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Graylog
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/**
 * This file is part of Graylog.
 *
 * Graylog is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Graylog is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Graylog.  If not, see .
 */
/*
 * This file is part of Graylog.
 *
 * Graylog is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Graylog is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Graylog.  If not, see .
 */
package org.graylog.plugins.pipelineprocessor.codegen.compiler;

import com.google.common.collect.Lists;

import org.graylog.plugins.pipelineprocessor.codegen.PipelineClassloader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Collections;
import java.util.List;
import java.util.Map;

import javax.tools.Diagnostic;
import javax.tools.ToolProvider;
import javax.validation.constraints.NotNull;

public class JavaCompiler {
    private static final Logger log = LoggerFactory.getLogger(JavaCompiler.class);

    private static final javax.tools.JavaCompiler JAVA_COMPILER = ToolProvider.getSystemJavaCompiler();

    public JavaCompiler() {
    }

    @NotNull
    private Map compileFromSource(@NotNull String className, @NotNull String javaCode) {
        if (JAVA_COMPILER == null) {
            log.error("No compiler present, unable to compile {}", className);
            return Collections.emptyMap();
        }

        final InMemoryFileManager memoryFileManager = new InMemoryFileManager(JAVA_COMPILER.getStandardFileManager(null, null, null));
        List errors = Lists.newArrayList();
        JAVA_COMPILER.getTask(null, memoryFileManager, diagnostic -> {
            if (diagnostic.getKind() == Diagnostic.Kind.ERROR) {
                errors.add(diagnostic);
            }
        }, null, null, Collections.singleton(new JavaSourceFromString(className, javaCode))).call();
        Map result = memoryFileManager.getAllClassBytes();
        if (!errors.isEmpty()) {
            throw new PipelineCompilationException(errors);
        }
        return result;
    }

    public Class loadFromString(@NotNull PipelineClassloader classLoader, @NotNull String className, @NotNull String source) throws ClassNotFoundException {
        for (Map.Entry entry : compileFromSource(className, source).entrySet()) {
            String name = entry.getKey();
            byte[] bytes = entry.getValue();
            classLoader.defineClass(name, bytes);
        }
        return classLoader.loadClass(className);
    }
}