95 lines
3.8 KiB
Plaintext
95 lines
3.8 KiB
Plaintext
.\" Copyright (C) Caldera International Inc. 2001-2002. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions are
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.\" met:
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.\"
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.\" Redistributions of source code and documentation must retain the above
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.\" copyright notice, this list of conditions and the following
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.\" disclaimer.
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.\"
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.\" Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\"
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.\" This product includes software developed or owned by Caldera
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.\" International, Inc. Neither the name of Caldera International, Inc.
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.\" nor the names of other contributors may be used to endorse or promote
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.\" products derived from this software without specific prior written
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.\" permission.
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.\"
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.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
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.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) RISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
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.\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" @(#)ss.. 8.1 (Berkeley) 6/8/93
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.\"
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.\" $FreeBSD$
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.EH 'PSD:15-%''Yacc: Yet Another Compiler-Compiler'
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.OH 'Yacc: Yet Another Compiler-Compiler''PSD:15-%'
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.\".RP
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.ND "July 31, 1978"
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.TL
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Yacc:
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Yet Another Compiler-Compiler
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.AU "MH 2C-559" 3968
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Stephen C. Johnson
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AT&T Bell Laboratories
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Murray Hill, New Jersey 07974
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.AI
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.AB
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.PP
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Computer program input generally has some structure;
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in fact, every computer program that does input can be thought of as defining
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an ``input language'' which it accepts.
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An input language may be as complex as a programming language, or as simple as
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a sequence of numbers.
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Unfortunately, usual input facilities
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are limited, difficult to use,
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and often are lax about checking their inputs for validity.
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.PP
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Yacc provides a general tool for describing
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the input to a computer program.
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The Yacc user specifies the structures
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of his input, together with code to be invoked as
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each such structure is recognized.
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Yacc turns such a specification into a subroutine that
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handles the input process;
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frequently, it is convenient and appropriate to have most
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of the flow of control in the user's application
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handled by this subroutine.
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.PP
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The input subroutine produced by Yacc calls a user-supplied routine to
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return the next basic input item.
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Thus, the user can specify his input in terms of individual input characters, or
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in terms of higher level constructs such as names and numbers.
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The user-supplied routine may also handle idiomatic features such as
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comment and continuation conventions, which typically defy easy grammatical specification.
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.PP
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Yacc is written in portable C.
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The class of specifications accepted is a very general one: LALR(1)
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grammars with disambiguating rules.
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.PP
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In addition to compilers for C, APL, Pascal, RATFOR, etc., Yacc
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has also been used for less conventional languages,
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including a phototypesetter language, several desk calculator languages, a document retrieval system,
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and a Fortran debugging system.
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.AE
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.\" .OK
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.\"Computer Languages
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.\"Compilers
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.\"Formal Language Theory
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.\" .CS 23 11 34 0 0 8
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