Fwd: [PATCH] Add support for resetting '__file__' and '__line__'.

[Raphael 'kena' Poss]

Dear all,

I posted the mail below to m4-patches a while ago, but I haven't seen any 
reaction; did my mail server do anything wrong?

Begin doorgestuurd bericht:

> Van: Raphael 'kena' Poss <address@hidden>
> Datum: 6 oktober 2010 22:59:43 GMT+02:00
> Aan: address@hidden
> Onderwerp: [PATCH] Add support for resetting '__file__' and '__line__'.
> 
> Please review the patch below.
> 
> Context:
> 
> Op 3 jul 2009, om 15:37 heeft Raphaël “Kena” Poss het volgende geschreven:
> 
>> as part of a project I am looking for ways to perform context-insensitive 
>> but parameterized substitutions on C code.  It happens that m4 delivers well 
>> for what I need to do. Except for the following.
>> [...] using m4 after the C preprocessor mostly works, but then m4 does not 
>> recognize the location markers (#line) inserted by the preprocessor and 
>> therefore most m4 errors are reported at an incorrect location, and 
>> multi-line expansions cause m4 to use wrong relative numbers in new 
>> synclines. [...]
>> I tried a possible route forward by replacing any occurrence of "#line X" in 
>> the m4 input by m4_define(`__line__', X), but unfortunately that doesn't 
>> seem to help. Is there an option to allow __line__ (and __file__) to be 
>> reset by macros?
> 
> Patch:
> 
> * src/input.c (reset_line, reset_file): Add functions to reset the
> current location.
> * src/m4.h: Declare them.
> * src/builtin.c (m4___file__, m4___line__): Use them.
> 
> * doc/m4.texinfo (Location): Document the new feature. Add a
> test.
> * NEWS: Document the new feature.
> ---
> ChangeLog      |   12 ++++++++++++
> NEWS           |    2 ++
> doc/m4.texinfo |   39 ++++++++++++++++++++++++++++++++++-----
> src/builtin.c  |   26 ++++++++++++++++++++------
> src/input.c    |   19 +++++++++++++++++++
> src/m4.h       |    5 +++++
> 6 files changed, 92 insertions(+), 11 deletions(-)
> 
> diff --git a/ChangeLog b/ChangeLog
> index 5e5889e..9761fb0 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,15 @@
> +2010-10-06  Raphael 'kena' Poss  <address@hidden>
> +
> +     Add support for resetting '__file__' and '__line__'.
> +     * src/input.c (reset_line, reset_file): Add functions to reset the
> +     current location.
> +     * src/m4.h: Declare them.
> +     * src/builtin.c (m4___file__, m4___line__): Use them.
> +
> +     * doc/m4.texinfo (Location): Document the new feature. Add a
> +     test.
> +     * NEWS: Document the new feature.
> +
> 2010-08-30  Eric Blake  <address@hidden>
> 
>       Clean up compiler warnings.
> diff --git a/NEWS b/NEWS
> index 1afe792..c45462a 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -3,6 +3,8 @@ GNU M4 NEWS - User visible changes.
> * Noteworthy changes in Version 1.6 (????-??-??) [stable]
>   Released by ????, based on git versions 1.4.10b.x-* and 1.5.*
> 
> +** Add support for resetting '__file__' and '__line__'.
> +
> ** Fix regressions introduced in 1.4.10b:
> *** Using `builtin' or `indir' to perform nested `shift' calls triggered
>     an assertion failure (not present in 1.4.11).
> diff --git a/doc/m4.texinfo b/doc/m4.texinfo
> index 91b8e00..c803c35 100644
> --- a/doc/m4.texinfo
> +++ b/doc/m4.texinfo
> @@ -7779,11 +7779,12 @@
> Line numbers start at 1 for each file.  If the file was found due to the
> @option{-I} option or @env{M4PATH} environment variable, that is
> reflected in the file name.  The syncline option (@option{-s},
> address@hidden features, , Invoking m4}), and the
> address@hidden and @samp{l} flags of @code{debugmode} (@pxref{Debugmode}),
> -also use this notion of current file and line.  Redefining the three
> -location macros has no effect on syncline, debug, warning, or error
> -message output.
> address@hidden features, , Invoking m4}), and the @samp{f} and
> address@hidden flags of @code{debugmode} (@pxref{Debugmode}), also use this
> +notion of current file and line.  Redefining the three location macros
> +has no effect on syncline, debug, warning, or error message output,
