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package org.eclipse.cdt.internal.ui.text;
/*
* (c) Copyright IBM Corp. 2000, 2001.
* All Rights Reserved.
*/
import java.io.IOException;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
/**
* Reads from a document either forwards or backwards. May be configured to
* skip comments and strings.
*/
public class CCodeReader extends SingleCharReader {
/** The EOF character */
public static final int EOF= -1;
private boolean fSkipComments= false;
private boolean fSkipStrings= false;
private boolean fForward= false;
private IDocument fDocument;
private int fOffset;
private int fEnd= -1;
private int fCachedLineNumber= -1;
private int fCachedLineOffset= -1;
public CCodeReader() {
}
/**
* Returns the offset of the last read character. Should only be called after read has been called.
*/
public int getOffset() {
return fForward ? fOffset -1 : fOffset;
}
public void configureForwardReader(IDocument document, int offset, int length, boolean skipComments, boolean skipStrings) throws IOException {
fDocument= document;
fOffset= offset;
fSkipComments= skipComments;
fSkipStrings= skipStrings;
fForward= true;
fEnd= Math.min(fDocument.getLength(), fOffset + length);
}
public void configureBackwardReader(IDocument document, int offset, boolean skipComments, boolean skipStrings) throws IOException {
fDocument= document;
fOffset= offset;
fSkipComments= skipComments;
fSkipStrings= skipStrings;
fForward= false;
try {
fCachedLineNumber= fDocument.getLineOfOffset(fOffset);
} catch (BadLocationException x) {
throw new IOException(x.getMessage());
}
}
/*
* @see Reader#close()
*/
public void close() throws IOException {
fDocument= null;
}
/*
* @see SingleCharReader#read()
*/
public int read() throws IOException {
try {
return fForward ? readForwards() : readBackwards();
} catch (BadLocationException x) {
throw new IOException(x.getMessage());
}
}
private void gotoCommentEnd() throws BadLocationException {
while (fOffset < fEnd) {
char current= fDocument.getChar(fOffset++);
if (current == '*') {
if (fOffset < fEnd && fDocument.getChar(fOffset) == '/') {
++ fOffset;
return;
}
}
}
}
private void gotoStringEnd(char delimiter) throws BadLocationException {
while (fOffset < fEnd) {
char current= fDocument.getChar(fOffset++);
if (current == '\\') {
// ignore escaped characters
++ fOffset;
} else if (current == delimiter) {
return;
}
}
}
private void gotoLineEnd() throws BadLocationException {
int line= fDocument.getLineOfOffset(fOffset);
fOffset= fDocument.getLineOffset(line + 1);
}
private int readForwards() throws BadLocationException {
while (fOffset < fEnd) {
char current= fDocument.getChar(fOffset++);
switch (current) {
case '/':
if (fSkipComments && fOffset < fEnd) {
char next= fDocument.getChar(fOffset);
if (next == '*') {
// a comment starts, advance to the comment end
++ fOffset;
gotoCommentEnd();
continue;
} else if (next == '/') {
// '//'-comment starts, advance to the line end
gotoLineEnd();
continue;
}
}
return current;
case '"':
case '\'':
if (fSkipStrings) {
gotoStringEnd(current);
continue;
}
return current;
}
return current;
}
return EOF;
}
private void handleSingleLineComment() throws BadLocationException {
int line= fDocument.getLineOfOffset(fOffset);
if (line < fCachedLineNumber) {
fCachedLineNumber= line;
fCachedLineOffset= fDocument.getLineOffset(line);
int offset= fOffset;
while (fCachedLineOffset < offset) {
char current= fDocument.getChar(offset--);
if (current == '/' && fCachedLineOffset <= offset && fDocument.getChar(offset) == '/') {
fOffset= offset;
return;
}
}
}
}
private void gotoCommentStart() throws BadLocationException {
while (0 < fOffset) {
char current= fDocument.getChar(fOffset--);
if (current == '*' && 0 <= fOffset && fDocument.getChar(fOffset) == '/')
return;
}
}
private void gotoStringStart(char delimiter) throws BadLocationException {
while (0 < fOffset) {
char current= fDocument.getChar(fOffset);
if (current == delimiter) {
if ( !(0 <= fOffset && fDocument.getChar(fOffset -1) == '\\'))
return;
}
-- fOffset;
}
}
private int readBackwards() throws BadLocationException {
while (0 < fOffset) {
-- fOffset;
handleSingleLineComment();
char current= fDocument.getChar(fOffset);
switch (current) {
case '/':
if (fSkipComments && fOffset > 1) {
char next= fDocument.getChar(fOffset - 1);
if (next == '*') {
// a comment ends, advance to the comment start
fOffset -= 2;
gotoCommentStart();
continue;
}
}
return current;
case '"':
case '\'':
if (fSkipStrings) {
-- fOffset;
gotoStringStart(current);
continue;
}
return current;
}
return current;
}
return EOF;
}
}
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