/*
* Copyright 2008 CoreMedia AG
*
* 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 net.jangaroo.jooc;
import java.io.IOException;
import java.io.Writer;
/**
* <p>An SubstitutingWriter is a FilterWriter that replaces
* each character in the output stream
* with the String obtained by calling the abstract method substitute
* on the characters.</p>
* <p>Characters for which substitute returns null are output verbatim.</p>
* <p>The implementation is fairly efficient in the number of calls to
* the various out.write methods.</p>
*
* @author Axel Wienberg
*/
public abstract class SubstitutingWriter extends java.io.FilterWriter {
public SubstitutingWriter(Writer out) {
super(out);
}
/**
* What should be printed instead of character <code>c</code>?
* This method is always called synchronized on <code>out</code>.
* Changes to the substitution function should therefore also be synchronized on <code>out</code>.
*
* @param c the character
* @return the string to be printed, or null for "no change", i.e. just <code>c</code>
*/
protected abstract String substitute(char c);
protected void writeReplacement(String replacement) throws java.io.IOException {
out.write(replacement);
}
/**
* Write a single character, applying the substitution.
*
* @throws java.io.IOException If an I/O error occurs
*/
public void write(int c) throws IOException {
char ch = (char) c;
String replacement = substitute(ch);
if (replacement == null) {
out.write(c);
} else {
writeReplacement(replacement);
}
}
/**
* Write a portion of an array of characters, applying the substitution.
*
* @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
* @throws java.io.IOException If an I/O error occurs
*/
public void write(char cbuf[], int off, int len) throws IOException {
int nextToWrite = off;
int guard = off + len;
for (; off < guard; ++off) {
String replacement = substitute(cbuf[off]);
if (replacement != null) {
if (nextToWrite < off) {
out.write(cbuf, nextToWrite, off - nextToWrite);
}
writeReplacement(replacement);
nextToWrite = off + 1;
}
}
if (nextToWrite < off) {
out.write(cbuf, nextToWrite, off - nextToWrite);
}
}
/**
* Write a portion of a string, applying the substitution.
*
* @param str String to be written
* @param off Offset from which to start reading characters
* @param len Number of characters to be written
* @throws java.io.IOException If an I/O error occurs
*/
public void write(String str, int off, int len) throws IOException {
int nextToWrite = off;
int guard = off + len;
for (; off < guard; ++off) {
String replacement = substitute(str.charAt(off));
if (replacement != null) {
if (nextToWrite < off) {
out.write(str, nextToWrite, off - nextToWrite);
}
writeReplacement(replacement);
nextToWrite = off + 1;
}
}
if (nextToWrite < off) {
out.write(str, nextToWrite, off - nextToWrite);
}
}
}