Prune blank nodes.

Author: gkellogg

lib/compact.js

@@ -869,6 +869,12 @@ api.removePreserve = (ctx, input, options) => {
     // 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 &&

lib/frame.js

@@ -25,59 +25,38 @@ module.exports = api;
  *
  * @return the framed output.
  */
-api.frameMerged = (input, frame, options) => {
+api.frameMergedOrDefault = (input, frame, options) => {
   // create framing state
   const state = {
     options: options,
-    graph: '@merged',
+    graph: '@default',
     graphMap: {'@default': {}},
     graphStack: [],
     subjectStack: [],
-    link: {}
+    link: {},
+    bnodeMap: {}
   };
 
   // produce a map of all graphs and name each bnode
   // FIXME: currently uses subjects from @merged graph only
   const issuer = new util.IdentifierIssuer('_:b');
   _createNodeMap(input, state.graphMap, '@default', issuer);
-  state.graphMap['@merged'] = _mergeNodeMapGraphs(state.graphMap);
-  state.subjects = state.graphMap['@merged'];
+  if(options.merged) {
+    state.graphMap['@merged'] = _mergeNodeMapGraphs(state.graphMap);
+    state.graph = '@merged'
+  }
+  state.subjects = state.graphMap[state.graph];
 
   // frame the subjects
   const framed = [];
   api.frame(state, Object.keys(state.subjects).sort(), frame, framed);
-  return framed;
-};
 
-/**
- * Performs JSON-LD `default` framing.
- * FIXME: maybe just rename frameMerged and perform selection logic in one place
- *
- * @param input the expanded JSON-LD to frame.
- * @param frame the expanded JSON-LD frame to use.
- * @param options the framing options.
- *
- * @return the framed output.
- */
-api.frameDefault = (input, frame, options) => {
-  // create framing state
-  const state = {
-    options: options,
-    graph: '@default',
-    graphMap: {'@default': {}},
-    graphStack: [],
-    subjectStack: [],
-    link: {}
-  };
-
-  // produce a map of all graphs and name each bnode
-  const issuer = new util.IdentifierIssuer('_:b');
-  _createNodeMap(input, state.graphMap, '@default', issuer);
-  state.subjects = state.graphMap['@default'];
+  // If pruning blank nodes, find those to prune
+  if(options.pruneBlankNodeIdentifiers) {
+    // remove all blank nodes appearing only once, done in compaction
+    options.bnodesToClear = Object.keys(state.bnodeMap).filter(id => state.bnodeMap[id].length === 1);
+  }
 
-  // frame the subjects
-  const framed = [];
-  api.frame(state, Object.keys(state.subjects).sort(), frame, framed);
   return framed;
 };
 
@@ -133,6 +112,9 @@ api.frame = (state, subjects, frame, parent, property = null) => {
     // start output for subject
     const output = {};
     output['@id'] = id;
+    if(id.indexOf('_:') === 0) {
+      util.addValue(state.bnodeMap, id, output, {propertyIsArray: true});
+    }
     state.link[id] = output;
 
     // if embed is @never or if a circular reference would be created by an

lib/jsonld.js

@@ -48,8 +48,7 @@ const {fromRDF: _fromRDF} = require('./fromRdf');
 const {toRDF: _toRDF} = require('./toRdf');
 
 const {
-  frameMerged: _frameMerged,
-  frameDefault: _frameDefault
+  frameMergedOrDefault: _frameMergedOrDefault
 } = require('./frame');
 
 const {
@@ -426,7 +425,8 @@ jsonld.frame = util.callbackify(async function(input, frame, options) {
     explicit: false,
     requireAll: true,
     omitDefault: false,
-    pruneBlankNodeIdentifiers: true
+    pruneBlankNodeIdentifiers: true,
+    bnodesToClear: []
   });
 
   // if frame is a string, attempt to dereference remote document
@@ -463,13 +463,9 @@ jsonld.frame = util.callbackify(async function(input, frame, options) {
   // if the unexpanded frame includes a key expanding to @graph, frame the default graph, otherwise, the merged graph
   let framed;
   // FIXME should look for aliases of @graph
-  if('@graph' in frame) {
-    // do default framing
-    framed = _frameDefault(expanded, expandedFrame, opts);
-  } else {
-    // do merged framing
-    framed = _frameMerged(expanded, expandedFrame, opts);
-  }
+  opts.merged = !('@graph' in frame);
+  // do framing
+  framed = _frameMergedOrDefault(expanded, expandedFrame, opts);
 
   // compact result (force @graph option to true, skip expansion,
   // check for linked embeds)