MultiLineComment.java Source code

Introduction

Here is the source code for MultiLineComment.java

Source

//Send questions, comments, bug reports, etc. to the authors:

//Rob Warner (rwarner@interspatial.com)
//Robert Harris (rbrt_harris@yahoo.com)

import org.eclipse.swt.*;
import org.eclipse.swt.custom.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

import java.util.LinkedList;
import java.util.ArrayList;

import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.widgets.Display;

/**
 * This program demonstrates multiline comments. It uses MultiLineCommentListener
 * to do the syntax coloring
 */
public class MultiLineComment {
    /**
     * Runs the application
     */
    public void run() {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("Multiline Comments");
        createContents(shell);
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

    /**
     * Creates the main window contents
     * 
     * @param shell the main window
     */
    private void createContents(Shell shell) {
        shell.setLayout(new FillLayout());
        final StyledText styledText = new StyledText(shell, SWT.BORDER | SWT.H_SCROLL | SWT.V_SCROLL);

        // Add the line style listener
        final MultiLineCommentListener lineStyleListener = new MultiLineCommentListener();
        styledText.addLineStyleListener(lineStyleListener);

        // Add the modification listener
        styledText.addExtendedModifyListener(new ExtendedModifyListener() {
            public void modifyText(ExtendedModifyEvent event) {
                // Recalculate the comments
                lineStyleListener.refreshMultilineComments(styledText.getText());

                // Redraw the text
                styledText.redraw();
            }
        });
    }

    /**
     * The application entry point
     * 
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        new MultiLineComment().run();
    }
}
//Send questions, comments, bug reports, etc. to the authors:

//Rob Warner (rwarner@interspatial.com)
//Robert Harris (rbrt_harris@yahoo.com)
/**
 * This class supports multiline comments. It turns comments green.
 */
class MultiLineCommentListener implements LineStyleListener {
    // Markers for multiline comments
    private static final String COMMENT_START = "/*";
    private static final String COMMENT_END = "*/";

    // Color for comments
    private static final Color COMMENT_COLOR = Display.getCurrent().getSystemColor(SWT.COLOR_DARK_GREEN);

    // Offsets for all multiline comments
    List commentOffsets;

    /**
     * MultilineCommentListener constructor
     */
    public MultiLineCommentListener() {
        commentOffsets = new LinkedList();
    }

    /**
     * Refreshes the offsets for all multiline comments in the parent StyledText.
     * The parent StyledText should call this whenever its text is modified. Note
     * that this code doesn't ignore comment markers inside strings.
     * 
     * @param text the text from the StyledText
     */
    public void refreshMultilineComments(String text) {
        // Clear any stored offsets
        commentOffsets.clear();

        // Go through all the instances of COMMENT_START
        for (int pos = text.indexOf(COMMENT_START); pos > -1; pos = text.indexOf(COMMENT_START, pos)) {
            // offsets[0] holds the COMMENT_START offset
            // and COMMENT_END holds the ending offset
            int[] offsets = new int[2];
            offsets[0] = pos;

            // Find the corresponding end comment.
            pos = text.indexOf(COMMENT_END, pos);

            // If no corresponding end comment, use the end of the text
            offsets[1] = pos == -1 ? text.length() - 1 : pos + COMMENT_END.length() - 1;
            pos = offsets[1];

            // Add the offsets to the collection
            commentOffsets.add(offsets);
        }
    }

    /**
     * Called by StyledText to get the styles for a line
     * 
     * @param event the event
     */
    public void lineGetStyle(LineStyleEvent event) {
        // Create a collection to hold the StyleRanges
        List styles = new ArrayList();

        // Store the length for convenience
        int length = event.lineText.length();

        for (int i = 0, n = commentOffsets.size(); i < n; i++) {
            int[] offsets = (int[]) commentOffsets.get(i);

            // If starting offset is past current line--quit
            if (offsets[0] > event.lineOffset + length)
                break;

            // Check if we're inside a multiline comment
            if (offsets[0] <= event.lineOffset + length && offsets[1] >= event.lineOffset) {
                // Calculate starting offset for StyleRange
                int start = Math.max(offsets[0], event.lineOffset);

                // Calculate length for style range
                int len = Math.min(offsets[1], event.lineOffset + length) - start + 1;

                // Add the style range
                styles.add(new StyleRange(start, len, COMMENT_COLOR, null));
            }
        }

        // Copy all the ranges into the event
        event.styles = (StyleRange[]) styles.toArray(new StyleRange[0]);
    }
}