org.openstreetmap.atlas.utilities.command.ReflectionUtilities Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of atlas Show documentation
"Library to load OSM data into an Atlas format"
There is a newer version: 7.0.8
package org.openstreetmap.atlas.utilities.command;

import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;

import org.openstreetmap.atlas.exception.CoreException;
import org.openstreetmap.atlas.utilities.command.abstractcommand.AbstractAtlasShellToolsCommand;
import org.openstreetmap.atlas.utilities.command.abstractcommand.AtlasShellToolsMarkerInterface;

import io.github.classgraph.ClassGraph;
import io.github.classgraph.ClassInfoList;
import io.github.classgraph.ScanResult;

/**
 * @author lcram
 */
public final class ReflectionUtilities
{
    @SuppressWarnings("unchecked")
    public static Set getSubcommandInstances()
    {
        final List> subcommandClasses = new ArrayList<>();
        final Set instantiatedCommands = new HashSet<>();
        try (ScanResult scanResult = new ClassGraph().enableAllInfo().scan())
        {
            final ClassInfoList classInfoList = scanResult
                    .getClassesImplementing(AtlasShellToolsMarkerInterface.class.getName());
            classInfoList.loadClasses().forEach(klass -> subcommandClasses
                    .add((Class) klass));
        }
        subcommandClasses.stream().forEach(klass -> instantiateSubcommand(klass.getName())
                .ifPresent(instantiatedCommands::add));
        return instantiatedCommands;
    }

    private static Optional instantiateSubcommand(
            final String classname)
    {
        final Class subcommandClass;
        try
        {
            subcommandClass = Class.forName(classname);
        }
        catch (final ClassNotFoundException exception)
        {
            throw new CoreException("Class {} was not found", classname, exception);
        }

        if (Modifier.isAbstract(subcommandClass.getModifiers()))
        {
            return Optional.empty();
        }

        final Constructor constructor;
        try
        {
            constructor = subcommandClass.getConstructor();
        }
        catch (final NoSuchMethodException exception)
        {
            throw new CoreException("Class {} does not have a matching constructor", classname,
                    exception);
        }
        catch (final SecurityException exception)
        {
            throw new CoreException("Error instantiating class {}", classname, exception);
        }

        final AbstractAtlasShellToolsCommand subcommand;
        try
        {
            subcommand = (AbstractAtlasShellToolsCommand) constructor.newInstance(new Object[] {}); // NOSONAR
        }
        catch (final ClassCastException exception)
        {
            throw new CoreException("Class {} not a subtype of {}", classname,
                    AbstractAtlasShellToolsCommand.class.getName(), exception);
        }
        catch (final Exception exception)
        {
            throw new CoreException("Error instantiating class {}", classname, exception);
        }

        return Optional.of(subcommand);
    }

    private ReflectionUtilities()
    {

    }
}