/*
 * 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.
 */

// Aug 21, 2000:
//   Fixed bug in isElement and made HTMLdtd public.
//   Contributed by Eric SCHAEFFER" <eschaeffer@posterconseil.com>

package org.apache.xml.serialize;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Hashtable;
import java.util.Locale;

import org.apache.xerces.dom.DOMMessageFormatter;

Utility class for accessing information specific to HTML documents. The HTML DTD is expressed as three utility function groups. Two methods allow for checking whether an element requires an open tag on printing (isEmptyTag) or on parsing (isOptionalClosing). 

Two other methods translate character references from name to value and
from value to name. A small entities resource is loaded into memory the
first time any of these methods is called for fast and efficient access.
Author:
Assaf Arkin
Deprecated:
This class was deprecated in Xerces 2.9.0. It is recommended 
that new applications use JAXP's Transformation API for XML (TrAX) for 
serializing HTML. See the Xerces documentation for more information.
Version:
$Revision: 699892 $ $Date: 2008-09-29 02:38:27 +0530 (Mon, 29 Sep 2008) $/**
 * Utility class for accessing information specific to HTML documents.
 * The HTML DTD is expressed as three utility function groups. Two methods
 * allow for checking whether an element requires an open tag on printing
 * ({@link #isEmptyTag}) or on parsing ({@link #isOptionalClosing}).
 * <P>
 * Two other methods translate character references from name to value and
 * from value to name. A small entities resource is loaded into memory the
 * first time any of these methods is called for fast and efficient access.
 *
 * @deprecated This class was deprecated in Xerces 2.9.0. It is recommended 
 * that new applications use JAXP's Transformation API for XML (TrAX) for 
 * serializing HTML. See the Xerces documentation for more information.
 * @version $Revision: 699892 $ $Date: 2008-09-29 02:38:27 +0530 (Mon, 29 Sep 2008) $
 * @author <a href="mailto:arkin@intalio.com">Assaf Arkin</a>
 */
public final class HTMLdtd
{

    
Public identifier for HTML 4.01 (Strict) document type.
/**
     * Public identifier for HTML 4.01 (Strict) document type.
     */
    public static final String HTMLPublicId = "-//W3C//DTD HTML 4.01//EN";

    
System identifier for HTML 4.01 (Strict) document type.
/**
     * System identifier for HTML 4.01 (Strict) document type.
     */
    public static final String HTMLSystemId =
        "http://www.w3.org/TR/html4/strict.dtd";

    
Public identifier for XHTML 1.0 (Strict) document type.
/**
     * Public identifier for XHTML 1.0 (Strict) document type.
     */
    public static final String XHTMLPublicId =
        "-//W3C//DTD XHTML 1.0 Strict//EN";

    
System identifier for XHTML 1.0 (Strict) document type.
/**
     * System identifier for XHTML 1.0 (Strict) document type.
     */
    public static final String XHTMLSystemId =
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd";

    
Table of reverse character reference mapping. Character codes are held
as single-character strings, mapped to their reference name.
/**
     * Table of reverse character reference mapping. Character codes are held
     * as single-character strings, mapped to their reference name.
     */
    private static Hashtable        _byChar;


    
Table of entity name to value mapping. Entities are held as strings,
character references as Character objects.
/**
     * Table of entity name to value mapping. Entities are held as strings,
     * character references as <TT>Character</TT> objects.
     */
    private static Hashtable        _byName;


    private static Hashtable        _boolAttrs;


    
Holds element definitions.
/**
     * Holds element definitions.
     */
    private static Hashtable        _elemDefs;


    
Locates the HTML entities file that is loaded upon initialization.
This file is a resource loaded with the default class loader.
/**
     * Locates the HTML entities file that is loaded upon initialization.
     * This file is a resource loaded with the default class loader.
     */
    private static final String     ENTITIES_RESOURCE = "HTMLEntities.res";


    
Only opening tag should be printed.
/**
     * Only opening tag should be printed.
     */
    private static final int ONLY_OPENING = 0x0001;

    
Element contains element content only.
/**
     * Element contains element content only.
     */
    private static final int ELEM_CONTENT = 0x0002;


    
Element preserve spaces.
/**
     * Element preserve spaces.
     */
    private static final int PRESERVE     = 0x0004;


    
Optional closing tag.
/**
     * Optional closing tag.
     */
    private static final int OPT_CLOSING  = 0x0008;


