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/*******************************************************************************
* Copyright (c) 2000, 2012 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.text.readers;
import java.io.IOException;
import java.io.Reader;
/**
* Reads the text contents from a reader and computes for each character
* a potential substitution. The substitution may eat more characters than
* only the one passed into the computation routine.
*
* Moved into this package from org.eclipse.jface.internal.text.revisions
.
*
* @since 3.14
*/
public abstract class SubstitutionReader extends SingleCharacterReader {
protected static final String LINE_DELIM= System.getProperty("line.separator", "\n"); //$NON-NLS-1$ //$NON-NLS-2$
private Reader fReader;
protected boolean fWasWhiteSpace;
private int fCharAfterWhiteSpace;
/**
* Tells whether white space characters are skipped.
*/
private boolean fSkipWhiteSpace= true;
private boolean fReadFromBuffer;
private StringBuilder fBuffer;
private int fIndex;
protected SubstitutionReader(Reader reader) {
fReader= reader;
fBuffer= new StringBuilder();
fIndex= 0;
fReadFromBuffer= false;
fCharAfterWhiteSpace= -1;
fWasWhiteSpace= true;
}
/**
* Computes the substitution for the given character and if necessary
* subsequent characters. Implementation should use nextChar
* to read subsequent characters.
*
* @param c the character to be substituted
* @return the substitution for c
* @throws IOException in case computing the substitution fails
*/
protected abstract String computeSubstitution(int c) throws IOException;
/**
* Returns the internal reader.
*
* @return the internal reader
*/
protected Reader getReader() {
return fReader;
}
/**
* Returns the next character.
* @return the next character
* @throws IOException in case reading the character fails
*/
protected int nextChar() throws IOException {
fReadFromBuffer= (fBuffer.length() > 0);
if (fReadFromBuffer) {
char ch= fBuffer.charAt(fIndex++);
if (fIndex >= fBuffer.length()) {
fBuffer.setLength(0);
fIndex= 0;
}
return ch;
}
int ch= fCharAfterWhiteSpace;
if (ch == -1) {
ch= fReader.read();
}
if (fSkipWhiteSpace && Character.isWhitespace((char)ch)) {
do {
ch= fReader.read();
} while (Character.isWhitespace((char)ch));
if (ch != -1) {
fCharAfterWhiteSpace= ch;
return ' ';
}
} else {
fCharAfterWhiteSpace= -1;
}
return ch;
}
/**
* @see Reader#read()
*/
@Override
public int read() throws IOException {
int c;
do {
c= nextChar();
while (!fReadFromBuffer && c != -1) {
String s= computeSubstitution(c);
if (s == null)
break;
if (!s.isEmpty())
fBuffer.insert(0, s);
c= nextChar();
}
} while (fSkipWhiteSpace && fWasWhiteSpace && (c == ' '));
fWasWhiteSpace= (c == ' ' || c == '\r' || c == '\n');
return c;
}
/**
* @see Reader#ready()
*/
@Override
public boolean ready() throws IOException {
return fReader.ready();
}
/**
* @see Reader#close()
*/
@Override
public void close() throws IOException {
fReader.close();
}
/**
* @see Reader#reset()
*/
@Override
public void reset() throws IOException {
fReader.reset();
fWasWhiteSpace= true;
fCharAfterWhiteSpace= -1;
fBuffer.setLength(0);
fIndex= 0;
}
protected final void setSkipWhitespace(boolean state) {
fSkipWhiteSpace= state;
}
protected final boolean isSkippingWhitespace() {
return fSkipWhiteSpace;
}
}