PageUp and PageDown navigate sections, chunks in Rmd/Rpres

src/gwt/src/org/rstudio/core/client/js/JsUtil.java

@@ -90,6 +90,39 @@ public void remove()
          }
       };
    }
+
+   public static <T extends JavaScriptObject> Iterable<T> asReverseIterable(final JsArray<T> array)
+   {
+      return new Iterable<T>()
+      {
+         @Override
+         public Iterator<T> iterator()
+         {
+            return new Iterator<T>()
+            {
+               int index_ = array.length() - 1;
+
+               @Override
+               public boolean hasNext()
+               {
+                  return index_ > 0;
+               }
+
+               @Override
+               public T next()
+               {
+                  return array.get(index_--);
+               }
+
+               @Override
+               public void remove()
+               {
+                  throw new UnsupportedOperationException();
+               }
+            };
+         }
+      };
+   }
 
    public static boolean areEqual(JsArrayString a, JsArrayString b)
    {

src/gwt/src/org/rstudio/studio/client/common/filetypes/TextFileType.java

@@ -359,6 +359,9 @@ public HashSet<AppCommand> getSupportedCommands(Commands commands)
       {
          results.add(commands.toggleDocumentOutline());
       }
+
+      results.add(commands.goToNextSection());
+      results.add(commands.goToPrevSection());
       results.add(commands.findReplace());
       results.add(commands.findNext());
       results.add(commands.findPrevious());

src/gwt/src/org/rstudio/studio/client/workbench/commands/Commands.cmd.xml

@@ -487,6 +487,8 @@ well as menu structures (for main menu and popup menus).
          <shortcut refid="shrinkSelection" value="Ctrl+Shift+Down" if="!org.rstudio.core.client.BrowseCap.isMacintosh()"/>
          <shortcut refid="expandSelection" value="Cmd+Alt+Shift+Up" if="org.rstudio.core.client.BrowseCap.isMacintosh()"/>
          <shortcut refid="shrinkSelection" value="Cmd+Alt+Shift+Down" if="org.rstudio.core.client.BrowseCap.isMacintosh()"/>
+         <shortcut refid="goToNextSection" value="PageDown"/>
+         <shortcut refid="goToPrevSection" value="PageUp"/>
          <shortcut value="Cmd+Alt+Up" title="Add cursor above current cursor"/>
          <shortcut value="Cmd+Alt+Down" title="Add cursor below current cursor"/>
          <shortcut value="Ctrl+Alt+Shift+Up" title="Move active cursor up"/>
@@ -1283,6 +1285,14 @@ well as menu structures (for main menu and popup menus).
         menuLabel="Shrink Selection"
         desc="Shrink selection"
         context="editor"/>
+
+   <cmd id="goToNextSection"
+        label="Go to Next Section"
+        context="editor"/>
+
+   <cmd id="goToPrevSection"
+        label="Go to Previous Section"
+        context="editor"/>
 
    <cmd id="expandRaggedSelection"
         label="Expand Ragged Selection"

src/gwt/src/org/rstudio/studio/client/workbench/commands/Commands.java

@@ -107,6 +107,8 @@
    public abstract AppCommand toggleDocumentOutline();
    public abstract AppCommand expandSelection();
    public abstract AppCommand shrinkSelection();
+   public abstract AppCommand goToNextSection();
+   public abstract AppCommand goToPrevSection();
    public abstract AppCommand expandRaggedSelection();
    public abstract AppCommand extractFunction();
    public abstract AppCommand extractLocalVariable();

src/gwt/src/org/rstudio/studio/client/workbench/views/source/Source.java

@@ -322,6 +322,8 @@ public Source(Commands commands,
       dynamicCommands_.add(commands.shrinkSelection());
       dynamicCommands_.add(commands.toggleDocumentOutline());
       dynamicCommands_.add(commands.knitWithParameters());
+      dynamicCommands_.add(commands.goToNextSection());
+      dynamicCommands_.add(commands.goToPrevSection());
       for (AppCommand command : dynamicCommands_)
       {
          command.setVisible(false);

src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/AceEditor.java

@@ -1854,6 +1854,16 @@ public boolean isCursorInSingleLineString()
    {
       return StringUtil.isEndOfLineInRStringState(getCurrentLineUpToCursor());
    }
+
+   public void gotoPageUp()
+   {
+      widget_.getEditor().gotoPageUp();
+   }
+
+   public void gotoPageDown()
+   {
+      widget_.getEditor().gotoPageDown();
+   }
 
    public void scrollToBottom()
    {

src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/DocDisplay.java

@@ -201,6 +201,9 @@ DocDisplay.AnchoredSelection createAnchoredSelection(Position start,
    void scrollCursorIntoViewIfNecessary(int rowsAround);
    boolean isCursorInSingleLineString();
 
