org.eclipse.text/projection/org/eclipse/jface/text/projection/ProjectionMapping.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.text.projection;

import org.eclipse.jface.text.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.BadPositionCategoryException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IDocumentInformationMapping;
import org.eclipse.jface.text.IDocumentInformationMappingExtension;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.Region;

/**
 * Internal class. Do not use. Only public for testing purposes.
 * <p>
 * Implementation of <code>IDocumentInformationMapping</code> for the
 * projection mapping between a master and a slave document.
 * 
 * @since 3.0
 */
public class ProjectionMapping implements IDocumentInformationMapping , IDocumentInformationMappingExtension, IMinimalMapping {
	
	private static final int LEFT=  -1;
	private static final int NONE=   0;
	private static final int RIGHT= +1;
	
	/** The master document */
	private IDocument fMasterDocument;
	/** The position category used to manage the projection fragments inside the master document */
	private String fFragmentsCategory;
	/** The projection document */
	private IDocument fSlaveDocument;
	/** The position category to manage the projection segments inside the slave document. */
	private String fSegmentsCategory;


	/**
	 * Creates a new mapping between the given parent document and the given projection document.
	 * 
	 * @param masterDocument the master document
	 * @param fragmentsCategory the position category of the parent document used to manage the projected regions
	 * @param slaveDocument the slave document
	 * @param segmentsCategory the position category of the projection document used to manage the fragments
	 */
	public ProjectionMapping(IDocument masterDocument, String fragmentsCategory, IDocument slaveDocument, String segmentsCategory) {
		fMasterDocument= masterDocument;
		fFragmentsCategory= fragmentsCategory;
		fSlaveDocument= slaveDocument;
		fSegmentsCategory= segmentsCategory;
	}
	
	private Position[] getSegments() {
		try {
			return fSlaveDocument.getPositions(fSegmentsCategory);
		} catch (BadPositionCategoryException e) {
		}
		
		return new Position[0];
	}
	
	private Position[] getFragments() {
		try {
			return fMasterDocument.getPositions(fFragmentsCategory);
		} catch (BadPositionCategoryException e) {
		}
		
		return new Position[0];
	}
	
	private int findSegmentIndex(int offset) throws BadLocationException {
		Position[] segments= getSegments();
		if (segments.length == 0) {
			if (offset > 0)
				throw new BadLocationException();
			return -1;
		}
		
		try {
			int index= fSlaveDocument.computeIndexInCategory(fSegmentsCategory, offset);
			if (index == segments.length && offset > (segments[index-1].offset + segments[index-1].length))
				throw new BadLocationException();
			
			if (index < segments.length && offset == segments[index].offset)
				return index;
			
			if (index > 0)
				index--;
				
			return index;
			
		} catch (BadPositionCategoryException e) {
			throw new IllegalStateException();
		}
	}

	private Segment findSegment(int offset) throws BadLocationException {
		
		if (offset < 0 || getImageLength() < offset)
			throw new BadLocationException();

		int index= findSegmentIndex(offset);
		if (index == -1) {
			
			Segment s= new Segment(0, 0);
			Fragment f= new Fragment(0, 0);
			s.fragment= f;
			f.segment= s;
			return s;
		}
				
		Position[] segments= getSegments();
		return (Segment) segments[index];	
	}
	
	private int findFragmentIndex(int offset, int extensionDirection) throws BadLocationException {
		try {
			
			Position[] fragments= getFragments();
			if (fragments.length == 0)
				return -1;
			
			int index= fMasterDocument.computeIndexInCategory(fFragmentsCategory, offset);
			
			if (index < fragments.length && offset == fragments[index].offset)
				return index;
			
			if (0 < index && index <= fragments.length && fragments[index - 1].includes(offset))
				return index - 1;
			
			switch(extensionDirection) {
				case LEFT:
					return Math.max(index - 1, 0);
				case RIGHT:
					return Math.min(index, fragments.length - 1);
			}
				
			return -1;
			
		} catch (BadPositionCategoryException e) {
			throw new IllegalStateException();
		}
	}

	private Fragment findFragment(int offset) throws BadLocationException {
		
		int length= fMasterDocument.getLength();
		if (offset < 0 || length < offset)
			throw new BadLocationException();
		
		int index= findFragmentIndex(offset, NONE);
		Position[] fragments= getFragments();
		if (index == -1) {
			if (fragments.length > 0) {
				Fragment last= (Fragment) fragments[fragments.length - 1];
				if (last.getOffset() + last.getLength() == offset)
					return last;
			}
			return null;
		}
		return (Fragment) fragments[index];
	}
	
	private Fragment[] findFragments(IRegion region, boolean exact) throws BadLocationException {
		int offset= region.getOffset();
		if (offset < 0 || fMasterDocument.getLength() < offset)
			throw new BadLocationException();
		
		int inclusiveEndOffset= region.getOffset() + region.getLength() - 1;
		if (inclusiveEndOffset < 0 || fMasterDocument.getLength() < inclusiveEndOffset)
			throw new BadLocationException();
		
		int startIndex= findFragmentIndex(offset, exact ? NONE : LEFT);
		if (startIndex == -1)
			return new Fragment[0];
		
		int endIndex= findFragmentIndex(inclusiveEndOffset, exact ? NONE : RIGHT);
		if (endIndex == -1)
			return new Fragment[0];
		
