how to use libcpp (GCC c lexer)

how to use libcpp (GCC c lexer)

[Giovanni Gherdovich]

Hi all.

Is anybody familiar with the GCC lexer, locate at libcpp/lex.c in the
GCC source tree?
http://gcc.gnu.org/viewcvs/trunk/libcpp/
http://gcc.gnu.org/onlinedocs/cppinternals/Lexer.html#Lexer

I'd like to do lexical analysis on some C source code for educational purposes,
but I am having troubles in finding entry points to the libcpp library.

As I read at http://gcc.gnu.org/onlinedocs/cppinternals/Lexer.html#Lexer ,
cpp_get_token() should be the main API call, defined at libcpp/macro.c ,
but I can't locate client code in GCC sources (which is, where the
lexer is called),
nor testcases that could illustrate me, for instance,
how to cook the input to get it into a cpp_reader struct
(the type required for cpp_get_token()'s input).

So: what's the entry point to libcpp? Where do I find examples of calls, if any?

Cheers,
Giovanni

PS: please CC your reply to me, since I am not a subscriber of gcc-help.

Re: how to use libcpp (GCC c lexer)

[Ian Lance Taylor]

On Tue, Oct 9, 2012 at 8:33 AM, Giovanni Gherdovich
<g.gherdovich@gmail.com> wrote:
>
> Is anybody familiar with the GCC lexer, locate at libcpp/lex.c in the
> GCC source tree?
> http://gcc.gnu.org/viewcvs/trunk/libcpp/
> http://gcc.gnu.org/onlinedocs/cppinternals/Lexer.html#Lexer
>
> I'd like to do lexical analysis on some C source code for educational purposes,
> but I am having troubles in finding entry points to the libcpp library.
>
> As I read at http://gcc.gnu.org/onlinedocs/cppinternals/Lexer.html#Lexer ,
> cpp_get_token() should be the main API call, defined at libcpp/macro.c ,
> but I can't locate client code in GCC sources (which is, where the
> lexer is called),
> nor testcases that could illustrate me, for instance,
> how to cook the input to get it into a cpp_reader struct
> (the type required for cpp_get_token()'s input).
>
> So: what's the entry point to libcpp? Where do I find examples of calls, if any?

In current mainline, the main call from gcc to libcpp is in
gcc/c-family/c-lex.c, which calls cpp_get_token and
cpp_get_token_with_location.  The cpp_reader is set up by the call to
cpp_create_reader in c_common_init_options in c-family/c-opts.c.

Ian

Re: how to use libcpp (GCC c lexer)

[Giovanni Gherdovich]

Hello Ian,

2012/10/9 Ian Lance Taylor <iant@google.com>:
> [...]
> In current mainline, the main call from gcc to libcpp is in
> gcc/c-family/c-lex.c, which calls cpp_get_token and
> cpp_get_token_with_location.  The cpp_reader is set up by the call to
> cpp_create_reader in c_common_init_options in c-family/c-opts.c.
>
> Ian

thank you very much for your answer.

Cheers,
Giovanni