RE/flex debug logs and assertions. More...

#include <cassert>
#include <cstdio>

Include dependency graph for debug.h:

This graph shows which files directly or indirectly include this file:

Macros
#define	ASSERT(c)
	If ASSERT not defined, make ASSERT a no-op. More...

#define	DBGXIFY(S) DBGIFY_(S)

#define	DBGIFY_(S) #S

#define	DBGFILE DBGXIFY(DEBUG) ".log"

#define	DBGSTR(S) (S?S:"(NULL)")

#define	_DBGLOG(...) ( REFLEX_DBGOUT_(DBGFILE, __FILE__, __LINE__), ::fprintf(REFLEX_DBGFD_, "" __VA_ARGS__), ::fflush(REFLEX_DBGFD_))

#define	_DBGLOGN(...) ( ::fprintf(REFLEX_DBGFD_, "\n " __VA_ARGS__), ::fflush(REFLEX_DBGFD_) )

#define	_DBGLOGA(...) ( ::fprintf(REFLEX_DBGFD_, "" __VA_ARGS__), ::fflush(REFLEX_DBGFD_) )

#define	DBGCHK(c) (void)0

#define	DBGLOG(...) (void)0

#define	DBGLOGN(...) (void)0

#define	DBGLOGA(...) (void)0

Functions
void	REFLEX_DBGOUT_ (const char log, const char file, int line)

Variables
FILE *	REFLEX_DBGFD_

Detailed Description

RE/flex debug logs and assertions.

Author: Robert van Engelen - engel.nosp@m.en@g.nosp@m.enivi.nosp@m.a.co.nosp@m.m

Copyright: (c) 2016-2020, Robert van Engelen, Genivia Inc. All rights reserved.; (c) BSD-3 License - see LICENSE.txt

Exploiting macro magic to simplify debug logging.

Usage

Enable macro DEBUG to debug the compiled source code:

Source files compiled with	DBGLOG(...) entry added to
`c++ -DDEBUG`	`DEBUG.log`
`c++ -DDEBUG=TEST`	`TEST.log`
`c++ -DDEBUG=`	`stderr`

DBGLOG(format, ...) creates a timestamped log entry with a printf-formatted message. The log entry is added to a log file or sent to stderr as specified:

DBGLOGN(format, ...) creates a log entry without a timestamp.

DBGLOGA(format, ...) appends the formatted string to the previous log entry.

DBGCHK(condition) calls assert(condition) when compiled in DEBUG mode.

The utility macro DBGSTR(const char *s) returns string s or "(null)" when s == NULL.

Note: to temporarily enable debugging a specific block of code without globally debugging all code, use a leading underscore, e.g. _DBGLOG(format, ...). This appends the debugging information to DEBUG.log.

Warning: Be careful to revert these statements by removing the leading underscore for production-quality code.

Example

#include <reflex/debug.h>
int main(int argc, char *argv[])
{
  FILE *fd;
  DBGLOG("Program start");
  if ((fd = fopen("foo.bar", "r")) == NULL)
  {
    DBGLOG("Error %d: %s ", errno, DBGSTR(strerror(errno)));
    for (int i = 1; i < argc; ++i)
      DBGLOGA(" %s", argv[1]);
  }
  else
  {
    DBGCHK(fd != NULL);
    // OK, so go ahead to read foo.bar ...
    // ...
    fclose(fd);
  }
  DBGLOG("Program end");
}

Compiled with -DDEBUG this example logs the following messages in DEBUG.log:

140201/225654.692194   example.cpp:11   Program has started
140201/225654.692564   example.cpp:15   Error 2: No such file or directory
140201/225654.692577   example.cpp:17   Program ended

The first column records the date (140201 is February 1, 2014) and the time (225654 is 10:56PM + 54 seconds) with microsecond fraction. The second column records the source code file name and the line number of the DBGLOG command. The third column shows the printf-formatted message.

The DEBUG.log file is created in the current directory when it does not already exist.

Techniques used:

Variadic macros with __VA_ARGS__.
Standard predefined macros __FILE__ and __LINE__.
Macro "stringification": expand content of macro DEBUG as a string in a macro body.
#if DEBUG + 0 to test whether macro DEBUG is set to a value, since DEBUG is 1 when set without a value (for example at the command line).
"" __VA_ARGS__ forces __VA_ARGS__ to start with a literal format string (printf security advisory).

Macro Definition Documentation

#define _DBGLOG ( ... ) ( REFLEX_DBGOUT_(DBGFILE, __FILE__, __LINE__), ::fprintf(REFLEX_DBGFD_, "" __VA_ARGS__), ::fflush(REFLEX_DBGFD_))

#define _DBGLOGA ( ... ) ( ::fprintf(REFLEX_DBGFD_, "" __VA_ARGS__), ::fflush(REFLEX_DBGFD_) )

#define _DBGLOGN ( ... ) ( ::fprintf(REFLEX_DBGFD_, "\n " __VA_ARGS__), ::fflush(REFLEX_DBGFD_) )

#define ASSERT ( c )

If ASSERT not defined, make ASSERT a no-op.

#define DBGCHK ( c ) (void)0

#define DBGFILE DBGXIFY(DEBUG) ".log"

#define DBGIFY_ ( S ) #S

#define DBGLOG ( ... ) (void)0

#define DBGLOGA ( ... ) (void)0

#define DBGLOGN ( ... ) (void)0

#define DBGSTR ( S ) (S?S:"(NULL)")

#define DBGXIFY ( S ) DBGIFY_(S)

Function Documentation

void REFLEX_DBGOUT_	(	const char *	log,
		const char *	file,
		int	line
	)

Variable Documentation

FILE* REFLEX_DBGFD_

Macros