ext_Ptr.cpp

#include "hphp/runtime/ext/extension.h"
#include "hphp/runtime/base/execution-context.h"
#include "hphp/runtime/vm/native-data.h"

void add(int *x, int *y, int *result) {
  *result = *x + *y;
}

namespace HPHP {

template<typename T>
struct SWIG_Ptr : public SweepableResourceData {
private:
  T* m_ptr;
public:
  DECLARE_RESOURCE_ALLOCATION(SWIG_Ptr)
  CLASSNAME_IS("SWIG_Ptr")
  const String& o_getClassNameHook() const override { return classnameof(); }

  explicit SWIG_Ptr(T* ptr) : m_ptr(ptr) {}
  virtual ~SWIG_Ptr() { close(); }
  void close() {
    if (m_ptr) {
      delete m_ptr;
    }
    m_ptr = nullptr;
  }
  T* get() { return m_ptr; }
};

template<typename T> inline void SWIG_Ptr<T>::sweep() { close(); }

Resource HHVM_FUNCTION(retPtr, int v) {
  int* r = new int;
  *r = v;
  return Resource(req::make<SWIG_Ptr<int>>(r));
}

int HHVM_FUNCTION(getVal, const Resource& a) {
  auto ta = dyn_cast_or_null<SWIG_Ptr<int>>(a);
  auto fa = ta->get();
  return *fa;
}

void HHVM_FUNCTION(add, const Resource& a, const Resource& b, const Resource& c) {
  auto ta = dyn_cast_or_null<SWIG_Ptr<int>>(a);
  auto fa = ta->get();
  auto tb = dyn_cast_or_null<SWIG_Ptr<int>>(b);
  auto fb = tb->get();  
  auto tc = dyn_cast_or_null<SWIG_Ptr<int>>(c);
  auto fc = tc->get();
  add(fa, fb, fc);
  // A return would be something like: return Resource(req::make<SWIG_Ptr<int>>(tc));
}

class PtrExtension : public Extension {
 public:
  PtrExtension(): Extension("Ptr", "1.0") {}
  void moduleInit() override {
    HHVM_FE(add);
    HHVM_FE(retPtr);
    HHVM_FE(getVal);
    loadSystemlib();
  }
} s_Ptr_extension;

HHVM_GET_MODULE(Ptr);
}

ext_Ptr.php

<?hh
<<__Native>>
function add(resource $a, resource $b, resource $c): void;

<<__Native>>
function retPtr(int $x): Resource;

<<__Native>>
function getVal(resource $x): int;

runme.php

<?php
	$a = retPtr(37);
	$b = retPtr(42);
	$c = retPtr(0);  // $c must be defined and not null.

	print "	a = ".getVal($a)."\n";
	print "	b = ".getVal($b)."\n";

	# Call the add() function wuth some pointers
	add($a, $b, $c);

	print " ".getVal($a)." + ".getVal($b)." = ".getVal($c)."\n";
?>