Copyright (c) 2000, 2015 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.text;


import java.util.LinkedList;


A text store that optimizes a given source text store for sequential rewriting.
While rewritten it keeps a list of replace command that serve as patches for
the source store. Only on request, the source store is indeed manipulated
by applying the patch commands to the source text store.
Since:
2.0
Deprecated:
since 3.3 as GapTextStore performs better even for sequential rewrite scenarios/**
 * A text store that optimizes a given source text store for sequential rewriting.
 * While rewritten it keeps a list of replace command that serve as patches for
 * the source store. Only on request, the source store is indeed manipulated
 * by applying the patch commands to the source text store.
 *
 * @since 2.0
 * @deprecated since 3.3 as {@link GapTextStore} performs better even for sequential rewrite scenarios
 */
@Deprecated
public class SequentialRewriteTextStore implements ITextStore {

	
A buffered replace command.
/**
	 * A buffered replace command.
	 */
	private static class Replace {
		public int newOffset;
		public final int offset;
		public final int length;
		public final String text;

		public Replace(int offset, int newOffset, int length, String text) {
			this.newOffset= newOffset;
			this.offset= offset;
			this.length= length;
			this.text= text;
		}
	}

	
The list of buffered replacements. /** The list of buffered replacements. */
	private LinkedList<Replace> fReplaceList;
	
The source text store /** The source text store */
	private ITextStore fSource;
	
A flag to enforce sequential access. /** A flag to enforce sequential access. */
	private static final boolean ASSERT_SEQUENTIALITY= false;


	
Creates a new sequential rewrite store for the given source store.
Params:
source – the source text store/**
	 * Creates a new sequential rewrite store for the given source store.
	 *
	 * @param source the source text store
	 */
	public SequentialRewriteTextStore(ITextStore source) {
		fReplaceList= new LinkedList<>();
		fSource= source;
	}

	
Returns the source store of this rewrite store.
Returns:
 the source store of this rewrite store/**
	 * Returns the source store of this rewrite store.
	 *
	 * @return  the source store of this rewrite store
	 */
	public ITextStore getSourceStore() {
		commit();
		return fSource;
	}

	@Override
	public void replace(int offset, int length, String text) {
		if (text == null)
			text= ""; //$NON-NLS-1$

		if (fReplaceList.isEmpty()) {
			fReplaceList.add(new Replace(offset, offset, length, text));

		} else {
			Replace firstReplace= fReplaceList.getFirst();
			Replace lastReplace= fReplaceList.getLast();

			// backward
			if (offset + length <= firstReplace.newOffset) {
				int delta= text.length() - length;
				if (delta != 0) {
					for (Replace replace : fReplaceList) {
						replace.newOffset += delta;
					}
				}

				fReplaceList.addFirst(new Replace(offset, offset, length, text));

			// forward
			} else if (offset >= lastReplace.newOffset + lastReplace.text.length()) {
				int delta= getDelta(lastReplace);
				fReplaceList.add(new Replace(offset - delta, offset, length, text));

			} else if (ASSERT_SEQUENTIALITY) {
				throw new IllegalArgumentException();

			} else {
				commit();
				fSource.replace(offset, length, text);
			}
		}
	}

	@Override
	public void set(String text) {
		fSource.set(text);
		fReplaceList.clear();
	}

	@Override
	public String get(int offset, int length) {

		if (fReplaceList.isEmpty())
			return fSource.get(offset, length);


		Replace firstReplace= fReplaceList.getFirst();
		Replace lastReplace= fReplaceList.getLast();

		// before
		if (offset + length <= firstReplace.newOffset) {
			return fSource.get(offset, length);

			// after
		} else if (offset >= lastReplace.newOffset + lastReplace.text.length()) {
			int delta= getDelta(lastReplace);
			return fSource.get(offset - delta, length);

		} else if (ASSERT_SEQUENTIALITY) {
			throw new IllegalArgumentException();

		} else {

			int delta= 0;
			for (Replace replace : fReplaceList) {
				if (offset + length < replace.newOffset) {
					return fSource.get(offset - delta, length);

				} else if (offset >= replace.newOffset && offset + length <= replace.newOffset + replace.text.length()) {
					return replace.text.substring(offset - replace.newOffset, offset - replace.newOffset + length);

				} else if (offset >= replace.newOffset + replace.text.length()) {
					delta= getDelta(replace);
					continue;

				} else {
					commit();
					return fSource.get(offset, length);
				}
			}

			return fSource.get(offset - delta, length);
		}

	}

	
Returns the difference between the offset in the source store and the "same" offset in the
rewrite store after the replace operation.
Params:
replace – the replace command
Returns:
the difference/**
	 * Returns the difference between the offset in the source store and the "same" offset in the
	 * rewrite store after the replace operation.
	 *
	 * @param replace the replace command
	 * @return the difference
	 */
	private static final int getDelta(Replace replace) {
		return replace.newOffset - replace.offset + replace.text.length() - replace.length;
	}

	@Override
	public char get(int offset) {
		if (fReplaceList.isEmpty())
			return fSource.get(offset);

		Replace firstReplace= fReplaceList.getFirst();
		Replace lastReplace= fReplaceList.getLast();

		// before
		if (offset < firstReplace.newOffset) {
			return fSource.get(offset);

			// after
		} else if (offset >= lastReplace.newOffset + lastReplace.text.length()) {
			int delta= getDelta(lastReplace);
			return fSource.get(offset - delta);

		} else if (ASSERT_SEQUENTIALITY) {
			throw new IllegalArgumentException();

		} else {

			int delta= 0;
			for (Replace replace : fReplaceList) {
				if (offset < replace.newOffset)
					return fSource.get(offset - delta);

				else if (offset < replace.newOffset + replace.text.length())
					return replace.text.charAt(offset - replace.newOffset);

				delta= getDelta(replace);
			}

			return fSource.get(offset - delta);
		}
	}

	@Override
	public int getLength() {
		if (fReplaceList.isEmpty())
			return fSource.getLength();

		Replace lastReplace= fReplaceList.getLast();
		return fSource.getLength() + getDelta(lastReplace);
	}

	
Disposes this rewrite store.
/**
	 * Disposes this rewrite store.
	 */
	public void dispose() {
		fReplaceList= null;
		fSource= null;
	}

	
Commits all buffered replace commands.
/**
	 * Commits all buffered replace commands.
	 */
	private void commit() {

		if (fReplaceList.isEmpty())
			return;

		StringBuilder buffer= new StringBuilder();

		int delta= 0;
		for (Replace replace : fReplaceList) {
			int offset= buffer.length() - delta;
			buffer.append(fSource.get(offset, replace.offset - offset));
			buffer.append(replace.text);
			delta= getDelta(replace);
		}

		int offset= buffer.length() - delta;
		buffer.append(fSource.get(offset, fSource.getLength() - offset));

		fSource.set(buffer.toString());
		fReplaceList.clear();
	}
}