    
Element is empty (also means only opening tag)
/**
     * Element is empty (also means only opening tag)
     */
    private static final int EMPTY        = 0x0010 | ONLY_OPENING;


    
Allowed to appear in head.
/**
     * Allowed to appear in head.
     */
    private static final int ALLOWED_HEAD = 0x0020;


    
When opened, closes P.
/**
     * When opened, closes P.
     */
    private static final int CLOSE_P      = 0x0040;


    
When opened, closes DD or DT.
/**
     * When opened, closes DD or DT.
     */
    private static final int CLOSE_DD_DT  = 0x0080;


    
When opened, closes itself.
/**
     * When opened, closes itself.
     */
    private static final int CLOSE_SELF   = 0x0100;


    
When opened, closes another table section.
/**
     * When opened, closes another table section.
     */
    private static final int CLOSE_TABLE  = 0x0200;


    
When opened, closes TH or TD.
/**
     * When opened, closes TH or TD.
     */
    private static final int CLOSE_TH_TD  = 0x04000;


    
Returns true if element is declared to be empty. HTML elements are
defines as empty in the DTD, not by the document syntax.
Params:
tagName – The element tag name (upper case)
Returns:
True if element is empty/**
     * Returns true if element is declared to be empty. HTML elements are
     * defines as empty in the DTD, not by the document syntax.
     *
     * @param tagName The element tag name (upper case)
     * @return True if element is empty
     */
    public static boolean isEmptyTag( String tagName )
    {
        return isElement( tagName, EMPTY );
    }


    
Returns true if element is declared to have element content.
Whitespaces appearing inside element content will be ignored,
other text will simply report an error.
Params:
tagName – The element tag name (upper case)
Returns:
True if element content/**
     * Returns true if element is declared to have element content.
     * Whitespaces appearing inside element content will be ignored,
     * other text will simply report an error.
     *
     * @param tagName The element tag name (upper case)
     * @return True if element content
     */
    public static boolean isElementContent( String tagName )
    {
        return isElement( tagName, ELEM_CONTENT );
    }


    
Returns true if element's textual contents preserves spaces.
This only applies to PRE and TEXTAREA, all other HTML elements
do not preserve space.
Params:
tagName – The element tag name (upper case)
Returns:
True if element's text content preserves spaces/**
     * Returns true if element's textual contents preserves spaces.
     * This only applies to PRE and TEXTAREA, all other HTML elements
     * do not preserve space.
     *
     * @param tagName The element tag name (upper case)
     * @return True if element's text content preserves spaces
     */
    public static boolean isPreserveSpace( String tagName )
    {
        return isElement( tagName, PRESERVE );
    }


    
Returns true if element's closing tag is optional and need not
exist. An error will not be reported for such elements if they
are not closed. For example, LI is most often not closed.
Params:
tagName – The element tag name (upper case)
Returns:
True if closing tag implied/**
     * Returns true if element's closing tag is optional and need not
     * exist. An error will not be reported for such elements if they
     * are not closed. For example, <tt>LI</tt> is most often not closed.
     *
     * @param tagName The element tag name (upper case)
     * @return True if closing tag implied
     */
    public static boolean isOptionalClosing( String tagName )
    {
        return isElement( tagName, OPT_CLOSING );
    }


    
Returns true if element's closing tag is generally not printed.
For example, LI should not print the closing tag.
Params:
tagName – The element tag name (upper case)
Returns:
True if only opening tag should be printed/**
     * Returns true if element's closing tag is generally not printed.
     * For example, <tt>LI</tt> should not print the closing tag.
     *
     * @param tagName The element tag name (upper case)
     * @return True if only opening tag should be printed
     */
    public static boolean isOnlyOpening( String tagName )
    {
        return isElement( tagName, ONLY_OPENING );
    }


