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    BaseIRI.js IRIs.js N3DataFactory.js N3Lexer.js N3Parser.js N3Reasoner.js N3Store.js N3StoreFactory.js N3StreamParser.js N3StreamWriter.js N3Util.js N3Writer.js Util.js index.js

  • N3StreamParser.js

  • §

    N3StreamParser parses a text stream into a quad stream.

    import { Transform } from 'readable-stream';
import N3Parser from './N3Parser';
  • §

    Constructor

    export default class N3StreamParser extends Transform {
  constructor(options) {
    super({ decodeStrings: true });
    this._readableState.objectMode = true;
  • §

    Set up parser with dummy stream to obtain data and end callbacks

        const parser = new N3Parser(options);
    let onData, onEnd;

    const callbacks = {
  • §

    Handle quads by pushing them down the pipeline

          onQuad: (error, quad) => { error && this.emit('error', error) || quad && this.push(quad); },
  • §

    Emit prefixes through the prefix event

          onPrefix: (prefix, uri) => { this.emit('prefix', prefix, uri); },
    };

    if (options && options.comments)
      callbacks.onComment = comment => { this.emit('comment', comment); };

    parser.parse({
      on: (event, callback) => {
        switch (event) {
        case 'data': onData = callback; break;
        case 'end':   onEnd = callback; break;
        }
      },
    }, callbacks);
  • §

    Implement Transform methods through parser callbacks

        this._transform = (chunk, encoding, done) => { onData(chunk); done(); };
    this._flush = done => { onEnd(); done(); };
  }
  • §

    Parses a stream of strings

      import(stream) {
    stream.on('data',  chunk => { this.write(chunk); });
    stream.on('end',   ()      => { this.end(); });
    stream.on('error', error => { this.emit('error', error); });
    return this;
  }
}