org.armedbear.lisp.URLStream Maven / Gradle / Ivy

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/*
 * URLStream.java
 *
 * Copyright (C) 2010 Mark Evenson
 * $Id$
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obligated to do so.  If you do not wish to do so, delete this
 * exception statement from your version.
 */

package org.armedbear.lisp;

import static org.armedbear.lisp.Lisp.*;

import java.io.File;
import java.io.InputStream;
import java.io.Reader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;

/** 
 * Stream interface for a URL.
 * 
 * Currently only supports reading from the stream.
 */
public final class URLStream extends Stream
{
    private final Pathname pathname;
    private final InputStream input;
    private final Reader reader;
    private final int bytesPerUnit;

    public URLStream(Pathname pathname, String namestring,
                     LispObject elementType, LispObject direction,
                     LispObject ifExists, LispObject format)
        throws IOException
    {
        super(Symbol.URL_STREAM);
        Debug.assertTrue(direction == Keyword.INPUT);
        isInputStream = true;

        super.setExternalFormat(format);
        
        this.pathname = pathname;
        this.elementType = elementType;

        this.input = pathname.getInputStream();
        if (elementType == Symbol.CHARACTER || elementType == Symbol.BASE_CHAR) {
            isCharacterStream = true;
            bytesPerUnit = 1;
            InputStreamReader isr = new InputStreamReader(input);
            this.reader = (Reader) new BufferedReader(isr);
            initAsCharacterInputStream(this.reader);
        } else {
            isBinaryStream = true;
            int width = Fixnum.getValue(elementType.cadr());
            bytesPerUnit = width / 8;
            this.reader = null;
            initAsBinaryInputStream(this.input);
        }
    }

    @Override
    public LispObject typeOf()
    {
        return Symbol.URL_STREAM;
    }

    @Override
    public LispObject classOf()
    {
        return BuiltInClass.URL_STREAM;
    }

    @Override
    public LispObject typep(LispObject typeSpecifier)
    {
        if (typeSpecifier == Symbol.URL_STREAM)
            return T;
        if (typeSpecifier == BuiltInClass.URL_STREAM)
            return T;
        return super.typep(typeSpecifier);
    }

    @Override
    public void setExternalFormat(LispObject format) {
        super.setExternalFormat(format);
    }

    public Pathname getPathname()
    {
        return pathname;
    }

    // unused 20200418 ME
    public Reader getReader()
    {
        return reader;
    }

    /**
     * Accessing the underlying java.io.InputStream can be helpful
     * when utlizing Java-side frameworks like Apache Jena built on
     * the java.io abstractions.  State should only be mutated if you
     * know what you are doing.
     * 
     * c.f. 
     **/
    public InputStream getInputStream()
    {
        return input;
    }

    // unused 20200418 ME
    public int getBytesPerUnit() {
        return bytesPerUnit;
    }
    @Override
    public void _close()
    {
        try {
            if (input != null) {
                input.close();
            }
            if (reader != null) {
                reader.close();
            }
            setOpen(false);
        }
        catch (IOException e) {
            error(new StreamError(this, e));
        }
    }

    @Override
    public String printObject()
    {
        StringBuffer sb = new StringBuffer();
        sb.append(Symbol.URL_STREAM.printObject());
        String namestring = pathname.getNamestring();
        if (namestring != null) {
            sb.append(" ");
            sb.append(namestring);
        }
        return unreadableString(sb.toString());
    }
}