/*******************************************************************************
* Copyright (c) 2000, 2005 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 de.ovgu.cide.utils;
import cide.gast.ASTVisitor;
import cide.gast.IASTNode;
/**
* For a give range finds the node covered and the node covering.
*/
public class NodeFinder extends ASTVisitor {
/**
* A visitor that maps a selection to a given IASTNode. The result node is
* determined as follows:
* <ul>
* <li>first the visitor tries to find a node with the exact start and
* length</li>
* <li>if no such node exists than the node that encloses the range defined
* by start and end is returned.</li>
* <li>if the length is zero than also nodes are considered where the
* node's start or end position matches <code>start</code>.</li>
* <li>otherwise <code>null</code> is returned.</li>
* </ul>
*/
public static IASTNode perform(IASTNode root, int start, int length) {
NodeFinder finder = new NodeFinder(start, length);
root.accept(finder);
IASTNode result = finder.getCoveredNode();
if (result == null || result.getStartPosition() != start
|| result.getLength() != length) {
return finder.getCoveringNode();
}
return result;
}
private int fStart;
private int fEnd;
private IASTNode fCoveringNode;
private IASTNode fCoveredNode;
public NodeFinder(int offset, int length) {
fStart = offset;
fEnd = offset + length;
}
public boolean visit(IASTNode node) {
int nodeStart = node.getStartPosition();
int nodeEnd = nodeStart + node.getLength();
if (nodeEnd < fStart || fEnd < nodeStart) {
return false;
}
if (nodeStart <= fStart && fEnd <= nodeEnd) {
fCoveringNode = node;
}
if (fStart <= nodeStart && nodeEnd <= fEnd) {
if (fCoveringNode == node) { // nodeStart == fStart && nodeEnd ==
// fEnd
fCoveredNode = node;
return true; // look further for node with same length as
// parent
} else if (fCoveredNode == null) { // no better found
fCoveredNode = node;
}
return false;
}
return true;
}
/**
* Returns the covered node. If more than one nodes are covered by the
* selection, the returned node is first covered node found in a top-down
* traversal of the AST
*
* @return IASTNode
*/
public IASTNode getCoveredNode() {
return fCoveredNode;
}
/**
* Returns the covering node. If more than one nodes are covering the
* selection, the returned node is last covering node found in a top-down
* traversal of the AST
*
* @return IASTNode
*/
public IASTNode getCoveringNode() {
return fCoveringNode;
}
}