c interfaces and implementations techniques for creating reusable software

LINK DOWNLOAD MIỄN PHÍ TÀI LIỆU "c interfaces and implementations techniques for creating reusable software": http://123doc.vn/document/558247-c-interfaces-and-implementations-techniques-for-creating-reusable-software.htm

Addison-Wesley Professional Computing Series
Brian W. Kernighan, Consulting Editor
Ken Arnold/John Peyton, A C User’s Guide to ANSI C
Tom Cargill, C++ Programming Style
William R. Cheswick/Steven M. Bellovin, Firewalls and Internet Security: Repelling
the Wily Hacker
David A. Curry, UNIX® System Security: A Guide for Users and System
Administrators
Erich Gamma/Richard Helm/Ralph Johnson/John Vlissides, Design Patterns:
Elements of Reusable Object-Oriented Software
David R. Hanson, C Interfaces and Implementations: Techniques for Creating
Reusable Software
John Lakos, Large Scale C++ Software Design
Scott Meyers, Effective C++: 50 Specific Ways to Improve Your Programs and
Designs
Scott Meyers, More Effective C++: 35 New Ways to Improve Your Programs and
Designs
Robert B. Murray, C++ Strategies and Tactics
David R. Musser/Atul Saini, STL Tutorial and Reference Guide: C++ Programming
with the Standard Template Library
John K. Ousterhout, Tcl and the Tk Toolkit
Craig Partridge, Gigabit Networking
J. Stephen Pendergrast Jr., Desktop KornShell Graphical Programming
Radia Perlman, Interconnections: Bridges and Routers
David M. Piscitello/A. Lyman Chapin, Open Systems Networking: TCP/IP and OSI
Stephen A. Rago, UNIX® System V Network Programming
Curt Schimmel, UNIX® Systems for Modern Architectures: Symmetric
Multiprocessing and Caching for Kernel Programmers
W. Richard Stevens, Advanced Programming in the UNIX® Environment
W. Richard Stevens, TCP/IP Illustrated, Volume 1: The Protocols
W. Richard Stevens, TCP/IP Illustrated, Volume 3: TCP for Transactions, HTTP,
NNTP, and the UNIX Domain Protocols
Gary R. Wright/W. Richard Stevens, TCP/IP Illustrated, Volume 2: The
Implementation
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

David R. Hanson
Princeton University
▲
▼▼
ADDISON-WESLEY
An imprint of Addison Wesley Longman, Inc.
Reading, Massachusetts
•
Harlow, England
•
Menlo Park, California
Berkeley, California
•
Don Mills, Ontario
•
Sydney
Bonn
•
Amsterdam
•
Tokyo
•
Mexico City
I
MPLEMENTATIONS
I
NTERFACES
C
AND
Techniques for Creating
Reusable Software
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Licensed by
Frank Liu
1740749

This book was prepared from camera-ready copy supplied by the author.
Many of the designations used by manufacturers and sellers to distinguish their
products are claimed as trademarks. Where those designations appear in this
book and Addison Wesley Longman, Inc. was aware of a trademark claim, the
designations have been printed in initial caps or all caps.
The authors and publishers have taken care in the preparation of this book, but
make no expressed or implied warranty of any kind and assume no responsibility
for errors or omissions. No liability is assumed for incidental or consequential
damages in connection with or arising out of the use of the information or
programs contained herein.
The publisher offers discounts on this book when ordered in quantity for special
sales.
For more information, please contact:
Corporate & Professional Publishing Group
Addison Wesley Longman, Inc.
One Jacob Way
Reading, Massachusetts 01867
Library of Congress Cataloging-in-Publication Data
Hanson, David R.
C interfaces and implementations : techniques for creating
reusable software / David R. Hanson.
p. cm. –– (Addison-Wesley professional computing series)
Includes bibliographical references and index.
ISBN 0-201-49841-3 (pbk.)
1. C (Computer program language) 2. Computer software–
–Reusability I. Title. II. Series.
QA76.73.C15H37 1996
005.13'3––dc20 96-28817
CIP
Copyright © 1997 by David R. Hanson.
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form, or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior written
permission of the publisher.
Printed in the United States of America. Published simultaneously in Canada.
Text design by Wilson Graphics & Design (Kenneth J. Wilson).
Text printed on recycled and acid-free paper.
ISBN 0-201-49841-3
2 3 4 5 6 7 8 9 10-MA-00999897
Second printing, January 1997
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

