org.eclipse.jface.text.Document.java Source code

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Here is the source code for org.eclipse.jface.text.Document.java

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/*******************************************************************************
 * Copyright (c) 2000, 2010 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.jface.text;

/**
 * Default document implementation. Uses a {@link org.eclipse.jface.text.GapTextStore} wrapped
 * inside a {@link org.eclipse.jface.text.CopyOnWriteTextStore} as text store.
 * <p>
 * The used line tracker considers the following strings as line delimiters: "\n", "\r", "\r\n". In
 * case of a text replacement across line delimiter boundaries and with different line delimiters,
 * the line tracker might have to be repaired. Use
 * {@link #isLineInformationRepairNeeded(int, int, String)} before doing the text replace if you
 * have the need to discover such a situation.
 * </p>
 * <p>
 * The document is ready to use. It has a default position category for which a default position
 * updater is installed.
 * </p>
 * <p>
 * <strong>Performance:</strong> The implementation should perform reasonably well for typical
 * source code documents. It is not designed for very large documents of a size of several
 * megabytes. Space-saving implementations are initially used for both the text store and the line
 * tracker; the first modification after a {@link #set(String) set} incurs the cost to transform the
 * document structures to efficiently handle updates.
 * </p>
 * <p>
 * See {@link GapTextStore} and <code>TreeLineTracker</code> for algorithmic behavior of the used
 * document structures.
 * </p>
 * 
 * @see org.eclipse.jface.text.GapTextStore
 * @see org.eclipse.jface.text.CopyOnWriteTextStore
 */
public class Document extends AbstractDocument {
    /**
     * Creates a new empty document.
     */
    public Document() {
        super();
        setTextStore(new CopyOnWriteTextStore(new GapTextStore()));
        setLineTracker(new DefaultLineTracker());
        completeInitialization();
    }

    /**
     * Creates a new document with the given initial content.
     *
     * @param initialContent the document's initial content
     */
    public Document(String initialContent) {
        super();
        setTextStore(new CopyOnWriteTextStore(new GapTextStore()));
        setLineTracker(new DefaultLineTracker());
        getStore().set(initialContent);
        getTracker().set(initialContent);
        completeInitialization();
    }

    /*
     * @see org.eclipse.jface.text.IRepairableDocumentExtension#isLineInformationRepairNeeded(int, int, java.lang.String)
     * @since 3.4
     */
    public boolean isLineInformationRepairNeeded(int offset, int length, String text) throws BadLocationException {
        if ((0 > offset) || (0 > length) || (offset + length > getLength()))
            throw new BadLocationException();

        return isLineInformationRepairNeeded(text) || isLineInformationRepairNeeded(get(offset, length));
    }

    /**
     * Checks whether the line information needs to be repaired.
     *
     * @param text the text to check
     * @return <code>true</code> if the line information must be repaired
     * @since 3.4
     */
    private boolean isLineInformationRepairNeeded(String text) {
        if (text == null)
            return false;

        int length = text.length();
        if (length == 0)
            return false;

        int rIndex = text.indexOf('\r');
        int nIndex = text.indexOf('\n');
        if (rIndex == -1 && nIndex == -1)
            return false;

        if (rIndex > 0 && rIndex < length - 1 && nIndex > 1 && rIndex < length - 2)
            return false;

        String defaultLD = null;
        try {
            defaultLD = getLineDelimiter(0);
        } catch (BadLocationException x) {
            return true;
        }

        if (defaultLD == null)
            return false;

        defaultLD = getDefaultLineDelimiter();

        if (defaultLD.length() == 1) {
            if (rIndex != -1 && !"\r".equals(defaultLD)) //$NON-NLS-1$
                return true;
            if (nIndex != -1 && !"\n".equals(defaultLD)) //$NON-NLS-1$
                return true;
        } else if (defaultLD.length() == 2)
            return rIndex == -1 || nIndex - rIndex != 1;

        return false;
    }

}