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| export * from "./lib/SparqlXmlParser"; | ||
| export * from "./lib/SparqlXmlBindingsTransformer"; |
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| import {Transform, TransformCallback} from "stream"; | ||
| import {SparqlXmlParser} from "./SparqlXmlParser"; | ||
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| /** | ||
| * Transforms a stream of SPARQL JSON bindings object to parsed bindings. | ||
| */ | ||
| export class SparqlXmlBindingsTransformer extends Transform { | ||
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| private readonly parser: SparqlXmlParser; | ||
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| constructor(parser: SparqlXmlParser) { | ||
| super({ objectMode: true }); | ||
| this.parser = parser; | ||
| } | ||
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| public _transform(chunk: any, encoding: string, callback: TransformCallback): void { | ||
| callback(null, this.parser.parseXmlBindings(chunk)); | ||
| } | ||
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| } |
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| import * as DefaultDataFactory from "@rdfjs/data-model"; | ||
| import * as RDF from "rdf-js"; | ||
| import {Readable} from "stream"; | ||
| import {SparqlXmlBindingsTransformer} from "./SparqlXmlBindingsTransformer"; | ||
| // tslint:disable-next-line:no-var-requires | ||
| const XmlStream = require('xml-stream'); | ||
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| /** | ||
| * Parser for the SPARQL Query Results XML format. | ||
| * @see https://www.w3.org/TR/rdf-sparql-XMLres/ | ||
| */ | ||
| export class SparqlXmlParser { | ||
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| private readonly dataFactory: RDF.DataFactory; | ||
| private readonly prefixVariableQuestionMark?: boolean; | ||
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| constructor(settings?: ISettings) { | ||
| settings = settings || {}; | ||
| this.dataFactory = settings.dataFactory || DefaultDataFactory; | ||
| this.prefixVariableQuestionMark = !!settings.prefixVariableQuestionMark; | ||
| } | ||
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| /** | ||
| * Convert a SPARQL XML bindings response stream to a stream of bindings objects. | ||
| * | ||
| * The bindings stream will emit a 'variables' event that will contain | ||
| * the array of variables (as RDF.Variable[]), as defined in the response head. | ||
| * | ||
| * @param {NodeJS.ReadableStream} sparqlResponseStream A SPARQL XML response stream. | ||
| * @return {NodeJS.ReadableStream} A stream of bindings. | ||
| */ | ||
| public parseXmlResultsStream(sparqlResponseStream: NodeJS.ReadableStream): NodeJS.ReadableStream { | ||
| const variables: RDF.Variable[] = []; | ||
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| const rawResultStream = new Readable({ objectMode: true }); | ||
| rawResultStream._read = () => { return; }; | ||
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| const xmlParser = new XmlStream(sparqlResponseStream); | ||
| xmlParser.collect('binding', true); | ||
| xmlParser.on('error', (error: Error) => resultStream.emit('error', error)); | ||
| xmlParser.on('endElement: head > variable', (node: any) => variables.push(this.dataFactory.variable(node.$.name))); | ||
| xmlParser.on('endElement: results result', (bindings: any) => rawResultStream.push(bindings)); | ||
| xmlParser.on('end', () => { | ||
| resultStream.emit('variables', variables); | ||
| rawResultStream.push(null); | ||
| }); | ||
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| const resultStream = rawResultStream.pipe(new SparqlXmlBindingsTransformer(this)); | ||
| sparqlResponseStream.on('error', (error) => resultStream.emit('error', error)); | ||
| return resultStream; | ||
| } | ||
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| /** | ||
| * Convert a SPARQL XML result binding to a bindings object. | ||
| * @param rawBindings A SPARQL XML result binding. | ||
| * @return {IBindings} A bindings object. | ||
| */ | ||
| public parseXmlBindings(rawBindings: any): IBindings { | ||
| const bindings: IBindings = {}; | ||
| for (const binding of rawBindings.binding) { | ||
| const key = binding.$.name; | ||
| let value: RDF.Term = null; | ||
| if (binding.bnode) { | ||
| value = this.dataFactory.blankNode(binding.bnode); | ||
| } else if (binding.literal) { | ||
| if (binding.literal.$ && binding.literal.$['xml:lang']) { | ||
| value = this.dataFactory.literal(binding.literal.$text, binding.literal.$['xml:lang']); | ||
| } else if (binding.literal.$ && binding.literal.$.datatype) { | ||
| value = this.dataFactory.literal(binding.literal.$text, | ||
| this.dataFactory.namedNode(binding.literal.$.datatype)); | ||
| } else { | ||
| value = this.dataFactory.literal(binding.literal); | ||
| } | ||
| } else { | ||
| value = this.dataFactory.namedNode(binding.uri); | ||
| } | ||
| bindings[this.prefixVariableQuestionMark ? ('?' + key) : key] = value; | ||
| } | ||
| return bindings; | ||
| } | ||
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| /** | ||
| * Convert a SPARQL XML boolean response stream to a promise resolving to a boolean. | ||
| * This will reject if the given reponse was not a valid boolean response. | ||
| * @param {NodeJS.ReadableStream} sparqlResponseStream A SPARQL XML response stream. | ||
| * @return {NodeJS.ReadableStream} A stream of bindings. | ||
| */ | ||
| public parseXmlBooleanStream(sparqlResponseStream: NodeJS.ReadableStream): Promise<boolean> { | ||
| return new Promise((resolve, reject) => { | ||
| sparqlResponseStream.on('error', reject); | ||
| const xmlParser = new XmlStream(sparqlResponseStream); | ||
| xmlParser.on('error', reject); | ||
| xmlParser.on('endElement: boolean', (node: any) => resolve(node.$text === 'true')); | ||
| xmlParser.on('end', () => reject(new Error('No valid ASK response was found.'))); | ||
| }); | ||
| } | ||
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| } | ||
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| /** | ||
| * Constructor settings object interface for {@link SparqlXmlParser}. | ||
| */ | ||
| export interface ISettings { | ||
| /** | ||
| * A custom datafactory. | ||
| */ | ||
| dataFactory?: RDF.DataFactory; | ||
| /** | ||
| * If variable names should be prefixed with a quotation mark. | ||
| */ | ||
| prefixVariableQuestionMark?: boolean; | ||
| } | ||
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| /** | ||
| * A bindings object. | ||
| */ | ||
| export interface IBindings { | ||
| [key: string]: RDF.Term; | ||
| } |
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