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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.xmlparser;

import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;

import org.apache.jasper.compiler.Localizer;

/**
 * A simple ASCII byte reader. This is an optimized reader for reading
 * byte streams that only contain 7-bit ASCII characters.
 *
 * @author Andy Clark, IBM
 */
public class ASCIIReader extends Reader {

    //
    // Data
    //

    /** Input stream. */
    private final InputStream fInputStream;

    /** Byte buffer. */
    private final byte[] fBuffer;

    //
    // Constructors
    //

    /**
     * Constructs an ASCII reader from the specified input stream
     * and buffer size.
     *
     * @param inputStream The input stream.
     * @param size        The initial buffer size.
     */
    public ASCIIReader(InputStream inputStream, int size) {
        fInputStream = inputStream;
        fBuffer = new byte[size];
    }

    //
    // Reader methods
    //

    /**
     * Read a single character.  This method will block until a character is
     * available, an I/O error occurs, or the end of the stream is reached.
     *
     * 

Subclasses that intend to support efficient single-character input * should override this method. * * @return The character read, as an integer in the range 0 to 127 * (0x00-0x7f), or -1 if the end of the stream has * been reached * * @exception IOException If an I/O error occurs */ @Override public int read() throws IOException { int b0 = fInputStream.read(); if (b0 > 0x80) { throw new IOException(Localizer.getMessage("jsp.error.xml.invalidASCII", Integer.toString(b0))); } return b0; } // read():int /** * Read characters into a portion of an array. This method will block * until some input is available, an I/O error occurs, or the end of the * stream is reached. * * @param ch Destination buffer * @param offset Offset at which to start storing characters * @param length Maximum number of characters to read * * @return The number of characters read, or -1 if the end of the * stream has been reached * * @exception IOException If an I/O error occurs */ @Override public int read(char ch[], int offset, int length) throws IOException { if (length > fBuffer.length) { length = fBuffer.length; } int count = fInputStream.read(fBuffer, 0, length); for (int i = 0; i < count; i++) { int b0 = (0xff & fBuffer[i]); // Convert to unsigned if (b0 > 0x80) { throw new IOException(Localizer.getMessage("jsp.error.xml.invalidASCII", Integer.toString(b0))); } ch[offset + i] = (char)b0; } return count; } // read(char[],int,int) /** * Skip characters. This method will block until some characters are * available, an I/O error occurs, or the end of the stream is reached. * * @param n The number of characters to skip * * @return The number of characters actually skipped * * @exception IOException If an I/O error occurs */ @Override public long skip(long n) throws IOException { return fInputStream.skip(n); } // skip(long):long /** * Tell whether this stream is ready to be read. * * @return True if the next read() is guaranteed not to block for input, * false otherwise. Note that returning false does not guarantee that the * next read will block. * * @exception IOException If an I/O error occurs */ @Override public boolean ready() throws IOException { return false; } // ready() /** * Tell whether this stream supports the mark() operation. */ @Override public boolean markSupported() { return fInputStream.markSupported(); } // markSupported() /** * Mark the present position in the stream. Subsequent calls to reset() * will attempt to reposition the stream to this point. Not all * character-input streams support the mark() operation. * * @param readAheadLimit Limit on the number of characters that may be * read while still preserving the mark. After * reading this many characters, attempting to * reset the stream may fail. * * @exception IOException If the stream does not support mark(), * or if some other I/O error occurs */ @Override public void mark(int readAheadLimit) throws IOException { fInputStream.mark(readAheadLimit); } // mark(int) /** * Reset the stream. If the stream has been marked, then attempt to * reposition it at the mark. If the stream has not been marked, then * attempt to reset it in some way appropriate to the particular stream, * for example by repositioning it to its starting point. Not all * character-input streams support the reset() operation, and some support * reset() without supporting mark(). * * @exception IOException If the stream has not been marked, * or if the mark has been invalidated, * or if the stream does not support reset(), * or if some other I/O error occurs */ @Override public void reset() throws IOException { fInputStream.reset(); } // reset() /** * Close the stream. Once a stream has been closed, further read(), * ready(), mark(), or reset() invocations will throw an IOException. * Closing a previously-closed stream, however, has no effect. * * @exception IOException If an I/O error occurs */ @Override public void close() throws IOException { fInputStream.close(); } // close() } // class ASCIIReader





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