Allow empty lists to be compacted to any @list container term.

Author: dlongley

lib/compact.js

@@ -432,48 +432,55 @@ api.compactIri = ({
         containers.push('@list');
       }
       const list = value['@list'];
-      let commonLanguage = (list.length === 0) ? defaultLanguage : null;
-      let commonType = null;
-      for(let i = 0; i < list.length; ++i) {
-        const item = list[i];
-        let itemLanguage = '@none';
-        let itemType = '@none';
-        if(_isValue(item)) {
-          if('@language' in item) {
-            itemLanguage = item['@language'];
-          } else if('@type' in item) {
-            itemType = item['@type'];
+      if(list.length === 0) {
+        // any empty list can be matched against any term that uses the
+        // @list container regardless of @type or @language
+        typeOrLanguage = '@any';
+        typeOrLanguageValue = '@none';
+      } else {
+        let commonLanguage = (list.length === 0) ? defaultLanguage : null;
+        let commonType = null;
+        for(let i = 0; i < list.length; ++i) {
+          const item = list[i];
+          let itemLanguage = '@none';
+          let itemType = '@none';
+          if(_isValue(item)) {
+            if('@language' in item) {
+              itemLanguage = item['@language'];
+            } else if('@type' in item) {
+              itemType = item['@type'];
+            } else {
+              // plain literal
+              itemLanguage = '@null';
+            }
           } else {
-            // plain literal
-            itemLanguage = '@null';
+            itemType = '@id';
+          }
+          if(commonLanguage === null) {
+            commonLanguage = itemLanguage;
+          } else if(itemLanguage !== commonLanguage && _isValue(item)) {
+            commonLanguage = '@none';
+          }
+          if(commonType === null) {
+            commonType = itemType;
+          } else if(itemType !== commonType) {
+            commonType = '@none';
+          }
+          // there are different languages and types in the list, so choose
+          // the most generic term, no need to keep iterating the list
+          if(commonLanguage === '@none' && commonType === '@none') {
+            break;
           }
-        } else {
-          itemType = '@id';
-        }
-        if(commonLanguage === null) {
-          commonLanguage = itemLanguage;
-        } else if(itemLanguage !== commonLanguage && _isValue(item)) {
-          commonLanguage = '@none';
-        }
-        if(commonType === null) {
-          commonType = itemType;
-        } else if(itemType !== commonType) {
-          commonType = '@none';
         }
-        // there are different languages and types in the list, so choose
-        // the most generic term, no need to keep iterating the list
-        if(commonLanguage === '@none' && commonType === '@none') {
-          break;
+        commonLanguage = commonLanguage || '@none';
+        commonType = commonType || '@none';
+        if(commonType !== '@none') {
+          typeOrLanguage = '@type';
+          typeOrLanguageValue = commonType;
+        } else {
+          typeOrLanguageValue = commonLanguage;
         }
       }
-      commonLanguage = commonLanguage || '@none';
-      commonType = commonType || '@none';
-      if(commonType !== '@none') {
-        typeOrLanguage = '@type';
-        typeOrLanguageValue = commonType;
-      } else {
-        typeOrLanguageValue = commonLanguage;
-      }
     } else {
       if(_isValue(value)) {
         if('@language' in value && !('@index' in value)) {

lib/context.js

@@ -601,10 +601,12 @@ api.getInitialContext = (options) => {
         if(!entry[container]) {
           entry[container] = {
             '@language': {},
-            '@type': {}
+            '@type': {},
+            '@any': {}
           };
         }
         entry = entry[container];
+        _addPreferredTerm(term, entry['@any'], '@none');
 
         if(mapping.reverse) {
           // term is preferred for values using @reverse

tests/test-common.js

@@ -29,7 +29,7 @@ const manifest = options.manifest || {
 const TEST_TYPES = {
   'jld:CompactTest': {
     skip: {
-      regex: [/#t0073/, /#t0074/],
+      regex: [/#t0073/],
       specVersion: ['json-ld-1.1']
     },
     fn: 'compact',