plugins/org.eclipse.dltk.javascript.ui/src/org/eclipse/dltk/javascript/internal/ui/text/folding/JavaScriptCommentFoldingBlockProvider.java

/*******************************************************************************
 * Copyright (c) 2010 xored software, Inc.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 * 
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     xored software, Inc. - initial API and Implementation (Alex Panchenko)
 *******************************************************************************/
package org.eclipse.dltk.javascript.internal.ui.text.folding;

import java.util.List;

import org.eclipse.dltk.javascript.internal.ui.text.JSPartitioningProvider;
import org.eclipse.dltk.javascript.ui.text.IJavaScriptPartitions;
import org.eclipse.dltk.ui.text.folding.IFoldingBlockKind;
import org.eclipse.dltk.ui.text.folding.IFoldingContent;
import org.eclipse.dltk.ui.text.folding.PartitioningFoldingBlockProvider;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;

public class JavaScriptCommentFoldingBlockProvider extends
		PartitioningFoldingBlockProvider {

	public JavaScriptCommentFoldingBlockProvider() {
		super(JSPartitioningProvider.getInstance());
	}

	public void computeFoldableBlocks(IFoldingContent content) {
		if (isFoldingComments()) {
			computeBlocksForPartitionType(content,
					IJavaScriptPartitions.JS_SINGLE_LINE_COMMENT,
					JavaScriptFoldingBlockKind.COMMENT, isCollapseComments());
			computeBlocksForPartitionType(content,
					IJavaScriptPartitions.JS_MULTI_LINE_COMMENT,
					JavaScriptFoldingBlockKind.COMMENT, isCollapseComments());
		}
		if (isFoldingDocs())
			computeBlocksForPartitionType(content,
					IJavaScriptPartitions.JS_DOC,
					JavaScriptFoldingBlockKind.JSDOC, isCollapseDocs());
	}

    @Override
    protected void reportRegions(Document document, List<IRegion> regions,
                    IFoldingBlockKind kind, boolean collapse)
                    throws BadLocationException {
            if ((kind == JavaScriptFoldingBlockKind.COMMENT || kind == JavaScriptFoldingBlockKind.JSDOC)
                            && collapse != isCollapseHeaderComment() && !regions.isEmpty()) {
                    final IRegion first = regions.get(0);
                    if (first.getOffset() == 0 && isFileHeader(document, first)) {
                            requestor.acceptBlock(first.getOffset(), first.getOffset()
                                            + first.getLength(), kind, null /* no element */,
                                            isCollapseHeaderComment());
                            super.reportRegions(document,
                                            regions.subList(1, regions.size()), kind, collapse);
                            return;
                    }
            }
            super.reportRegions(document, regions, kind, collapse);
    }

    private boolean isFileHeader(IDocument document, IRegion region)
                    throws BadLocationException {
            int endPos = region.getOffset() + region.getLength();
            String txtAfterComment = document.get(endPos,
                            Math.min(20, document.getLength() - endPos));
            int lineDelimiterCount = 0;
            for (int i = 0; i < txtAfterComment.length(); i++) {
                    char c = txtAfterComment.charAt(i);
                    if (c == 'f') {
                            if (txtAfterComment.substring(i).startsWith("function"))
                                    return false;
                    } else if (c == 'v') {
                            if (txtAfterComment.substring(i).startsWith("var"))
                                    return false;
                    } else if (lineDelimiterCount == 1) {
                            // if after 1 line delimiter still no function
                            // or var is found then it is a header.
                            return true;
                    } else if (c == '\n') {
                            lineDelimiterCount++;
                    } else if (c == '\r') {
                            lineDelimiterCount++;
                            if (i + 1 < txtAfterComment.length()
                                            && txtAfterComment.charAt(i + 1) == '\n')
                                    i++; // skip \r\n
                    }
                    if (lineDelimiterCount == 2) {
                            return true;
                    }
            }
            return false;
    }
}