fr.boreal.io.csv.RLSCSVParser Maven / Gradle / Ivy

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package fr.boreal.io.csv;

import fr.boreal.io.api.Parser;
import fr.lirmm.boreal.util.stream.ArrayBlockingStream;

import java.io.File;
import java.io.FileNotFoundException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * @author Florent Tornil
 * 
 *         This class parses an RLS file into RLSCSVResults
 * 
 *         Retrieves CSV files from a configuration file inspired from RLS
 *         syntax
 *         {@literal ...}
 *         Each line of the configuration file defines a CSV file as well as the
 *         predicate it defines.
 *
 */
public class RLSCSVParser implements Parser {

	private final ArrayBlockingStream buffer = new ArrayBlockingStream<>(512);
	private static final ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();

	/**
	 * @param file RLS configuration file to parse
	 */
	public RLSCSVParser(File file) {
		new Thread(new Producer(file, buffer)).start();
	}

	/**
	 * @param filepath to RLS configuration file
	 */
	public RLSCSVParser(String filepath) {
		this(new File(filepath));
	}

	@Override
	public boolean hasNext() {
		return buffer.hasNext();
	}

	@Override
	public RLSCSVResult next() {
		return buffer.next();
	}

	@Override
	public void close() {
		this.buffer.close();
		executor.shutdownNow();
	}

	//
	// Private class Producer
	//

	static class Producer implements Runnable {

        private final File file;
		private final ArrayBlockingStream buffer;

		public Producer(File file, ArrayBlockingStream buffer) {
			this.file = file;
			this.buffer = buffer;
		}

		@Override
		public void run() {
            String regex = "^@source (.*)\\[(\\d)]: load-csv\\(\"(.*)\"\\) \\.$";
            Pattern pattern = Pattern.compile(regex);

			try (Scanner scanner = new Scanner(this.file)) {
				while (scanner.hasNextLine()) {
					String line = scanner.nextLine();
					Matcher matcher = pattern.matcher(line);
					if (matcher.find() && matcher.groupCount() == 3) {

						String resolvedCSVPath = resolveCSVFilePath(matcher.group(3));

						this.buffer.write(new RLSCSVResult(matcher.group(1), Integer.parseInt(matcher.group(2)),
								resolvedCSVPath));
					}
				}
			} catch (FileNotFoundException e) {
				e.printStackTrace();
			}
			this.buffer.close();
		}

		private String resolveCSVFilePath(String path) throws FileNotFoundException {
			String resolvedPath;

			var p = Paths.get(path);
			if (p.isAbsolute()) {
				resolvedPath = path;
			} else {
				// relative path from the configuration file
				Path configFilePath = Paths.get(file.getAbsolutePath());
				Path parentDir = configFilePath.getParent();
				resolvedPath = Path.of(parentDir.toString(), path).toString();
			}

			Path resolved = Paths.get(resolvedPath);
			if (Files.exists(resolved)) {
				return resolved.normalize().toAbsolutePath().toString();
			} else {
				throw new FileNotFoundException(resolvedPath + " does not exists");

			}

		}
	}
}