XMLEntityReader.java

/*
 * Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * Copyright 2005 The Apache Software Foundation.
 *
 * Licensed 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 com.sun.xml.internal.stream;

import java.io.IOException;

import com.sun.org.apache.xerces.internal.util.XMLStringBuffer;
import com.sun.org.apache.xerces.internal.xni.*;

/**
 * This class allows various parser scanners to scan basic XML constructs
 * from entities. This class works directly with the entity manager to
 * provide this functionality.
 * <p>
 * There is only one entity scanner and entity manager per parser. The
 * entity manager <em>could</em> implement the methods to perform entity
 * scanning, but the entity scanner class allows a cleaner separation
 * between entity management API and entity scanning.
 *
 * @author Andy Clark, IBM
 * @author Neeraj Bajaj Sun Microsystems
 * @author K.Venugopal Sun Microsystems
 *
 * @see XMLEntityHandler
 * @see XMLEntityManager
 */
public abstract class XMLEntityReader implements XMLLocator {

    //
    // Public methods
    //


    /**
     * Sets the encoding of the scanner. This method is used by the
     * scanners if the XMLDecl or TextDecl line contains an encoding
     * pseudo-attribute.
     * <p>
     * <strong>Note:</strong> The underlying character reader on the
     * current entity will be changed to accomodate the new encoding.
     * However, the new encoding is ignored if the current reader was
     * not constructed from an input stream (e.g. an external entity
     * that is resolved directly to the appropriate java.io.Reader
     * object).
     *
     * @param encoding The IANA encoding name of the new encoding.
     *
     * @throws IOException  Thrown if the new encoding is not supported.
     *
     * @see com.sun.org.apache.xerces.internal.util.EncodingMap
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isValidIANAEncoding
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isValidJavaEncoding
     */
    public abstract void setEncoding(String encoding)
    throws IOException;

    public abstract String getEncoding() ;

    public abstract int getCharacterOffset() ;

    /** the version of the current entity being scanned or the version of the entity on which reader is operating */
    public abstract void setVersion(String version) ;

    /** get the version of the entity on which reader is operating */
    public abstract String getVersion() ;

    /** Returns true if the current entity being scanned is external. */
    public abstract boolean isExternal();

    /**
     * Returns the next character on the input.
     * <p>
     * <strong>Note:</strong> The character is <em>not</em> consumed.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract int peekChar() throws IOException;

    /**
     * Returns the next character on the input.
     * <p>
     * <strong>Note:</strong> The character is consumed.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract int scanChar() throws IOException;

    /**
     * Returns a string matching the NMTOKEN production appearing immediately
     * on the input as a symbol, or null if NMTOKEN Name string is present.
     * <p>
     * <strong>Note:</strong> The NMTOKEN characters are consumed.
     * <p>
     * <strong>Note:</strong> The string returned must be a symbol. The
     * SymbolTable can be used for this purpose.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     *
     * @see com.sun.org.apache.xerces.internal.util.SymbolTable
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isName
     */
    public abstract String scanNmtoken() throws IOException;

    /**
     * Returns a string matching the Name production appearing immediately
     * on the input as a symbol, or null if no Name string is present.
     * <p>
     * <strong>Note:</strong> The Name characters are consumed.
     * <p>
     * <strong>Note:</strong> The string returned must be a symbol. The
     * SymbolTable can be used for this purpose.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     *
     * @see com.sun.org.apache.xerces.internal.util.SymbolTable
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isName
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isNameStart
     */
    public abstract String scanName() throws IOException;

    /**
     * Scans a qualified name from the input, setting the fields of the
     * QName structure appropriately.
     * <p>
     * <strong>Note:</strong> The qualified name characters are consumed.
     * <p>
     * <strong>Note:</strong> The strings used to set the values of the
     * QName structure must be symbols. The SymbolTable can be used for
     * this purpose.
     *
     * @param qname The qualified name structure to fill.
     *
     * @return Returns true if a qualified name appeared immediately on
     *         the input and was scanned, false otherwise.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     *
     * @see com.sun.org.apache.xerces.internal.util.SymbolTable
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isName
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isNameStart
     */
    public abstract boolean scanQName(QName qname) throws IOException;

