org.eclipse.xtext.ui.resource.PackageFragmentRootWalker.java Source code

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Here is the source code for org.eclipse.xtext.ui.resource.PackageFragmentRootWalker.java

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/*******************************************************************************
 * Copyright (c) 2009 itemis AG (http://www.itemis.eu) 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
 *******************************************************************************/
package org.eclipse.xtext.ui.resource;

import java.util.Collections;
import java.util.List;

import org.eclipse.jdt.core.IJarEntryResource;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IPackageFragment;
import org.eclipse.jdt.core.IPackageFragmentRoot;
import org.eclipse.jdt.core.JavaModelException;

import com.google.common.collect.Lists;

/**
 * @author Sven Efftinge - Initial contribution and API
 * @author Sebastian Zarnekow - Initial contribution and API
 */
public abstract class PackageFragmentRootWalker<T> {

    public static class TraversalState {

        private List<Object> parents;

        TraversalState(Object obj) {
            parents = Lists.<Object>newArrayList(obj);
        }

        public List<?> getParents() {
            return Collections.unmodifiableList(parents);
        }

        void pop() {
            parents.remove(parents.size() - 1);
        }

        void push(Object obj) {
            parents.add(obj);
        }

    }

    public T traverse(IPackageFragmentRoot root, boolean stopOnFirstResult) throws JavaModelException {
        T result = null;
        if (root.exists() && existsPhysically(root)) {
            Object[] resources = root.getNonJavaResources();
            TraversalState state = new TraversalState(root);
            for (Object object : resources) {
                if (object instanceof IJarEntryResource) {
                    result = traverse((IJarEntryResource) object, stopOnFirstResult, state);
                    if (stopOnFirstResult && result != null)
                        return result;
                }
            }

            IJavaElement[] children = root.getChildren();
            for (IJavaElement javaElement : children) {
                if (javaElement instanceof IPackageFragment) {
                    result = traverse((IPackageFragment) javaElement, stopOnFirstResult, state);
                    if (stopOnFirstResult && result != null)
                        return result;
                }
            }
        }
        return result;
    }

    private boolean existsPhysically(IPackageFragmentRoot root) throws JavaModelException {
        if (root.isExternal())
            return root.getPath().toFile().exists();
        else
            return root.getUnderlyingResource().exists();
    }

    protected T traverse(IPackageFragment pack, boolean stopOnFirstResult, TraversalState state)
            throws JavaModelException {
        T result = null;
        state.push(pack);
        IJavaElement[] children = pack.getChildren();
        for (IJavaElement iJavaElement : children) {
            if (iJavaElement instanceof IPackageFragment) {
                result = traverse((IPackageFragment) iJavaElement, stopOnFirstResult, state);
                if (stopOnFirstResult && result != null)
                    return result;
            }
        }
        Object[] resources = pack.getNonJavaResources();
        for (Object object : resources) {
            if (object instanceof IJarEntryResource) {
                result = traverse((IJarEntryResource) object, stopOnFirstResult, state);
                if (stopOnFirstResult && result != null)
                    return result;
            }
        }
        state.pop();
        return result;
    }

    protected T traverse(IJarEntryResource jarEntry, boolean stopOnFirstResult, TraversalState state) {
        T result = null;
        if (jarEntry.isFile()) {
            result = handle(jarEntry, state);
        } else {
            state.push(jarEntry);
            IJarEntryResource[] children = jarEntry.getChildren();
            for (IJarEntryResource child : children) {
                result = traverse(child, stopOnFirstResult, state);
                if (stopOnFirstResult && result != null)
                    return result;
            }
            state.pop();
        }
        return result;
    }

    protected abstract T handle(IJarEntryResource jarEntry, TraversalState state);

}