xi
P
REFACE
rogrammers are inundated with information about application pro-
gramming interfaces, or APIs. Yet, while most programmers use
APIs and the libraries that implement them in almost every appli-
cation they write, relatively few create and disseminate new, widely
applicable, APIs. Indeed, programmers seem to prefer to “roll their own”
instead of searching for a library that might meet their needs, perhaps
because it is easier to write application-specific code than to craft well-
designed APIs.
I’m as guilty as the next programmer: lcc, a compiler for ANSI/ISO C
written by Chris Fraser and myself, was built from the ground up. (lcc is
described in A Retargetable C Compiler: Design and Implementation,
Addison-Wesley, 1995.) A compiler exemplifies the kind of application
for which it is possible to use standard interfaces and to create inter-
faces that are useful elsewhere. Examples include interfaces for memory
management, string and symbol tables, and list manipulation. But lcc
uses only a few routines from the standard C library, and almost none of
its code can be used directly in other applications.
This book advocates a design methodology based on interfaces and
their implementations, and it illustrates this methodology by describing
24 interfaces and their implementations in detail. These interfaces span
a large part of the computing spectrum and include data structures,
arithmetic, string processing, and concurrent programming. The imple-
mentations aren’t toys — they’re designed for use in production code. As
described below, the source code is freely available.
There’s little support in the C programming language for the interface-
based design methodology. Object-oriented languages, like C++ and
Modula-3, have language features that encourage the separation of an
interface from its implementation. Interface-based design is independent
of any particular language, but it does require more programmer will-
power and vigilance in languages like C, because it’s too easy to pollute
an interface with implicit knowledge of its implementation and vice
versa.
P
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

xii
PREFACE
Once mastered, however, interface-based design can speed develop-
ment time by building upon a foundation of general-purpose interfaces
that can serve many applications. The foundation class libraries in some
C++ environments are examples of this effect. Increased reuse of existing
software — libraries of interface implementations — reduces initial
development costs. It also reduces maintenance costs, because more of
an application rests on well-tested implementations of general-purpose
interfaces.
The 24 interfaces come from several sources, and all have been
revised for this book. Some of the interfaces for data structures —
abstract data types — originated in lcc code, and in implementations of
the Icon programming language done in the late 1970s and early 1980s
(see R. E. Griswold and M. T. Griswold, The Icon Programming Language,
Prentice Hall, 1990). Others come from the published work of other pro-
grammers; the “Further Reading” sections at the end of each chapter give
the details.
Some of the interfaces are for data structures, but this is not a data
structures book, per se. The emphasis is more on algorithm engineering
— packaging data structures for general use in applications — than on
data-structure algorithms. Good interface design does rely on appropri-
ate data structures and efficient algorithms, however, so this book com-
plements traditional data structure and algorithms texts like Robert
Sedgewick’s Algorithms in C (Addison-Wesley, 1990).
Most chapters describe one interface and its implementation; a few
describe related interfaces. The “Interface” section in each chapter gives
a concise, detailed description of the interface alone. For programmers
interested only in the interfaces, these sections form a reference manual.
A few chapters include “Example” sections, which illustrate the use of
one or more interfaces in simple applications.
The “Implementation” section in each chapter is a detailed tour of the
code that implements the chapter’s interface. In a few cases, more than
one implementation for the same interface is described, which illustrates
an advantage of interface-based design. These sections are most useful
for those modifying or extending an interface or designing related inter-
faces. Many of the exercises explore design and implementation alterna-
tives. It should not be necessary to read an “Implementation” section in
order to understand how to use an interface.
The interfaces, examples, and implementations are presented as liter-
ate programs; that is, the source code is interleaved with its explanation
in an order that best suits understanding the code. The code is extracted
automatically from the text files for this book and assembled into the
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

