A custom search provider

In this tutorial we will implement a custom search for your RCP. Therefore we will first create the search logic and add UI components in a second step.
I found few resources on search functionality, here are some from the Eclipse FAQs:

• How do I implement a search operation 
• How do I write a Search dialog
• How do I display search results

To have something to search for we will look for files on the local file system. So this is our target for today:

 

Source code for this tutorial is available on github as a single zip archive, as a Team Project Set or you can browse the files online.

Step 1: Search Results


First create a new Plug-in Project and create a class FileSearchResult that implements ISearchResult. Therefore you need a dependency to org.eclipse.search.

package com.codeandme.searchprovider;

import java.io.File;
import java.util.Collection;
import java.util.HashSet;

import org.eclipse.core.runtime.ListenerList;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.search.ui.ISearchQuery;
import org.eclipse.search.ui.ISearchResult;
import org.eclipse.search.ui.ISearchResultListener;
import org.eclipse.search.ui.SearchResultEvent;

public class FileSearchResult implements ISearchResult {

 private final ISearchQuery fQuery;
 private final ListenerList fListeners = new ListenerList();

 private final Collection<File> fResult = new HashSet<File>();

 public FileSearchResult(ISearchQuery query) {
  fQuery = query;
 }

 @Override
 public String getLabel() {
  return fResult.size() + " file(s) found";
 }

 @Override
 public String getTooltip() {
  return "Found files in the filesystem";
 }

 @Override
 public ImageDescriptor getImageDescriptor() {
  return null;
 }

 @Override
 public ISearchQuery getQuery() {
  return fQuery;
 }

 @Override
 public void addListener(ISearchResultListener l) {
  fListeners.add(l);
 }

 @Override
 public void removeListener(ISearchResultListener l) {
  fListeners.remove(l);
 }

 private void notifyListeners(File file) {
  SearchResultEvent event = new FileSearchResultEvent(this, file);

  for (Object listener : fListeners.getListeners())
   ((ISearchResultListener) listener).searchResultChanged(event);
 }

 public void addFile(File file) {
  fResult.add(file);
  notifyListeners(file);
 }
}

Nothing special here, we will use addFile() later in this tutorial to add more and more files to our result set. Whenever the result changes, we need to inform interested listeners. So lets see how FileSearchResultEvent looks like:

package com.codeandme.searchprovider;

import java.io.File;

import org.eclipse.search.ui.ISearchResult;
import org.eclipse.search.ui.SearchResultEvent;

public class FileSearchResultEvent extends SearchResultEvent {

 private final File fAddedFile;

 protected FileSearchResultEvent(ISearchResult searchResult, File addedFile) {
  super(searchResult);
  fAddedFile = addedFile;
 }

 public File getAddedFile() {
  return fAddedFile;
 }
}

Even simpler! To update results incrementally we hold a reference to the added file.

Step 2: The search query

The main logic for a search is implemented as an ISearchQuery. It has 2 jobs: do the actual search and populate the search result.

package com.codeandme.searchprovider;

import java.io.File;
import java.io.FileFilter;
import java.util.Collection;
import java.util.HashSet;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.OperationCanceledException;
import org.eclipse.core.runtime.Status;
import org.eclipse.search.ui.ISearchQuery;
import org.eclipse.search.ui.ISearchResult;

public class FileSearchQuery implements ISearchQuery {

 private final File fRoot;
 private final String fFilter;
 private final boolean fRecursive;

 private final FileSearchResult fSearchResult;

 public FileSearchQuery(String root, String filter, boolean recursive) {
  fRoot = (root.isEmpty()) ? File.listRoots()[0] : new File(root);
  fFilter = filter;
  fRecursive = recursive;
  fSearchResult = new FileSearchResult(this);
 }

 @Override
 public IStatus run(IProgressMonitor monitor) throws OperationCanceledException {
  Collection<File> entries = new HashSet<File>();
  entries.add(fRoot);

  do {
   File entry = entries.iterator().next();
   entries.remove(entry);

   entry.listFiles(new FileFilter() {

    @Override
    public boolean accept(File pathname) {
     if ((pathname.isFile()) && (pathname.getName().contains(fFilter))) {
      // accept file
      fSearchResult.addFile(pathname);

      return true;
     }

     if ((pathname.isDirectory()) && (fRecursive))
      entries.add(pathname);

     return false;
    }
   });

  } while (!entries.isEmpty());

  return Status.OK_STATUS;
 }

 @Override
 public String getLabel() {
  return "Filesystem search";
 }

 @Override
 public boolean canRerun() {
  return true;
 }

 @Override
 public boolean canRunInBackground() {
  return true;
 }

 @Override
 public ISearchResult getSearchResult() {
  return fSearchResult;
 }
}

Our query needs 3 parameters:

• a root object
• a file name filter
• a recursive flag to scan subfolders

In the constructor we create the FileSearchResult and link it to our query. Then we traverse folders and add file by file to our search result. We do not check our input parameters very thoroughly for the sake of simplicity.

