/*
* 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.felix.webconsole.internal.filter;
import java.io.FilterWriter;
import java.io.IOException;
import java.io.Writer;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import org.apache.felix.webconsole.DefaultVariableResolver;
import org.apache.felix.webconsole.VariableResolver;
/**
* The <code>ResourceFilteringWriter</code> is a writer, which translates
* strings of the form <code>${some key text}</code> to a translation
* of the respective <i>some key text</i> or to the <i>some key text</i>
* itself if no translation is available from a resource bundle.
*/
class ResourceFilteringWriter extends FilterWriter
{
/**
* normal processing state, $ signs are recognized here
* proceeds to {@link #STATE_DOLLAR} if a $ sign is encountered
* proceeds to {@link #STATE_ESCAPE} if a \ sign is encountered
* otherwise just writes the character
*/
private static final int STATE_NULL = 0;
/**
* State after a $ sign has been recognized
* proceeds to {@value #STATE_BUFFERING} if a { sign is encountered
* otherwise proceeds to {@link #STATE_NULL} and writes the $ sign and
* the current character
*/
private static final int STATE_DOLLAR = 1;
/**
* buffers characters until a } is encountered
* proceeds to {@link #STATE_NULL} if a } sign is encountered and
* translates and writes buffered text before returning
* otherwise collects characters to gather the translation key
*/
private static final int STATE_BUFFERING = 2;
/**
* escaping the next character, if the character is a $ sign, the
* $ sign is writeted. otherwise the \ and the next character is
* written
* proceeds to {@link #STATE_NULL}
*/
private static final int STATE_ESCAPE = 3;
/**
* The ResourceBundle used for translation
*/
private final ResourceBundle locale;
private final VariableResolver variables;
/**
* The buffer to gather the text to be translated
*/
private final StringBuffer lineBuffer = new StringBuffer();
/**
* The current state, starts with {@link #STATE_NULL}
*/
private int state = STATE_NULL;
ResourceFilteringWriter( final Writer out, final ResourceBundle locale, final VariableResolver variables )
{
super( out );
this.locale = locale;
this.variables = ( variables != null ) ? variables : new DefaultVariableResolver();
}
/**
* Write a single character following the state machine:
* <table>
* <tr><th>State</th><th>Character</th><th>Task</th><th>Next State</th></tr>
* <tr><td>NULL</td><td>$</td><td> </td><td>DOLLAR</td></tr>
* <tr><td>NULL</td><td>\</td><td> </td><td>ESCAPE</td></tr>
* <tr><td>NULL</td><td>any</td><td>write c</td><td>NULL</td></tr>
* <tr><td>DOLLAR</td><td>{</td><td> </td><td>BUFFERING</td></tr>
* <tr><td>DOLLAR</td><td>any</td><td>write $ and c</td><td>NULL</td></tr>
* <tr><td>BUFFERING</td><td>}</td><td>translate and write translation</td><td>NULL</td></tr>
* <tr><td>BUFFERING</td><td>any</td><td>buffer c</td><td>BUFFERING</td></tr>
* <tr><td>ESACPE</td><td>$</td><td>write $</td><td>NULL</td></tr>
* <tr><td>ESCAPE</td><td>any</td><td>write \ and c</td><td>NULL</td></tr>
* </table>
*
* @exception IOException If an I/O error occurs
*/
public void write( int c ) throws IOException
{
switch ( state )
{
case STATE_NULL:
if ( c == '$' )
{
state = STATE_DOLLAR;
}
else if ( c == '\\' )
{
state = STATE_ESCAPE;
}
else
{
out.write( c );
}
break;
case STATE_DOLLAR:
if ( c == '{' )
{
state = STATE_BUFFERING;
}
else
{
state = STATE_NULL;
out.write( '$' );
out.write( c );
}
break;
case STATE_BUFFERING:
if ( c == '}' )
{
state = STATE_NULL;
super.write( translate() );
}
else
{
lineBuffer.append( ( char ) c );
}
break;
case STATE_ESCAPE:
state = STATE_NULL;
if ( c != '$' )
{
out.write( '\\' );
}
out.write( c );
break;
}
}
/**
* Writes each character calling {@link #write(int)}
*
* @param cbuf Buffer of characters to be written
* @param off Offset from which to start reading characters
* @param len Number of characters to be written
* @exception IOException If an I/O error occurs
*/
public void write( char cbuf[], int off, int len ) throws IOException
{
final int limit = off + len;
for ( int i = off; i < limit; i++ )
{
write( cbuf[i] );
}
}
/**
* Writes each character calling {@link #write(int)}
*
* @param str String to be written
* @param off Offset from which to start reading characters
* @param len Number of characters to be written
* @exception IOException If an I/O error occurs
*/
public void write( String str, int off, int len ) throws IOException
{
final int limit = off + len;
for ( int i = off; i < limit; i++ )
{
write( str.charAt( i ) );
}
}
/**
* Translates the current buffer contents and returns the translation.
* First the name is looked up in the variables, if not found the
* resource bundle is queried. If still not found, the buffer contents
* is returned unmodified.
*/
private String translate()
{
final String key = lineBuffer.toString();
lineBuffer.delete( 0, lineBuffer.length() );
String value = variables.resolve( key );
if ( value == null )
{
try
{
value = locale.getString( key );
}
catch ( MissingResourceException mre )
{
// ignore and write the key as the value
value = key;
}
}
return value;
}
}