net.sansa_stack.owl.spark.writers.KRSSSyntaxWriter.scala Maven / Gradle / Ivy

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package net.sansa_stack.owl.spark.writers

import java.io.{ByteArrayOutputStream, OutputStreamWriter}
import java.util.Collections

import net.sansa_stack.owl.spark.rdd.OWLAxiomsRDD
import org.semanticweb.owlapi.apibinding.OWLManager
import org.semanticweb.owlapi.krss2.renderer.KRSSObjectRenderer

import scala.collection.JavaConverters._

object KRSSSyntaxWriter extends OWLWriterBase {
  override def save(filePath: String, owlAxioms: OWLAxiomsRDD): Unit =
    owlAxioms.mapPartitions(partition => if (partition.hasNext) {
      val os = new ByteArrayOutputStream()
      val osWriter = new OutputStreamWriter(os)
      val renderer = new KRSSObjectRenderer(OWLManager.createOWLOntologyManager().createOntology(), osWriter)

      partition.foreach(axiom => {
        val ont = OWLManager.createOWLOntologyManager().createOntology(Seq(axiom).asJava)
        renderer.visit(ont)
      })
      osWriter.flush()

      Collections.singleton(os.toString("UTF-8").trim + nl).iterator().asScala

    } else {
      Iterator()
    }).saveAsTextFile(filePath)
}