The logic is implemented, now lets add some nice UI elements.

Step 3: Search Dialog

To add a new search page to the search dialog (main menu/Search/Search...) we use the extension point org.eclipse.search.searchPages.

 

Just provide id, label and a class reference to:

package com.codeandme.searchprovider.ui;

import org.eclipse.jface.dialogs.DialogPage;
import org.eclipse.search.ui.ISearchPage;
import org.eclipse.search.ui.ISearchPageContainer;
import org.eclipse.search.ui.NewSearchUI;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;

import com.codeandme.searchprovider.FileSearchQuery;

public class FileSearchPage extends DialogPage implements ISearchPage {

 private ISearchPageContainer fContainer;

 @Override
 public boolean performAction() {
  FileSearchQuery searchQuery = new FileSearchQuery("/home", "txt", true);
  NewSearchUI.runQueryInForeground(fContainer.getRunnableContext(), searchQuery);

  return true;
 }

 @Override
 public void setContainer(ISearchPageContainer container) {
  fContainer = container;
 }

 @Override
 public void createControl(Composite parent) {
  Composite root = new Composite(parent, SWT.NULL);

  [...]

  // need to set the root element
  setControl(root);
 }
}

I have removed the UI code from createControl() as it is not relevant here. If interested you can find it on github. The only important thing here is to set the root control using setControl().

performAction() starts the actual search. Therefore we create a query and run it either as foreground or as background job. By returning true we indicate that the search dialog shall be closed.

Step 4: Display search results

To add a new page to the Search View we need another extension point: org.eclipse.search.searchResultViewPages.

Add a new viewPage with an id and label. To link this page with search results of a certain kind we provide the class of search results this page can display. Set it to our FileSearchResult type. Finally we provide a class implementation for the page:

package com.codeandme.searchprovider.ui;

import org.eclipse.search.ui.ISearchResult;
import org.eclipse.search.ui.ISearchResultListener;
import org.eclipse.search.ui.ISearchResultPage;
import org.eclipse.search.ui.ISearchResultViewPart;
import org.eclipse.search.ui.SearchResultEvent;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.IActionBars;
import org.eclipse.ui.IMemento;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.part.IPageSite;

import com.codeandme.searchprovider.FileSearchResultEvent;

public class SearchResultPage implements ISearchResultPage, ISearchResultListener {

 private String fId;
 private Composite fRootControl;
 private IPageSite fSite;
 private Text ftext;

 @Override
 public Object getUIState() {
  return null;
 }

 @Override
 public void setInput(ISearchResult search, Object uiState) {
  search.addListener(this);
 }

 @Override
 public void setViewPart(ISearchResultViewPart part) {
 }

 @Override
 public void setID(String id) {
  fId = id;
 }

 @Override
 public String getID() {
  return fId;
 }

 @Override
 public String getLabel() {
  return "Filesystem Search Results";
 }

 @Override
 public IPageSite getSite() {
  return fSite;
 }

 @Override
 public void init(IPageSite site) throws PartInitException {
  fSite = site;
 }

 @Override
 public void createControl(Composite parent) {
  fRootControl = new Composite(parent, SWT.NULL);
  fRootControl.setLayout(new FillLayout(SWT.HORIZONTAL));

  ftext = new Text(fRootControl, SWT.BORDER | SWT.READ_ONLY | SWT.H_SCROLL | SWT.V_SCROLL | SWT.CANCEL | SWT.MULTI);
 }

 @Override
 public void dispose() {
  // nothing to do
 }

 @Override
 public Control getControl() {
  return fRootControl;
 }

 @Override
 public void setActionBars(IActionBars actionBars) {
 }

 @Override
 public void setFocus() {
  fRootControl.setFocus();
 }

 @Override
 public void restoreState(IMemento memento) {
  // nothing to do
 }

 @Override
 public void saveState(IMemento memento) {
  // nothing to do
 }

 @Override
 public void searchResultChanged(SearchResultEvent event) {
  if (event instanceof FileSearchResultEvent) {
   Display.getDefault().asyncExec(new Runnable() {
    @Override
    public void run() {
     String newText = ftext.getText() + "\n" + ((FileSearchResultEvent) event).getAddedFile().getAbsolutePath();
     ftext.setText(newText);
    }
   });
  }
 }
}

Lots of getters and setters, but nothing complicated. For this example we use a simple text control to add the names of found files. setInput() will be called by the framework to link this view with a search result. Now we attach a listeners to get notified on changes on the result.

I found one caveat while implementing: when your query code (from there we trigger searchResultChanged()) raises an exception, you do not get the output on the console as you might expect. Basically this means that your result page remains empty without any notification that something went wrong. Use the debugger to single step through your code in that case.