GotoMatchingFenceAction.java

package com.redhat.ceylon.eclipse.code.editor;

import static com.redhat.ceylon.eclipse.code.editor.CeylonEditor.getFences;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITextViewerExtension5;
import org.eclipse.jface.text.source.ICharacterPairMatcher;
import org.eclipse.jface.text.source.ISourceViewer;

class GotoMatchingFenceAction extends Action {
    
    private final CeylonEditor fEditor;

    public GotoMatchingFenceAction(CeylonEditor editor) {
        super("Go to Matching Fence");
        Assert.isNotNull(editor);
        fEditor= editor;
        setEnabled(true);
        //PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.GOTO_MATCHING_BRACKET_ACTION);
    }

    public void run() {
        gotoMatchingFence();
    }

    /**
     * Jumps to the matching bracket.
     */
    public void gotoMatchingFence() {
        ISourceViewer sourceViewer = fEditor.getCeylonSourceViewer();
        IDocument document= sourceViewer.getDocument();
        if (document == null)
            return;

        IRegion selection= fEditor.getSignedSelection();
        int selectionLength= Math.abs(selection.getLength());

        if (selectionLength > 1) {
            fEditor.setStatusLineErrorMessage("Invalid selection");
            sourceViewer.getTextWidget().getDisplay().beep();
            return;
        }

        // #26314
        int sourceCaretOffset= selection.getOffset() + selection.getLength();
        if (isSurroundedByBrackets(document, sourceCaretOffset))
            sourceCaretOffset -= selection.getLength();

        IRegion region= fEditor.getBracketMatcher().match(document, sourceCaretOffset);
        if (region == null) {
            fEditor.setStatusLineErrorMessage("No matching fence!");
            sourceViewer.getTextWidget().getDisplay().beep();
            return;
        }

        int offset= region.getOffset();
        int length= region.getLength();

        if (length < 1)
            return;

        int anchor= fEditor.getBracketMatcher().getAnchor();
        // http://dev.eclipse.org/bugs/show_bug.cgi?id=34195
        int targetOffset= (ICharacterPairMatcher.RIGHT == anchor) ? offset + 1: offset + length;

        boolean visible= false;
        if (sourceViewer instanceof ITextViewerExtension5) {
            ITextViewerExtension5 extension= (ITextViewerExtension5) sourceViewer;
            visible= (extension.modelOffset2WidgetOffset(targetOffset) > -1);
        } else {
            IRegion visibleRegion= sourceViewer.getVisibleRegion();
            // http://dev.eclipse.org/bugs/show_bug.cgi?id=34195
            visible= (targetOffset >= visibleRegion.getOffset() && targetOffset <= visibleRegion.getOffset() + visibleRegion.getLength());
        }

        if (!visible) {
            fEditor.setStatusLineErrorMessage("Matching fence is outside the currently selected element.");
            sourceViewer.getTextWidget().getDisplay().beep();
            return;
        }

        if (selection.getLength() < 0)
            targetOffset -= selection.getLength();

        sourceViewer.setSelectedRange(targetOffset, selection.getLength());
        sourceViewer.revealRange(targetOffset, selection.getLength());
    }

    private boolean isBracket(char character) {
        String[][] fences= getFences();
        for(int i= 0; i != fences.length; ++i) {
            if (fences[i][0].indexOf(character) >= 0)
                return true;
            if (fences[i][1].indexOf(character) >= 0)
                return true;
        }
        return false;
    }

    private boolean isSurroundedByBrackets(IDocument document, int offset) {
        if (offset == 0 || offset == document.getLength())
            return false;

        try {
            return isBracket(document.getChar(offset - 1)) &&
                   isBracket(document.getChar(offset));
        } catch (BadLocationException e) {
                return false;
        }
    }

 }