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/*******************************************************************************
* Copyright (c) 2005, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Anton Leherbauer (Wind River Systems)
* Bryan Wilkinson (QNX)
*******************************************************************************/
package org.eclipse.cdt.ui.text.contentassist;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.ITextViewer;
/**
* Describes the context of an invocation of content assist in a text viewer. The context knows the
* document, the invocation offset and can lazily compute the identifier prefix preceding the
* invocation offset. It may know the viewer.
* <p>
* Subclasses may add information to their environment. For example, source code editors may provide
* specific context information such as an AST.
* </p>
* <p>
* Clients may instantiate.
* </p>
* @noextend This class is not intended to be subclassed by clients.
* @since 4.0
*/
public class ContentAssistInvocationContext {
/* state */
private final ITextViewer fViewer;
private final IDocument fDocument;
private final int fOffset;
/* cached additional info */
private CharSequence fPrefix;
/**
* Equivalent to
* {@linkplain #ContentAssistInvocationContext(ITextViewer, int) ContentAssistInvocationContext(viewer, viewer.getSelectedRange().x)}.
*
* @param viewer the text viewer that content assist is invoked in
*/
public ContentAssistInvocationContext(ITextViewer viewer) {
this(viewer, viewer.getSelectedRange().x);
}
/**
* Creates a new context for the given viewer and offset.
*
* @param viewer the text viewer that content assist is invoked in
* @param offset the offset into the viewer's document where content assist is invoked at
*/
public ContentAssistInvocationContext(ITextViewer viewer, int offset) {
Assert.isNotNull(viewer);
fViewer= viewer;
fDocument= null;
fOffset= offset;
}
/**
* Creates a new context with no viewer or invocation offset set.
*/
protected ContentAssistInvocationContext() {
fDocument= null;
fViewer= null;
fOffset= -1;
}
/**
* Creates a new context for the given document and offset.
*
* @param document the document that content assist is invoked in
* @param offset the offset into the document where content assist is invoked at
*/
public ContentAssistInvocationContext(IDocument document, int offset) {
Assert.isNotNull(document);
Assert.isTrue(offset >= 0);
fViewer= null;
fDocument= document;
fOffset= offset;
}
/**
* Returns the invocation offset.
*
* @return the invocation offset
*/
public final int getInvocationOffset() {
return fOffset;
}
/**
* Returns the viewer, <code>null</code> if not available.
*
* @return the viewer, possibly <code>null</code>
*/
public final ITextViewer getViewer() {
return fViewer;
}
/**
* Returns the document that content assist is invoked on, or <code>null</code> if not known.
*
* @return the document or <code>null</code>
*/
public IDocument getDocument() {
if (fDocument == null) {
if (fViewer == null)
return null;
return fViewer.getDocument();
}
return fDocument;
}
/**
* Computes the identifier (as specified by {@link Character#isJavaIdentifierPart(char)}) that
* immediately precedes the invocation offset.
*
* @return the prefix preceding the content assist invocation offset, <code>null</code> if
* there is no document
* @throws BadLocationException if accessing the document fails
*/
public CharSequence computeIdentifierPrefix() throws BadLocationException {
if (fPrefix == null) {
IDocument document= getDocument();
if (document == null)
return null;
int end= getInvocationOffset();
int start= end;
while (--start >= 0) {
if (!Character.isJavaIdentifierPart(document.getChar(start)))
break;
}
start++;
fPrefix= document.get(start, end - start);
}
return fPrefix;
}
/**
* Called upon completion of the content assist. Used to free any resources
* used by the context.
*/
public void dispose() {
}
/**
* Invocation contexts are equal if they describe the same context and are of the same type.
* This implementation checks for <code>null</code> values and class equality. Subclasses
* should extend this method by adding checks for their context relevant fields (but not
* necessarily cached values).
* <p>
* Example:
*
* <pre>
* class MyContext extends ContentAssistInvocationContext {
* private final Object fState;
* private Object fCachedInfo;
*
* ...
*
* public boolean equals(Object obj) {
* if (!super.equals(obj))
* return false;
* MyContext other= (MyContext) obj;
* return fState.equals(other.fState);
* }
* }
* </pre>
*
* </p>
* <p>
* Subclasses should also extend {@link Object#hashCode()}.
* </p>
*
* @param obj {@inheritDoc}
* @return {@inheritDoc}
*/
@Override
public boolean equals(Object obj) {
if (obj == null)
return false;
if (!getClass().equals(obj.getClass()))
return false;
ContentAssistInvocationContext other= (ContentAssistInvocationContext) obj;
return (fViewer == null && other.fViewer == null || fViewer != null && fViewer.equals(other.fViewer)) && fOffset == other.fOffset && (fDocument == null && other.fDocument == null || fDocument != null && fDocument.equals(other.fDocument));
}
/*
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
return 23459213 << 5 | (fViewer == null ? 0 : fViewer.hashCode() << 3) | fOffset;
}
}
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