Navigating Program Structure
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## Navigating Program Structure

Select nodes in the program structure by clicking them (see label 2). If one node is related to one or more other nodes by an association the name of the association will appear below that node and will be displayed in italics. Links to other structure nodes appear in blue below the association. If there is no corresponding source for the link it will appear light-blue.

### Example: Exploring the "Spacewar" sample code

- Launch `ajbrowser`

- Choose "File -> Open" or click the "Open Build Configuration" button () and select the configuration file for debugging the spacewar example, in `examples/spacewar/debug.lst`.

- Click the "Build" button () to compile. The left pane should fill with a spacewar declaration tree. If there is a compiler error, the clickable error message shows up as in label 4.

  Note: If you did not set up your classpath, the compile will fail with a message that you need to install aspectjrt.jar on your compile classpath. To do that, select "Tools -> Options" or click the "Options" button (). Click the `Build Options` tab to view the Build Paths pane. Edit the classpath entry to use your install location. For example, if you ran from the base Aspectj directory, the classpath need only include `lib/aspectjrt.jar` (though the browser may populate the classpath with the bootclasspath and classpath initially.) Be sure to use the `lib/aspectjrt.jar` that came with the browser.

  >

- Different structure views: The structure tree at the left can display different orderings and granularity for structure:

  - The package hierarchy view shows the traditional hierarchy of package, class, and members.

  - The inheritance view shows the hierarchy from topmost parent classes through subclasses to members.

  - The crosscutting view shows the aspect members and the code they affect.

  - Additional buttons in the pane can be used to change the granularity and filter out items.

  Whenever you select an item in the tree view, the source pane scrolls to that item. If you select a leaf item representing another program element, then the tree selection will go to the corresponding node. (See below for how to use two panes to maintain your place.)

- When working with aspects, it helps to be able to navigate between different program elements:

  - When looking at a method, find the advice that affects it.

  - When looking at a pointcut, find the advice that uses it.

  - When looking at advice, find what it advises - e.g., method calls or executions, initializers, etc.

  - When looking at a type, find any aspects that declare members or supertypes of the type, or vice-versa.

  You can view the advice on a particular method using the default, hierarchical view. Navigate to the tree item for `spacewar.Registry.register(SpaceObject)` in the `debug.lst` config file. Now, in the lower, file view, you can see and navigate to the advice using the subtree whose parent is the `method affected by` relation.

  You can also use crosscutting view to see the advice using a pointcut or the methods affected by advice. For example, to see what advice uses a particular pointcut, navigate to the tree item for the pointcut `spacewar.Debug.allConstructorsCut()` in the `debug.lst` config file. You can see and navigate to the advice that uses the pointcut using the `pointcut used by` relation.

  As an example of seeing the methods affected by advice, while still in the same view, select the first `before` advice in `spacewar.Debug`. It has relation sub-trees for both `uses pointcut` and `affects constructions`. The `affects` relations will list different kinds of join points - constructor or method calls, etc.

  Note that the AspectJ browser can only display static structure (whether hierarchical or crosscutting). That means that dynamicly-determined pointcuts (like `cflow(pointcut)`) will not be shown as picking out static points in source code. Displayable pointcuts roughly correspond to those that can be used in a `declare error` statement.

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