package com.redhat.ceylon.eclipse.code.editor;
import static com.redhat.ceylon.eclipse.code.editor.CeylonEditor.getFences;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.DefaultTextDoubleClickStrategy;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.source.DefaultCharacterPairMatcher;
public class DoubleClickStrategy extends DefaultTextDoubleClickStrategy {
protected final IdentifierDetector fWordDetector;
protected final DefaultCharacterPairMatcher fPairMatcher;
public DoubleClickStrategy() {
fWordDetector = new IdentifierDetector();
StringBuilder sb= new StringBuilder();
String[][] fences= getFences();
for(int i= 0; i < fences.length; i++) {
sb.append(fences[i][0]);
sb.append(fences[i][1]);
}
fPairMatcher= new DefaultCharacterPairMatcher(sb.toString().toCharArray());
}
private final class IdentifierDetector {
private static final int UNKNOWN= -1;
/* states */
private static final int WS= 0;
private static final int ID= 1;
private static final int IDS= 2;
/* directions */
private static final int FORWARD= 0;
private static final int BACKWARD= 1;
/** The current state. */
private int fState;
/**
* The state at the anchor (if already detected by going the other way),
* or <code>UNKNOWN</code>.
*/
private int fAnchorState;
/** The current direction. */
private int fDirection;
/** The start of the detected word. */
private int fStart;
/** The end of the word. */
private int fEnd;
/**
* Initializes the detector at offset <code>anchor</code>.
*
* @param anchor the offset of the double click
*/
private void setAnchor(int anchor) {
fState= UNKNOWN;
fAnchorState= UNKNOWN;
fDirection= UNKNOWN;
fStart= anchor;
fEnd= anchor - 1;
}
private boolean isIdentifierStart(char c) {
return Character.isJavaIdentifierStart(c) && c!='$' || c=='\\';
}
private boolean isIdentifierPart(char c) {
return Character.isJavaIdentifierPart(c) && c!='$';
}
private boolean isWhitespace(char c) {
return c==' '||c=='\r'||c=='\n'||c=='\t'||c=='\f';
}
/**
* Try to add a character to the word going backward. Only call after forward calls!
*
* @param c the character to add
* @param offset the offset of the character
* @return <code>true</code> if further characters may be added to the word
*/
private boolean backward(char c, int offset) {
checkDirection(BACKWARD);
switch (fState) {
case IDS:
if (isWhitespace(c)) {
fState= WS;
return true;
}
if (isIdentifierStart(c)) {
fStart= offset;
fState= IDS;
return true;
}
if (isIdentifierPart(c)) {
fStart= offset;
fState= ID;
return true;
}
return false;
case ID:
if (isIdentifierStart(c)) {
fStart= offset;
fState= IDS;
return true;
}
if (isIdentifierPart(c)) {
fStart= offset;
fState= ID;
return true;
}
return false;
case WS:
if (isWhitespace(c)) {
return true;
}
return false;
case UNKNOWN:
if (c == '.') {
fEnd= offset - 1;
fState= IDS;
fAnchorState= fState;
return true;
}
return false;
default:
return false;
}
}
/**
* Try to add a character to the word going forward.
*
* @param c the character to add
* @param offset the offset of the character
* @return <code>true</code> if further characters may be added to the word
*/
private boolean forward(char c, int offset) {
checkDirection(FORWARD);
switch (fState) {
case WS:
if (isWhitespace(c)) {
fState= WS;
return true;
}
if (isIdentifierStart(c)) {
fEnd= offset;
fState= IDS;
return true;
}
return false;
case IDS:
case ID:
if (isIdentifierStart(c)) {
fEnd= offset;
fState= IDS;
return true;
}
if (isIdentifierPart(c)) {
fEnd= offset;
fState= ID;
return true;
}
return false;
case UNKNOWN:
if (isIdentifierStart(c)) {
fEnd= offset;
fState= IDS;
fAnchorState= fState;
return true;
}
if (isIdentifierPart(c)) {
fEnd= offset;
fState= ID;
fAnchorState= fState;
return true;
}
if (isWhitespace(c)) {
fState= WS;
fAnchorState= fState;
return true;
}
return false;
default:
return false;
}
}
/**
* If the direction changes, set state to be the previous anchor state.
*
* @param direction the new direction
*/
private void checkDirection(int direction) {
if (fDirection == direction)
return;
if (direction == FORWARD) {
if (fStart <= fEnd)
fState= fAnchorState;
else
fState= UNKNOWN;
} else if (direction == BACKWARD) {
if (fEnd >= fStart)
fState= fAnchorState;
else
fState= UNKNOWN;
}
fDirection= direction;
}
/**
* Returns the region containing <code>anchor</code> that is a java word.
*
* @param document the document from which to read characters
* @param anchor the offset around which to select a word
* @return the region describing a java word around <code>anchor</code>
*/
public IRegion getWordSelection(IDocument document, int anchor) {
try {
final int min= 0;
final int max= document.getLength();
setAnchor(anchor);
char c;
int offset= anchor;
while (offset < max) {
c= document.getChar(offset);
if (!forward(c, offset))
break;
++offset;
}
offset= anchor; // use to not select the previous word when right behind it
//offset= anchor - 1; // use to select the previous word when right behind it
while (offset >= min) {
c= document.getChar(offset);
if (!backward(c, offset))
break;
--offset;
}
return new Region(fStart, fEnd - fStart + 1);
}
catch (BadLocationException x) {
return new Region(anchor, 0);
}
}
}
protected IRegion findWord(IDocument document, int anchor) {
return fWordDetector.getWordSelection(document, anchor);
}
protected IRegion findExtendedDoubleClickSelection(IDocument document, int offset) {
IRegion match= fPairMatcher.match(document, offset);
if (match != null && match.getLength() >= 2)
return new Region(match.getOffset() + 1, match.getLength() - 2);
return findWord(document, offset);
}
}