jdk/src/share/classes/sun/io/CharToByteASCII.java

/*
 * Copyright 1997 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package sun.io;

public class CharToByteASCII extends CharToByteConverter {

    // Return the character set ID
    public String getCharacterEncoding()
    {
        return "ASCII";
    }

    private char highHalfZoneCode;

    public int flush(byte[] output, int outStart, int outEnd)
        throws MalformedInputException
    {
        if (highHalfZoneCode != 0) {
            highHalfZoneCode = 0;
            throw new MalformedInputException
                ("String ends with <High Half Zone code> of UTF16");
        }
        byteOff = charOff = 0;
        return 0;
    }

    /*
    * Character conversion
    */
    public int convert(char[] input, int inOff, int inEnd,
                       byte[] output, int outOff, int outEnd)
        throws MalformedInputException,
               UnknownCharacterException,
               ConversionBufferFullException
    {
        char    inputChar;          // Input character to be converted
        byte[]  outputByte;         // Output byte written to output
        byte[]  tmpArray = new byte[1];
        int     inputSize;          // Size of input
        int     outputSize;         // Size of output

        // Record beginning offsets
        charOff = inOff;
        byteOff = outOff;

        if (highHalfZoneCode != 0) {
            inputChar = highHalfZoneCode;
            highHalfZoneCode = 0;
            if (input[inOff] >= 0xdc00 && input[inOff] <= 0xdfff) {
                // This is legal UTF16 sequence.
                badInputLength = 1;
                throw new UnknownCharacterException();
            } else {
                // This is illegal UTF16 sequence.
                badInputLength = 0;
                throw new MalformedInputException
                    ("Previous converted string ends with " +
                     "<High Half Zone Code> of UTF16 " +
                     ", but this string is not begin with <Low Half Zone>");
            }
        }

        // Loop until we hit the end of the input
        while(charOff < inEnd) {
            outputByte = tmpArray;

            // Get the input character
            inputChar = input[charOff];

            // default outputSize
            outputSize = 1;

            // Assume this is a simple character
            inputSize = 1;

            // Is this a high surrogate?
            if(inputChar >= '\uD800' && inputChar <= '\uDBFF') {
                // Is this the last character in the input?
                if (charOff + 1 == inEnd) {
                    highHalfZoneCode = inputChar;
                    break;
                }

                // Is there a low surrogate following?
                inputChar = input[charOff + 1];
                if (inputChar >= '\uDC00' && inputChar <= '\uDFFF') {
                    // We have a valid surrogate pair.  Too bad we don't map
                    //  surrogates.  Is substitution enabled?
                    if (subMode) {
                        outputByte = subBytes;
                        outputSize = subBytes.length;
                        inputSize = 2;
                    } else {
                        badInputLength = 2;
                        throw new UnknownCharacterException();
                    }
                } else {
                    // We have a malformed surrogate pair
                    badInputLength = 1;
                    throw new MalformedInputException();
                }
            }
            // Is this an unaccompanied low surrogate?
            else if (inputChar >= '\uDC00' && inputChar <= '\uDFFF') {
                badInputLength = 1;
                throw new MalformedInputException();
            }
            // Not part of a surrogate, so try to convert
            else {
                // Is this character mappable?
                if (inputChar <= '\u007F') {
                    outputByte[0] = (byte)inputChar;
                } else {
                    // Is substitution enabled?
                    if (subMode) {
                        outputByte = subBytes;
                        outputSize = subBytes.length;
                    } else {
                        badInputLength = 1;
                        throw new UnknownCharacterException();
                    }
                }
            }

            // If we don't have room for the output, throw an exception
            if (byteOff + outputSize > outEnd)
                throw new ConversionBufferFullException();

            // Put the byte in the output buffer
            for (int i = 0; i < outputSize; i++) {
                output[byteOff++] = outputByte[i];
            }
            charOff += inputSize;
        }

        // Return the length written to the output buffer
        return byteOff-outOff;
    }

    // Determine if a character is mappable or not
    public boolean canConvert(char ch)
    {
        return (ch <= '\u007F');
    }

    // Reset the converter
    public void reset()
    {
        byteOff = charOff = 0;
        highHalfZoneCode = 0;
    }

    /**
     * returns the maximum number of bytes needed to convert a char
     */
    public int getMaxBytesPerChar()
    {
        return 1;
    }
}