Scala example source code file (CursorBuffer.java)

This example Scala source code file (CursorBuffer.java) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

charsequence, cursorbuffer, override, string, stringbuilder

The CursorBuffer.java Scala example source code

/*
 * Copyright (c) 2002-2007, Marc Prud'hommeaux. All rights reserved.
 *
 * This software is distributable under the BSD license. See the terms of the
 * BSD license in the documentation provided with this software.
 */

package scala.tools.jline.console;

/**
 * A holder for a {@link StringBuilder} that also contains the current cursor position.
 *
 * @author <a href="mailto:mwp1@cornell.edu">Marc Prud'hommeaux</a>
 * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
 * @since 2.0
 */
public class CursorBuffer
{
    private boolean overTyping = false;

    public int cursor = 0;

    public final StringBuilder buffer = new StringBuilder();

    public boolean isOverTyping() {
        return overTyping;
    }

    public void setOverTyping(final boolean b) {
        overTyping = b;
    }

    public int length() {
        return buffer.length();
    }

    /**
     * Gets the character to the left of the cursor.
     */
    public char charLeftOfCursor() {
        if (cursor <= 0) {
            return 0;
        }

        return buffer.charAt(cursor - 1);
    }

    /**
     * Gets the character at the cursor.
     */
    public char charAtCursor() {
        if (cursor < 0 || cursor >= buffer.length()) {
            return 0;
        }
        return buffer.charAt(cursor);
    }

    /**
     * Write the specific character into the buffer, setting the cursor position
     * ahead one. The text may overwrite or insert based on the current setting
     * of {@link #isOverTyping}.
     *
     * @param c the character to insert
     */
    public void write(final char c) {
        buffer.insert(cursor++, c);
        if (isOverTyping() && cursor < buffer.length()) {
            buffer.deleteCharAt(cursor);
        }
    }

    /**
     * Insert the specified chars into the buffer, setting the cursor to the end of the insertion point.
     */
    public void write(final CharSequence str) {
        assert str != null;

        if (buffer.length() == 0) {
            buffer.append(str);
        }
        else {
            buffer.insert(cursor, str);
        }

        cursor += str.length();

        if (isOverTyping() && cursor < buffer.length()) {
            buffer.delete(cursor, (cursor + str.length()));
        }
    }

    public boolean clear() {
        if (buffer.length() == 0) {
            return false;
        }

        buffer.delete(0, buffer.length());
        cursor = 0;
        return true;
    }

    @Override
    public String toString() {
        return buffer.toString();
    }
}