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From: rose@.UUCP
Newsgroups: comp.lang.c++
Subject: Re: Yacc and lex with C++; is it possible?
Message-ID: <3271@think.UUCP>
Date: Sat, 4-Apr-87 14:40:14 EST
Article-I.D.: think.3271
Posted: Sat Apr  4 14:40:14 1987
Date-Received: Sun, 5-Apr-87 12:36:22 EST
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Reply-To: rose@think.com (John Rose)
Organization: Thinking Machines Corporation, Cambridge, MA
Lines: 29

Clifford Beshers writes:
>How well do yacc and lex work with C++?  Are there major problems, minor
>kludges.  Must yacc and lex be re-written in C++, and, if so, has this been
>done?

We use both Yacc and Lex with C++.  The Makefile is vanilla,
except for a line which says "CC = CC".  There is only one glitch,
which you may not care about:  If the YYSTYPE is a union of
types which have constructors, you've got to change it to
a struct, and probably give it an explicit member-wise operator=.

(Reason:  C++ supports guaranteed initialization.  The flip
side of this is that C++ will not trust the programmer with
uninitialized objects [when the type has G.I.], and so there's
no way to say "trust me, this union object contains a Foo,
and the Bar of it can stay uninitialized."  Yacc type-checks
your use of the union, so it should be trust-worthy.)

Making the union into a struct amounts to allocating separate
stacks, one for each type.

----------------------------------------------------------
John R. Rose                 Thinking Machines Corporation
245 First St., Cambridge, MA  02142         (617) 876-1111
rose@think.arpa				  ihnp4!think!rose
----------------------------------------------------------
John R. Rose                 Thinking Machines Corporation
245 First St., Cambridge, MA  02142         (617) 876-1111
rose@think.arpa				  ihnp4!think!rose