* apt-pkg/contrib/weakptr.h:

  - add a class WeakPointable which allows one to register weak pointers to
    an object which will be set to NULL when the object is deallocated.
* [ABI break] apt-pkg/acquire{-worker,-item,}.h:
  - subclass pkgAcquire::{Worker,Item,ItemDesc} from WeakPointable.

5 files changed, 69 insertions, 4 deletions

diff --git a/apt-pkg/acquire-item.h b/apt-pkg/acquire-item.h
index bafa8263a..b338b2a41 100644
--- a/apt-pkg/acquire-item.h
+++ b/apt-pkg/acquire-item.h
@@ -27,6 +27,7 @@
 #include <apt-pkg/pkgrecords.h>
 #include <apt-pkg/indexrecords.h>
 #include <apt-pkg/hashes.h>
+#include <apt-pkg/weakptr.h>
 
 /** \addtogroup acquire
  *  @{
@@ -46,7 +47,7 @@
  *
  *  \see pkgAcquire
  */
-class pkgAcquire::Item
+class pkgAcquire::Item : public WeakPointable
 {  
    protected:
    
diff --git a/apt-pkg/acquire-worker.h b/apt-pkg/acquire-worker.h
index 2942df69f..06283922e 100644
--- a/apt-pkg/acquire-worker.h
+++ b/apt-pkg/acquire-worker.h
@@ -20,6 +20,7 @@
 #define PKGLIB_ACQUIRE_WORKER_H
 
 #include <apt-pkg/acquire.h>
+#include <apt-pkg/weakptr.h>
 
 
 /** \brief A fetch subprocess.
@@ -41,7 +42,7 @@
  *
  *  \sa pkgAcqMethod, pkgAcquire::Item, pkgAcquire
  */
-class pkgAcquire::Worker
+class pkgAcquire::Worker : public WeakPointable
 {
    friend class pkgAcquire;
    
diff --git a/apt-pkg/acquire.h b/apt-pkg/acquire.h
index 9e91a9f67..8e2c21151 100644
--- a/apt-pkg/acquire.h
+++ b/apt-pkg/acquire.h
@@ -67,6 +67,7 @@
 #define PKGLIB_ACQUIRE_H
 
 #include <apt-pkg/macros.h>
+#include <apt-pkg/weakptr.h>
 
 #include <vector>
 #include <string>
@@ -376,7 +377,7 @@ class pkgAcquire
  *
  *  An item may have several assocated ItemDescs over its lifetime.
  */
-struct pkgAcquire::ItemDesc
+struct pkgAcquire::ItemDesc : public WeakPointable
 {
    /** \brief The URI from which to download this item. */
    string URI;
diff --git a/apt-pkg/contrib/weakptr.h b/apt-pkg/contrib/weakptr.h
new file mode 100644
index 000000000..5158e393c
--- /dev/null
+++ b/apt-pkg/contrib/weakptr.h
@@ -0,0 +1,62 @@
+/* weakptr.h - An object which supports weak pointers.
+ *
+ * Copyright (C) 2010 Julian Andres Klode <jak@debian.org>
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#ifndef WEAK_POINTER_H
+#define WEAK_POINTER_H
+
+#include <set>
+/**
+ * Class for objects providing support for weak pointers.
+ *
+ * This class allows for the registration of certain pointers as weak,
+ * which will cause them to be set to NULL when the destructor of the
+ * object is called.
+ */
+class WeakPointable {
+private:
+    std::set<WeakPointable**> pointers;
+
+public:
+
+    /**
+     * Add a new weak pointer.
+     */
+    inline void AddWeakPointer(WeakPointable** weakptr) {
+       pointers.insert(weakptr);
+    }
+
+    /**
+     * Remove the weak pointer from the list of weak pointers.
+     */
+    inline void RemoveWeakPointer(WeakPointable **weakptr) {
+       pointers.erase(weakptr);
+    }
+
+    /**
+     * Deconstruct the object, set all weak pointers to NULL.
+     */
+    ~WeakPointable() {
+        std::set<WeakPointable**>::iterator iter = pointers.begin();
+        while (iter != pointers.end())
+            **(iter++) = NULL;
+    }
+};
+
+#endif // WEAK_POINTER_H
diff --git a/apt-pkg/makefile b/apt-pkg/makefile
index bdd49c089..148ad581b 100644
--- a/apt-pkg/makefile
+++ b/apt-pkg/makefile
@@ -25,7 +25,7 @@ SOURCE = contrib/mmap.cc contrib/error.cc contrib/strutl.cc \
 	 contrib/fileutl.cc 
 HEADERS = mmap.h error.h configuration.h fileutl.h  cmndline.h netrc.h\
 	  md5.h crc-16.h cdromutl.h strutl.h sptr.h sha1.h sha256.h hashes.h \
-	  macros.h
+	  macros.h weakptr.h
 
 # Source code for the core main library
 SOURCE+= pkgcache.cc version.cc depcache.cc \