/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.ui.text.java;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.CompilationUnit;

/**
 * Context information for quick fix and quick assist processors.
 * <p>
 * Note: this interface is not intended to be implemented.
 * </p>
 *
 * @since 3.0
 *
 * @noimplement This interface is not intended to be implemented by clients.
 * @noextend This interface is not intended to be extended by clients.
 */
public interface IInvocationContext {

	/**
	 * @return the current compilation unit
	 */
	ICompilationUnit getCompilationUnit();

	/**
	 * @return the offset of the current selection
	 */
	int getSelectionOffset();

	/**
	 * @return the length of the current selection
	 */
	int getSelectionLength();

	/**
	 * Returns an AST of the compilation unit, possibly only a partial AST focused on the selection
	 * offset (see {@link org.eclipse.jdt.core.dom.ASTParser#setFocalPosition(int)}).
	 * The returned AST is shared and therefore protected and cannot be modified.
	 * The client must check the AST API level and do nothing if they are given an AST
	 * they can't handle.
	 * 
	 * @see org.eclipse.jdt.core.dom.AST#apiLevel()
	 * @return the root of the AST corresponding to the current compilation unit
	 */
	CompilationUnit getASTRoot();

	/**
	 * If the AST contains nodes whose range is equal to the selection, returns the innermost of those nodes.
	 * Otherwise, returns the first node in a preorder traversal of the AST, where the complete node range is covered by the selection.
	 *
	 * @return the covered node, or <code>null</code> if the selection is empty or too short to cover an entire node
	 */
	ASTNode getCoveredNode();
	
	/**
	 * Returns the innermost node that fully contains the selection. A node also contains the zero-length selection on either end.
	 * <p>
	 * If more than one node covers the selection, the returned node is the last covering node found in a preorder traversal of the AST.
	 * This implies that for a zero-length selection between two adjacent sibling nodes, the node on the right is returned.
	 * </p>
	 *
	 * @return the covering node
	 */
	ASTNode getCoveringNode();

}