Copyright (c) 2000, 2007 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, 2007 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.templates;

import org.eclipse.core.runtime.Assert;

import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.Position;

Instances of this class describe the context of a template as a region of
a document. That region may be either specified by its offset and length, or
by a Position which may or may not be registered with the
document.

Clients may instantiate and extend this class.

Since:
3.0/**
 * Instances of this class describe the context of a template as a region of
 * a document. That region may be either specified by its offset and length, or
 * by a <code>Position</code> which may or may not be registered with the
 * document.
 * <p>
 * Clients may instantiate and extend this class.
 * </p>
 *
 * @since 3.0
 */
public class DocumentTemplateContext extends TemplateContext {

	
The text of the document. /** The text of the document. */
	private final IDocument fDocument;
	
The region of the document described by this context. We store a
position since clients may specify the document region as (updateable)
Positions.
/**
	 * The region of the document described by this context. We store a
	 * position since clients may specify the document region as (updateable)
	 * Positions.
	 */
	private final Position fPosition;
	
The original offset of this context. Will only be updated by the setter
method.
/**
	 * The original offset of this context. Will only be updated by the setter
	 * method.
	 */
	private int fOriginalOffset;
	
The original length of this context. Will only be updated by the setter
method.
/**
	 * The original length of this context. Will only be updated by the setter
	 * method.
	 */
	private int fOriginalLength;

	
Creates a document template context.
Params:
type – the context type
document – the document this context applies to
offset – the offset of the document region
length – the length of the document region/**
	 * Creates a document template context.
	 *
	 * @param type the context type
	 * @param document the document this context applies to
	 * @param offset the offset of the document region
	 * @param length the length of the document region
	 */
	public DocumentTemplateContext(TemplateContextType type, IDocument document, int offset, int length) {
		this(type, document, new Position(offset, length));
	}

	
Creates a document template context. The supplied Position
will be queried to compute the getStart and
getEnd methods, which will therefore answer updated
position data if it is registered with the document.
Params:
type – the context type
document – the document this context applies to
position – the position describing the area of the document which
       forms the template context
Since:
3.1/**
	 * Creates a document template context. The supplied <code>Position</code>
	 * will be queried to compute the <code>getStart</code> and
	 * <code>getEnd</code> methods, which will therefore answer updated
	 * position data if it is registered with the document.
	 *
	 * @param type the context type
	 * @param document the document this context applies to
	 * @param position the position describing the area of the document which
	 *        forms the template context
	 * @since 3.1
	 */
	public DocumentTemplateContext(TemplateContextType type, IDocument document, Position position) {
		super(type);

		Assert.isNotNull(document);
		Assert.isNotNull(position);
		Assert.isTrue(position.getOffset() <= document.getLength());

		fDocument= document;
		fPosition= position;
		fOriginalOffset= fPosition.getOffset();
		fOriginalLength= fPosition.getLength();
	}

	
Returns the document.
Returns:
the document/**
	 * Returns the document.
	 *
	 * @return the document
	 */
	public IDocument getDocument() {
		return fDocument;
	}

	
Returns the completion offset within the string of the context.
Returns:
the completion offset within the string of the context/**
	 * Returns the completion offset within the string of the context.
	 *
	 * @return the completion offset within the string of the context
	 */
	public int getCompletionOffset() {
		return fOriginalOffset;
	}

	
Sets the completion offset.
Params:
newOffset – the new completion offset/**
	 * Sets the completion offset.
	 *
	 * @param newOffset the new completion offset
	 */
	protected void setCompletionOffset(int newOffset) {
		fOriginalOffset= newOffset;
		fPosition.setOffset(newOffset);
	}

	
Returns the completion length within the string of the context.
Returns:
the completion length within the string of the context/**
	 * Returns the completion length within the string of the context.
	 *
	 * @return the completion length within the string of the context
	 */
	public int getCompletionLength() {
		return fOriginalLength;
	}

	
Sets the completion length.
Params:
newLength – the new completion length/**
	 * Sets the completion length.
	 *
	 * @param newLength the new completion length
	 */
	protected void setCompletionLength(int newLength) {
		fOriginalLength= newLength;
		fPosition.setLength(newLength);
	}

	
Returns the keyword which triggered template insertion.
Returns:
the keyword which triggered template insertion/**
	 * Returns the keyword which triggered template insertion.
	 *
	 * @return the keyword which triggered template insertion
	 */
	public String getKey() {
		int offset= getStart();
		int length= getEnd() - offset;
		try {
			return fDocument.get(offset, length);
		} catch (BadLocationException e) {
			return ""; //$NON-NLS-1$
		}
	}

	
Returns the beginning offset of the keyword.
Returns:
the beginning offset of the keyword/**
	 * Returns the beginning offset of the keyword.
	 *
	 * @return the beginning offset of the keyword
	 */
	public int getStart() {
		return fPosition.getOffset();
	}

	
Returns the end offset of the keyword.
Returns:
the end offset of the keyword/**
	 * Returns the end offset of the keyword.
	 *
	 * @return the end offset of the keyword
	 */
	public int getEnd() {
		return fPosition.getOffset() + fPosition.getLength();
	}

	@Override
	public boolean canEvaluate(Template template) {
		return true;
	}

	@Override
	public TemplateBuffer evaluate(Template template) throws BadLocationException, TemplateException {
		if (!canEvaluate(template))
			return null;

		TemplateTranslator translator= new TemplateTranslator();
		TemplateBuffer buffer= translator.translate(template);

		getContextType().resolve(buffer, this);

		return buffer;
	}
}