+   void gotoPageDown();
+   void gotoPageUp();
+
    void ensureRowVisible(int row);
 
    InputEditorSelection search(String needle,

src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/ScopeList.java

@@ -15,6 +15,7 @@
 package org.rstudio.studio.client.workbench.views.source.editors.text;
 
 import com.google.gwt.core.client.JsArray;
+
 import org.rstudio.core.client.StringUtil;
 import org.rstudio.core.client.js.JsUtil;
 import org.rstudio.studio.client.workbench.views.source.editors.text.ace.Range;
@@ -104,6 +105,16 @@ public Scope[] getScopes()
    {
       return scopes_.toArray(new Scope[scopes_.size()]);
    }
+
+   public Scope get(int index)
+   {
+      return scopes_.get(index);
+   }
+
+   public int size()
+   {
+      return scopes_.size();
+   }
 
    public void removeAll(ScopePredicate shouldRemove)
    {

src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/TextEditingTarget.java

@@ -746,6 +746,90 @@ public void onDocTabDragStateChanged(
             });
    }
 
+   private boolean moveCursorToNextSectionOrChunk()
+   {
+      Scope current = docDisplay_.getCurrentScope();
+      ScopeList scopes = new ScopeList(docDisplay_);
+      Position cursorPos = docDisplay_.getCursorPosition();
+
+      int n = scopes.size();
+      for (int i = 0; i < n; i++)
+      {
+         Scope scope = scopes.get(i);
+         if (!(scope.isChunk() || scope.isSection()))
+            continue;
+
+         if (scope.equals(current))
+            continue;
+
+         if (scope.getPreamble().isAfter(cursorPos))
+         {
+            if (scope.getPreamble().getRow() - cursorPos.getRow() < 50)
+            {
+               docDisplay_.setCursorPosition(scope.getPreamble());
+               return true;
+            }
+            return false;
+         }
+      }
+
+      return false;
+   }
+
+   private boolean moveCursorToPreviousSectionOrChunk()
+   {
+      ScopeList scopes = new ScopeList(docDisplay_);
+      Position cursorPos = docDisplay_.getCursorPosition();
+
+      int n = scopes.size();
+      for (int i = n - 1; i >= 0; i--)
+      {
+         Scope scope = scopes.get(i);
+         if (!(scope.isChunk() || scope.isSection()))
+            continue;
+
+         if (scope.getPreamble().isBefore(cursorPos))
+         {
+            if (cursorPos.getRow() - scope.getPreamble().getRow() < 50)
+            {
+               docDisplay_.setCursorPosition(scope.getPreamble());
+               return true;
+            }
+            return false;
+         }
+      }
+
+      return false;
+   }
+
+   @Handler
+   void onGoToNextSection()
+   {
+      if (docDisplay_.getFileType().isRmd() || docDisplay_.getFileType().isRpres())
+      {
+         if (!moveCursorToNextSectionOrChunk())
+            docDisplay_.gotoPageDown();
+      }
+      else
+      {
+         docDisplay_.gotoPageDown();
+      }
+   }
+
+   @Handler
+   void onGoToPrevSection()
+   {
+      if (docDisplay_.getFileType().isRmd() || docDisplay_.getFileType().isRpres())
+      {
+         if (!moveCursorToPreviousSectionOrChunk())
+            docDisplay_.gotoPageUp();
+      }
+      else
+      {
+         docDisplay_.gotoPageUp();
+      }
+   }
+
    public void onExecuteUserCommand(final ExecuteUserCommandEvent event)
    {
       withSavedDoc(new Command()

src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/ace/AceEditorNative.java

@@ -239,7 +239,16 @@ private static native <T> JavaScriptObject addEventListenerInternal(
    private static native void invokeFunctor(JavaScriptObject functor) /*-{
       functor();
    }-*/;
+
+   public final native void scrollPageUp() /*-{ this.scrollPageUp(); }-*/;
+   public final native void scrollPageDown() /*-{ this.scrollPageDown(); }-*/;
 
+   public final native void gotoPageUp() /*-{ this.gotoPageUp(); }-*/;
+   public final native void gotoPageDown() /*-{ this.gotoPageDown(); }-*/;
+
+   public final native void selectPageUp() /*-{ this.selectPageUp(); }-*/;
+   public final native void selectPageDown() /*-{ this.selectPageDown(); }-*/;
+
    public final native void scrollToRow(int row) /*-{
       this.scrollToRow(row);
    }-*/;

src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/ace/Position.java

@@ -81,5 +81,10 @@ public native final void setPosition(Position position) /*-{
       this.row = position.row;
       this.column = position.column;
    }-*/;
+
+   public final String asString()
+   {
+      return "[" + getRow() + ", " + getColumn() + "]";
+   }
 
 }