X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fptr.h;h=93b16416f5471d9bd9eb165fd7d159767a3f2522;hp=1d1b49d2c94e78ebbe430bb8e2d6ef10baec3ebe;hb=8dc09f48182574d792a2ed7c37b66831d9267a6c;hpb=68fdf425abf14d016d5f95ee7b9d06a19a3c5926

diff --git a/ginac/ptr.h b/ginac/ptr.h
index 1d1b49d2..93b16416 100644
--- a/ginac/ptr.h
+++ b/ginac/ptr.h
@@ -23,6 +23,7 @@
 #ifndef __GINAC_PTR_H__
 #define __GINAC_PTR_H__
 
+#include <cstddef> // for size_t
 #include <functional>
 #include <iosfwd>
 
@@ -30,12 +31,28 @@
 
 namespace GiNaC {
 
+
+/** Base class for reference-counted objects. */
+class refcounted {
+public:
+	refcounted() throw() : refcount(0) {}
+
+	size_t add_reference() throw() { return ++refcount; }
+	size_t remove_reference() throw() { return --refcount; }
+	size_t get_refcount() const throw() { return refcount; }
+	void set_refcount(size_t r) throw() { refcount = r; }
+
+private:
+	size_t refcount; ///< reference counter
+};
+
+
 /** Class of (intrusively) reference-counted pointers that support
  *  copy-on-write semantics.
  *
  *  Requirements for T:
- *    T::refcount member that supports ++refcount, --refcount, refcount = 1,
- *      refcount == 0 and refcount > 1
+ *    must support the refcounted interface (usually by being derived
+ *      from refcounted)
  *    T* T::duplicate() member function (only if makewriteable() is used) */
 template <class T> class ptr {
 	friend class std::less< ptr<T> >;
@@ -48,48 +65,48 @@ public:
     // no default ctor: a ptr is never unbound
 
 	/** Bind ptr to newly created object, start reference counting. */
-	ptr(T *t) : p(t) { GINAC_ASSERT(p); p->refcount = 1; }
+	ptr(T *t) throw() : p(t) { GINAC_ASSERT(p); p->set_refcount(1); }
 
 	/** Bind ptr to existing reference-counted object. */
-	explicit ptr(T &t) : p(&t) { ++p->refcount; }
+	explicit ptr(T &t) throw() : p(&t) { p->add_reference(); }
 
-	ptr(const ptr & other) : p(other.p) { ++p->refcount; }
+	ptr(const ptr & other) throw() : p(other.p) { p->add_reference(); }
 
 	~ptr()
 	{
-		if (--p->refcount == 0)
+		if (p->remove_reference() == 0)
 			delete p;
 	}
 
 	ptr &operator=(const ptr & other)
 	{
-		// NB: must first increment other.p->refcount, since other might be *this.
-		++other.p->refcount;
-		if (--p->refcount == 0)
+		// NB: must first add reference to "other", since other might be *this.
+		other.p->add_reference();
+		if (p->remove_reference() == 0)
 			delete p;
 		p = other.p;
 		return *this;
 	}
 
-	T &operator*() const { return *p; }
-	T *operator->() const { return p; }
+	T &operator*() const throw() { return *p; }
+	T *operator->() const throw() { return p; }
 
-	friend inline T *get_pointer(const ptr & x) { return x.p; }
+	friend inline T *get_pointer(const ptr & x) throw() { return x.p; }
 
 	/** Announce your intention to modify the object bound to this ptr.
 	 *  This ensures that the object is not shared by any other ptrs. */
 	void makewritable()
 	{
-		if (p->refcount > 1) {
+		if (p->get_refcount() > 1) {
 			T *p2 = p->duplicate();
-			p2->refcount = 1;
-			--p->refcount;
+			p2->set_refcount(1);
+			p->remove_reference();
 			p = p2;
 		}
 	}
 
 	/** Swap the bound object of this ptr with another ptr. */
-	void swap(ptr & other)
+	void swap(ptr & other) throw()
 	{
 		T *t = p;
 		p = other.p;
@@ -102,22 +119,22 @@ public:
 	// to different (probably derived) types and raw pointers.
 
 	template <class U>
-	bool operator==(const ptr<U> & rhs) const { return p == get_pointer(rhs); }
+	bool operator==(const ptr<U> & rhs) const throw() { return p == get_pointer(rhs); }
 
 	template <class U>
-	bool operator!=(const ptr<U> & rhs) const { return p != get_pointer(rhs); }
+	bool operator!=(const ptr<U> & rhs) const throw() { return p != get_pointer(rhs); }
 
 	template <class U>
-	inline friend bool operator==(const ptr & lhs, const U * rhs) { return lhs.p == rhs; }
+	inline friend bool operator==(const ptr & lhs, const U * rhs) throw() { return lhs.p == rhs; }
 
 	template <class U>
-	inline friend bool operator!=(const ptr & lhs, const U * rhs) { return lhs.p != rhs; }
+	inline friend bool operator!=(const ptr & lhs, const U * rhs) throw() { return lhs.p != rhs; }
 
 	template <class U>
-	inline friend bool operator==(const U * lhs, const ptr & rhs) { return lhs == rhs.p; }
+	inline friend bool operator==(const U * lhs, const ptr & rhs) throw() { return lhs == rhs.p; }
 
 	template <class U>
-	inline friend bool operator!=(const U * lhs, const ptr & rhs) { return lhs != rhs.p; }
+	inline friend bool operator!=(const U * lhs, const ptr & rhs) throw() { return lhs != rhs.p; }
 
 	inline friend std::ostream & operator<<(std::ostream & os, const ptr<T> & rhs)
 	{
@@ -130,6 +147,7 @@ private:
 
 } // namespace GiNaC
 
+
 namespace std {
 
 /** Specialization of std::less for ptr<T> to enable ordering of ptr<T>
@@ -144,4 +162,4 @@ template <class T> struct less< GiNaC::ptr<T> >
 
 } // namespace std
 
-#endif // ndef __GINAC_UTILS_H__
+#endif // ndef __GINAC_PTR_H__