Resolve @type when using type-scoped contexts against previous context.

Author: dlongley

lib/compact.js

@@ -161,12 +161,15 @@ api.compact = ({
     if(types.length > 1) {
       types = Array.from(types).sort();
     }
+    // find all type-scoped contexts based on current context, prior to
+    // updating it
+    const typeContext = activeCtx;
     for(const type of types) {
       const compactedType = api.compactIri(
-        {activeCtx, iri: type, relativeTo: {vocab: true}});
+        {activeCtx: typeContext, iri: type, relativeTo: {vocab: true}});
 
       // Use any type-scoped context defined on this value
-      const ctx = _getContextValue(activeCtx, compactedType, '@context');
+      const ctx = _getContextValue(typeContext, compactedType, '@context');
       if(!_isUndefined(ctx)) {
         activeCtx = _processContext({
           activeCtx,
@@ -184,13 +187,16 @@ api.compact = ({
 
       // compact @id and @type(s)
       if(expandedProperty === '@id' || expandedProperty === '@type') {
+        // if using a type-scoped context, resolve type values against previous
+        // context
+        const isType = expandedProperty === '@type';
+        const valueContext = isType ?
+          (activeCtx.previousContext || activeCtx) : activeCtx;
         let compactedValue = _asArray(expandedValue).map(
           expandedIri => api.compactIri({
-            activeCtx,
+            activeCtx: valueContext,
             iri: expandedIri,
-            relativeTo: {
-              vocab: expandedProperty === '@type'
-            }
+            relativeTo: {vocab: isType}
           }));
         if(compactedValue.length === 1) {
           compactedValue = compactedValue[0];