/*

 * Copyright (c) 2005, 2006, 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.

 *

 * 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 evalexpr;

import java.io.ByteArrayOutputStream;

import java.io.FilterOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.Reader;

import java.io.StringReader;

import java.net.URI;

import java.net.URISyntaxException;

import java.nio.CharBuffer;

import java.util.HashMap;

import java.util.Map;

import javax.tools.*;

import javax.tools.JavaFileObject.Kind;

/**

 * A file manager for compiling strings to byte arrays.

 * This file manager delegates to another file manager

 * to lookup classes on boot class path.

 *

 * If you write code that depends on this, you do so at your own

 * risk.  This code and its internal interfaces are subject to change

 * or deletion without notice.</b></p>

 * @author Peter von der Ahé

 */

public final class MemoryFileManager extends ForwardingJavaFileManager {

    /**

     * Maps binary class names to class files stored as byte arrays.

     */

    private Map<String, byte[]> classes;

    /**

     * Creates a JavaFileObject representing the given compilation unit.

     * @param name a name representing this source code, for example, the name of a class

     * @param code a compilation unit (source code for a Java program)

     * @return a JavaFileObject represtenting the given compilation unit

     */

    public static JavaFileObject makeSource(String name, String code) {

        return new JavaSourceFromString(name, code);

    }

    /**

     * Construct a memory file manager which delegates to the specified

     * file manager for unknown sources.

     * @param fileManager a file manager used to look up class files on class path, etc.

     */

    public MemoryFileManager(JavaFileManager fileManager) {

        super(fileManager);

        classes = new HashMap<String, byte[]>();

    }

    /**

     * Get a class loader which first search the classes stored

     * by this file mananger.

     * @return a class loader for compiled files

     */

    @Override

    public ClassLoader getClassLoader(Location location) {

        return new ByteArrayClassLoader(classes);

    }

    @Override

    public JavaFileObject getJavaFileForOutput(Location location,

                                               String name,

                                               Kind kind,

                                               FileObject originatingSource)

        throws UnsupportedOperationException

    {

        if (originatingSource instanceof JavaSourceFromString) {

            return new JavaClassInArray(name);

        } else {

            throw new UnsupportedOperationException();

        }

    }

    protected static URI uriFromString(String uri) {

        try {

            return new URI(uri);

        } catch (URISyntaxException e) {

            throw new IllegalArgumentException(e);

        }

    }

    /**

     * A file object representing a Java class file stored in a byte array.

     */

    private class JavaClassInArray extends SimpleJavaFileObject {

        private String name;

        /**

         * Constructs a JavaClassInArray object.

         * @param name binary name of the class to be stored in this file object

         */

        JavaClassInArray(String name) {

            super(uriFromString("mfm:///" + name.replace('.','/') + Kind.CLASS.extension),

                  Kind.CLASS);

            this.name = name;

        }

        public OutputStream openOutputStream() {

            return new FilterOutputStream(new ByteArrayOutputStream()) {

                public void close() throws IOException {

                    out.close();

                    ByteArrayOutputStream bos = (ByteArrayOutputStream)out;

                    classes.put(name, bos.toByteArray());

                    System.out.println("compiled " + name);

                }

            };

        }

    }

    /**

     * A file object used to represent source coming from a string.

     */

    private static class JavaSourceFromString extends SimpleJavaFileObject {

        /**

         * The source code of this "file".

         */

        final String code;

        /**

         * Constructs a new JavaSourceFromString.

         * @param name the name of the compilation unit represented by this file object

         * @param code the source code for the compilation unit represented by this file object

         */

        JavaSourceFromString(String name, String code) {

            super(uriFromString("mfm:///" + name.replace('.','/') + Kind.SOURCE.extension),

                  Kind.SOURCE);

            this.code = code;

        }

        @Override

        public CharSequence getCharContent(boolean ignoreEncodingErrors) {

            return code;

        }

    }

}