should parse a named graph in a list',
+      shouldParse(parser, '<s> <p> ({<a> <b> <c>}) .',
+                  ['s', 'p', '_:b1'],
+                  ...list(['_:b1', '_:b0']),
+                  ['a', 'b', 'c', '_:b0']
+                  ));
+
+    describe('should parse a named graph as the second element in a list',
+      shouldParse(parser, '<s> <p> (<x> {<a> <b> <c>}) .',
+                  ['s', 'p', '_:b0'],
+                  ...list(['_:b0', 'x'], ['_:b2', '_:b1']),
+                  ['a', 'b', 'c', '_:b1']
+                  ));
+
+    describe('should parse a named graph as the second element in a list of 3 elements',
+      shouldParse(parser, '<s> <p> (<x> {<a> <b> <c>} <y>) .',
+                  ['s', 'p', '_:b0'],
+                  ...list(['_:b0', 'x'], ['_:b2', '_:b1'], ['_:b3', 'y']),
+                  ['a', 'b', 'c', '_:b1']
+                  ));
+
+    describe('should parse a named graph in a subject list',
+      shouldParse(parser, '({<a> <b> <c>}) <p> <o> .',
+                  ['_:b1', 'p', 'o'],
+                  ...list(['_:b1', '_:b0']),
+                  ['a', 'b', 'c', '_:b0']
+                  ));
+
+    describe('should parse a named graph as the second element in a subject list',
+      shouldParse(parser, '(<x> {<a> <b> <c>}) <p> <o> .',
+                  ['_:b0', 'p', 'o'],
+                  ...list(['_:b0', 'x'], ['_:b2', '_:b1']),
+                  ['a', 'b', 'c', '_:b1']
+                  ));
+
+    describe('should parse a named graph as the second element in a subject list with 3 elements',
+      shouldParse(parser, '(<x> {<a> <b> <c>} <y>) <p> <o> .',
+                  ['_:b0', 'p', 'o'],
+                  ...list(['_:b0', 'x'], ['_:b2', '_:b1'], ['_:b3', 'y']),
+                  ['a', 'b', 'c', '_:b1']
+                  ));
+
     describe('should parse a @forSome statement with multiple entities',
       shouldParse(parser, '@prefix a: <a:>. @base <b:>. @forSome a:x, <y>, a:z. a:x <y> a:z.',
                   ['_:b0', '_:b1', '_:b2']));
@@ -2154,7 +2196,7 @@ describe('Parser', () => {
     describe('should parse a formula as list item',
         shouldParse(parser, '<a> <findAll> ( <b> { <b> a <type>. <b> <something> <foo> } <o> ).',
         ['a', 'findAll', '_:b0'],
-        ...list(['_:b0', 'b'], ['_:b2', 'o']),
+        ...list(['_:b0', 'b'], ['_:b2', '_:b1'], ['_:b3', 'o']),
         ['b', 'something', 'foo', '_:b1'],
         ['b', 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type', 'type', '_:b1']
     ));