@mnakhla/rocketrml/src/helper/replace.js

This is a forked rocketrml mapper for the RDF mapping language

const clone = (obj) => JSON.parse(JSON.stringify(obj));

const isJsonLDReference = (obj) => obj['@id'] && Object.keys(obj).length === 1;

// may create circular data-structure (probably not common in rml though)
const jsonLDGraphToObj = (graph, deleteReplaced = false) => {
  if (graph.some((n) => !n['@id'])) {
    throw new Error('node without id');
  }
  const replacedIds = [];
  const obj = Object.fromEntries(graph.map((node) => [node['@id'], node]));
  for (const id in obj) {
    for (const key in obj[id]) {
      if (Array.isArray(obj[id][key])) {
        // case array, else single obj
        for (const index in obj[id][key]) {
          if (
            isJsonLDReference(obj[id][key][index]) &&
            obj[obj[id][key][index]['@id']]
          ) {
            // if its reference and the reference id is included in the graph
            replacedIds.push(obj[id][key][index]['@id']);
            obj[id][key][index] = obj[obj[id][key][index]['@id']];
          }
        }
      } else if (isJsonLDReference(obj[id][key]) && obj[obj[id][key]['@id']]) {
        // if its reference and the reference id is included in the graph
        replacedIds.push(obj[id][key]['@id']);
        obj[id][key] = obj[obj[id][key]['@id']];
      }
    }
  }
  if (deleteReplaced) {
    for (const deleteId of replacedIds) {
      delete obj[deleteId]; // only deletes the reference to the replaced object not those where the object was inserted into
    }
  }
  return Object.values(obj);
};

const replace = (graph) => {
  const connectedGraph = jsonLDGraphToObj(graph, true);
  // test for circular deps & remove links
  try {
    const graphCopy = clone(connectedGraph);
    return graphCopy;
  } catch (e) {
    console.error(
      'Could not replace, circular dependencies when replacing nodes',
    );
    return graph;
  }
};

module.exports.replace = replace;
module.exports.jsonLDGraphToObj = jsonLDGraphToObj;