		Position[] fragments= getFragments();
		while (startIndex <= endIndex && !fragments[startIndex].overlapsWith(region.getOffset(), region.getLength()))
			++startIndex;
		
		while (endIndex >= startIndex && !fragments[endIndex].overlapsWith(region.getOffset(), region.getLength()))
			--endIndex;
		
		int length= Math.max(0, endIndex - startIndex + 1);
		Fragment[] result= new Fragment[length];
		for (int i= 0; i < length; i++)
			result[i]= (Fragment) fragments[startIndex + i];
		return result;
	}
	
	private IRegion toImageRegion(IRegion originRegion, boolean exact) throws BadLocationException {
		if (originRegion.getLength() == 0) {
			int imageOffset= toImageOffset(originRegion.getOffset());
			return imageOffset == -1 ? null : new Region(imageOffset, 0);
		}
		
		Fragment[] fragments= findFragments(originRegion, exact);
		if (fragments.length > 0) {
			
			// translate start offset
			Fragment fragment= fragments[0];
			int originOffset= originRegion.getOffset();
			int relative= originOffset - fragment.getOffset();
			if (relative < 0) {
				Assert.isTrue(!exact);
				relative= 0;
			}
			int imageOffset= fragment.segment.getOffset() + relative;
			
			// translate end offset
			fragment= fragments[fragments.length - 1];
			int exclusiveOriginEndOffset= originRegion.getOffset() + originRegion.getLength();
			relative= exclusiveOriginEndOffset - fragment.getOffset();
			if (relative > fragment.getLength()) {
				Assert.isTrue(!exact);
				int delta= relative - fragment.getLength();
				relative -= delta;
			}
			int exclusiveImageEndOffset= fragment.segment.getOffset() + relative;
			
			return new Region(imageOffset, exclusiveImageEndOffset - imageOffset);
		}
		
		return null;
	}
	
	private IRegion createOriginStartRegion(Segment original, int offsetShift) {
		return new Region(original.fragment.getOffset() + offsetShift, original.fragment.getLength() - offsetShift);
	}
	
	private IRegion createOriginRegion(Segment origin) {
		return new Region(origin.fragment.getOffset(), origin.fragment.getLength());
	}
	
	private IRegion createOriginEndRegion(Segment original, int lengthReduction) {
		return new Region(original.fragment.getOffset(), original.fragment.getLength() - lengthReduction);
	}
	
	private IRegion getIntersectingRegion(IRegion left, IRegion right) {
		int offset= Math.max(left.getOffset(), right.getOffset());
		int exclusiveEndOffset= Math.min(left.getOffset() + left.getLength(), right.getOffset() + right.getLength());
		if (exclusiveEndOffset < offset)
			return null;
		return new Region(offset, exclusiveEndOffset - offset);
	}
	
	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#getCoverage()
	 */
	public IRegion getCoverage() {
		Position[] fragments= getFragments();
		if (fragments != null && fragments.length > 0) {
			Position first=fragments[0];
			Position last= fragments[fragments.length -1];
			return  new Region(first.offset, (last.offset + last.length) - first.offset);
		}
		return new Region(0, 0);
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toOriginOffset(int)
	 */
	public int toOriginOffset(int imageOffset) throws BadLocationException {
		Segment segment= findSegment(imageOffset);
		int relative= imageOffset - segment.offset;
		return segment.fragment.offset + relative;	
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toOriginRegion(org.eclipse.jface.text.IRegion)
	 */
	public IRegion toOriginRegion(IRegion imageRegion) throws BadLocationException {
		int imageOffset= imageRegion.getOffset();
		int imageLength= imageRegion.getLength();
		
		if (imageLength == 0) {
			if (imageOffset == 0 && getImageLength() == 0)
				return new Region(0, fMasterDocument.getLength());
			return new Region(toOriginOffset(imageOffset), 0);
		}
		
		int originOffset= toOriginOffset(imageOffset);
		int inclusiveImageEndOffset= imageOffset + imageLength -1;
		int inclusiveOriginEndOffset= toOriginOffset(inclusiveImageEndOffset);
		
		return new Region(originOffset, (inclusiveOriginEndOffset + 1) - originOffset);
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toOriginLines(int)
	 */
	public IRegion toOriginLines(int imageLine) throws BadLocationException {
		IRegion imageRegion= fSlaveDocument.getLineInformation(imageLine);
		IRegion originRegion= toOriginRegion(imageRegion);
		
		int originStartLine= fMasterDocument.getLineOfOffset(originRegion.getOffset());
		if (originRegion.getLength() == 0)
			return new Region(originStartLine, 1);
			
		int inclusiveOriginEndOffset= originRegion.getOffset() + originRegion.getLength() -1;
		int originEndLine= fMasterDocument.getLineOfOffset(inclusiveOriginEndOffset);
		return new Region(originStartLine, (originEndLine + 1) - originStartLine);
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toOriginLine(int)
	 */
	public int toOriginLine(int imageLine) throws BadLocationException {
		IRegion lines= toOriginLines(imageLine);
		return (lines.getLength() > 1 ? -1 : lines.getOffset());
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toImageOffset(int)
	 */
	public int toImageOffset(int originOffset) throws BadLocationException {
		Fragment fragment= findFragment(originOffset);
		if (fragment != null) {
			int relative= originOffset - fragment.offset;
			return fragment.segment.offset + relative;	
		}
		return -1;
	}
	
