1 files changed, 70 insertions, 0 deletions
diff --git a/utils/int_or_pointer.h b/utils/int_or_pointer.h
new file mode 100755
index 00000000..4b6a9e4a
--- /dev/null
+++ b/utils/int_or_pointer.h
@@ -0,0 +1,70 @@
+#ifndef INT_OR_POINTER_H
+#define INT_OR_POINTER_H
+
+// if you ever wanted to store a discriminated union of pointer/integer without an extra boolean flag, this will do it, assuming your pointers are never odd.
+
+// check lsb for expected tag?
+#ifndef IOP_CHECK_LSB
+# define IOP_CHECK_LSB 1
+#endif
+#if IOP_CHECK_LSB
+# define iop_assert(x) assert(x)
+#else
+# define iop_assert(x)
+#endif
+
+#include <assert.h>
+#include <iostream>
+
+template <class Pointed=void,class Int=size_t>
+struct IntOrPointer {
+  typedef Pointed pointed_type;
+  typedef Int integer_type;
+  typedef Pointed *value_type;
+  typedef IntOrPointer<Pointed,Int> self_type;
+  IntOrPointer(int j) { *this=j; }
+  IntOrPointer(size_t j) { *this=j; }
+  IntOrPointer(value_type v) { *this=v; }
+  bool is_integer() const { return i&1; }
+  bool is_pointer() const { return !(i&1); }
+  value_type & pointer() { return p; }
+  const value_type & pointer() const { iop_assert(is_pointer()); return p; }
+  integer_type integer() const { iop_assert(is_integer()); return i >> 1; }
+  void set_integer(Int j) { i=2*j+1; }
+  void set_pointer(value_type p_) { p=p_;iop_assert(is_pointer()); }
+  void operator=(unsigned j) { i = 2*(integer_type)j+1; }
+  void operator=(int j) { i = 2*(integer_type)j+1; }
+  template <class C>
+  void operator=(C j) { i = 2*(integer_type)j+1; }
+  void operator=(value_type v) { p=v; }
+  IntOrPointer() {}
+  IntOrPointer(const self_type &s) : p(s.p) {}
+  void operator=(const self_type &s) { p=s.p; }
+  template <class C>
+  bool operator ==(C* v) const { return p==v; }
+  template <class C>
+  bool operator ==(const C* v) const { return p==v; }
+  template <class C>
+  bool operator ==(C j) const { return integer() == j; }
+  bool operator ==(self_type s) const { return p==s.p; }
+  bool operator !=(self_type s) const { return p!=s.p; }
+  template <class O> void print(O&o) const
+  {
+    if (is_integer())
+      o << integer();
+    else {
+      o << "0x" << std::hex << (size_t)pointer() << std::dec;
+    }
+  }
+  friend inline std::ostream& operator<<(std::ostream &o,self_type const& s) {
+    s.print(o); return o;
+  }
+protected:
+  union {
+    value_type p; // must be even (guaranteed unless you're pointing at packed chars)
+    integer_type i; // stored as 2*data+1, so only has half the range (one less bit) of a normal integer_type
+  };
+};
+
+
+#endif