For maintainers involved in understanding and reengineering large software, locating source code fragments that match certain patterns is a critical task. Existing solutions to the problem are few, and they either involve manual, painstaking scans of the source code using tools based on regular expressions, or the use of large, integrated software engineering environments that include simple patternbased query processors in their toolkits. We present a framework in which pattern languages are used to specify interesting code features. The pattern languages are derived by extending the source programming language with pattern-matching symbols. We describe SCRUPLE, a finite state machine-based source code search tool, that efficiently implements this framework. We also present experimental performance results obtained from a SCRUPLE prototype, and the user interface of a source code browser built on top of SCRUPLE. Keywords: Reverse engineering, software maintenance, software reengineer...

The Jakarta Tool Suite (JTS) aims to reduce substantially the cost of generator development by providing domainindependent tools for creating domain-specific languages and component-based generators called GenVoca generators. JTS is a set of precompiler-compiler tools for extending industrial programming languages (e.g., Java) with domain-specific constructs. JTS is itself a GenVoca generator, where precompilers for JTS-extended languages are constructed from components.

We present an approach for the generation of components for a software renovation factory. These components are generated from a context-free grammar definition that recognizes the code that has to be renovated. We generate analysis and transformation components that can be instantiated with a specific transformation or analysis task. We apply our approach to COBOL and we discuss the construction of realistic software renovation components using our approach.

Several real-world problems call for more parsing power than is offered by the widely used and well-established deterministic parsing techniques. These techniques also create an artificial divide between lexical and context-free analysis phases, at the cost of significant complexity at their interface. In this paper we present the fusion of generalized LR parsing and scannerless parsing. This combination supports syntax definitions in which all aspects (lexical and context-free) of the syntax of a language are defined explicitly in one formalism. Furthermore, there are no restrictions on the class of grammars, thus allowing a natural syntax tree structure. Ambiguities that arise through the use of unrestricted grammars are handled by explicit disambiguation constructs, instead of implicit defaults that are taken by traditional scanner and parser generators. Hence, a syntax definition becomes a full declarative description of a language. Disambiguation constructs can be interpreted as filters on parse forests. Depending on the kind of disambiguation, filters can be applied at parser generation time, at parse time, or after parsing. Scannerless generalized LR parsing is a viable technique that has been applied in various industrial and academic projects.

Software engineers maintaining an existing software system often depend on the mechanized extraction of information from system artifacts. Some useful kinds of information—source models—are well known: call graphs, file dependences, etc. Predicting every kind of source model that a software engineer may need is impossible. We have developed a lightweight approach for generating flexible and tolerant source model extractors from lexical specifications. The approach is lightweight in that the specifications are relatively small and easy to write. It is flexible in that there are few constraints on the kinds of artifacts from which source models are extracted (e.g., we can extract from source code, structured data files, documentation, etc.). It is tolerant in that there are few constraints on the condition of the artifacts. For example, we can extract from source that cannot necessarily be compiled. Our approach extends the kinds of source models that can be easily produced from lexical information while avoiding the constraints and brittleness of most parser-based approaches. We have developed tools to support this approach and applied the tools to the extraction of a number of different source models (file dependences, event interactions, call graphs) from a variety of system artifacts (C, C��, CLOS, Eiffel, TCL, structured data). We discuss our approach and describe

Meta programs manipulate structured representations, i.e., abstract syntax trees, of programs. The conceptual distance between the concrete syntax meta-programmers use to reason about programs and the notation for abstract syntax manipulation provided by general pur- pose (meta-) programming languages is too great for many applications. In this paper it is shown how the syntax definition formalism SDF can be employed to fit any meta-programming language with concrete syn- tax notation for composing and analyzing object programs. As a case study, the addition of concrete syntax to the program transformation language Stratego is presented. The approach is then generalized to arbitrary meta-languages.

We evaluate the parsing technology used by people working in the reengineering industry. We discuss parser generators and complete systems like Yacc, TXL, TAMPR, REFINE, CobolTransformer, COSMOS, and ASF+SDF. We explain the merits and drawbacks of the various techniques. We conclude that current technology may cause problems for the reengineering industry and that modular and/or compositional parsing techniques are a possible solution. Categories and Subject Description: D.2.6 [Software Engineering ]: Programming Environments---Interactive; D.2.7 [Software Engineering]: Distribution and Maintenance--- Restructuring; D.3.4. [Processors]: Parsing. Additional Key Words and Phrases: Reengineering, System renovation, Parsing, Generalized LR parsing, compositional grammars, modular grammars. 1 Introduction A hardly controversial statement in the reengineering community is that in order to reengineer software it is convenient to parse it. Maybe due to the overall agreement on this issue, ...

Term rewriting is an appealing technique for performing program analysis and program transformation. Tree (term) traversal is frequently used but is not supported by standard term rewriting.

TXL is a special-purpose programming language designed for creating, manipulating and rapidly prototyping language descriptions, tools and applications. TXL is designed to allow explicit programmer control over the interpretation, application, order and backtracking of both parsing and rewriting rules. Using first order functional programming at the higher level and term rewriting at the lower level, TXL provides for flexible programming of traversals, guards, scope of application and parameterized context. This flexibility has allowed TXL users to express and experiment with both new ideas in parsing, such as robust, island and agile parsing, and new paradigms in rewriting, such as XML markup, rewriting strategies and contextualized rules, without any change to TXL itself. This paper outlines the history, evolution and concepts of TXL with emphasis on its distinctive style and philosophy, and gives examples of its use in expressing and applying recent new paradigms in language processing.

TXL is a special-purpose programming language designed for creating, manipulating and rapidly prototyping language descriptions, tools and applications. TXL is designed to allow explicit programmer control over the interpretation, application, order and backtracking of both parsing and rewriting rules. Using first order functional programming at the higher level and term rewriting at the lower level, TXL provides for flexible programming of traversals, strategies, guards, scope of application and parameterized context. This flexibility has allowed TXL users to express and experiment with both new ideas in parsing, such as robust, island and agile parsing, and new paradigms in rewriting, such as XML markup, rewriting strategies and contextualized rules, without any change to TXL itself. In this paper I outline the history, evolution and concepts of TXL with emphasis on what makes it di#erent from other language manipulation tools, and give examples of its use in expressing and applying recent new paradigms in language processing.