C is a general-purpose programming language. It has been closely associated with the UNIX operating system where it was developed, since both the system and most of the programs that run on it are written in C. The language, however, is not tied to any one operating system or machine; and although it has been called a ‘‘system programming language’’ because it is useful for writing compilers and operating systems, it has been used equally well to write major programs in many different domains. Many of the important ideas of C stem from the language BCPL, developed by Martin Richards. The influence of BCPL on C proceeded indirectly through the language B, which was written by Ken Thompson in 1970 for the first UNIX system on the DEC PDP-7. BCPL and B are ‘‘typeless’’ languages. By contrast, C provides a variety of data types. The fundamental types are characters, and integers and floating point numbers of several sizes. In addition, there is a hierarchy of derived data types created with pointers, arrays, structures and unions. Expressions are formed from operators and operands; any expression, including an assignment or a function call, can be a statement. Pointers provide for machine-independent address arithmetic. C provides the fundamental control-flow constructions required for well-structured programs: statement grouping, decision making (if-else), selecting one of a set of possible values (switch), looping with the termination test at the top (while, for) or at the bottom (do), and early loop exit (break). Functions may return values of basic types, structures, unions, or pointers. Any function may be called recursively. Local variables are typically ‘‘automatic’’, or created anew with each invocation. Function definitions may not be nested but variables may be declared in a block-structured fashion. The functions of a C program may exist in separate source files that are compiled separately. Variables may be internal to a function, external but known only within a single source file, or visible to the entire program.

Traditional file system development is difficult. Stackable file systems promise to ease the development of file systems by offering a mechanism for incremental development. Unfortunately, existing methods often require writing complex low-level kernel code that is specific to a single operating system platform and also difficult to port. We propose a new language, FiST, to describe stackable file systems. FiST uses operations common to file system interfaces. From a single description, FiST’s compiler produces file system modules for multiple platforms. The generated code handles many kernel details, freeing developers to concentrate on the main issues of their file systems. This paper describes the design, implementation, and evaluation of FiST. We extended file system functionality in a portable way without changing existing kernels. We built several file systems using FiST on Solaris, FreeBSD, and Linux. Our experiences with these examples shows the following benefits of FiST: average code size over other stackable file systems is reduced ten times; average development time is reduced seven times; performance overhead of stacking is 1–2%. 1

Grammarware comprises grammars and all grammar-dependent software, i.e., software artifacts that directly involve grammar knowledge. The term grammar is meant here in the widest sense to include XML schemas, syntax definitions, interface descriptions, APIs, and interaction protocols. The most obvious examples of grammar-dependent software are document processors, parsers, import/export functionality, and generative programming tools. Even though grammarware is so omnipresent, it is somewhat neglected --- from an engineering point of view. We lay out an agenda that is meant to promote research on improving the quality of grammarware and on increasing the productivity of grammarware development.

this paper, we introduce the ANTLR (ANother Tool for Language Recognition) parser generator, which addresses all these issues. ANTLR is a component of the Purdue Compiler Construction Tool Set (PCCTS)

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.

The Transmogrifier C hardware description language is almost identical to the C programming language, making it attractive to the large community of C-language programmers. This paper describes the semantics of the language and presents a Transmogrifier C compiler that targets the Xilinx 4000 FPGA. The compiler is operational and has produced several working circuits, including a graphics display driver.

research relevant to the design and application of high performance scientific computers. We test our ideas by designing, building, and using real systems. The systems we build are research prototypes; they are not intended to become products. There is a second research laboratory located in Palo Alto, the Systems Research Center (SRC). Other Digital research groups are located in Paris (PRL) and in Cambridge,

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, ...

We describe our experience building a fault-tolerant data-base using the Paxos consensus algorithm. Despite the existing literature in the field, building such a database proved to be non-trivial. We describe selected algorithmic and engineering problems encountered, and the solutions we found for them. Our measurements indicate that we have built a competitive system. 1