import java.io.File;

import java.io.IOException;

import java.nio.charset.Charset;

import java.util.*;

import javax.tools.*;

import static javax.tools.StandardLocation.CLASS_PATH;

import static javax.tools.StandardLocation.SOURCE_PATH;

import static javax.tools.StandardLocation.CLASS_OUTPUT;

public class ToolTester {

public final File test_src = new File(System.getProperty("test.src", "."));

public final File test_classes = new File(System.getProperty("test.classes", "."));

public final List<File> test_class_path = pathToFiles(System.getProperty("test.class.path"),

Arrays.asList(test_classes));

public final JavaCompiler tool = ToolProvider.getSystemJavaCompiler();

public final StandardJavaFileManager fm = getFileManager(tool, null, null);

public JavaCompiler.CompilationTask task = null;

public final StandardJavaFileManager getFileManager(JavaCompiler tool,

DiagnosticListener<JavaFileObject> dl,

Charset encoding) {

StandardJavaFileManager fm = tool.getStandardFileManager(dl, null, encoding);

try {

fm.setLocation(SOURCE_PATH, Arrays.asList(test_src));

fm.setLocation(CLASS_PATH, test_class_path);

fm.setLocation(CLASS_OUTPUT, Arrays.asList(test_classes));

} catch (IOException e) {

throw new AssertionError(e);

}

return fm;

}

protected List<File> pathToFiles(String path, List<File> defaultPath) {

List<File> files = new ArrayList<>();

for (String f: path.split(File.pathSeparator)) {

if (f.isEmpty())

continue;

File file = new File(f);

if (file.exists())

files.add(file);

}

if (files.isEmpty())

files.addAll(defaultPath);

return files;

}

protected <T> List<T> join(List<T> a, List<T> b) {

if (a.isEmpty())

return b;

if (b.isEmpty())

return a;

List<T> result = new ArrayList<>();

result.addAll(a);

result.addAll(b);

return result;

}

}