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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * particular file as subject to the "Classpath" exception as provided
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 * 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).
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 *
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package javax.swing.text.html.parser;

import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.HTML;
import javax.swing.text.ChangedCharSetException;

import java.util.*;
import java.io.*;
import java.net.*;


A Parser for HTML Documents (actually, you can specify a DTD, but
you should really only use this class with the html dtd in swing).
Reads an InputStream of HTML and
invokes the appropriate methods in the ParserCallback class. This
is the default parser used by HTMLEditorKit to parse HTML url's.

This will message the callback for all valid tags, as well as
tags that are implied but not explicitly specified. For example, the
html string (<p>blah) only has a p tag defined. The callback
will see the following methods:

  1. handleStartTag(html, ...)
    2. 
    
  2. handleStartTag(head, ...)
    3. 
    
  3. handleEndTag(head)
    4. 
    
  4. handleStartTag(body, ...)
    5. 
    
  5. handleStartTag(p, ...)
    6. 
    
  6. handleText(...)
    7. 
    
  7. handleEndTag(p)
    8. 
    
  8. handleEndTag(body)
    9. 
    
  9. handleEndTag(html)
    10. 


The items in italic are implied, that is, although they were not
explicitly specified, to be correct html they should have been present
(head isn't necessary, but it is still generated). For tags that
are implied, the AttributeSet argument will have a value of
Boolean.TRUE for the key
HTMLEditorKit.ParserCallback.IMPLIED.

HTML.Attributes defines a type safe enumeration of html attributes.
If an attribute key of a tag is defined in HTML.Attribute, the
HTML.Attribute will be used as the key, otherwise a String will be used.
For example <p foo=bar class=neat> has two attributes. foo is
not defined in HTML.Attribute, where as class is, therefore the
AttributeSet will have two values in it, HTML.Attribute.CLASS with
a String value of 'neat' and the String key 'foo' with a String value of
'bar'.

The position argument will indicate the start of the tag, comment
or text. Similar to arrays, the first character in the stream has a
position of 0. For tags that are
implied the position will indicate
the location of the next encountered tag. In the first example,
the implied start body and html tags will have the same position as the
p tag, and the implied end p, html and body tags will all have the same
position.

As html skips whitespace the position for text will be the position
of the first valid character, eg in the string '\n\n\nblah'
the text 'blah' will have a position of 3, the newlines are skipped.


For attributes that do not have a value, eg in the html
string <foo blah> the attribute blah
does not have a value, there are two possible values that will be
placed in the AttributeSet's value:

    

  • If the DTD does not contain an definition for the element, or the
    definition does not have an explicit value then the value in the
    AttributeSet will be HTML.NULL_ATTRIBUTE_VALUE.

  • If the DTD contains an explicit value, as in:
    <!ATTLIST OPTION selected (selected) #IMPLIED>
    this value from the dtd (in this case selected) will be used.




Once the stream has been parsed, the callback is notified of the most
likely end of line string. The end of line string will be one of
\n, \r or \r\n, which ever is encountered the most in parsing the
stream.

