Introduce live tracing facility

Set LIBSASS_TRACE to any value
in the environment to watch
a very verbose output live.

Author: saper

Makefile.am

@@ -48,6 +48,7 @@ libsass_la_SOURCES = \
 	context.cpp context.hpp \
 	contextualize.cpp contextualize.hpp \
 	contextualize_eval.cpp contextualize_eval.hpp \
+	debug.cpp \
 	error_handling.cpp error_handling.hpp \
 	eval.cpp eval.hpp \
 	expand.cpp expand.hpp \

debug.cpp

@@ -0,0 +1,25 @@
+#include <stdio.h>
+#include <sstream>
+
+#include "debug.hpp"
+
+Log::Log() {} 
+
+std::ostringstream& Log::Get(TLogLevel level, void *p, const char *f, const char *filen, int lineno)
+{
+   os << "[LIBSASS] " << p << ":" << f << " " << filen << ":" << lineno << " ";
+   messageLevel = level;
+   return os;
+}
+std::ostringstream& Log::Get(TLogLevel level, const char *f, const char *filen, int lineno)
+{
+   os << "[LIBSASS] " << "] " << f << " " << filen << ":" << lineno << " ";
+   messageLevel = level;
+   return os;
+}
+Log::~Log()
+{
+   os << std::endl;
+   fprintf(stderr, "%s", os.str().c_str());
+   fflush(stderr);
+}

debug.hpp

@@ -16,6 +16,33 @@ enum dbg_lvl_t : uint32_t {
 	ALL = UINT32_MAX
 };
 
+enum TLogLevel {logINFO, logTRACE};
+static TLogLevel LogReportingLevel = getenv("LIBSASS_TRACE") ? logTRACE : logINFO;
+class Log
+{
+public:
+  Log();
+  virtual ~Log();
+  std::ostringstream& Get(TLogLevel level, void *p, const char *f, const char *filen, int lineno);
+  std::ostringstream& Get(TLogLevel level, const char *f, const char *filen, int lineno);
+public:
+protected:
+  std::ostringstream os;
+private:
+  Log(const Log&);
+  Log& operator =(const Log&);
+private:
+  TLogLevel messageLevel;
+};
+
+#define TRACE() \
+  if (logTRACE > LogReportingLevel) ; \
+  else Log().Get(logTRACE, __func__, __FILE__, __LINE__)
+
+#define TRACEINST(obj) \
+  if (logTRACE > LogReportingLevel) ; \
+  else Log().Get(logTRACE, (obj), __func__, __FILE__, __LINE__)
+
 #ifdef DEBUG
 
 #ifndef DEBUG_LVL