	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMappingExtension#toExactImageRegion(org.eclipse.jface.text.IRegion)
	 */
	public IRegion toExactImageRegion(IRegion originRegion) throws BadLocationException {
		return toImageRegion(originRegion, true);
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toImageRegion(org.eclipse.jface.text.IRegion)
	 */
	public IRegion toImageRegion(IRegion originRegion) throws BadLocationException {
		return toImageRegion(originRegion, false);
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toImageLine(int)
	 */
	public int toImageLine(int originLine) throws BadLocationException {
		IRegion originRegion= fMasterDocument.getLineInformation(originLine);
		IRegion imageRegion= toImageRegion(originRegion);
		if (imageRegion == null) {
			int imageOffset= toImageOffset(originRegion.getOffset());
			if (imageOffset > -1)
				imageRegion= new Region(imageOffset, 0);
			else
				return -1;
		}
	
		int startLine= fSlaveDocument.getLineOfOffset(imageRegion.getOffset());
		if (imageRegion.getLength() == 0)
			return startLine;
			
		int endLine= fSlaveDocument.getLineOfOffset(imageRegion.getOffset() + imageRegion.getLength());
		if (endLine != startLine)
			throw new IllegalStateException();
		
		return startLine;
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMapping#toClosestImageLine(int)
	 */
	public int toClosestImageLine(int originLine) throws BadLocationException {
		try {
			
			int imageLine= toImageLine(originLine);
			if (imageLine > -1)
				return imageLine;
			
			Position[] fragments= getFragments();
			if (fragments.length == 0)
				return -1;
			
			IRegion originLineRegion= fMasterDocument.getLineInformation(originLine);
			int index= fMasterDocument.computeIndexInCategory(fFragmentsCategory, originLineRegion.getOffset());
			
			if (0 < index && index < fragments.length) {
				Fragment left= (Fragment) fragments[index - 1];
				int leftDistance= originLineRegion.getOffset() - (left.getOffset() + left.getLength());
				Fragment right= (Fragment) fragments[index];
				int rightDistance= right.getOffset() - (originLineRegion.getOffset() + originLineRegion.getLength());
				
				if (leftDistance <= rightDistance)
					originLine= fMasterDocument.getLineOfOffset(left.getOffset() + Math.max(left.getLength() - 1, 0));
				else
					originLine= fMasterDocument.getLineOfOffset(right.getOffset());
				
			} else if (index == 0) {
				Fragment right= (Fragment) fragments[index];
				originLine= fMasterDocument.getLineOfOffset(right.getOffset());
			} else if (index == fragments.length) {
				Fragment left= (Fragment) fragments[index - 1];
				originLine= fMasterDocument.getLineOfOffset(left.getOffset() + left.getLength());
			}
			
			return toImageLine(originLine);
			
		} catch (BadPositionCategoryException x) {
		}
		
		return -1;
	}
	
	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMappingExtension#toExactOriginRegions(org.eclipse.jface.text.IRegion)
	 */
	public IRegion[] toExactOriginRegions(IRegion imageRegion) throws BadLocationException {
		
		if (imageRegion.getLength() == 0)
			return new IRegion[] { new Region(toOriginOffset(imageRegion.getOffset()), 0) };
		
		int endOffset= imageRegion.getOffset() + imageRegion.getLength();
		Position[] segments= getSegments();
		int firstIndex= findSegmentIndex(imageRegion.getOffset());
		int lastIndex= findSegmentIndex(endOffset - 1);
		
		int resultLength= lastIndex - firstIndex + 1;
		IRegion[] result= new IRegion[resultLength];
		
		// first
		result[0]= createOriginStartRegion((Segment) segments[firstIndex], imageRegion.getOffset() - segments[firstIndex].getOffset());
		// middles
		for (int i= 1; i < resultLength - 1; i++)
			result[i]= createOriginRegion((Segment) segments[firstIndex + i]);
		// last
		Segment last= (Segment) segments[lastIndex];
		int segmentEndOffset= last.getOffset() + last.getLength(); 
		IRegion lastRegion= createOriginEndRegion(last, segmentEndOffset - endOffset);
		if (resultLength > 1) {
			// first != last
			result[resultLength - 1]= lastRegion;
		} else {
			// merge first and last
			result[0]= getIntersectingRegion(result[0], lastRegion);
		}
		
		return result;
	}

	/*
	 * @see org.eclipse.jface.text.IDocumentInformationMappingExtension#getImageLength()
	 */
	public int getImageLength() {
		Position[] segments= getSegments();
		int length= 0;
		for (int i= 0; i < segments.length; i++)
			length += segments[i].length;
		return length;
	}
}