SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package java.io;

import cc.squirreljme.runtime.cldc.annotation.Api;
import cc.squirreljme.runtime.cldc.io.CodecFactory;
import cc.squirreljme.runtime.cldc.io.Decoder;

/**
 * This is a reader which adapts to an input stream and decodes the input
 * bytes into characters.
 *
 * @since 2018/10/13
 */
@Api
public class InputStreamReader
    extends Reader
{
    /** The input source. */
    private final InputStream _in;
    
    /** The decoder to use. */
    private final Decoder _decoder;
    
    /** The input read storage. */
    private final byte[] _store;
    
    /**
     * Initializes the reader from the given input stream using the default
     * encoding.
     *
     * @param __in The input byte source.
     * @throws NullPointerException On null arguments.
     * @since 2018/10/13
     */
    @Api
    public InputStreamReader(InputStream __in)
        throws NullPointerException
    {
        if (__in == null)
            throw new NullPointerException("NARG");
        
        this._in = __in;
        
        Decoder d;
        this._decoder = (d = CodecFactory.defaultDecoder());
        this._store = new byte[d.maximumSequenceLength()];
    }
    
    /**
     * Initializes the reader from the given input stream using the default
     * encoding.
     *
     * @param __in The input byte source.
     * @param __enc The encoding to decode.
     * @throws NullPointerException On null arguments.
     * @throws UnsupportedEncodingException If the encoding is not supported.
     * @since 2018/10/13
     */
    @Api
    public InputStreamReader(InputStream __in, String __enc)
        throws NullPointerException, UnsupportedEncodingException
    {
        if (__in == null)
            throw new NullPointerException("NARG");
        
        this._in = __in;
        
        Decoder d;
        this._decoder = (d = CodecFactory.decoder(__enc));
        this._store = new byte[d.maximumSequenceLength()];
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/12/06
     */
    @Override
    public void close()
        throws IOException
    {
        this._in.close();
    }
    
    /**
     * Returns the name of the encoding.
     *
     * @return The encoding name.
     * @since 2018/12/08
     */
    @Api
    public String getEncoding()
    {
        return this._decoder.encodingName();
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/11/22
     */
    @Override
    public int read()
        throws IOException
    {
        InputStream in = this._in;
        Decoder decoder = this._decoder;
        byte[] store = this._store;
        int storelen = 0,
            declimit = store.length;
        
        // Read characters
        for (;;)
        {
            /* {@squirreljme.error ZZ0o Read of input byte sequence exceeded
            the maximum specified sequence length. (The store length)} */
            if (storelen >= declimit)
                throw new IOException("ZZ0o " + storelen);
            
            // Read byte from input stream
            int brc = in.read(store, storelen, 1);
            
            // Reached EOF from the input bytes
            if (brc < 0)
            {
                // No characters were read, so this is a complete EOF
                if (storelen <= 0)
                    return -1;
                
                // Try to decode whatever was read, if it ends up not being
                // valid then just use the replacement character because it
                // probably got chopped off
                int cha = decoder.decode(store, 0, storelen);
                if (cha >= 0)
                    return (char)cha;
                else
                    return (char)0xFFFD;
            }
            
            // Increment the store length since bytes were read
            storelen++;
            
            // Try to decode a character, if it decodes to a valid character we
            // just store that
            int cha = decoder.decode(store, 0, storelen);
            if (cha >= 0)
                return (char)cha;
        }
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/10/13
     */
    @Override
    public int read(char[] __c, int __o, int __l)
        throws IOException
    {
        if (__c == null)
            throw new NullPointerException("NARG");
        if (__o < 0 || __l < 0 || (__o + __l) < 0 || (__o + __l) > __c.length)
            throw new IndexOutOfBoundsException("IOOB");
        
        InputStream in = this._in;
        Decoder decoder = this._decoder;
        byte[] store = this._store;
        int storelen = 0,
            declimit = store.length;
        
        int rv = 0,
            baseo = __o;
        for (int o = __o; rv < __l;)
        {
            /* {@squirreljme.error ZZ0p Read of input byte sequence exceeded
            the maximum specified sequence length. (The store length)} */
            if (storelen >= declimit)
                throw new IOException("ZZ0p " + storelen);
            
            // Read byte from input stream
            int brc = in.read(store, storelen, 1);
            
            // Reached EOF from the input bytes
            if (brc < 0)
            {
                // No characters were read, so this is a complete EOF
                // However if there were characters sitting in the output we
                // need to return those
                if (storelen <= 0)
                    return (rv > 0 ? rv : brc);
                
                // Try to decode whatever was read, if it ends up not being
                // valid then just use the replacement character because it
                // probably got chopped off
                int cha = decoder.decode(store, 0, storelen);
                if (cha >= 0)
                    __c[o++] = (char)cha;
                else
                    __c[o++] = (char)0xFFFD;
                rv++;
                
                // There could have been characters placed before this, so
                // this should be at least 1
                return rv;
            }
            
            // Increment the store length since bytes were read
            storelen++;
            
            // Try to decode a character, if it decodes to a valid character we
            // just store that
            int cha = decoder.decode(store, 0, storelen);
            if (cha >= 0)
            {
                __c[o++] = (char)cha;
                storelen = 0;
                rv++;
            }
        }
        
        return rv;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/10/13
     */
    @Override
    public boolean ready()
        throws IOException
    {
        // If the number of available bytes is at least the maximum sequence
        // length then we can read a single character without blocking
        return this._in.available() >= this._store.length;
    }
}