first outline of test and aggregate initialisation problem

- the test will use some really private data types,
  valid only within the scope of the test function.

- invoking the builder for real got me into problems
  with the aggregate initialisation I'd used.
  Maybe it's the function pointers? Anyway, working
  around that by definint a telescope ctor

src/lib/diff/tree-mutator-collection-binding.hpp

@@ -86,12 +86,21 @@
         
         Coll& collection;
         
-        SEL isApplicable;
         MAT matches;
         CTR construct;
+        SEL isApplicable;
         ASS assign;
         MUT openSub;
         
+        CollectionBinding(Coll& coll, MAT m, CTR c, SEL s, ASS a, MUT u)
+          : collection(coll)
+          , matches(m)
+          , construct(c)
+          , isApplicable(s)
+          , assign(a)
+          , openSub(u)
+          { }
+        
         
         /* === content manipulation API === */
         
@@ -305,6 +314,7 @@
     struct CollectionBindingBuilder
       : CollectionBinding<COLL,MAT,CTR,SEL,ASS,MUT>
       {
+        using CollectionBinding<COLL,MAT,CTR,SEL,ASS,MUT>::CollectionBinding;
         
         template<class FUN>
         CollectionBindingBuilder<COLL, FUN ,CTR,SEL,ASS,MUT>
@@ -393,13 +403,13 @@
         static bool
         default_contentMatch (GenNode const& spec, Elm const& elm)
           {
-            return spec.matches(elm);
+            //return spec.matches(elm);
           }
         
         static Elm
         default_construct_from_payload (GenNode const& spec)
           {
-            return spec.data.get<Elm>();
+            //return spec.data.get<Elm>();
           }
         
         static bool
@@ -423,23 +433,23 @@
         
         using FallbackBindingConfiguration
             = CollectionBindingBuilder<Coll
-                                      ,decltype(default_contentMatch)
-                                      ,decltype(default_construct_from_payload)
-                                      ,decltype(disable_selector)
-                                      ,decltype(disable_assignment)
-                                      ,decltype(disable_childMutation)
+                                      ,decltype(&default_contentMatch)
+                                      ,decltype(&default_construct_from_payload)
+                                      ,decltype(&disable_selector)
+                                      ,decltype(&disable_assignment)
+                                      ,decltype(&disable_childMutation)
                                       >;
         
         static FallbackBindingConfiguration
         attachTo (Coll& coll)
           {
-            return { coll
-                   , disable_selector
-                   , default_contentMatch
-                   , default_construct_from_payload
-                   , disable_assignment
-                   , disable_childMutation
-                   };
+            return FallbackBindingConfiguration{ coll
+                                               , default_contentMatch
+                                               , default_construct_from_payload
+                                               , disable_selector
+                                               , disable_assignment
+                                               , disable_childMutation
+                                               };
           }
       };
     

src/lib/diff/tree-mutator.hpp

@@ -351,7 +351,7 @@ namespace diff{
         Builder<Collection<BIN>>
         attach (BIN&& collectionBindingSetup)
           {
-            return Collection<BIN> (std::forward<BIN>(collectionBindingSetup));
+            return Collection<BIN> (std::forward<BIN>(collectionBindingSetup), *this);
           }
         
         /** set up a diagnostic layer, binding to TestMutationTarget.

tests/library/diff/tree-manipulation-binding-test.cpp

@@ -273,10 +273,33 @@ namespace test{
         }
       
       
+      /** @test map mutation primitives onto a STL collection managed locally. */
       void
       mutateCollection()
         {
-          TODO ("define how to map the mutation primitives onto a generic collection");
+          MARK_TEST_FUN;
+          
+          // some private data structures
+          struct Data
+            {
+              string key;
+              string val;
+              
+              operator string()                const { return _Fmt{"≺%s∫%s≻"} % key % val; }
+              bool operator== (Data const& o)  const { return key==o.key and val==o.val; }
+              bool operator!= (Data const& o)  const { return not (*this == o); }
+            };
+          
+          using VecD = std::vector<Data>;
+          using MapD = std::map<string, VecD>;
+          
+          VecD target;
+          
+          // now set up a binding to these opaque private structures...
+          auto mutator =
+          TreeMutator::build()
+            .attach (collection(target));
+
         }