# PreMain.java

    /*******************************************************************************
     * Copyright (c) 2009, 2013 Mountainminds GmbH & Co. KG and Contributors
     * All rights reserved. This program and the accompanying materials
     * are made available under the terms of the Eclipse Public License v1.0
     * which accompanies this distribution, and is available at
     * http://www.eclipse.org/legal/epl-v10.html
     *
     * Contributors:
     *    Marc R. Hoffmann - initial API and implementation
     *
     *******************************************************************************/
    package org.jacoco.agent.rt.internal;

    import java.lang.instrument.Instrumentation;

    import org.jacoco.core.runtime.AgentOptions;
    import org.jacoco.core.runtime.IRuntime;
    import org.jacoco.core.runtime.ModifiedSystemClassRuntime;

    /**
     * The agent which is referred as the <code>Premain-Class</code>. The agent
     * configuration is provided with the agent parameters in the command line.
     */
    public final class PreMain {

    	private PreMain() {
    		// no instances
    	}

    	/**
    	 * This method is called by the JVM to initialize Java agents.
    	 *
    	 * @param options
    	 *            agent options
    	 * @param inst
    	 *            instrumentation callback provided by the JVM
    	 * @throws Exception
    	 *             in case initialization fails
    	 */
    	public static void premain(final String options, final Instrumentation inst)
    			throws Exception {

    		final AgentOptions agentOptions = new AgentOptions(options);

    		final Agent agent = Agent.getInstance(agentOptions);

    		final IRuntime runtime = createRuntime(inst);
    		runtime.startup(agent.getData());
    		inst.addTransformer(new CoverageTransformer(runtime, agentOptions,
    				IExceptionLogger.SYSTEM_ERR));
    	}

    	private static IRuntime createRuntime(final Instrumentation inst)
    			throws Exception {
    		return ModifiedSystemClassRuntime.createFor(inst, "java/util/UUID");
    	}

    }