001// Copyright 2004, 2005 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry.engine;
016
017import org.apache.tapestry.IMarkupWriter;
018import org.apache.tapestry.NestedMarkupWriter;
019
020/**
021 * A {@link IMarkupWriter}that does absolutely <em>nothing</em>; this is used during the rewind
022 * phase of the request cycle when output is discarded anyway.
023 * 
024 * @author Howard Lewis Ship, David Solis
025 * @since 0.2.9
026 */
027
028public class NullWriter implements NestedMarkupWriter
029{
030    private static IMarkupWriter shared;
031
032    public static IMarkupWriter getSharedInstance()
033    {
034        if (shared == null)
035            shared = new NullWriter();
036
037        return shared;
038    }
039
040    public String getBuffer()
041    {
042        return null;
043    }
044
045    public void printRaw(char[] buffer, int offset, int length)
046    {
047    }
048
049    public void printRaw(String value)
050    {
051    }
052
053    public void println()
054    {
055    }
056
057    public void print(char[] data, int offset, int length)
058    {
059    }
060
061    public void print(char value)
062    {
063    }
064
065    public void print(int value)
066    {
067    }
068
069    public void print(String value)
070    {
071    }
072
073    /**
074     * Returns <code>this</code>: since a NullWriter doesn't actually do anything, one is as good
075     * as another!.
076     */
077
078    public NestedMarkupWriter getNestedWriter()
079    {
080        return this;
081    }
082
083    public String getContentType()
084    {
085        return null;
086    }
087
088    public void flush()
089    {
090    }
091
092    public void end()
093    {
094    }
095
096    public void end(String name)
097    {
098    }
099
100    public void comment(String value)
101    {
102    }
103
104    public void closeTag()
105    {
106    }
107
108    public void close()
109    {
110    }
111
112    /**
113     * Always returns false.
114     */
115
116    public boolean checkError()
117    {
118        return false;
119    }
120
121    public void beginEmpty(String name)
122    {
123    }
124
125    public void begin(String name)
126    {
127    }
128
129    public void attribute(String name, int value)
130    {
131    }
132
133    public void attribute(String name, String value)
134    {
135    }
136
137    /**
138     * @see org.apache.tapestry.IMarkupWriter#attribute(java.lang.String, boolean)
139     * @since 3.0
140     */
141
142    public void attribute(String name, boolean value)
143    {
144    }
145
146    /**
147     * @see org.apache.tapestry.IMarkupWriter#attributeRaw(java.lang.String, java.lang.String)
148     * @since 3.0
149     */
150
151    public void attributeRaw(String name, String value)
152    {
153    }
154
155    public void print(char[] data, int offset, int length, boolean raw)
156    {
157    }
158
159    public void print(String value, boolean raw)
160    {
161    }
162}