AspectJ is a convenient Aspect-Oriented programming (AOP) extension of Java, which addresses cross-cutting concerns but breaks encapsulation. In this project, we analyze and visualize impacts caused by aspects. Impacts are classified by a new classification system, analyzed using static analyses, and visualized with an Eclipse plug-in. Thus, hidden effect of aspects can be understood and analyzed by programmers easily.

We presented different ways that advice and inter-type declarations can interfere with the state and computation of a base program and proposed a concise classification of impacts caused by them crosscutting the base program. We classified these impacts as

• state impacts --- which are caused by advice affecting the state of base program, and
• computation impacts --- which are caused by advice affecting the computation of base program,
• shadowing impacts --- which are caused by inter-type declarations affecting the field reference of base program, and
• lookup impacts --- which are caused by inter-type declarations affecting the method lookup of base program.

In addition, we further classified state impacts into direct state impacts and indirect state impacts; and classified computation impacts as addition, elimination, definite-substitution, conditional-substitution and mixed. Our definition of a base program follows the principle that ``everything except me'', and our tool covers interference between aspects naturally.

Based on this classification, we implemented static impact analyses in the abc compiler to analyze all kinds of advice and inter-type declarations. By using the points-to analysis and side-effect analysis supported by Soot, our impact analyses system can give precise estimations of impacts. Our approach also produces an informative analysis report. In the report, we not only report the impact information, but also report the causes of impacts, so we can guide the programmer to understand the key impacts of aspects on their program.

We also integrated these analyses into an IDE. We integrated our toolkit into Eclipse and produced an interactive tree-structure view of the report that both allows programmers to view the impacts in a more graphical manner and allows programmers to navigate directly to the parts of the source code involved in the impacts. In addition, we generate markers into the source code editor so that programmers can be aware of the impacts when browsing the source code. Moreover, we provide the function to link the impact report view to the current editing location in the source code editor so that programmers can focus on the impacts only related to the source code being edited.