Demangling C++ Names

March 26th, 2008 by Joe Ranieri

RuntimeException.stack is one of the most useful things to be added to REALbasic. However, we can make it a bit better by demangling any C++ function names that might be in the stack trace.

Function CPPDemangle(name as string) As string
  //! Demangles a C++ function name. Returns an empty string on failure.
  //! Only works on Mac OS X.
 
  #if targetMacOS
      declare function __cxa_demangle lib "/usr/lib/libstdc++.6.dylib" ( name as CString, _
      outBuffer as ptr, outLength as ptr, byref outState as integer ) as CString
    declare sub free lib "System" ( value as CString )
    const kStateSuccess = 0
 
    dim state as integer
    dim demangledString as CString = __cxa_demangle( name, nil, nil, state )
 
    if state = kStateSuccess then
      // create our RB string, then free the string demangle gave us
      dim result as string = demangledString
      free( demangledString )
 
      return result
    end if
  #endif
End Function

Then you can apply this function to the exception’s stack like so:

Function GetErrorStack(err as RuntimeException) As string()
  //! Gets the stack trace for our exception. This differs from
 //! RuntimeException.stack in that it demangles C++ names.
 
  // this can crash in some cases, giving us a completely useless crash log
  // <rb-feedback://keeqghwg>, hopefully this will be fixed someday...
  dim stack() as string = err.stack
  dim cleanedStack() as string
 
  // the order of RB's "for each" isn't defined <rb-feedback://hdcdbgfi>, so we have
  // to use a normal loop
  for i as integer = 0 to stack.ubound
    dim name as string = stack( i )
    dim demangledName as string = cppDemangle( name )
 
    if demangledName <> "" then
      cleanedStack.append( demangledName )
    else
      cleanedStack.append( name )
    end if
  next
 
  return cleanedStack
End Function

So, instead of seeing “__ZN14RuntimeListbox7GetTextE15getTextSelectorll” in an exception trace, you will see “RuntimeListbox::GetText(getTextSelector, long, long)“. Much, much easier on the eyes. :)


COMMENTS

One Response to “Demangling C++ Names”

  1. charles Says:

    This is most handy.

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