Author:     Sunita Mani
/**
 * A Parser for HTML Documents (actually, you can specify a DTD, but
 * you should really only use this class with the html dtd in swing).
 * Reads an InputStream of HTML and
 * invokes the appropriate methods in the ParserCallback class. This
 * is the default parser used by HTMLEditorKit to parse HTML url's.
 * <p>This will message the callback for all valid tags, as well as
 * tags that are implied but not explicitly specified. For example, the
 * html string (&lt;p&gt;blah) only has a p tag defined. The callback
 * will see the following methods:
 * <ol><li><i>handleStartTag(html, ...)</i></li>
 *     <li><i>handleStartTag(head, ...)</i></li>
 *     <li><i>handleEndTag(head)</i></li>
 *     <li><i>handleStartTag(body, ...)</i></li>
 *     <li><i>handleStartTag(p, ...)</i></li>
 *     <li><i>handleText(...)</i></li>
 *     <li><i>handleEndTag(p)</i></li>
 *     <li><i>handleEndTag(body)</i></li>
 *     <li><i>handleEndTag(html)</i></li>
 * </ol>
 * The items in <i>italic</i> are implied, that is, although they were not
 * explicitly specified, to be correct html they should have been present
 * (head isn't necessary, but it is still generated). For tags that
 * are implied, the AttributeSet argument will have a value of
 * <code>Boolean.TRUE</code> for the key
 * <code>HTMLEditorKit.ParserCallback.IMPLIED</code>.
 * <p>HTML.Attributes defines a type safe enumeration of html attributes.
 * If an attribute key of a tag is defined in HTML.Attribute, the
 * HTML.Attribute will be used as the key, otherwise a String will be used.
 * For example &lt;p foo=bar class=neat&gt; has two attributes. foo is
 * not defined in HTML.Attribute, where as class is, therefore the
 * AttributeSet will have two values in it, HTML.Attribute.CLASS with
 * a String value of 'neat' and the String key 'foo' with a String value of
 * 'bar'.
 * <p>The position argument will indicate the start of the tag, comment
 * or text. Similar to arrays, the first character in the stream has a
 * position of 0. For tags that are
 * implied the position will indicate
 * the location of the next encountered tag. In the first example,
 * the implied start body and html tags will have the same position as the
 * p tag, and the implied end p, html and body tags will all have the same
 * position.
 * <p>As html skips whitespace the position for text will be the position
 * of the first valid character, eg in the string '\n\n\nblah'
 * the text 'blah' will have a position of 3, the newlines are skipped.
 * <p>
 * For attributes that do not have a value, eg in the html
 * string <code>&lt;foo blah&gt;</code> the attribute <code>blah</code>
 * does not have a value, there are two possible values that will be
 * placed in the AttributeSet's value:
 * <ul>
 * <li>If the DTD does not contain an definition for the element, or the
 *     definition does not have an explicit value then the value in the
 *     AttributeSet will be <code>HTML.NULL_ATTRIBUTE_VALUE</code>.
 * <li>If the DTD contains an explicit value, as in:
 *     <code>&lt;!ATTLIST OPTION selected (selected) #IMPLIED&gt;</code>
 *     this value from the dtd (in this case selected) will be used.
 * </ul>
 * <p>
 * Once the stream has been parsed, the callback is notified of the most
 * likely end of line string. The end of line string will be one of
 * \n, \r or \r\n, which ever is encountered the most in parsing the
 * stream.
 *
 * @author      Sunita Mani
 */
public class DocumentParser extends javax.swing.text.html.parser.Parser {

    private int inbody;
    private int intitle;
    private int inhead;
    private int instyle;
    private int inscript;
    private boolean seentitle;
    private HTMLEditorKit.ParserCallback callback = null;
    private boolean ignoreCharSet = false;
    private static final boolean debugFlag = false;

    
Creates document parser with the specified dtd. 
Params:
  • dtd – the dtd.
/**
     * Creates document parser with the specified {@code dtd}.
     *
     * @param dtd the dtd.
     */
    public DocumentParser(DTD dtd) {
        super(dtd);
    }

    
Parse an HTML stream, given a DTD.

Params:
  • in – the reader to read the source from
  • callback – the callback
  • ignoreCharSet – if true the charset is ignored
Throws:
/**
     * Parse an HTML stream, given a DTD.
     *
     * @param in the reader to read the source from
     * @param callback the callback
     * @param ignoreCharSet if {@code true} the charset is ignored
     * @throws IOException if an I/O error occurs
     */
    public void parse(Reader in, HTMLEditorKit.ParserCallback callback, boolean ignoreCharSet) throws IOException {
        this.ignoreCharSet = ignoreCharSet;
        this.callback = callback;
        parse(in);
        // end of line
        callback.handleEndOfLineString(getEndOfLineString());
    }

    
Handle Start Tag.

/**
     * Handle Start Tag.
     */
    protected void handleStartTag(TagElement tag) {

