摘要:

AbstractThis paper presents a lexical analyser for inflected Arabic words. An augmented transition network (ATN) technique was used to represent the context‐sensitive knowledge about the relation between a stem and inflectional additions. An exhaustive‐search algorithm is developed to traverse the ATN, generating all possible interpretations of an inflected Arabic word. The arcs of the ATN are augmented with rules containing conditions and actions. More than one rule is associated with some arcs. The states of the ATN are represented by Pascal procedu

ISSN:0038-0644    

DOI:10.1002/spe.4380230602

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractProgrammers spend considerable time debugging code. Symbolic debuggers provide some help but the task remains complex and difficult. Other than breakpoints and tracing, these tools provide little high‐level help. Programmers must perform many tasks manually that the tools could perform automatically, such as finding which statements in the program affect the value of an output variable for a given test case, and what was the value of a given variable when the control last reached a given program location. If debugging tools provided explicit support for these tasks, the debugging process could be automated to a significant extent.In this paper we present a debugging model, based on dynamic program slicing and execution backtracking techniques, that easily lends itself to automation. This model is based on experience with using these techniques to debug software. We also present a prototype debugging tool, SPYDER, that explicitly supports the proposed model, and with which we are performing further debugging researc

ISSN:0038-0644    

DOI:10.1002/spe.4380230603

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe acceptance of the C programming language by academia and industry is partially responsible for the ‘software crisis’. The simple, trusting semantics of C mask many common faults, such as range violations, which would be detected and reported at run‐time by programs coded in a robust language such as Ada.Ada is a registered trademark of the U.S. Government (Ada Joint Program Office)This needlessly complicates the debugging of C programs. Although the assert macro lets programmers add run‐time consistency checks to their programs, the number of instantiations of this macro needed to make a C program robust makes it highly unlikely that any programmer could correctly perform the task. We make some unobtrusive extensions to the C language which support the efficient detection of faults at run‐time without reducing the readability of the source code. Examples of the extensions are automatic checking of error codes returned by library routines, constrained subtypes and detection of references to uninitialized and/or non‐existent arr

ISSN:0038-0644    

DOI:10.1002/spe.4380230604

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSpecifications of information systems applications are often based on the use of entity‐relationship (ER) and data‐flow diagrams (DFD), which cover, respectively, the conceptual modelling of data and funtions. This paper introduces VLP: an executable visual language for formal specifications and prototyping which integrates ER and DFD diagrams in a semantically rigorous and clear way. Unlike existing commercial products (so‐called CASE tools), which can support good‐quality documentation, simple forms of consistency checking and bookkeeping, VLP also supports executable specifications, which provide a prototype of the desired application. After reviewing the principles of VLP, the paper outlines the structure of the ECASET environment in which VLP is embedded. In particular, it shows how the environment supports the stepwise derivation of specifications, from informal to formal, and how it supports specification‐in

ISSN:0038-0644    

DOI:10.1002/spe.4380230605

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper describes the object‐oriented design of a novel application, for control of complex theatricalset effects defined by an appropriate language. Besides giving a general description of the proposed system, the paper presents the language and its programming environment, which is intended for inexperienced users and integrates facilities to create, edit, check and run the effect scripts. The description of the implementation demonstrates the relevance of an object‐oriented approach when it is associated with compiler techniques. The object paradigm is used to build support classes such as character streams, run‐time values or symbols as well as syntactic objects. Each syntactic‐object class models a different LL(1) grammar non‐terminal and allows for an object‐oriented predictive parsing. Moreover, organizing the instances of these classes as an object‐based parse tree simplifies parsing, unparsing, syntax‐directed editing, syntax‐directed help, interpretation, etc. The description of these various operations shows the flexibility of our method, e.g. with respect to an iterative prototyping of the language an

ISSN:0038-0644    

DOI:10.1002/spe.4380230606

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper, we present the design of an operating‐system emulator. This software interface provides the services of one operating system (Oberon) on a machine running a different operating system (Macintosh), by mapping the functions of the first onto equivalent calls to the second. The construction of this emulator proceeded in four distinct phases, documented here through examples from each of these phases. We believe that our four‐phase approach can be beneficial whenever a larger software system needs to be adapted from one architecture onto another. In conclusion, we relate some of the lessons learned and propose guidelines for similar engineering proje

ISSN:0038-0644    

DOI:10.1002/spe.4380230607

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0038-0644    

DOI:10.1002/spe.4380230601

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY