groovy-core/src/main/groovy/xml/streamingmarkupsupport/StreamingMarkupWriter.java

/*
 * Copyright 2003-2007 the original author or authors.
 *
 * 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 groovy.xml.streamingmarkupsupport;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;

public class StreamingMarkupWriter extends Writer {
	protected final Writer writer;
    protected final String encoding;
    protected final CharsetEncoder encoder;
    protected boolean writingAttribute = false;
    protected boolean haveHighSurrogate = false;
    protected StringBuffer surrogatePair = new StringBuffer(2);
	private final Writer escapedWriter =  new Writer() {
											/* (non-Javadoc)
											 * @see java.io.Writer#close()
											 */
											public void close() throws IOException {
												StreamingMarkupWriter.this.close();
											}
											
											/* (non-Javadoc)
											 * @see java.io.Writer#flush()
											 */
											public void flush() throws IOException {
												StreamingMarkupWriter.this.flush();
											}
		
											/* (non-Javadoc)
											 * @see java.io.Writer#write(int)
											 */
											public void write(final int c) throws IOException {
												if (c == '<') {
													StreamingMarkupWriter.this.writer.write("&lt;");
												} else if (c == '>') {
													StreamingMarkupWriter.this.writer.write("&gt;");
                                                   } else if (c == '&') {
                                                       StreamingMarkupWriter.this.writer.write("&amp;");
                                                   } else {
													StreamingMarkupWriter.this.write(c);
												}
											}
											
											/* (non-Javadoc)
											 * @see java.io.Writer#write(char[], int, int)
											 */
											public void write(final char[] cbuf, int off, int len) throws IOException {
												while (len-- > 0){
													write(cbuf[off++]);
												}
											}
                                            
                                               public void setWritingAttribute(final boolean writingAttribute) {
                                                   StreamingMarkupWriter.this.writingAttribute = writingAttribute;
                                               }
											
											public Writer excaped() {
												return escapedWriter;
											}
											
											public Writer unescaped() {
												return StreamingMarkupWriter.this;
											}
										};

    public StreamingMarkupWriter(final Writer writer, final String encoding) {
        this.writer = writer;
        
        if (encoding != null) {
            this.encoding = encoding;
        } else if (writer instanceof OutputStreamWriter) {
            this.encoding = ((OutputStreamWriter)writer).getEncoding();
        } else {
            this.encoding = "US-ASCII";
        }
        
        this.encoder = Charset.forName(this.encoding).newEncoder();
    }
    
    public StreamingMarkupWriter(final Writer writer) {
        this(writer, null);
    }
    
    /* (non-Javadoc)
     * @see java.io.Writer#close()
     */
    public void close() throws IOException {
        this.writer.close();
    }
    
    /* (non-Javadoc)
     * @see java.io.Writer#flush()
     */
    public void flush() throws IOException {
        this.writer.flush();
    }
    
    /* (non-Javadoc)
     * @see java.io.Writer#write(int)
     */
    public void write(final int c) throws IOException {
        if (c >= 0XDC00 && c <= 0XDFFF) {
            // Low surrogate
            this.surrogatePair.append((char)c);
            
            if (this.encoder.canEncode(this.surrogatePair)) {
                this.writer.write(this.surrogatePair.toString());
            } else {
                this.writer.write("&#x");
                this.writer.write(Integer.toHexString(0X10000 + ((this.surrogatePair.charAt(0) & 0X3FF) << 10) + (c & 0X3FF)));
                this.writer.write(';');
            }
            
            this.haveHighSurrogate = false;
            this.surrogatePair.setLength(0);
        } else {
            if (this.haveHighSurrogate) {
                this.haveHighSurrogate = false;
                this.surrogatePair.setLength(0);
                throw new IOException("High Surrogate not followed by Low Surrogate");
            }
            
            if (c >= 0XD800 && c <= 0XDBFF) {
                // High surrogate
                this.surrogatePair.append((char)c);
                this.haveHighSurrogate = true;
            
            } else if (!this.encoder.canEncode((char)c)) {
                this.writer.write("&#x");
                this.writer.write(Integer.toHexString(c));
                this.writer.write(';');
            } else if (c == '\'' && this.writingAttribute) {
                this.writer.write("&apos;");
            } else {
                this.writer.write(c);
            }
        }
    }
    
    /* (non-Javadoc)
     * @see java.io.Writer#write(char[], int, int)
     */
    public void write(final char[] cbuf, int off, int len) throws IOException {
        while (len-- > 0){
            write(cbuf[off++]);
        }
    }
    
    public void setWritingAttribute(final boolean writingAttribute) {
        this.writingAttribute = writingAttribute;
    }
    
    public Writer escaped() {
        return this.escapedWriter;
    }
    
    public Writer unescaped() {
        return this;
    }
    
    public String getEncoding() {
        return this.encoding;
    }
}