摘要:

AbstractResearch on the aesthetic layout of trees has been largely concerned with the special case of binary trees with small constant‐sized nodes. Yet, without otherwise requiring the power of general graph‐layout algorithms, many layout problems involven‐ary trees with variable‐sized nodes. This paper addresses the general issue of the aesthetic layout of such trees. Two algorithms are presented for the layout of generalized trees, and general issues, such as appropriate aesthetics, are discussed. The algorithms described are suitable for such tasks as the layout of class hierarchies, directory trees and tableau‐sty

ISSN:0038-0644    

DOI:10.1002/spe.4380230802

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractOf the parser generating tools currently in use, yacc (or one of its several variants) is perhaps the most frequently employed. However, because of inherent ambiguities there are some languages (such as C++) that a yacc‐generated parser cannot successfully compile. This paper describes a set of minor modifications to yacc‐like tools that allows them to be used in a straightforward way to parse ambiguities and, more generally, grammars that require an indefinite amount of lookahead. Required changes to the lexical analyzer are also discussed, and the application of these techniques is illustrated within the context of specific examp

ISSN:0038-0644    

DOI:10.1002/spe.4380230803

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe allocation and disposal of memory is a ubiquitous operation in most programs. Rarely do programmers concern themselves with details of memory allocators; most assume that memory allocators provided by the system perform well. Yet, in some applications, programmers use domain‐specific knowledge in an attempt to improve the speed or memory utilization of memory allocators.In this paper, we describe a program (CustoMalloc) that synthesizes a memory allocator customized for a specific application. Our experiments show that the synthesized allocators are uniformly faster and more space efficient than the Berkeley UNIX allocator. Constructing a custom allocator requires little programmer effort, usually taking only a few minutes. Experience has shown that the synthesized allocators are not overly sensitive to properties of input sets and the resulting allocators are superior even to domain‐specific allocators designed by programmers. Measurements show that synthesized allocators are from two to ten times faster than widely‐used alloc

ISSN:0038-0644    

DOI:10.1002/spe.4380230804

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractMany applications of graphical man‐machine interfaces require incremental update of an image, with controllable time granularity, having multiple views of the information, generated by modular, maintainable software having minimal resource overhead. A technique called differential evaluation is presented that addresses these needs. Instead of driving the display from a data structure, it uses anad‐hocdisplay procedure in conjunction with a FIFO cache to generate and maintain the display. Maintaining displays of variable structure is accomplished through the use of conditional mechanisms in the display procedure. The technique has been extended to meet many different needs, such as the use of graphic contexts, display of overlapping objects, double‐buffering, and a variety of user input schemes. The efficiency of the technique, in time and storage, permits its use with modest equipment. It has been used for several years in a number of industrial user inter

ISSN:0038-0644    

DOI:10.1002/spe.4380230805

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

Abstract‘Pictures that play’ are design diagrams that give enough visual cues to enable a person to trace causality sequences that cut across them, without referring to (or even knowing) the kind of details that would enable a tool to execute the design or to generate executable code. Playing design diagrams is particularly important while exploring alternative solutions during the early stages of designing all kinds of systems. It is done either by mentally tracing sequences across diagrams on paper or a computer screen, or physically tracing them on whiteboards with a pointer or finger during design meetings. Two complementary pictorial design notations are described and used together in an example to illustrate the concept of play and to show how to do it:timethreads, a new notation for causality sequences that cut across many components and across the system end‐to‐end, andmachine charts, an older notation for architecture presented here from a new angle. These notations are specifically designed to support play during the design process, not just record the end result. The focus is on real‐time and distributed (RTD) systems, but the approach has wider appl

ISSN:0038-0644    

DOI:10.1002/spe.4380230806

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

ISSN:0038-0644    

DOI:10.1002/spe.4380230801

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY