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const _ = require('deepdash')(require('lodash')); |
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const check = require('check-types'); |
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const { JgfNode } = require('./jgfNode'); |
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const { JgfEdge } = require('./jgfEdge'); |
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const { JgfGraph } = require('./jgfGraph'); |
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const { JgfMultiGraph } = require('./jgfMultiGraph'); |
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/** |
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* Transforms graphs or multi graphs to json or vice versa. |
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* |
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* Note that this is just called decorator for semantic reasons and does not follow and does not intend to follow |
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* the GoF decorator design pattern. |
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*/ |
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class JgfJsonDecorator { |
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/** |
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* Creates a Jgf graph or multi graph from JSON. |
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* @param {object} json JSON to be transformed to a graph or multigraph. This has to be according to the JGF. |
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* @throws Error if json can not be transformed to a graph or multi graph. |
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* @returns {JgfGraph|JgfMultiGraph} The created Jgf graph or multi graph object. |
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*/ |
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static fromJson(json) { |
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if (check.assigned(json.graph)) { |
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return this._graphFromJson(json.graph); |
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} |
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if (check.assigned(json.graphs)) { |
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let graph = new JgfMultiGraph(json.type, json.label, json.metadata); |
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_.each(json.graphs, (graphJson) => { |
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graph.addGraph(this._graphFromJson(graphJson)) |
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}); |
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return graph; |
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} |
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throw new Error('Passed json has to to have a "graph" or "graphs" property.'); |
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} |
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/** |
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* Creates a single JGF graph from JSON. |
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* @param {object} graphJson |
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* @returns {JgfGraph} |
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* @private |
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*/ |
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static _graphFromJson(graphJson) { |
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let graph = new JgfGraph(graphJson.type, graphJson.label, graphJson.directed, graphJson.metadata); |
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_.each(graphJson.nodes, (node) => { |
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graph.addNode(new JgfNode(node.id, node.label, node.metadata)); |
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}); |
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_.each(graphJson.edges, (edge) => { |
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graph.addEdge(new JgfEdge(edge.source, edge.target, edge.relation, edge.label, edge.metadata, edge.directed)); |
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}); |
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return graph; |
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} |
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static _guardAgainstInvalidGraphObject(graph) { |
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if (!check.instance(graph, JgfGraph) && !check.instance(graph, JgfMultiGraph)) { |
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throw new Error('JgfJsonDecorator can only decorate graphs or multi graphs.'); |
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} |
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} |
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/** |
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* Transforms either a graph or a multi graph object to a JSON representation as per the spec. |
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* @param {JgfGraph|JgfMultiGraph} graph The graph to be transformed to JSON. |
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* @throws Error if the passed graph or multi graph can not be transformed to JSON. |
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* @returns {object} A JSON representation of the passed graph or multi graph as according to the JGF. |
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*/ |
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static toJson(graph) { |
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this._guardAgainstInvalidGraphObject(graph); |
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const isSingleGraph = check.instance(graph, JgfGraph); |
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let allGraphsJson = { |
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graphs: [], |
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}; |
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this._transformGraphsToJson(graph, allGraphsJson); |
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if (isSingleGraph) { |
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return this._removeNullValues({ graph: allGraphsJson.graphs[0] }); |
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} |
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allGraphsJson.type = graph.type; |
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allGraphsJson.label = graph.label; |
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allGraphsJson.metadata = graph.metadata; |
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return this._removeNullValues(allGraphsJson); |
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} |
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static _transformGraphsToJson(graph, allGraphsJson) { |
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let normalizedGraph = this._normalizeToMultiGraph(graph); |
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_.each(normalizedGraph.graphs, (singleGraph) => { |
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let singleGraphJson = { |
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type: singleGraph.type, |
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label: singleGraph.label, |
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directed: singleGraph.directed, |
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metadata: singleGraph.metadata, |
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nodes: [], |
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edges: [], |
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}; |
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this._nodesToJson(singleGraph, singleGraphJson); |
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this._edgesToJson(singleGraph, singleGraphJson); |
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allGraphsJson.graphs.push(singleGraphJson); |
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}); |
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} |
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static _removeNullValues(json) { |
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return _.filterDeep(json, (value) => value !== null); |
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} |
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/** |
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* @param {JgfGraph} graph |
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* @param {object} json |
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* @private |
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*/ |
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static _edgesToJson(graph, json) { |
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_.each(graph.edges, (edge) => { |
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json.edges.push({ |
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source: edge.source, |
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target: edge.target, |
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relation: edge.relation, |
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label: edge.label, |
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metadata: edge.metadata, |
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directed: edge.directed, |
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}); |
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}); |
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} |
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/** |
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* @param {JgfGraph} graph |
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* @param {object} json |
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* @private |
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*/ |
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static _nodesToJson(graph, json) { |
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_.each(graph.nodes, (node) => { |
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json.nodes.push({ |
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id: node.id, |
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label: node.label, |
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metadata: node.metadata, |
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}); |
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}); |
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} |
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static _normalizeToMultiGraph(graph) { |
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let normalizedGraph = graph; |
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if (check.instance(graph, JgfGraph)) { |
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normalizedGraph = new JgfMultiGraph(); |
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normalizedGraph.addGraph(graph); |
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} |
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return normalizedGraph; |
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} |
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} |
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161
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module.exports = { |
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JgfJsonDecorator, |
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}; |