    
Returns true if the opening of one element (tagName) implies
the closing of another open element (openTag). For example,
every opening LI will close the previously open LI,
and every opening BODY will close the previously open HEAD.
Params:
tagName – The newly opened element
openTag – The already opened element
Returns:
True if closing tag closes opening tag/**
     * Returns true if the opening of one element (<tt>tagName</tt>) implies
     * the closing of another open element (<tt>openTag</tt>). For example,
     * every opening <tt>LI</tt> will close the previously open <tt>LI</tt>,
     * and every opening <tt>BODY</tt> will close the previously open <tt>HEAD</tt>.
     *
     * @param tagName The newly opened element
     * @param openTag The already opened element
     * @return True if closing tag closes opening tag
     */
    public static boolean isClosing( String tagName, String openTag )
    {
        // Several elements are defined as closing the HEAD
        if ( openTag.equalsIgnoreCase( "HEAD" ) )
            return ! isElement( tagName, ALLOWED_HEAD );
        // P closes iteself
        if ( openTag.equalsIgnoreCase( "P" ) )
            return isElement( tagName, CLOSE_P );
        // DT closes DD, DD closes DT
        if ( openTag.equalsIgnoreCase( "DT" ) || openTag.equalsIgnoreCase( "DD" ) )
            return isElement( tagName, CLOSE_DD_DT );
        // LI and OPTION close themselves
        if ( openTag.equalsIgnoreCase( "LI" ) || openTag.equalsIgnoreCase( "OPTION" ) )
            return isElement( tagName, CLOSE_SELF );
        // Each of these table sections closes all the others
        if ( openTag.equalsIgnoreCase( "THEAD" ) || openTag.equalsIgnoreCase( "TFOOT" ) ||
             openTag.equalsIgnoreCase( "TBODY" ) || openTag.equalsIgnoreCase( "TR" ) ||
             openTag.equalsIgnoreCase( "COLGROUP" ) )
            return isElement( tagName, CLOSE_TABLE );
        // TD closes TH and TH closes TD
        if ( openTag.equalsIgnoreCase( "TH" ) || openTag.equalsIgnoreCase( "TD" ) )
            return isElement( tagName, CLOSE_TH_TD );
        return false;
    }


    
Returns true if the specified attribute it a URI and should be
escaped appropriately. In HTML URIs are escaped differently
than normal attributes.
Params:
tagName – The element's tag name
attrName – The attribute's name/**
     * Returns true if the specified attribute it a URI and should be
     * escaped appropriately. In HTML URIs are escaped differently
     * than normal attributes.
     *
     * @param tagName The element's tag name
     * @param attrName The attribute's name
     */
    public static boolean isURI( String tagName, String attrName )
    {
        // Stupid checks.
        return ( attrName.equalsIgnoreCase( "href" ) || attrName.equalsIgnoreCase( "src" ) );
    }


    
Returns true if the specified attribute is a boolean and should be
printed without the value. This applies to attributes that are true
if they exist, such as selected (OPTION/INPUT).
Params:
tagName – The element's tag name
attrName – The attribute's name/**
     * Returns true if the specified attribute is a boolean and should be
     * printed without the value. This applies to attributes that are true
     * if they exist, such as selected (OPTION/INPUT).
     *
     * @param tagName The element's tag name
     * @param attrName The attribute's name
     */
    public static boolean isBoolean( String tagName, String attrName )
    {
        String[] attrNames;

        attrNames = (String[]) _boolAttrs.get( tagName.toUpperCase(Locale.ENGLISH) );
        if ( attrNames == null )
            return false;
        for ( int i = 0 ; i < attrNames.length ; ++i )
            if ( attrNames[ i ].equalsIgnoreCase( attrName ) )
                return true;
        return false;
    }


    
Returns the value of an HTML character reference by its name. If the
reference is not found or was not defined as a character reference,
returns EOF (-1).
Params:
name – Name of character reference
Returns:
Character code or EOF (-1)/**
     * Returns the value of an HTML character reference by its name. If the
     * reference is not found or was not defined as a character reference,
     * returns EOF (-1).
     *
     * @param name Name of character reference
     * @return Character code or EOF (-1)
     */
    public static int charFromName( String name )
    {
        Object    value;

        initialize();
        value = _byName.get( name );
        if ( value != null && value instanceof Integer ) {
            return ( (Integer) value ).intValue();
        }
        return -1;
    }


    
Returns the name of an HTML character reference based on its character
value. Only valid for entities defined from character references. If no
such character value was defined, return null.
Params:
value – Character value of entity
Returns:
Entity's name or null/**
     * Returns the name of an HTML character reference based on its character
     * value. Only valid for entities defined from character references. If no
     * such character value was defined, return null.
     *
     * @param value Character value of entity
     * @return Entity's name or null
     */
    public static String fromChar(int value )
    {
       if (value > 0xffff)
            return null;

        String name;

        initialize();
        name = (String) _byChar.get( new Integer( value ) );
        return name;
    }


