| /******************************************************************************* |
| * Copyright (c) 2005, 2015 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 |
| *******************************************************************************/ |
| package org.eclipse.ui.internal.texteditor.quickdiff.compare.equivalence; |
| |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.ConcurrentModificationException; |
| |
| import org.eclipse.core.runtime.Assert; |
| |
| import org.eclipse.jface.text.BadLocationException; |
| import org.eclipse.jface.text.DocumentEvent; |
| import org.eclipse.jface.text.IDocument; |
| import org.eclipse.jface.text.IRegion; |
| |
| /** |
| * @since 3.2 |
| */ |
| public final class DocumentEquivalenceClass { |
| |
| private static final boolean DEBUG= false; |
| |
| private final ArrayList<Hash> fHashes; |
| private IDocument fDocument; |
| private final IHashFunction fHashFunction; |
| |
| public DocumentEquivalenceClass(IDocument document) { |
| this(document, new DJBHashFunction()); |
| } |
| |
| public DocumentEquivalenceClass(IDocument document, IHashFunction hashFunction) { |
| fDocument= document; |
| Hash[] nulls= new Hash[fDocument.getNumberOfLines()]; |
| fHashes= new ArrayList<>(Arrays.asList(nulls)); |
| |
| if (hashFunction == null) |
| throw new NullPointerException("hashFunction"); //$NON-NLS-1$ |
| fHashFunction= hashFunction; |
| } |
| |
| /** |
| * Returns the equivalence hash for line <code>line</code>. |
| * |
| * @param line the line for which to get the equivalent hash |
| * @return the hash in the equivalence class defined by the hash |
| * function |
| * @throws IndexOutOfBoundsException if <code>line</code> is not a |
| * legal document line |
| * @throws ConcurrentModificationException if the document is |
| * modified concurrently to this method call |
| */ |
| public Hash getHash(int line) { |
| try { |
| return internalGetHash(line); |
| } catch (BadLocationException x) { |
| throw new ConcurrentModificationException(); |
| } |
| } |
| |
| private Hash internalGetHash(int line) throws BadLocationException { |
| Hash hash= fHashes.get(line); |
| if (hash == null) { |
| if (fDocument == null) |
| throw new AssertionError("hash cannot be null after loadAndForget"); //$NON-NLS-1$ |
| |
| IRegion lineRegion= fDocument.getLineInformation(line); |
| String lineContents= fDocument.get(lineRegion.getOffset(), lineRegion.getLength()); |
| hash= fHashFunction.computeHash(lineContents); |
| fHashes.set(line, hash); |
| } |
| |
| return hash; |
| } |
| |
| /** |
| * Cleanses the lines affected by the document event from the |
| * internal hash cache. Must be called before the document is |
| * modified (in documentAboutToBeChanged). |
| * |
| * @param event the document event |
| */ |
| public void update(DocumentEvent event) { |
| if (fDocument == null) |
| throw new IllegalStateException("update must not be called after loadAndForget"); //$NON-NLS-1$ |
| try { |
| internalUpdate(event); |
| } catch (BadLocationException x) { |
| throw new ConcurrentModificationException(); |
| } |
| } |
| |
| private void internalUpdate(DocumentEvent event) throws BadLocationException { |
| int linesBefore= fDocument.getNumberOfLines(event.getOffset(), event.getLength()); |
| String text= event.getText(); |
| int linesAfter= (text == null ? 0 : fDocument.computeNumberOfLines(text)) + 1; |
| int firstLine= fDocument.getLineOfOffset(event.getOffset()); |
| |
| int delta= linesAfter - linesBefore; |
| int changed= Math.min(linesAfter, linesBefore); |
| |
| if (delta > 0) { |
| Hash[] nulls= new Hash[delta]; |
| fHashes.addAll(firstLine + changed, Arrays.asList(nulls)); |
| } else if (delta < 0) { |
| fHashes.subList(firstLine, firstLine - delta).clear(); |
| } |
| Collections.fill(fHashes.subList(firstLine, firstLine + changed), null); |
| } |
| |
| /** |
| * @return the number of items |
| */ |
| public int getCount() { |
| return fHashes.size(); |
| } |
| |
| public void setDocument(IDocument document) { |
| Assert.isNotNull(document); |
| if (DEBUG) |
| Assert.isTrue(document.get().equals(fDocument.get())); |
| fDocument= document; |
| } |
| |
| /** |
| * Computes all hashes and forgets the document. Don't call update |
| * afterwards. |
| */ |
| public void loadAndForget() { |
| int count= getCount(); |
| for (int line= 0; line < count; line++) |
| getHash(line); |
| |
| fDocument= null; |
| } |
| } |