/*******************************************************************************
* Copyright (c) 2009 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
* Zend Technologies
*******************************************************************************/
package org.eclipse.php.astview;
import org.eclipse.php.core.ast.nodes.ASTNode;
import org.eclipse.php.core.ast.visitor.ApplyAll;
/**
* For a give range finds the node covered and the node covering.
*/
public class NodeFinder extends ApplyAll {
/**
* A visitor that maps a selection to a given ASTNode. 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 ASTNode perform(ASTNode root, int start, int length) {
NodeFinder finder= new NodeFinder(start, length);
root.accept(finder);
ASTNode result= finder.getCoveredNode();
if (result == null || result.getStart() != start || result.getLength() != length) {
return finder.getCoveringNode();
}
return result;
}
private int fStart;
private int fEnd;
private ASTNode fCoveringNode;
private ASTNode fCoveredNode;
public NodeFinder(int offset, int length) {
fStart= offset;
fEnd= offset + length;
}
protected boolean apply(ASTNode node) {
int nodeStart= node.getStart();
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 ASTNode
*/
public ASTNode 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 ASTNode
*/
public ASTNode getCoveringNode() {
return fCoveringNode;
}
}