Pass type-scoped context for value expansion.

Author: dlongley

lib/expand.js

@@ -52,6 +52,9 @@ module.exports = api;
  * @param insideList true if the element is a list, false if not.
  * @param insideIndex true if the element is inside an index container,
  *          false if not.
+ * @param typeScopedContext an optional type-scoped active context for
+ *          expanding values of nodes that were expressed according to
+ *          a type-scoped context.
  * @param expansionMap(info) a function that can be used to custom map
  *          unmappable values (or to throw an error when they are detected);
  *          if this function returns `undefined` then the default behavior
@@ -66,6 +69,7 @@ api.expand = ({
   options = {},
   insideList = false,
   insideIndex = false,
+  typeScopedContext = null,
   expansionMap = () => undefined
 }) => {
   // nothing to expand
@@ -152,11 +156,16 @@ api.expand = ({
 
   // recursively expand object:
 
-  // First determine if any type-scoped context should be reverted; it should
-  // only be reverted when the following are all true:
+  // first, expand the active property
+  const expandedActiveProperty = _expandIri(
+    activeCtx, activeProperty, {vocab: true}, options);
+
+  // second, determine if any type-scoped context should be reverted; it
+  // should only be reverted when the following are all true:
   // 1. `element` is not a value or subject reference
   // 2. `insideIndex` is false
-  const typeScopedContext = activeCtx.previousContext ? activeCtx : null;
+  typeScopedContext = typeScopedContext ||
+    (activeCtx.previousContext ? activeCtx : null);
   let keys = Object.keys(element).sort();
   let mustRevert = !insideIndex;
   if(mustRevert && typeScopedContext && keys[0] !== '@context') {
@@ -165,7 +174,7 @@ api.expand = ({
       const expandedProperty = _expandIri(
         typeScopedContext, keys[0], {vocab: true}, options);
       if(expandedProperty === '@id') {
-        // subject reference found, use type-scoped context to expand it
+        // subject reference found, do not revert
         mustRevert = false;
       }
     } else if(keys.length <= 2) {
@@ -174,8 +183,9 @@ api.expand = ({
         const expandedProperty = _expandIri(
           typeScopedContext, key, {vocab: true}, options);
         if(expandedProperty === '@value') {
-          // value found, use type-scoped context to expand it
+          // value found, ensure type-scoped context is used to expand it
           mustRevert = false;
+          activeCtx = typeScopedContext;
           break;
         }
       }
@@ -218,10 +228,6 @@ api.expand = ({
     }
   }
 
-  // expand the active property
-  const expandedActiveProperty = _expandIri(
-    activeCtx, activeProperty, {vocab: true}, options);
-
   // process each key and value in element, ignoring @nest content
   let rval = {};
   _expandObject({
@@ -232,6 +238,7 @@ api.expand = ({
     expandedParent: rval,
     options,
     insideList,
+    typeScopedContext,
     expansionMap});
 
   // get property count on expanded output