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/*
* Copyright (c) 2010, 2014, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package jdk.nashorn.internal.codegen;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Collections;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import jdk.nashorn.internal.ir.Block;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.ir.LexicalContext;
import jdk.nashorn.internal.ir.Node;
import jdk.nashorn.internal.ir.Statement;
import jdk.nashorn.internal.ir.visitor.NodeVisitor;
import jdk.nashorn.internal.runtime.options.Options;
/**
* This static utility class performs serialization of FunctionNode ASTs to a byte array.
* The format is a standard Java serialization stream, deflated.
*/
final class AstSerializer {
// Experimentally, we concluded that compression level 4 gives a good tradeoff between serialization speed
// and size.
private static final int COMPRESSION_LEVEL = Options.getIntProperty("nashorn.serialize.compression", 4);
static byte[] serialize(final FunctionNode fn) {
final ByteArrayOutputStream out = new ByteArrayOutputStream();
final Deflater deflater = new Deflater(COMPRESSION_LEVEL);
try (final ObjectOutputStream oout = new ObjectOutputStream(new DeflaterOutputStream(out, deflater))) {
oout.writeObject(removeInnerFunctionBodies(fn));
} catch (final IOException e) {
throw new AssertionError("Unexpected exception serializing function", e);
} finally {
deflater.end();
}
return out.toByteArray();
}
private static FunctionNode removeInnerFunctionBodies(final FunctionNode fn) {
return (FunctionNode)fn.accept(new NodeVisitor<LexicalContext>(new LexicalContext()) {
@Override
public Node leaveBlock(final Block block) {
if (lc.isFunctionBody() && lc.getFunction(block) != lc.getOutermostFunction()) {
return block.setStatements(lc, Collections.<Statement>emptyList());
}
return super.leaveBlock(block);
}
});
}
}
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