Re: How to parse and call c++ constructors?

Detlef Meyer-Eltz <Meyer-Eltz@t-online.de>
18 Sep 2005 00:43:36 -0400

          From comp.compilers

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From: Detlef Meyer-Eltz <Meyer-Eltz@t-online.de>
Newsgroups: comp.compilers
Date: 18 Sep 2005 00:43:36 -0400
Organization: Compilers Central
References: 05-09-072
Keywords: C++, parse

> Given a file,:


> A {
> B {
> text="cucu"
> }
> }


> So, to show the actions too:
> A { <-- a =new A();
> B { <-- a->_b =new B();
> text="cucu" <-- a->_b->text = $2;
> }
> }


> How can this be done without errors?




I assume, that you used a yacc grammar for parsing your file. Please
excuse, that I can't really help you with yacc, but I cannot resist to
take your example as a demonstration of a statement, which I just made
here a week ago: the integration of semantic code in LL-parsers is a
very intuitive task. Your example could be implemented by the
TextTransformer as follows:


A[aptr a] ::=


"A" {_ a =new A(); _}
"{"
B[a->_b]
"}"




B[bptr b] ::=


"B" {_ b =new B(); _}
"{"
"text" "=" STRING
{_
// the text is the first sub-expression of STRING
b->text = new char[State.length(1) + 1];
strcpy(b->text, State.str(1).c_str());
_}
"}"


( To make it more general, you could use a factory, which delivers an
adequate class pointer to a class name. )


Regards


Detlef Meyer-Eltz




--
mailto:Meyer-Eltz@t-online.de


url: http://www.texttransformer.de
url: http://www.texttransformer.com


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