Member Avatar for shouvik.d

I want to write a parser for C++ which can extract methods and members pertaining to a particular class(es) in a CPP file. I used Parser Generattor tool by BumbleBee softwares and did all the project settings as required by them but still keep on getting fatal errors in Exception Class(of Visual Studio 6 Library).

Is there a proper tool wherein I can integrate lex and yacc with VC++ 6.0.

Urgent Help Required. Please help

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  • Latest Post Latest Post by Member #46692

Dani AI

Generated

Brief, practical guidance for the two problems shown in this thread (the scanner/input-type mismatch and the "untyped $$" semantic-value warnings), plus a few compatibility tips that actually work when you must stay on VC++ 6.0.

The input-type mismatch

  • The generated lexer in this thread appears to use a C++ stream pointer for its input while the caller is passing a C FILE. If the scanner's header declares an std::istream input, open the source with an std::ifstream and pass its address (matching the member name in the generated header). Do not try to cast a FILE to an istream; that is undefined and will fail to compile on VC6.
  • If you cannot change call sites, regenerate or reconfigure the generator to produce a C-style interface (FILE*), or edit the generated header to expose the input type you need. Also inspect the generated header first to confirm the exact member name and type before changing code.

Example (illustrative):

#include <fstream>

std::ifstream in("file.cpp");
if (!in.is_open()) { /* handle error */ }

/* If the scanner's API expects a C++ stream pointer, pass &in.
   Replace 'scanner.inputPtr' with the actual member name from the header. */
scanner.inputPtr = &in;
parser.parse();

The "untyped $$" / semantic-value problem

  • That warning means the parser has no declared semantic value type for the productions you use with $n/$$. Define a union (or use your generator's C++-value mechanism) and tag tokens/nonterminals with their field names so $$ is typed.
  • For old toolchains avoid putting non-POD C++ objects directly into a C union; use pointers (or switch to the parser's C++ API if available).

Example Bison/Yacc sketch:

%union {
  char *sval;
  ASTNode *node;
}

%token <sval> IDENT
%type  <node> class_decl member_decl

class_decl:
    CLASS IDENT '{' member_list '}' { $$ = new ClassNode($2, $4); }
;

Additional tips

  • Check the generated header for the exact names/types (input pointer, YYSTYPE/%union) before changing code. was correct to point at a stream-vs-FILE mismatch; 's suggestion to try a more modern compiler is pragmatic—VC6 has many STL/ABI quirks. If upgrading is impossible, prefer generating C-style lex/yacc code or use pointers for semantic values to keep things compatible.

Recommended Answers

All 10 Replies

Member Avatar for ithelp

Why not code in linux/unix env?

Member Avatar for shouvik.d

I can't shift to Linux becoz my existing project is in VC++ 6.0 and I've to add parsing functionality to it. Hence you can see the problem here.

Member Avatar for Ancient Dragon

maybe you should contact BumbleBee. Also possible that VC++ 6.0 is too old. You might try a more current compiler such as the free VC++ 2005 Express.

Member Avatar for Rashakil Fol

Perhaps you could use the Spirit parser combinator library instead.

Member Avatar for shouvik.d

Well the problem is not with Bumblebee. When I used a sample project from then also I faced the same error as mentioned below.

error C2440: '=' : cannot convert from 'struct _iobuf *' to 'class std::basic_istream<char,struct std::char_traits<char> > *'

for the code line

FILE   *temp,
         *f;
lexer.yyin = f;

lexer is the object of the class CLexRC wherein CLexRC loks like this in first line of the class

class YYEXPLEXER YYFAR CLexRC : public _YL yyclexer {

please help.

Member Avatar for Rashakil Fol

It's assigning an uninitialized FILE* to another value? There's something wrong with that picture. Anyway, it looks like the yyin member is of type std::basic_istream<char, struct std::char_traits<char> >*, and the code is trying to assign a FILE* to it. At least, that's what the error message says.

Member Avatar for shouvik.d

so how to type cast it. I'm understanding the error but as a matter of fact the CPP file is not manually written. it gets generated by Bumblebee Parser Generator. I saw this kind of file stream assignment to most of the projects

What shall I do ?:sweat:

Member Avatar for shouvik.d

I'm now able to run lex files fine but while utilizing the yacc stack descriptors like '$$' it is giving the following error:

warning Y4003: '$$' : attribute is untyped

thought this is a warning now. If I'm assigning anything to it or trying to use string copy then it is throwing an error.

please help.

Member Avatar for shouvik.d

please help. I'm not able to $$ at all. the error Untyped Attribute is repeated at any case.

PLease help me it is kind of urgent.

Member Avatar for Member #46692

Urgent, I'm sure. Maybe you should have started your homework earlier. He he.

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