    
Initialize upon first access. Will load all the HTML character references
into a list that is accessible by name or character value and is optimized
for character substitution. This method may be called any number of times
but will execute only once.
/**
     * Initialize upon first access. Will load all the HTML character references
     * into a list that is accessible by name or character value and is optimized
     * for character substitution. This method may be called any number of times
     * but will execute only once.
     */
    private static void initialize()
    {
        InputStream     is = null;
        BufferedReader  reader = null;
        int             index;
        String          name;
        String          value;
        int             code;
        String          line;

        // Make sure not to initialize twice.
        if ( _byName != null )
            return;
        try {
            _byName = new Hashtable();
            _byChar = new Hashtable();
            is = HTMLdtd.class.getResourceAsStream( ENTITIES_RESOURCE );
            if ( is == null ) {
            	throw new RuntimeException( 
				    DOMMessageFormatter.formatMessage(
				    DOMMessageFormatter.SERIALIZER_DOMAIN,
                    "ResourceNotFound", new Object[] {ENTITIES_RESOURCE}));
            }    
            reader = new BufferedReader( new InputStreamReader( is, "ASCII" ) );
            line = reader.readLine();
            while ( line != null ) {
                if ( line.length() == 0 || line.charAt( 0 ) == '#' ) {
                    line = reader.readLine();
                    continue;
                }
                index = line.indexOf( ' ' );
                if ( index > 1 ) {
                    name = line.substring( 0, index );
                    ++index;
                    if ( index < line.length() ) {
                        value = line.substring( index );
                        index = value.indexOf( ' ' );
                        if ( index > 0 )
                            value = value.substring( 0, index );
                        code = Integer.parseInt( value );
                                        defineEntity( name, (char) code );
                    }
                }
                line = reader.readLine();
            }
            is.close();
        }  catch ( Exception except ) {
			throw new RuntimeException( 
				DOMMessageFormatter.formatMessage(
				DOMMessageFormatter.SERIALIZER_DOMAIN,
                "ResourceNotLoaded", new Object[] {ENTITIES_RESOURCE, except.toString()}));        	
        } finally {
            if ( is != null ) {
                try {
                    is.close();
                } catch ( Exception except ) { }
            }
        }
    }


    
Defines a new character reference. The reference's name and value are
supplied. Nothing happens if the character reference is already defined.

Unlike internal entities, character references are a string to single
character mapping. They are used to map non-ASCII characters both on
parsing and printing, primarily for HTML documents. '<amp;' is an
example of a character reference.
Params:
name – The entity's name
value – The entity's value/**
     * Defines a new character reference. The reference's name and value are
     * supplied. Nothing happens if the character reference is already defined.
     * <P>
     * Unlike internal entities, character references are a string to single
     * character mapping. They are used to map non-ASCII characters both on
     * parsing and printing, primarily for HTML documents. '&lt;amp;' is an
     * example of a character reference.
     *
     * @param name The entity's name
     * @param value The entity's value
     */
    private static void defineEntity( String name, char value )
    {
        if ( _byName.get( name ) == null ) {
            _byName.put( name, new Integer( value ) );
            _byChar.put( new Integer( value ), name );
        }
    }


    private static void defineElement( String name, int flags )
    {
        _elemDefs.put( name, new Integer( flags ) );
    }


    private static void defineBoolean( String tagName, String attrName )
    {
        defineBoolean( tagName, new String[] { attrName } );
    }


    private static void defineBoolean( String tagName, String[] attrNames )
    {
        _boolAttrs.put( tagName, attrNames );
    }


    private static boolean isElement( String name, int flag )
    {
        Integer flags;

        flags = (Integer) _elemDefs.get( name.toUpperCase(Locale.ENGLISH) );
        if ( flags == null ) {
            return false;
        }
        return ( ( flags.intValue() & flag ) == flag );
    }


