Replace removePreserve.

Replaced removePreserve with cleanupPreserve and cleanupNulls.

Author: gkellogg

CHANGELOG.md

@@ -28,6 +28,7 @@
   - `embed` to "@once" and warn on "@first" or "@last".
   - `pruneBlankNodeIdentifiers` based on processingMode.
   - `omitGraph` based on processingMode.
+- replaced removePreserve with cleanupPreserve and cleanupNulls
 
 ### Added
 - Support for `"@import"`.

lib/compact.js

@@ -1067,95 +1067,6 @@ api.compactValue = ({activeCtx, activeProperty, value, options}) => {
   };
 };
 
-/**
- * Removes the @preserve keywords as the last step of the compaction
- * algorithm when it is running on framed output.
- *
- * @param ctx the active context used to compact the input.
- * @param input the framed, compacted output.
- * @param options the compaction options used.
- *
- * @return the resulting output.
- */
-api.removePreserve = (ctx, input, options) => {
-  // recurse through arrays
-  if(_isArray(input)) {
-    const output = [];
-    for(let i = 0; i < input.length; ++i) {
-      const result = api.removePreserve(ctx, input[i], options);
-      // drop nulls from arrays
-      if(result !== null) {
-        output.push(result);
-      }
-    }
-    input = output;
-  } else if(_isObject(input)) {
-    // remove @preserve
-    if('@preserve' in input) {
-      if(input['@preserve'] === '@null') {
-        return null;
-      }
-      return input['@preserve'];
-    }
-
-    // skip @values
-    if(_isValue(input)) {
-      return input;
-    }
-
-    // recurse through @lists
-    if(_isList(input)) {
-      input['@list'] = api.removePreserve(ctx, input['@list'], options);
-      return input;
-    }
-
-    // handle in-memory linked nodes
-    const idAlias = api.compactIri({
-      activeCtx: ctx,
-      iri: '@id',
-      relativeTo: {vocab: true}
-    });
-    if(input.hasOwnProperty(idAlias)) {
-      const id = input[idAlias];
-      if(options.link.hasOwnProperty(id)) {
-        const idx = options.link[id].indexOf(input);
-        if(idx !== -1) {
-          // already visited
-          return options.link[id][idx];
-        }
-        // prevent circular visitation
-        options.link[id].push(input);
-      } else {
-        // prevent circular visitation
-        options.link[id] = [input];
-      }
-    }
-
-    // recurse through properties
-    const graphAlias = api.compactIri({
-      activeCtx: ctx,
-      iri: '@graph',
-      relativeTo: {vocab: true}
-    });
-    for(const prop in input) {
-      // potentially remove the id, if it is an unreference bnode
-      if(prop === idAlias && options.bnodesToClear.includes(input[prop])) {
-        delete input[idAlias];
-        continue;
-      }
-
-      let result = api.removePreserve(ctx, input[prop], options);
-      const container = _getContextValue(ctx, prop, '@container') || [];
-      if(options.compactArrays && _isArray(result) && result.length === 1 &&
-        container.length === 0 && prop !== graphAlias) {
-        result = result[0];
-      }
-      input[prop] = result;
-    }
-  }
-  return input;
-};
-
 /**
  * Picks the preferred compaction term from the given inverse context entry.
  *

lib/frame.js

@@ -59,7 +59,9 @@ api.frameMergedOrDefault = (input, frame, options) => {
       Object.keys(state.bnodeMap).filter(id => state.bnodeMap[id].length === 1);
   }
 
-  return framed;
+  // remove @preserve from results
+  options.link = {};
+  return _cleanupPreserve(framed, options);
 };
 
 /**
@@ -316,6 +318,50 @@ api.frame = (state, subjects, frame, parent, property = null) => {
   }
 };
 
+/**
+ * Replace `@null` with `null`, removing it from arrays.
+ *
+ * @param input the framed, compacted output.
+ * @param options the framing options used.
+ *
+ * @return the resulting output.
+ */
+api.cleanupNull = (input, options) => {
+  // recurse through arrays
+  if(types.isArray(input)) {
+    const noNulls = input.map(v => api.cleanupNull(v, options));
+    return noNulls.filter(v => v); // removes nulls from array
+  }
+
+  if(input === '@null') {
+    return null;
+  }
+
+  if(types.isObject(input)) {
+    // handle in-memory linked nodes
+    if(input.hasOwnProperty('@id')) {
+      const id = input['@id'];
+      if(options.link.hasOwnProperty(id)) {
+        const idx = options.link[id].indexOf(input);
+        if(idx !== -1) {
+          // already visited
+          return options.link[id][idx];
+        }
+        // prevent circular visitation
+        options.link[id].push(input);
+      } else {
+        // prevent circular visitation
+        options.link[id] = [input];
+      }
+    }
+
+    for(const key in input) {
+      input[key] = api.cleanupNull(input[key], options);
+    }
+  }
+  return input;
+};
+
 /**
  * Creates an implicit frame when recursing through subject matches. If
  * a frame doesn't have an explicit frame for a particular property, then
@@ -614,6 +660,68 @@ function _removeEmbed(state, id) {
   removeDependents(id);
 }
 
+/**
+ * Removes the @preserve keywords from expanded result of framing.
+ *
+ * @param input the framed, framed output.
+ * @param options the framing options used.
+ *
+ * @return the resulting output.
+ */
+function _cleanupPreserve(input, options) {
+  // recurse through arrays
+  if(types.isArray(input)) {
+    return input.map(value => _cleanupPreserve(value, options));
+  }
+
+  if(types.isObject(input)) {
+    // remove @preserve
+    if('@preserve' in input) {
+      return input['@preserve'][0];
+    }
+
+    // skip @values
+    if(graphTypes.isValue(input)) {
+      return input;
+    }
+
+    // recurse through @lists
+    if(graphTypes.isList(input)) {
+      input['@list'] = _cleanupPreserve(input['@list'], options);
+      return input;
+    }
+
+    // handle in-memory linked nodes
+    if(input.hasOwnProperty('@id')) {
+      const id = input['@id'];
+      if(options.link.hasOwnProperty(id)) {
+        const idx = options.link[id].indexOf(input);
+        if(idx !== -1) {
+          // already visited
+          return options.link[id][idx];
+        }
+        // prevent circular visitation
+        options.link[id].push(input);
+      } else {
+        // prevent circular visitation
+        options.link[id] = [input];
+      }
+    }
+
+    // recurse through properties
+    for(const prop in input) {
+      // potentially remove the id, if it is an unreference bnode
+      if(prop === '@id' && options.bnodesToClear.includes(input[prop])) {
+        delete input['@id'];
+        continue;
+      }
+
+      input[prop] = _cleanupPreserve(input[prop], options);
+    }
+  }
+  return input;
+};
+
 /**
  * Adds framing output to the given parent.
  *