org.wikidata.query.rdf.tool.CliUtils Maven / Gradle / Ivy

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Tools to sync Wikibase to RDF stores. Also contains overall integration tests that rely on everything else.
There is a newer version: 0.3.2
package org.wikidata.query.rdf.tool;

import static org.wikidata.query.rdf.tool.StreamUtils.utf8;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.Reader;
import java.io.Writer;
import java.net.URI;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import com.google.common.io.Files;

/**
 * Utilities for command line scripts.
 */
public final class CliUtils {
    /**
     * Build a reader for the uri.
     *
     * @throws IOException if it is thrown opening the files and such
     */
    public static Reader reader(String uri) throws IOException {
        return utf8(inputStream(uri));
    }

    /**
     * Get an input stream for a uri. If the uri looks like a gzip file then
     * unzips it on the fly.
     *
     * @throws IOException if it is thrown opening the files and such
     */
    public static InputStream inputStream(String uri) throws IOException {
        if (uri.equals("-")) {
            return ForbiddenOk.systemDotIn();
        }
        InputStream stream;
        if (!uri.contains(":/")) {
            stream = new BufferedInputStream(new FileInputStream(uri));
        } else {
            stream = URI.create(uri).toURL().openStream();
        }
        if (uri.endsWith(".gz")) {
            stream = new GZIPInputStream(stream);
        }
        return stream;
    }

    /**
     * Build a writer for the uri.
     *
     * @throws IOException if it is thrown opening the files and such
     */
    public static Writer writer(String uri) throws IOException {
        return utf8(outputStream(uri));
    }

    /**
     * Get an output stream for a file. If the file is - then returns stdin
     * instead. If the file looks like a gzip file then zips it on the fly. Also
     * creates the file file's parent directories if they don't already exist.
     *
     * @throws IOException if it is thrown opening the files and such
     */
    public static OutputStream outputStream(String out) throws IOException {
        if (out.equals("-")) {
            return ForbiddenOk.systemDotOut();
        }
        Files.createParentDirs(new File(out));
        OutputStream stream = new BufferedOutputStream(new FileOutputStream(out));
        if (out.endsWith(".gz")) {
            stream = new GZIPOutputStream(stream);
        }
        return stream;
    }

    /**
     * Methods in this class are ignored by the forbiddenapis checks. Thus you
     * need to really really really be sure what you are putting in here is
     * right.
     *
     * Methods on this class are public but a fairy dies every time you abuse
     * them.
     */
    public static class ForbiddenOk {
        /**
         * Get System.in. CliTools should be allowed to use System.in/out/err.
         * This is private because we only want them to be used by cli tools.
         */
        public static InputStream systemDotIn() {
            return System.in;
        }

        /**
         * Get System.out. CliTools should be allowed to use System.in/out/err.
         * This is private because we only want them to be used by cli tools.
         */
        public static PrintStream systemDotOut() {
            return System.out;
        }

        /**
         * Get System.err. CliTools should be allowed to use System.in/out/err.
         * This is private because we only want them to be used by cli tools.
         */
        public static PrintStream systemDotErr() {
            return System.err;
        }
    }

    private CliUtils() {
        // Uncallable utility constructor
    }
}