code up the obvious part of the AdviceSystem implementation

src/lib/advice.hpp

@@ -171,7 +171,6 @@ namespace advice {
     protected:
       void publishProvision (PointOfAdvice*);
       void discardSolutions ();
-      void publishBindingChange();
       void publishRequestBindingChange();
       
       void registerRequest();
@@ -240,11 +239,12 @@ namespace advice {
       defineBinding (Literal topic)
         {
           setBindingPattern (Binding(topic).addTypeGuard<AD>());
-          publishBindingChange();
+          maybe_rePublish();
         }
       
     private:
       PointOfAdvice* storeCopy (AD const& advice_given);
+      void maybe_rePublish ();
     };
   
   
@@ -289,12 +289,29 @@ namespace advice {
       @throw  error::External on allocation problems, plus anything
               the advice data may throw during copy construction. */
   template<class AD>
-  PointOfAdvice*
+  inline PointOfAdvice*
   Provision<AD>::storeCopy (AD const& advice_given)
-    {
+  {
-      typedef ActiveProvision<AD> Holder;
+    typedef ActiveProvision<AD> Holder;
-      return new(getBuffer(sizeof(Holder))) Holder (*this, advice_given);
+    return new(getBuffer(sizeof(Holder))) Holder (*this, advice_given);
-    }
+  }
+  
+  
+  /** @internal in case we've already published this provision,
+   *            we temporarily need a new provision entry, to allow the
+   *            AdviceSystem implementation to rewrite the internal index
+   */
+  template<class AD>
+  inline void
+  Provision<AD>::maybe_rePublish ()
+  {
+    typedef const ActiveProvision<AD> AdviceProvision;
+    AdviceProvision* solution = static_cast<AdviceProvision*> (getSolution (*this));
+    
+    if (solution)    // create copy of the data holder, using the new binding 
+      publishProvision (storeCopy (solution->getAdvice()));
+  }
+  
 
   
     
@@ -346,6 +363,7 @@ namespace advice {
       defineBinding (Literal topic)
         {
           setBindingPattern (Binding(topic).addTypeGuard<AD>());
+    ////////////////////////////////////////////////////////////////////////////TODO: conceptual mismatch here! we don't have an "old entry", because we ourselves are the entry ;-)
           publishRequestBindingChange();
         }
     };

src/lib/advice/advice.cpp

@@ -23,13 +23,50 @@
 
 #include "lib/advice.hpp"
 #include "lib/advice/index.hpp"
+#include "lib/singleton.hpp"
+#include "include/logging.h"
 
+#include <boost/noncopyable.hpp>
+
+using lib::Singleton;
 
 namespace lib {
 namespace advice {
   
 //  LUMIERA_ERROR_DEFINE (MISSING_INSTANCE, "Existing ID registration without associated instance");
   
+  namespace { // ======= implementation of the AdviceSystem ============
+    
+    class AdviceSystem
+      : public Index<PointOfAdvice>
+      , boost::noncopyable
+      {
+        
+      public:
+        AdviceSystem()
+          {
+            INFO (library, "Initialising Advice Index tables.");
+          }
+        
+       ~AdviceSystem()
+          {
+            INFO (library, "Shutting down Advice system.");
+          }
+      };
+    
+    
+    /** hidden implementation-level access to the AdviceSystem */
+    Singleton<AdviceSystem> aSys;
+    
+    
+  } //(End) AdviceSystem implementation
+
+  
+  
+  
+  
+  /*  ====== AdviceLink : access point for Provisions and Requests ====== */  
+  
   
   /** allocate raw storage for a buffer holding the actual piece of advice.
       We need to manage this internally, as the original advice::Provision
@@ -45,30 +82,49 @@ namespace advice {
   }
   
   
+  /** when the Provision actually sets advice data, this is copied
+   *  into an internal buffer within the AdviceSystem. We then use the
+   *  Index to remember the presence of this advice data and to detect
+   *  possible matches with existing advice::Request entries.
+   *  @param adviceData pointer to the copied data,
+   *         actually pointing to an ActiveProvision<AD>
+   */
   void
-  AdviceLink::publishProvision (PointOfAdvice*)
+  AdviceLink::publishProvision (PointOfAdvice* newProvision)
   {
-    UNIMPLEMENTED ("change advice provision registration");
+    const PointOfAdvice* previousProvision (getSolution (*this));
+    setSolution (this, newProvision);
+    
+    if (!previousProvision && newProvision)
+      aSys().addProvision (*newProvision);
+    else
+    if (previousProvision && newProvision)
+      aSys().modifyProvision (*previousProvision, *newProvision);
+    else
+    if (previousProvision && !newProvision)
+      aSys().removeProvision (*previousProvision);  ////////////////////////////TODO: don't we need to release buffer storage here?
   }
   
   
+  /** when advice is retracted explicitly,
+   *  after removing the provision index entry
+   *  we also need to re-process any requests
+   *  which happen to match our binding... 
+   */
   void
   AdviceLink::discardSolutions ()
   {
-    UNIMPLEMENTED ("notify index of retracted advice");
+    const PointOfAdvice* existingProvision (getSolution (*this));
-  }
+    setSolution (this, NULL );
-  
+    if (existingProvision)
-  
+      aSys().removeProvision (*existingProvision);  ////////////////////////////TODO: don't we need to release buffer storage here?
-  void
-  AdviceLink::publishBindingChange ()
-  {
-    UNIMPLEMENTED ("propagate binding change to index");
   }
   
   
   void
   AdviceLink::publishRequestBindingChange()
   {
+    ////////////////////////////////////////////////////////////////////////////TODO: conceptual mismatch here! we don't have an "old entry", because we ourselves are the entry ;-)
     UNIMPLEMENTED ("propagate binding change to index");
   }
   
@@ -76,14 +132,14 @@ namespace advice {
   void
   AdviceLink::registerRequest()
   {
-    UNIMPLEMENTED ("registrate request with the index");
+    aSys().addRequest (*this);
   }
   
   
   void
   AdviceLink::deregisterRequest()
   {
-    UNIMPLEMENTED ("detach request from index");
+    aSys().removeRequest (*this);
   }
 
 

src/lib/advice/index.hpp

@@ -350,7 +350,9 @@ namespace advice {
               requestEntries_[nKey].append (newEntry);
             }
           else
-            requestEntries_[nKey].overwrite (oldRef, newEntry);
+            {
+              requestEntries_[nKey].overwrite (oldRef, newEntry);
+            }
           provisionEntries_[nKey].publish_latest_solution (newEntry);
         }