    static
    {
        _elemDefs = new Hashtable();
        defineElement( "ADDRESS", CLOSE_P );
        defineElement( "AREA", EMPTY );
        defineElement( "BASE",  EMPTY | ALLOWED_HEAD );
        defineElement( "BASEFONT", EMPTY );
        defineElement( "BLOCKQUOTE", CLOSE_P );
        defineElement( "BODY", OPT_CLOSING );
        defineElement( "BR", EMPTY );
        defineElement( "COL", EMPTY );
        defineElement( "COLGROUP", ELEM_CONTENT | OPT_CLOSING | CLOSE_TABLE );
        defineElement( "DD", OPT_CLOSING | ONLY_OPENING | CLOSE_DD_DT );
        defineElement( "DIV", CLOSE_P );
        defineElement( "DL", ELEM_CONTENT | CLOSE_P );
        defineElement( "DT", OPT_CLOSING | ONLY_OPENING | CLOSE_DD_DT );
        defineElement( "FIELDSET", CLOSE_P );
        defineElement( "FORM", CLOSE_P );
        defineElement( "FRAME", EMPTY | OPT_CLOSING );
        defineElement( "H1", CLOSE_P );
        defineElement( "H2", CLOSE_P );
        defineElement( "H3", CLOSE_P );
        defineElement( "H4", CLOSE_P );
        defineElement( "H5", CLOSE_P );
        defineElement( "H6", CLOSE_P );
        defineElement( "HEAD", ELEM_CONTENT | OPT_CLOSING );
        defineElement( "HR", EMPTY | CLOSE_P );
        defineElement( "HTML", ELEM_CONTENT | OPT_CLOSING );
        defineElement( "IMG", EMPTY );
        defineElement( "INPUT", EMPTY );
        defineElement( "ISINDEX", EMPTY | ALLOWED_HEAD );
        defineElement( "LI", OPT_CLOSING | ONLY_OPENING | CLOSE_SELF );
        defineElement( "LINK", EMPTY | ALLOWED_HEAD );
        defineElement( "MAP", ALLOWED_HEAD );
        defineElement( "META", EMPTY | ALLOWED_HEAD );
        defineElement( "OL", ELEM_CONTENT | CLOSE_P );
        defineElement( "OPTGROUP", ELEM_CONTENT );
        defineElement( "OPTION", OPT_CLOSING | ONLY_OPENING | CLOSE_SELF );
        defineElement( "P", OPT_CLOSING | CLOSE_P | CLOSE_SELF );
        defineElement( "PARAM", EMPTY );
        defineElement( "PRE", PRESERVE | CLOSE_P );
        defineElement( "SCRIPT", ALLOWED_HEAD | PRESERVE );
        defineElement( "NOSCRIPT", ALLOWED_HEAD | PRESERVE );
        defineElement( "SELECT", ELEM_CONTENT );
        defineElement( "STYLE", ALLOWED_HEAD | PRESERVE );
        defineElement( "TABLE", ELEM_CONTENT | CLOSE_P );
        defineElement( "TBODY", ELEM_CONTENT | OPT_CLOSING | CLOSE_TABLE );
        defineElement( "TD", OPT_CLOSING | CLOSE_TH_TD );
        defineElement( "TEXTAREA", PRESERVE );
        defineElement( "TFOOT", ELEM_CONTENT | OPT_CLOSING | CLOSE_TABLE );
        defineElement( "TH", OPT_CLOSING | CLOSE_TH_TD );
        defineElement( "THEAD", ELEM_CONTENT | OPT_CLOSING | CLOSE_TABLE );
        defineElement( "TITLE", ALLOWED_HEAD );
        defineElement( "TR", ELEM_CONTENT | OPT_CLOSING | CLOSE_TABLE );
        defineElement( "UL", ELEM_CONTENT | CLOSE_P );

        _boolAttrs = new Hashtable();
        defineBoolean( "AREA", "href" );
        defineBoolean( "BUTTON", "disabled" );
        defineBoolean( "DIR", "compact" );
        defineBoolean( "DL", "compact" );
        defineBoolean( "FRAME", "noresize" );
        defineBoolean( "HR", "noshade" );
        defineBoolean( "IMAGE", "ismap" );
        defineBoolean( "INPUT", new String[] { "defaultchecked", "checked", "readonly", "disabled" } );
        defineBoolean( "LINK", "link" );
        defineBoolean( "MENU", "compact" );
        defineBoolean( "OBJECT", "declare" );
        defineBoolean( "OL", "compact" );
        defineBoolean( "OPTGROUP", "disabled" );
        defineBoolean( "OPTION", new String[] { "default-selected", "selected", "disabled" } );
        defineBoolean( "SCRIPT", "defer" );
        defineBoolean( "SELECT", new String[] { "multiple", "disabled" } );
        defineBoolean( "STYLE", "disabled" );
        defineBoolean( "TD", "nowrap" );
        defineBoolean( "TH", "nowrap" );
        defineBoolean( "TEXTAREA", new String[] { "disabled", "readonly" } );
        defineBoolean( "UL", "compact" );

        initialize();
    }



}