pf4j/pf4j/src/main/java/org/pf4j/processor/LegacyExtensionStorage.java

/*
 * Copyright (C) 2012-present the original author or authors.
 *
 * 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
 *
 *     http://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.pf4j.processor;

import javax.annotation.processing.FilerException;
import javax.tools.FileObject;
import javax.tools.StandardLocation;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.Reader;
import java.nio.file.NoSuchFileException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.regex.Pattern;

/**
 * Stores {@link org.pf4j.Extension}s in {@code META-INF/extensions.idx}.
 *
 * @author Decebal Suiu
 */
public class LegacyExtensionStorage extends ExtensionStorage {

    public static final String EXTENSIONS_RESOURCE = "META-INF/extensions.idx";

    private static final Pattern COMMENT = Pattern.compile("#.*");
    private static final Pattern WHITESPACE = Pattern.compile("\\s+");

    public LegacyExtensionStorage(ExtensionAnnotationProcessor processor) {
        super(processor);
    }

    public static void read(Reader reader, Set<String> entries) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(reader);

        String line;
        while ((line = bufferedReader.readLine()) != null) {
            line = COMMENT.matcher(line).replaceFirst("");
            line = WHITESPACE.matcher(line).replaceAll("");
            if (line.length() > 0) {
                entries.add(line);
            }
        }

        bufferedReader.close();
    }

    @Override
    public Map<String, Set<String>> read() {
        Map<String, Set<String>> extensions = new HashMap<>();

        try {
            FileObject file = getFiler().getResource(StandardLocation.CLASS_OUTPUT, "", EXTENSIONS_RESOURCE);
            // TODO try to calculate the extension point
            Set<String> entries = new HashSet<>();
            read(file.openReader(true), entries);
            extensions.put(null, entries);
        } catch (FileNotFoundException | NoSuchFileException e) {
            // doesn't exist, ignore
        } catch (FilerException e) {
            // re-opening the file for reading or after writing is ignorable
        } catch (IOException e) {
            error(e.getMessage());
        }

        return extensions;
    }

    @Override
    public void write(Map<String, Set<String>> extensions) {
        try {
            FileObject file = getFiler().createResource(StandardLocation.CLASS_OUTPUT, "", EXTENSIONS_RESOURCE);
            BufferedWriter writer = new BufferedWriter(file.openWriter());
            writer.write("# Generated by PF4J"); // write header
            writer.newLine();
            for (Map.Entry<String, Set<String>> entry : extensions.entrySet()) {
                for (String extension : entry.getValue()) {
                    writer.write(extension);
                    writer.newLine();
                }
            }

            writer.close();
        } catch (FileNotFoundException e) {
            // it's the first time, create the file
        } catch (FilerException e) {
            // re-opening the file for reading or after writing is ignorable
        } catch (IOException e) {
            error(e.toString());
        }
    }

}