> +although the line numbers and file names can be reset as described
> +below.
> 
> This example reuses the file @file{incl.m4} mentioned earlier
> (@pxref{Include}):
> @@ -7841,6 +7842,34 @@
> @result{}12
> @end example
> 
> +The @address@hidden and @address@hidden macros take an optional
> +argument which allow to reset the current input file name and line
> +number, respectively. If @option{-s} is enabled, a synchronization line
> +will be emitted at the next newline in the input. Input line numbers
> +will autoincrement from the new value, and the file name will stay
> +active for the current input source until the input source is exhausted
> +or the name is reset again. This feature can be used when the input to
> +M4 already contains synchronization information, as when M4 is used as a
> +filter between a preprocessor and a compiler.
> +
> address@hidden options: -s
> address@hidden
> +$ @kbd{m4 -s}
> +foo __line__(42)bar __line__
> +baz __line__
> +__line__
> address@hidden 1 "stdin"
> address@hidden bar 42
> address@hidden 43
> address@hidden 43
> address@hidden
> +foo __file__(`newname')bar __file__
> +baz __file__
> address@hidden bar newname
> address@hidden 46 "newname"
> address@hidden newname
> address@hidden example
> +
> The @address@hidden macro behaves like @samp{$0} in shell
> terminology.  If you invoke @code{m4} through an absolute path or a link
> with a different spelling, rather than by relying on a @env{PATH} search
> diff --git a/src/builtin.c b/src/builtin.c
> index bc0cde2..fd57970 100644
> --- a/src/builtin.c
> +++ b/src/builtin.c
> @@ -1613,17 +1613,31 @@ m4_errprint (struct obstack *obs, int argc, 
> macro_arguments *argv)
> static void
> m4___file__ (struct obstack *obs, int argc, macro_arguments *argv)
> {
> -  bad_argc (arg_info (argv), argc, 0, 0);
> -  obstack_grow (obs, curr_quote.str1, curr_quote.len1);
> -  obstack_grow (obs, current_file, strlen (current_file));
> -  obstack_grow (obs, curr_quote.str2, curr_quote.len2);
> +  bad_argc (arg_info (argv), argc, 0, 1);
> +  if (argc > 1)
> +    reset_file (ARG (1));
> +  else
> +    {
> +      obstack_grow (obs, curr_quote.str1, curr_quote.len1);
> +      obstack_grow (obs, current_file, strlen (current_file));
> +      obstack_grow (obs, curr_quote.str2, curr_quote.len2);
> +    }
> }
> 
> static void
> m4___line__ (struct obstack *obs, int argc, macro_arguments *argv)
> {
> -  bad_argc (arg_info (argv), argc, 0, 0);
> -  shipout_int (obs, current_line);
> +  int line;
> +
> +  bad_argc (arg_info (argv), argc, 0, 1);
> +  if (argc > 1)
> +    {
> +      if (!numeric_arg (arg_info (argv), ARG (1), ARG_LEN (1), &line))
> +     return;
> +      reset_line (line);
> +    }
> +  else
> +    shipout_int (obs, current_line);
> }
> 
> static void
> diff --git a/src/input.c b/src/input.c
> index 04f0991..316d4bd 100644
> --- a/src/input.c
> +++ b/src/input.c
> @@ -2226,3 +2226,22 @@ lex_debug (void)
>     print_token ("lex", t, &td);
> }
> #endif /* DEBUG_INPUT */
> +
> +/*---------------------------------.
> + | Reset the current line counter. |
> + `--------------------------------*/
> +void reset_line(int line)
> +{
> +  isp->line = line;
> +  input_change = true;
> +}
> +
> +/*-------------------------------.
> + | Reset the current file title. |
> + `------------------------------*/
> +void reset_file(const char *title)
> +{
> +  isp->file = (char *) obstack_copy0 (&file_names, title, strlen (title));
> +  output_current_line = -1;
> +  input_change = true;
> +}
> diff --git a/src/m4.h b/src/m4.h
> index d333c24..b2662ef 100644
> --- a/src/m4.h
> +++ b/src/m4.h
> @@ -565,6 +565,11 @@ void expand_format (struct obstack *, int, 
> macro_arguments *);
> void produce_frozen_state (const char *);
> void reload_frozen_state (const char *);
> 
> +/* File: input.c --- input sources.  */
> +
> +void reset_line (int);
> +void reset_file (const char *);
> +
> /* Debugging the memory allocator.  */
> 
> #ifdef WITH_DMALLOC
> -- 
> 1.7.2.3
> 
> 
> 
> 
> _______________________________________________
> M4-patches mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/m4-patches