ORGANIZATION
xiii
order dictated by the C programming language. Other book-length exam-
ples of literate programming in C include A Retargetable C Compiler and
The Stanford GraphBase: A Platform for Combinatorial Computing by
D. E. Knuth (Addison-Wesley, 1993).
Organization
The material in this book falls into the following broad categories:
Most readers will benefit from reading all of Chapters 1 through 4,
because these chapters form the framework for the rest of the book. The
remaining chapters can be read in any order, although some of the later
chapters refer to their predecessors.
Chapter 1 covers literate programming and issues of programming
style and efficiency. Chapter 2 motivates and describes the interface-
based design methodology, defines the relevant terminology, and tours
two simple interfaces and their implementations. Chapter 3 describes
Foundations 1. Introduction
2. Interfaces and Implementations
4. Exceptions and Assertions
5. Memory Management
6. More Memory Management
Data Structures 7. Lists
8. Tables
9. Sets
10. Dynamic Arrays
11. Sequences
12. Rings
13. Bit Vectors
Strings 3. Atoms
14. Formatting
15. Low-Level Strings
16. High-Level Strings
Arithmetic 17. Extended-Precision Arithmetic
18. Arbitrary-Precision Arithmetic
19. Multiple-Precision Arithmetic
Threads 20. Threads
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

xiv
PREFACE
the prototypical Atom interface, which is the simplest production-quality
interface in this book. Chapter 4 introduces exceptions and assertions,
which are used in every interface. Chapters 5 and 6 describe the memory
management interfaces used by almost all the implementations. The rest
of the chapters each describe an interface and its implementation.
Instructional Use
I assume that readers understand C at the level covered in undergradu-
ate introductory programming courses, and have a working understand-
ing of fundamental data structures at the level presented in texts like
Algorithms in C. At Princeton, the material in this book is used in sys-
tems programming courses from the sophomore to first-year graduate
levels. Many of the interfaces use advanced C programming techniques,
such as opaque pointers and pointers to pointers, and thus serve as non-
trivial examples of those techniques, which are useful in systems pro-
gramming and data structure courses.
This book can be used for courses in several ways, the simplest being
in project-oriented courses. In a compiler course, for example, students
often build a compiler for a toy language. Substantial projects are com-
mon in graphics courses as well. Many of the interfaces can simplify the
projects in these kinds of courses by eliminating some of the grunt pro-
gramming needed to get such projects off the ground. This usage helps
students realize the enormous savings that reuse can bring to a project,
and it often induces them to try interface-based design for their own
parts of the project. This latter effect is particularly valuable in team
projects, because that’s a way of life in the “real world.”
Interfaces and implementations are the focus of Princeton’s sopho-
more-level systems programming course. Assignments require students
to be interface clients, implementors, and designers. In one assignment,
for example, I distribute Section 8.1’s Table interface, the object code
for its implementation, and the specifications for Section 8.2’s word fre-
quency program, wf. The students must implement wf using only my
object code for Table. In the next assignment, they get the object code
for wf, and they must implement Table. Sometimes, I reverse these
assignments, but both orders are eye-openers for most students. They
are unaccustomed to having only object code for major parts of their
program, and these assignments are usually their first exposure to the
semiformal notation used in interfaces and program specification.
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

INSTRUCTIONAL USE
xv
Initial assignments also introduce checked runtime errors and asser-
tions as integral parts of interface specifications. Again, it takes a few
assignments before students begin to appreciate the value of these con-
cepts. I forbid “unannounced” crashes; that is, crashes that are not
announced by an assertion failure diagnostic. Programs that crash get a
grade of zero. This penalty may seem unduly harsh, but it gets the stu-
dents’ attention. They also gain an appreciation of the advantages of safe
languages, like ML and Modula-3, in which unannounced crashes are
impossible. (This grading policy is less harsh than it sounds, because in
multipart assignments, only the offending part is penalized, and differ-
ent assignments have different weights. I’ve given many zeros, but none
has ever caused a course grade to shift by a whole point.)
Once students have a few interfaces under their belts, later assign-
ments ask them to design new interfaces and to live with their design
choices. For example, one of Andrew Appel’s favorite assignments is a
primality testing program. Students work in groups to design the inter-
faces for the arbitrary-precision arithmetic that is needed for this assign-
ment. The results are similar to the interfaces described in Chapters 17
through 19. Different groups design interfaces, and a postassignment
comparison of these interfaces, in which the groups critique one
anothers’ work, is always quite revealing. Kai Li accomplishes similar
goals with a semester-long project that builds an X-based editor using
the Tcl/Tk system (J. K. Ousterhout, Tcl and the Tk Toolkit, Addison-
Wesley, 1994) and editor-specific interfaces designed and implemented
by the students. Tk itself provides another good example of interface-
based design.
In advanced courses, I usually package assignments as interfaces and
give the students free rein to revise and improve on them, and even to
change the goals of the assignment. Giving them a starting point reduces
the time required for assignment, and allowing substantial changes
encourages creative students to explore alternatives. The unsuccessful
alternatives are often more educational than the successful ones. Stu-
dents invariably go down the wrong road, and they pay for it with greatly
increased development time. When, in hindsight, they understand their
mistakes, they come to appreciate that designing good interfaces is hard,
but worth the effort, and they almost always become converts to
interface-based design.
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

