RGCCTranslationUnit: R interface to GCC source code information

Description Usage Arguments Author(s)

This function examines the body of a C/C++ routine or method and finds the references to variables that are neither parameters or declared within the body.

This requires that the TU contain information about the body of routine/methods. This typically requires compiling the code with g++, even if the code is regular C.

1	freeVariables(def, nodes, vars = list())

`def`	the node defining the routine (not the body)
`nodes`	the TU parser object providing the list of all the TU nodes
`vars`	this is a named list of variables that we pass from function to function as we process each expression and build up a collection of local variables that we have encountered within the scope.