org.pkl.config.java.mapper.ClassRegistry Maven / Gradle / Ivy
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/*
* Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.pkl.config.java.mapper;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.HashSet;
import java.util.Properties;
import java.util.Set;
import org.pkl.config.java.InvalidMappingException;
import org.pkl.core.PClassInfo;
import org.pkl.core.util.IoUtils;
import org.pkl.core.util.Nullable;
/**
* Describes mappings of Pkl class names to their corresponding Java classes.
*
* This is used by {@link ValueMapper} to pick the correct Java class when mapping Pkl into Java.
*
*
Mappings are determined by scanning the
* /META-INF/org/pkl/config/java/mapper/classes directory for properties files.
*
*
Property files should be in the form of
* org.pkl.config.java.mapper.[PKL_CLASS_NAME]=[JAVA_REFLECTION_CLASS_NAME]
*
*
Mappings are optional, and only required if Pkl types are polymorphic.
*
*
They are generated by the Java and Kotlin code generators, and can be handwritten if not using
* codegen.
*/
public class ClassRegistry {
private static final Properties classMappings = new Properties();
private static final Object lock = new Object();
private static final String CLASSES_DIRECTORY = "/META-INF/org/pkl/config/java/mapper/classes";
private static final String PREFIX = "org.pkl.config.java.mapper.";
private static final Set loadedModules = new HashSet<>();
private ClassRegistry() {}
static @Nullable Class get(PClassInfo pklClassInfo) {
var pklModuleName = pklClassInfo.getModuleName();
var pklClassName = pklClassInfo.getQualifiedName();
initClassMappings(pklModuleName);
var javaName = classMappings.getProperty(PREFIX + pklClassInfo.getQualifiedName());
if (javaName == null) {
return null;
}
try {
return Class.forName(javaName);
} catch (ClassNotFoundException e) {
throw new InvalidMappingException(pklClassName, javaName, e);
}
}
private static void initClassMappings(String pklModuleName) {
synchronized (lock) {
if (loadedModules.contains(pklModuleName)) {
return;
}
loadedModules.add(pklModuleName);
var url =
ClassRegistry.class.getResourceAsStream(
CLASSES_DIRECTORY + "/" + IoUtils.encodePath(pklModuleName) + ".properties");
if (url == null) {
return;
}
try {
classMappings.load(url);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}
}
}