        Element elem = tag.getElement();
        if (elem == dtd.body) {
            inbody++;
        } else if (elem == dtd.html) {
        } else if (elem == dtd.head) {
            inhead++;
        } else if (elem == dtd.title) {
            intitle++;
        } else if (elem == dtd.style) {
            instyle++;
        } else if (elem == dtd.script) {
            inscript++;
        }
        if (debugFlag) {
            if (tag.fictional()) {
                debug("Start Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());
            } else {
                debug("Start Tag: " + tag.getHTMLTag() + " attributes: " +
                      getAttributes() + " pos: " + getCurrentPos());
            }
        }
        if (tag.fictional()) {
            SimpleAttributeSet attrs = new SimpleAttributeSet();
            attrs.addAttribute(HTMLEditorKit.ParserCallback.IMPLIED,
                               Boolean.TRUE);
            callback.handleStartTag(tag.getHTMLTag(), attrs,
                                    getBlockStartPosition());
        } else {
            callback.handleStartTag(tag.getHTMLTag(), getAttributes(),
                                    getBlockStartPosition());
            flushAttributes();
        }
    }


    protected void handleComment(char[] text) {
        if (debugFlag) {
            debug("comment: ->" + new String(text) + "<-"
                  + " pos: " + getCurrentPos());
        }
        callback.handleComment(text, getBlockStartPosition());
    }

    
Handle Empty Tag.

/**
     * Handle Empty Tag.
     */
    protected void handleEmptyTag(TagElement tag) throws ChangedCharSetException {

        Element elem = tag.getElement();
        if (elem == dtd.meta && !ignoreCharSet) {
            SimpleAttributeSet atts = getAttributes();
            if (atts != null) {
                String content = (String)atts.getAttribute(HTML.Attribute.CONTENT);
                if (content != null) {
                    if ("content-type".equalsIgnoreCase((String)atts.getAttribute(HTML.Attribute.HTTPEQUIV))) {
                        if (!content.equalsIgnoreCase("text/html") &&
                                !content.equalsIgnoreCase("text/plain")) {
                            throw new ChangedCharSetException(content, false);
                        }
                    } else if ("charset" .equalsIgnoreCase((String)atts.getAttribute(HTML.Attribute.HTTPEQUIV))) {
                        throw new ChangedCharSetException(content, true);
                    }
                }
            }
        }
        if (inbody != 0 || elem == dtd.meta || elem == dtd.base || elem == dtd.isindex || elem == dtd.style || elem == dtd.link) {
            if (debugFlag) {
                if (tag.fictional()) {
                    debug("Empty Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());
                } else {
                    debug("Empty Tag: " + tag.getHTMLTag() + " attributes: "
                          + getAttributes() + " pos: " + getCurrentPos());
                }
            }
            if (tag.fictional()) {
                SimpleAttributeSet attrs = new SimpleAttributeSet();
                attrs.addAttribute(HTMLEditorKit.ParserCallback.IMPLIED,
                                   Boolean.TRUE);
                callback.handleSimpleTag(tag.getHTMLTag(), attrs,
                                         getBlockStartPosition());
            } else {
                callback.handleSimpleTag(tag.getHTMLTag(), getAttributes(),
                                         getBlockStartPosition());
                flushAttributes();
            }
        }
    }

    
Handle End Tag.

/**
     * Handle End Tag.
     */
    protected void handleEndTag(TagElement tag) {
        Element elem = tag.getElement();
        if (elem == dtd.body) {
            inbody--;
        } else if (elem == dtd.title) {
            intitle--;
            seentitle = true;
        } else if (elem == dtd.head) {
            inhead--;
        } else if (elem == dtd.style) {
            instyle--;
        } else if (elem == dtd.script) {
            inscript--;
        }
        if (debugFlag) {
            debug("End Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());
        }
        callback.handleEndTag(tag.getHTMLTag(), getBlockStartPosition());

    }

    
Handle Text.

/**
     * Handle Text.
     */
    protected void handleText(char[] data) {
        if (data != null) {
            if (inscript != 0) {
                callback.handleComment(data, getBlockStartPosition());
                return;
            }
            if (inbody != 0 || ((instyle != 0) ||
                                ((intitle != 0) && !seentitle))) {
                if (debugFlag) {
                    debug("text:  ->" + new String(data) + "<-" + " pos: " + getCurrentPos());
                }
                callback.handleText(data, getBlockStartPosition());
            }
        }
    }

    /*
     * Error handling.
     */
    protected void handleError(int ln, String errorMsg) {
        if (debugFlag) {
            debug("Error: ->" + errorMsg + "<-" + " pos: " + getCurrentPos());
        }
        /* PENDING: need to improve the error string. */
        callback.handleError(errorMsg, getCurrentPos());
    }


    /*
     * debug messages
     */
    private void debug(String msg) {
        System.out.println(msg);
    }
}