Global Program Analysis in an Interactive Environment SSL-80-1

This dissertation describes a programming tool, implemented in Lisp, called SCOPE. The basic idea behind SCOPE can be stated simply: SCOPE analyzes a user's programs, remembers what it sees, is able to answer questions based on the facts it remembers, and is able to incrementally update the data base when a piece of the program changes. A variety of program information is available about cross references, data flow and program organization. Facts about programs are stored in a data base: to answer a question, SCOPE retrieves and makes inferences based on information in the data base. SCOPE is interactive because it keeps track of which part of the programs have changed during the course of an editing and debugging session, and is able to automatically and incrementally update its data base. Because SCOPE performs whatever re-analysis is necessary to answer the question when the question is asked. SCOPE maintains the illusion that the data base is always up to date—other than the additional wait time, it is as if SCOPE knew the answer all along.
SCOPE'S foundation is a representation system in which properties of pieces of programs can be expressed. The objects of SCOPE'S language are pieces of programs, and in part, definitions of symbols—e.g., the definition of a procedure or a data structure. SCOPE does not model properties of individual statements or expressions in the program; SCOPE knows only individual facts about procedures variables data structures and other pieces of a program which can be assigned as the definition of symbols. The facts are relations between the name of a definition and other symbols. For example, one of the relations that SCOPE keeps track of is Call: Call[FN₁,FN₂] holds if the definition whose name is FN₁ contains a call to a procedure named FN₂.
SCOPE has two interfaces: one to the user and one to other programs. The user interface is an English-like command language which allows for a uniform command structure and convenient defaults: the most frequently used commands are the easiest to type. All of the power available with the command language is accessible through the program interface as well. The compiler and various other utilities use the program interface.