ltk/org.eclipse.statet.ltk.core/src/org/eclipse/statet/ltk/core/LTKUtils.java

/*=============================================================================#
 # Copyright (c) 2009, 2020 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ltk.core;

import java.util.List;

import org.eclipse.core.runtime.IAdaptable;

import org.eclipse.statet.jcommons.text.core.TextRegion;

import org.eclipse.statet.ltk.model.core.elements.IModelElement;
import org.eclipse.statet.ltk.model.core.elements.ISourceElement;
import org.eclipse.statet.ltk.model.core.elements.ISourceStructElement;
import org.eclipse.statet.ltk.model.core.elements.ISourceUnit;


public class LTKUtils {
	
	
	public static IModelElement getModelElement(final Object element) {
		if (element instanceof IModelElement) {
			return (IModelElement) element;
		}
		if (element instanceof IAdaptable) {
			return ((IAdaptable) element).getAdapter(IModelElement.class);
		}
		return null;
	}
	
	public static ISourceUnit getSourceUnit(final IModelElement element) {
		if (element instanceof ISourceUnit) {
			return (ISourceUnit) element;
		}
		if (element instanceof ISourceElement) {
			return ((ISourceElement) element).getSourceUnit();
		}
		return null;
	}
	
	public static ISourceStructElement getCoveringSourceElement(final ISourceStructElement root, final TextRegion region) {
		return getCoveringSourceElement(root, region.getStartOffset(), region.getEndOffset());
	}
	
	public static ISourceStructElement getCoveringSourceElement(final ISourceStructElement root,
			final int startOffset, final int endOffset) {
		ISourceStructElement ok= root;
		CHECK: while (ok != null) {
			final List<? extends ISourceStructElement> children= ok.getSourceChildren(null);
			for (final ISourceStructElement child : children) {
				final TextRegion sourceRange= child.getSourceRange();
				final TextRegion docRange= child.getDocumentationRange();
				final int childOffset= (docRange != null) ?
						Math.min(sourceRange.getStartOffset(), docRange.getStartOffset()) :
						sourceRange.getStartOffset();
				if (startOffset >= childOffset) {
					final int childEnd= (docRange != null) ?
							Math.max(sourceRange.getEndOffset(), docRange.getEndOffset()) :
							sourceRange.getEndOffset();
					if ((startOffset < endOffset) ?
							(endOffset <= childEnd) : (endOffset < childEnd)) {
						ok= child;
						continue CHECK;
					}
				}
				else {
					break CHECK;
				}
			}
			break CHECK;
		}
		return ok;
	}
	
	public static int searchCoveringSourceElement(final List<? extends ISourceStructElement> elements,
			final int offset) {
		// binary search
		int low= 0;
		int high= elements.size() - 1;
		while (low <= high) {
			final int mid= (low + high) >> 1;
			final TextRegion region= elements.get(mid).getSourceRange();
			
			if (region.getEndOffset() < offset) {
				low= mid + 1;
			}
			else if (region.getStartOffset() > offset) {
				high= mid - 1;
			}
			else {
				return mid;
			}
		}
		return -(low + 1);
	}
	
	public static <T extends ISourceStructElement> T getCoveringSourceElement(final List<T> elements,
			final int offset) {
		final int idx= searchCoveringSourceElement(elements, offset);
		if (idx >= 0) {
			return elements.get(idx);
		}
		return null;
	}
	
}