    /**
     * CHANGED:
     * Scans a range of parsed character data, This function appends the character data to
     * the supplied buffer.
     * <p>
     * <strong>Note:</strong> The characters are consumed.
     * <p>
     * <strong>Note:</strong> This method does not guarantee to return
     * the longest run of parsed character data. This method may return
     * before markup due to reaching the end of the input buffer or any
     * other reason.
     * <p>
     *
     * @param content The content structure to fill.
     *
     * @return Returns the next character on the input, if known. This
     *         value may be -1 but this does <em>note</em> designate
     *         end of file.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract int scanContent(XMLString content) throws IOException;

    /**
     * Scans a range of attribute value data, setting the fields of the
     * XMLString structure, appropriately.
     * <p>
     * <strong>Note:</strong> The characters are consumed.
     * <p>
     * <strong>Note:</strong> This method does not guarantee to return
     * the longest run of attribute value data. This method may return
     * before the quote character due to reaching the end of the input
     * buffer or any other reason.
     * <p>
     * <strong>Note:</strong> The fields contained in the XMLString
     * structure are not guaranteed to remain valid upon subsequent calls
     * to the entity scanner. Therefore, the caller is responsible for
     * immediately using the returned character data or making a copy of
     * the character data.
     *
     * @param quote   The quote character that signifies the end of the
     *                attribute value data.
     * @param content The content structure to fill.
     *
     * @return Returns the next character on the input, if known. This
     *         value may be -1 but this does <em>note</em> designate
     *         end of file.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract int scanLiteral(int quote, XMLString content)
    throws IOException;

    /**
     * Scans a range of character data up to the specicied delimiter,
     * setting the fields of the XMLString structure, appropriately.
     * <p>
     * <strong>Note:</strong> The characters are consumed.
     * <p>
     * <strong>Note:</strong> This assumes that the internal buffer is
     * at least the same size, or bigger, than the length of the delimiter
     * and that the delimiter contains at least one character.
     * <p>
     * <strong>Note:</strong> This method does not guarantee to return
     * the longest run of character data. This method may return before
     * the delimiter due to reaching the end of the input buffer or any
     * other reason.
     * <p>
     * <strong>Note:</strong> The fields contained in the XMLString
     * structure are not guaranteed to remain valid upon subsequent calls
     * to the entity scanner. Therefore, the caller is responsible for
     * immediately using the returned character data or making a copy of
     * the character data.
     *
     * @param delimiter The string that signifies the end of the character
     *                  data to be scanned.
     * @param data      The data structure to fill.
     *
     * @return Returns true if there is more data to scan, false otherwise.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract boolean scanData(String delimiter, XMLStringBuffer data)
    throws IOException;

    /**
     * Skips a character appearing immediately on the input.
     * <p>
     * <strong>Note:</strong> The character is consumed only if it matches
     * the specified character.
     *
     * @param c The character to skip.
     *
     * @return Returns true if the character was skipped.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract boolean skipChar(int c) throws IOException;

    /**
     * Skips space characters appearing immediately on the input.
     * <p>
     * <strong>Note:</strong> The characters are consumed only if they are
     * space characters.
     *
     * @return Returns true if at least one space character was skipped.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     *
     * @see com.sun.org.apache.xerces.internal.util.XMLChar#isSpace
     */
    public abstract boolean skipSpaces() throws IOException;

    /**
     * Skips the specified string appearing immediately on the input.
     * <p>
     * <strong>Note:</strong> The characters are consumed only if they are
     * space characters.
     *
     * @param s The string to skip.
     *
     * @return Returns true if the string was skipped.
     *
     * @throws IOException  Thrown if i/o error occurs.
     * @throws EOFException Thrown on end of file.
     */
    public abstract boolean skipString(String s) throws IOException;

    public abstract void registerListener(XMLBufferListener listener);

} // class XMLEntityScanner