xvi
PREFACE
How to Get the Software
The software in this book has been tested on the following platforms:
A few of the implementations are machine-specific; they assume that the
machine has two’s-complement integer and IEEE floating-point arith-
metic, and that unsigned longs can hold object pointers.
The source code for everything in this book is available for anony-
mous ftp at ftp.cs.princeton.edu in pub/packages/cii. Use an ftp
client to connect to ftp.cs.princeton.edu, change to the directory
pub/packages/cii, and download the file README, which describes the
contents of the directory and how to download the distribution.
The most recent distributions are usually in files with names like
ciixy.tar.gz or ciixy.zip, where xy is the version number; for exam-
ple, 10 is version 1.0. ciixy.tar.gz is a U
NIX
tar file compressed with
gzip, and ciixy.zip is a ZIP file compatible with PKZIP version 2.04g.
The files in ciixy.zip are DOS/Windows text files; that is, their lines
end with carriage returns and linefeeds. ciixy.zip may also be available
on America Online, CompuServe, and other online services.
Information is also available on the World Wide Web at the URL
http://www.cs.princeton.edu/software/cii/. This page includes
instructions on reporting bugs.
processor operating systems compilers
SPARC SunOS 4.1 lcc 3.5
gcc 2.7.2
Alpha OSF/1 3.2A lcc 4.0
gcc 2.6.3
cc
MIPS R3000 IRIX 5.3 lcc 3.5
gcc 2.6.3
cc
MIPS R3000 Ultrix 4.3 lcc 3.5
gcc 2.5.7
Pentium Windows 95
Windows NT 3.51
Microsoft Visual C/C++ 4.0
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.

ACKNOWLEDGMENTS
xvii
Acknowledgments
I have been using some of the interfaces in this book for my own
research projects and in courses at the University of Arizona and Prince-
ton University since the late 1970s. Students in these courses have been
guinea pigs for my drafts of these interfaces. Their feedback over the
years has been an important contribution to both the code in this book
and its explanation. The Princeton students in several offerings of COS
217 and COS 596 deserve special thanks, because they suffered unknow-
ingly through the drafts of most of what’s in this book.
Interfaces are a way of life at Digital’s System Research Center (SRC),
and my 1992 and 1993 summers at SRC working on the Modula-3 project
erased any doubts I may have harbored about the efficacy of this
approach. My thanks to SRC for supporting my visits, and to Bill Kalsow,
Eric Muller, and Greg Nelson for many illuminating discussions.
My thanks to IDA’s Centers for Communications Research in Princeton
and La Jolla for their support during the summer of 1994 and during my
1995–96 sabbatical. The CCRs provided ideal hideouts at which to plan
and complete this book.
Technical interactions with colleagues and students have contributed
to this book in many ways. Even seemingly unrelated discussions have
provoked improvements in my code and in its explanation. Thanks to
Andrew Appel, Greg Astfalk, Jack Davidson, John Ellis, Mary Fernández,
Chris Fraser, Alex Gounares, Kai Li, Jacob Navia, Maylee Noah, Rob Pike,
Bill Plauger, John Reppy, Anne Rogers, and Richard Stevens. Careful
readings of my code and prose by Rex Jaeschke, Brian Kernighan, Taj
Khattra, Richard O’Keefe, Norman Ramsey, and David Spuler made a sig-
nificant contribution to the quality of both.
David R. Hanson
C Interfaces and Implementations: Techniques for Creating Reusable Software. C Interfaces and Implementations: Techniques for Creating Reusable Software, ISBN: 9780321562807
Prepared for frliu@microsoft.com, Frank Liu
Copyright © 1997 by David R. Hanson This download file is made available for personal use only and is subject to the Terms of Service. Any other use requires prior written consent from
the copyright owner. Unauthorized use, reproduction and/or distribution are strictly prohibited and violate applicable laws. All rights reserved.
Licensed by
Frank Liu
1740749