Improve container ordering for term selection due to json-ld/json-ld.org#569.

Author: gkellogg

lib/compact.js

@@ -501,7 +501,7 @@ api.compactIri = ({
         containers.push(
           '@graph@id', '@graph@id@set');
       }
-      containers.push('@graph', '@graph@set');
+      containers.push('@graph', '@graph@set', '@set');
       // allow indexmap if the graph is not indexed
       if(!('@index' in value)) {
         containers.push('@graph@index', '@graph@index@set', '@index', '@index@set');
@@ -586,23 +586,29 @@ api.compactIri = ({
         } else if('@type' in value) {
           typeOrLanguage = '@type';
           typeOrLanguageValue = value['@type'];
-        } else if(!('@index' in value)) {
-          // allw indexing by language even if no language present
-          containers.push('@language', '@language@set');
         }
       } else {
         typeOrLanguage = '@type';
         typeOrLanguageValue = '@id';
       }
-      if(_isObject(value) && !('@index' in value)) {
-        // allow indexing even if no @index present
-        containers.push('@index', '@index@set');
-      }
       containers.push('@set');
     }
 
     // do term selection
     containers.push('@none');
+
+    // an index map can be used to index values using @none, so add as a low priority
+    if(_isObject(value) && !('@index' in value)) {
+      // allow indexing even if no @index present
+      containers.push('@index', '@index@set');
+    }
+
+    // values without type or language can use @language map
+    if(_isValue(value) && Object.keys(value).length === 1) {
+      // allow indexing even if no @index present
+      containers.push('@language', '@language@set');
+    }
+
     const term = _selectTerm(
       activeCtx, iri, value, containers, typeOrLanguage, typeOrLanguageValue);
     if(term !== null) {