From 8b14096990ff0fe1969ace0bad933ff3dbbac8fc Mon Sep 17 00:00:00 2001
From: Antonin Portelli <antonin.portelli@me.com>
Date: Wed, 7 Mar 2018 15:12:18 +0000
Subject: [PATCH] Conversion of Grid tensors to std::vector made more elegant,
 also pair syntax changed to (x y) to avoid issues with JSON/XML

---
 lib/serialisation/BaseIO.h | 128 ++++++++++++++++++++++++-------------
 1 file changed, 83 insertions(+), 45 deletions(-)

diff --git a/lib/serialisation/BaseIO.h b/lib/serialisation/BaseIO.h
index 1af5acc6..5b37e1fb 100644
--- a/lib/serialisation/BaseIO.h
+++ b/lib/serialisation/BaseIO.h
@@ -34,74 +34,76 @@ Author: Guido Cossu <guido.cossu@ed.ac.uk>
 #include <Grid/tensors/Tensors.h>
 
 namespace Grid {
-  // Vector IO utilities ///////////////////////////////////////////////////////
-  // helper function to read space-separated values
+  // Grid scalar tensors to nested std::vectors //////////////////////////////////
   template <typename T>
-  std::vector<T> strToVec(const std::string s)
+  struct TensorToVec
   {
-    std::istringstream sstr(s);
-    T                  buf;
-    std::vector<T>     v;
-    
-    while(!sstr.eof())
-    {
-      sstr >> buf;
-      v.push_back(buf);
-    }
-    
-    return v;
-  }
-  
-  // output to streams for vectors
-  template < class T >
-  inline std::ostream & operator<<(std::ostream &os, const std::vector<T> &v)
+    typedef T type;
+  };
+
+  template <typename T>
+  struct TensorToVec<iScalar<T>>
   {
-    os << "[";
-    for (auto &x: v)
-    {
-      os << x << " ";
-    }
-    if (v.size() > 0)
-    {
-      os << "\b";
-    }
-    os << "]";
-    
-    return os;
-  }
-  
-  // convert Grid scalar tensors to std::vectors
-  template <typename T, typename V>
-  void tensorToVec(V &v, const T& t)
+    typedef TensorToVec<T>::type type;
+  };
+
+  template <typename T>
+  struct TensorToVec<iScalar<T>>
+  {
+    typedef TensorToVec<T>::type type;
+  };
+
+  template <typename T, int N>
+  struct TensorToVec<iVector<T, N>>
+  {
+    typedef std::vector<TensorToVec<T>::type> type;
+  };
+
+  template <typename T, int N>
+  struct TensorToVec<iMatrix<T, N>>
+  {
+    typedef std::vector<std::vector<TensorToVec<T>::type>> type;
+  };
+
+  template <typename T>
+  TensorToVec<T>::type tensorToVec(const T &t)
   {
     v = t;
   }
 
   template <typename T, typename V>
-  void tensorToVec(V &v, const iScalar<T>& t)
+  TensorToVec<iScalar<T>>::type tensorToVec(V &v, const iScalar<T>& t)
   {
-    tensorToVec(v, t._internal);
+    return tensorToVec(t._internal);
   }
 
-  template <typename T, typename V, int N>
-  void tensorToVec(std::vector<V> &v, const iVector<T, N>& t)
+  template <typename T, int N>
+  TensorToVec<iVector<T, N>>::type tensorToVec(const iVector<T, N>& t)
   {
+    TensorToVec<iVector<T, N>>::type v;
+
     v.resize(N);
     for (unsigned int i = 0; i < N; i++) 
     {
-      tensorToVec(v[i], t._internal[i]);
+      v[i] = tensorToVec(t._internal[i]);
     }
+
+    return v;
   }
 
-  template <typename T, typename V, int N>
-  void tensorToVec(std::vector<std::vector<V>> &v, const iMatrix<T, N>& t)
+  template <typename T, int N>
+  TensorToVec<iMatrix<T, N>>::type tensorToVec(const iMatrix<T, N>& t)
   {
+    TensorToVec<iMatrix<T, N>>::type v;
+
     v.resize(N, std::vector<V>(N));
     for (unsigned int i = 0; i < N; i++)
     for (unsigned int j = 0; j < N; j++) 
     {
-      tensorToVec(v[i][j], t._internal[i][j]);
+      v[i][j] = tensorToVec(t._internal[i][j]);
     }
+
+    return v;
   }
 
   // Vector element trait //////////////////////////////////////////////////////  
@@ -217,7 +219,43 @@ namespace Grid {
   template <class T1, class T2>
   inline std::ostream & operator<<(std::ostream &os, const std::pair<T1, T2> &p)
   {
-    os << "<" << p.first << " " << p.second << ">";
+    os << "{" << p.first << " " << p.second << "}";
+    return os;
+  }
+
+  // Vector IO utilities ///////////////////////////////////////////////////////
+  // helper function to read space-separated values
+  template <typename T>
+  std::vector<T> strToVec(const std::string s)
+  {
+    std::istringstream sstr(s);
+    T                  buf;
+    std::vector<T>     v;
+    
+    while(!sstr.eof())
+    {
+      sstr >> buf;
+      v.push_back(buf);
+    }
+    
+    return v;
+  }
+  
+  // output to streams for vectors
+  template < class T >
+  inline std::ostream & operator<<(std::ostream &os, const std::vector<T> &v)
+  {
+    os << "[";
+    for (auto &x: v)
+    {
+      os << x << " ";
+    }
+    if (v.size() > 0)
+    {
+      os << "\b";
+    }
+    os << "]";
+    
     return os;
   }