14. Structure View Factory

Edit pageLast modified: 19 March 2025

Reference: Structure View

Code: SimpleStructureViewFactory, SimpleStructureViewModel, SimpleStructureViewElement

tip

This page is part of multi-step Custom Language Support Tutorial. All previous steps must be executed in sequence for the code to work.

The structure view can be customized for a specific file type. Creating a structure view factory allows showing the structure of any file in the Structure tool window or by invoking Navigate | File Structure for easy navigation between items in the current editor.

Define a Structure View Factory

The SimpleStructureViewFactory implements PsiStructureViewFactory. The getStructureViewBuilder() implementation reuses the IntelliJ Platform class TreeBasedStructureViewBuilder. At this point the project will not compile until SimpleStructureViewModel is implemented below.

final class SimpleStructureViewFactory implements PsiStructureViewFactory {

  @Override
  public StructureViewBuilder getStructureViewBuilder(@NotNull final PsiFile psiFile) {
    return new TreeBasedStructureViewBuilder() {
      @NotNull
      @Override
      public StructureViewModel createStructureViewModel(@Nullable Editor editor) {
        return new SimpleStructureViewModel(editor, psiFile);
      }
    };
  }

}

Define a Structure View Model

The SimpleStructureViewModel is created by implementing StructureViewModel, which defines the model for data displayed in the standard structure view. It also extends StructureViewModelBase, an implementation that links the model to a text editor.

public class SimpleStructureViewModel extends StructureViewModelBase implements
    StructureViewModel.ElementInfoProvider {

  public SimpleStructureViewModel(@Nullable Editor editor, PsiFile psiFile) {
    super(psiFile, editor, new SimpleStructureViewElement(psiFile));
  }

  @NotNull
  public Sorter @NotNull [] getSorters() {
    return new Sorter[]{Sorter.ALPHA_SORTER};
  }


  @Override
  public boolean isAlwaysShowsPlus(StructureViewTreeElement element) {
    return false;
  }

  @Override
  public boolean isAlwaysLeaf(StructureViewTreeElement element) {
    return element.getValue() instanceof SimpleProperty;
  }

  @Override
  protected Class<?> @NotNull [] getSuitableClasses() {
    return new Class[]{SimpleProperty.class};
  }

}

Define a Structure View Element

The SimpleStructureViewElement implements StructureViewTreeElement and SortableTreeElement. The StructureViewTreeElement represents an element in the Structure View tree model. The SortableTreeElement represents an item in a smart tree that allows using text other than the presentable text as a key for alphabetic sorting.

public class SimpleStructureViewElement implements StructureViewTreeElement, SortableTreeElement {

  private final NavigatablePsiElement myElement;

  public SimpleStructureViewElement(NavigatablePsiElement element) {
    this.myElement = element;
  }

  @Override
  public Object getValue() {
    return myElement;
  }

  @Override
  public void navigate(boolean requestFocus) {
    myElement.navigate(requestFocus);
  }

  @Override
  public boolean canNavigate() {
    return myElement.canNavigate();
  }

  @Override
  public boolean canNavigateToSource() {
    return myElement.canNavigateToSource();
  }

  @NotNull
  @Override
  public String getAlphaSortKey() {
    String name = myElement.getName();
    return name != null ? name : "";
  }

  @NotNull
  @Override
  public ItemPresentation getPresentation() {
    ItemPresentation presentation = myElement.getPresentation();
    return presentation != null ? presentation : new PresentationData();
  }

  @Override
  public TreeElement @NotNull [] getChildren() {
    if (myElement instanceof SimpleFile) {
      List<SimpleProperty> properties = PsiTreeUtil.getChildrenOfTypeAsList(myElement, SimpleProperty.class);
      List<TreeElement> treeElements = new ArrayList<>(properties.size());
      for (SimpleProperty property : properties) {
        treeElements.add(new SimpleStructureViewElement((SimplePropertyImpl) property));
      }
      return treeElements.toArray(new TreeElement[0]);
    }
    return EMPTY_ARRAY;
  }

}

Register the Structure View Factory

The SimpleStructureViewFactory implementation is registered with the IntelliJ Platform in the plugin configuration file using the com.intellij.lang.structureViewExtension extension point.

<extensions defaultExtensionNs="com.intellij">
  <lang.psiStructureViewFactory
      language="Simple"
      implementationClass="org.intellij.sdk.language.SimpleStructureViewFactory"/>
</extensions>

Run the Project

Run the project by using the Gradle runIde task.

Open the test.simple file and open View | Tool Windows | Structure. The IDE now supports a structure view of the Simple Language:

Structure View