Exceptions: optional callback for exception throws.

This is to allow recording an error+stacktrace whenever an exception
is thrown, since that’s the point when the stack is interesting.

simgear/structure/exception.cxx

@@ -13,6 +13,8 @@
 
 #include <simgear/misc/sg_path.hxx>
 
+static ThrowCallback static_callback;
+
 ////////////////////////////////////////////////////////////////////////
 // Implementation of sg_location class.
 ////////////////////////////////////////////////////////////////////////
@@ -49,19 +51,7 @@ sg_location::sg_location (const char* path, int line, int column)
   setPath(path);
 }
 
-sg_location::~sg_location ()
+void sg_location::setPath(const char *path) {
-{
-}
-
-const char*
-sg_location::getPath () const
-{
-  return _path;
-}
-
-void
-sg_location::setPath (const char* path)
-{
   if (path) {
     strncpy(_path, path, max_path);
     _path[max_path -1] = '\0';
@@ -70,17 +60,9 @@ sg_location::setPath (const char* path)
   }
 }
 
-int
+const char *sg_location::getPath() const { return _path; }
-sg_location::getLine () const
-{
-  return _line;
-}
 
-void
+int sg_location::getLine() const { return _line; }
-sg_location::setLine (int line)
-{
-  _line = line;
-}
 
 int
 sg_location::getColumn () const
@@ -88,11 +70,6 @@ sg_location::getColumn () const
   return _column;
 }
 
-void
-sg_location::setColumn (int column)
-{
-  _column = column;
-}
 
 int
 sg_location::getByte () const
@@ -100,12 +77,6 @@ sg_location::getByte () const
   return _byte;
 }
 
-void
-sg_location::setByte (int byte)
-{
-  _byte = byte;
-}
-
 std::string
 sg_location::asString () const
 {
@@ -126,8 +97,8 @@ sg_location::asString () const
   return out.str();
 }
 
+bool sg_location::isValid() const { return strlen(_path) > 0; }
 
-
 ////////////////////////////////////////////////////////////////////////
 // Implementation of sg_throwable class.
 ////////////////////////////////////////////////////////////////////////
@@ -138,10 +109,14 @@ sg_throwable::sg_throwable ()
   _origin[0] = '\0';
 }
 
-sg_throwable::sg_throwable (const char* message, const char* origin)
+sg_throwable::sg_throwable(const char *message, const char *origin,
-{
+                           const sg_location &loc) {
   setMessage(message);
   setOrigin(origin);
+
+  if (static_callback) {
+    static_callback(_message, _origin, loc);
+  }
 }
 
 sg_throwable::~sg_throwable ()
@@ -228,16 +203,13 @@ sg_exception::sg_exception ()
 {
 }
 
-sg_exception::sg_exception (const char* message, const char* origin)
+sg_exception::sg_exception(const char *message, const char *origin,
-  : sg_throwable(message, origin)
+                           const sg_location &loc)
-{
+    : sg_throwable(message, origin, loc) {}
-}
 
 sg_exception::sg_exception(const std::string &message,
-                            const std::string& origin )
+                           const std::string &origin, const sg_location &loc)
-  : sg_throwable(message.c_str(), origin.c_str())
+    : sg_throwable(message.c_str(), origin.c_str(), loc) {}
-{
-}
 
 sg_exception::~sg_exception ()
 {
@@ -260,10 +232,7 @@ sg_io_exception::sg_io_exception (const char* message, const char* origin)
 sg_io_exception::sg_io_exception(const char *message,
                                  const sg_location &location,
                                  const char *origin)
-  : sg_exception(message, origin),
+    : sg_exception(message, origin, location), _location(location) {}
-    _location(location)
-{
-}
 
 sg_io_exception::sg_io_exception( const std::string& message,
                                   const std::string& origin )
@@ -274,10 +243,7 @@ sg_io_exception::sg_io_exception( const std::string& message,
 sg_io_exception::sg_io_exception(const std::string &message,
                                  const sg_location &location,
                                  const std::string &origin)
-  : sg_exception(message, origin),
+    : sg_exception(message, origin, location), _location(location) {}
-    _location(location)
-{
-}
 
 sg_io_exception::~sg_io_exception ()
 {
@@ -382,4 +348,9 @@ sg_range_exception::sg_range_exception(const std::string& message,
 sg_range_exception::~sg_range_exception ()
 {
 }
+
+////////////////////////////////////////////////////////////////////////
+
+void setThrowCallback(ThrowCallback cb) { static_callback = cb; }
+
 // end of exception.cxx

simgear/structure/exception.hxx

@@ -11,6 +11,7 @@
 #define __SIMGEAR_MISC_EXCEPTION_HXX 1
 
 #include <exception>
+#include <functional>
 #include <simgear/compiler.h>
 #include <string>
 
@@ -31,17 +32,20 @@ public:
   sg_location(const std::string& path, int line = -1, int column = -1);
   sg_location(const SGPath& path, int line = -1, int column = -1);
   explicit sg_location(const char* path, int line = -1, int column = -1);
-  virtual ~sg_location();
+
-  virtual const char* getPath() const;
+  ~sg_location() = default;
-  virtual void setPath (const char* path);
+
-  virtual int getLine () const;
+  const char *getPath() const;
-  virtual void setLine (int line);
+  int getLine() const;
-  virtual int getColumn () const;
+  int getColumn() const;
-  virtual void setColumn (int column);
+  int getByte() const;
-  virtual int getByte () const;
+
-  virtual void setByte (int byte);
+  std::string asString() const;
-  virtual std::string asString () const;
+  bool isValid() const;
+
 private:
+  void setPath(const char *p);
+
   char _path[max_path];
   int _line;
   int _column;
@@ -57,7 +61,9 @@ class sg_throwable : public std::exception
 public:
   enum {MAX_TEXT_LEN = 1024};
   sg_throwable ();
-  sg_throwable (const char* message, const char* origin = 0);
+  sg_throwable(const char *message, const char *origin = 0,
+               const sg_location &loc = {});
+
   virtual ~sg_throwable ();
   virtual const char* getMessage () const;
   virtual const std::string getFormattedMessage () const;
@@ -86,7 +92,7 @@ class sg_error : public sg_throwable
 public:
   sg_error ();
   sg_error (const char* message, const char* origin = 0);
-  sg_error (const std::string& message, const std::string& origin = "");  
+  sg_error(const std::string &message, const std::string &origin = {});
   virtual ~sg_error ();
 };
 
@@ -109,8 +115,10 @@ class sg_exception : public sg_throwable
 {
 public:
   sg_exception ();
-  sg_exception (const char* message, const char* origin = 0);
+  sg_exception(const char *message, const char *origin = 0,
-  sg_exception (const std::string& message, const std::string& = "");
+               const sg_location &loc = {});
+  sg_exception(const std::string &message, const std::string & = {},
+               const sg_location &loc = {});
   virtual ~sg_exception ();
 };
 
@@ -193,6 +201,17 @@ public:
   virtual ~sg_range_exception ();
 };
 
+using ThrowCallback = std::function<void(
+    const char *message, const char *origin, const sg_location &loc)>;
+
+/**
+ * @brief Specify a callback to be invoked when an exception is created.
+ *
+ * This is used to capture a stack-trace for our crash/error reporting system,
+ * if a callback is defined
+ */
+void setThrowCallback(ThrowCallback cb);
+
 #endif
 
 // end of exception.hxx