Hello Everybody,
I am trying to create tree data structure using C++ and Rcpp and use it
from R.
I want to incrementally build the tree by merging a tree with other tress.
So, I created a class for the tree and a class for the nodes in the tree.
The tree class has two constructors, the first one simply creates a tree
with a single leaf. The second constructor takes two external pointers
pointing to two trees and creates a new tree be joining the two trees with
a new node. In the R side I create a tree (tree1) and repeatedly add
another tree (tree2) in the first tree. Here is the C++ and R code.
#include <Rcpp.h>
class treeNode
{
public:
treeNode* left;
treeNode* right;
};
class tree
{
private:
treeNode* root;
public:
tree();
tree(SEXP, SEXP);
SEXP getPointer();
void addTree(SEXP ptr2);
};
tree::tree()
{
root = new treeNode;
root->left = NULL;
root->right = NULL;
}
// merge two tree and create a new tree
tree::tree(SEXP ptr1, SEXP ptr2)
{
Rcpp::XPtr<tree> tree1(ptr1);
Rcpp::XPtr<tree> tree2(ptr2);
root = new treeNode;
root->left = tree1->root;
root->right = tree2->root;
}
SEXP tree::getPointer()
{
Rcpp::XPtr<tree> ptr(this, true);
return ptr;
}
RCPP_MODULE(yada){
using namespace Rcpp ;
class_<tree>("tree")
.constructor()
.constructor<SEXP, SEXP>("create a new tree by merging two
existing trees")
.method("getPointer", &tree::getPointer, "getPointer")
;
}
I created a package called test and then call the functions from R side
The R code looks like the following:
require(test)
t1 = new(tree)
t2 = new(tree)
t1 = new(tree, t1$getPointer(), t2$getPointer())
gc()
t2 = new(tree)
t1 = new(tree, t1$getPointer(), t2$getPointer())
gc()
After second garbage collector call I am getting segmentation fault . Can
you please explain the right way to program this scenario? In particular,
when a C++ object is still used by another object through pointer how can I
prevent R garbage collector removing the object ?
Thanks
Ariful Azad
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