provide public interface to hold/unhold packages

We had this code lying around in apt-mark for a while now, but other
frontends need this (and similar) functionality as well, so its high
time that we provide a public interface in libapt for this stuff.

1 files changed, 52 insertions, 0 deletions

diff --git a/apt-pkg/statechanges.h b/apt-pkg/statechanges.h
new file mode 100644
index 000000000..fa60c5864
--- /dev/null
+++ b/apt-pkg/statechanges.h
@@ -0,0 +1,52 @@
+#include <apt-pkg/pkgcache.h>
+#include <apt-pkg/cacheset.h>
+#include <apt-pkg/macros.h>
+
+#include <memory>
+
+namespace APT
+{
+
+/** Simple wrapper class to abstract away the differences in storing different
+ *  states in different places potentially in different versions.
+ */
+class APT_PUBLIC StateChanges
+{
+public:
+   // getter/setter for the different states
+   APT::VersionVector& Hold();
+   void Hold(pkgCache::VerIterator const &Ver);
+   APT::VersionVector& Unhold();
+   void Unhold(pkgCache::VerIterator const &Ver);
+   APT::VersionVector& Error();
+
+   // forgets all unsaved changes
+   void Discard();
+
+   /** commit the staged changes to the database(s).
+    *
+    * Makes the needed calls to store the requested states.
+    * After this call the state containers will hold only versions
+    * for which the storing operation succeeded. Versions where the
+    * storing operation failed are collected in #Error(). Note that
+    * error is an upper bound as states are changed in batches so it
+    * isn't always clear which version triggered the failure exactly.
+    *
+    * @param DiscardOutput controls if stdout/stderr should be used
+    *   by subprocesses for (detailed) error reporting if needed.
+    * @return \b false if storing failed, true otherwise.
+    *   Note that some states might be applied even if the whole operation failed.
+    */
+   bool Save(bool const DiscardOutput = false);
+
+   StateChanges();
+   StateChanges(StateChanges&&);
+   StateChanges& operator=(StateChanges&&);
+   ~StateChanges();
+
+private:
+   class APT_HIDDEN Private;
+   std::unique_ptr<Private> d;
+};
+
+}