com.casualsuperman.portent.InstanceLocator Maven / Gradle / Ivy

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The meat and potatoes of the Portent code generator

There is a newer version: 0.3.1

package com.casualsuperman.portent;

import com.casualsuperman.portent.exceptions.EnvironmentException;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;

public class InstanceLocator {
	private final File root;
	private final List templateTypes;

	private Map> instances = null;

	public InstanceLocator(File root, Set templateTypes) {
		this.root = root;
		this.templateTypes = new ArrayList<>(templateTypes);
		// Longest to shortest
		this.templateTypes.sort(Comparator.comparing(String::length).reversed());
	}

	public synchronized void discover() {
		if (instances == null) {
			this.instances = new ConcurrentHashMap<>();
			try {
				Files.walkFileTree(root.toPath(), new SimpleFileVisitor() {
					@Override
					public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
						String name = file.getFileName().toString();
						for (String type : templateTypes) {
							if (name.endsWith('.' + type)) {
								instances.computeIfAbsent(type, t -> new ArrayList<>())
										.add(new Instance(root, root.toPath().relativize(file)));
								break;
							}
						}
						return FileVisitResult.CONTINUE;
					}
				});
			} catch (IOException ex) {
				throw new EnvironmentException("failed to scan for instances", ex);
			}
		}
	}

	public Map> getTemplateInstances() {
		if (instances == null) {
			throw new IllegalStateException("must call discover() before getting instances");
		}
		return Collections.unmodifiableMap(instances);
	}

}