added support to save app/gprop/mlp as YAML

eo/app/gprop/mlp.h

@@ -20,6 +20,10 @@
 #include <assert.h>
 #include <limits>
 
+#ifdef HAVE_LIBYAML_CPP
+#include <yaml-cpp/yaml.h>
+#endif // HAVE_LIBYAML_CPP
+
 
 namespace mlp
 {
@@ -125,6 +129,36 @@ namespace mlp
       if ( probability >= 1.0 || rng.uniform() < probability)
 	perturb_num(bias, magnitude);
     }
+
+    #ifdef HAVE_LIBYAML_CPP
+    friend YAML::Emitter& operator<<(YAML::Emitter& out, const mlp::neuron& n) {
+        n.emit_yaml(out);
+        return out;
+    }
+
+    void emit_yaml(YAML::Emitter&out) const {
+            out << YAML::BeginMap;
+            out << YAML::Key << "Class" << YAML::Value << "mlp::neuron";
+            #define MY_EMIT_MEMBER(emitter,member) emitter << YAML::Key << #member << YAML::Value << this->member
+            MY_EMIT_MEMBER(out,bias);
+            MY_EMIT_MEMBER(out,weight);
+            out << YAML::EndMap;
+            #undef MY_EMIT_MEMBER
+    }
+
+    friend void operator >>(const YAML::Node& node, mlp::neuron& n) {
+        n.load_yaml(node);
+    }
+
+    void load_yaml(const YAML::Node& node) {
+        #define MY_LOAD_MEMBER(doc,member) doc[#member] >> member
+        MY_LOAD_MEMBER(node, bias);
+        MY_LOAD_MEMBER(node, weight);
+        #undef MY_LOAD_MEMBER
+    }
+
+
+    #endif
  };
 }
 
@@ -140,8 +174,10 @@ namespace std {
     return is >> n.bias >> n.weight;
   }
 
+
 }
 
+
 namespace mlp {
 
   //---------------------------------------------------------------------------
@@ -190,6 +226,21 @@ namespace mlp {
       for(iterator n = begin(); n != end(); ++n)
 	n->perturb();
     }
+    #ifdef HAVE_LIBYAML_CPP
+    friend ostream& operator<<(YAML::Emitter& e, const layer &l) {
+        e << ((std::vector<neuron>)l);
+    }
+
+    friend void operator>>(const YAML::Node& n, layer &l) {
+        // These temporary variable shenanegins are necessary because 
+        // the compiler gets very confused about which template operator>> 
+        // function to use.
+        // This does not work:  n >> l;
+        // So we use a temporary variable thusly:
+        std::vector<mlp::neuron> *obviously_a_vector = &l;
+        n >> *obviously_a_vector;
+    }
+    #endif
 
   };
 
@@ -235,6 +286,11 @@ namespace mlp {
     net(istream &is) {
 	load(is);
     }
+    #ifdef HAVE_LIBYAML_CPP
+    net (YAML::Node &node) {
+        node >> *((std::vector<layer>*)this);
+    }
+    #endif
 
       /** Virtual destructor */
       virtual ~net() {};
@@ -305,10 +361,13 @@ namespace mlp {
         for(const_iterator l = begin(); l != end(); ++l)
 	   os << l->size() << " ";
         os << "\n";
-	os << *this;
-        os << "\n";
+        os << "< ";
+        for(const_iterator l = begin(); l != end(); ++l)
+	   os << *l << " ";
+        os << ">\n";
     }
 
+
     unsigned num_inputs()  const { return front().front().length() - 1; }
     unsigned num_outputs() const { return back().size(); }
     unsigned num_hidden_layers() const {