clef : new version using lvalues and moving rvalues

- change : all objects are by default
  stored now by reference, not by copy any more.
  Unless the trait force_copy_in_expr is true.
- rvalue refs are moved into the tree
- simplifies a lot the writing of lazy method, objects.
- added a macro for methods
- tests ok. Further check needed to control absence of copies...
- improved documentation

doc/reference/c++/clef/assign.rst

@@ -1,58 +1,70 @@
 .. highlight:: c
 
-Automatic assignment 
+Automatic assignment of containers 
-=======================
+===================================
 
-Principle
+Another use of expression is the automatic assignment of containers.
-----------------
 
-It is possible to use a subset of possible expressions as Left Hand Side (LHS) in an assignment statement, e.g. ::
+**Synopsis** : 
 
- A(x_)        = some_expression_of_x_
+ If C is a container, ::
- A[i_]        = some_expression_of_i_
- A(x_)(i_,j_) = some_expression_of_x_i_j
- A[x_](i_,j_) = some_expression_of_x_i_j
 
-* Right Hand Side (RHS) of the = statement can be any expression.
+  C(x_)        << some_expression_of_x_
-* Left Hand Side (LHS) of the = sign. A must be a `lazy-assignable`, called by [] or (), one or several time.
+  C[i_]        << some_expression_of_i_
+  C(x_)(i_,j_) << some_expression_of_x_i_j
+  C[x_](i_,j_) << some_expression_of_x_i_j
 
-This writing means that a regular function ::
+depending of course of the operator that the container support.
+The Right Hand Side (RHS) of the << statement can be any expression, 
+while Left Hand Side (LHS) of the << sign is a container supporting the operation (see below).
 
-  x_ -> some_expression_of_x_
+This statement simply will be rewritten by the CLEF library as ::
 
-will be given to A so that it can fill itself by evaluating this function.
+  triqs_clef_auto_assign (C, x_ -> some_expression_of_x_);                  // pseudo code
-A determines the range of value of x on which the function is called.
+  triqs_clef_auto_assign (C, [](auto x_) {return some_expression_of_x_;});  // or in C++ lambda syntax
 
-Example
+The function `triqs_clef_auto_assign` has to be overloaded for the container and the correct
----------
+functional form, and it is expected to fill C by evaluating this function.
+
+Such a function is provided for TRIQS objects (arrays, matrix, Green function),
+and also for some STL container like std::vector.
+
+Example :
 
 .. compileblock::
 
   #include "triqs/clef.hpp"
-  #include "triqs/clef/adapters/vector.hpp"
   #include <iostream> 
+  using namespace triqs::clef;
 
   int main() { 
-  int N = 10;
+  int N = 5;
   double pi = std::acos(-1);
-  std::vector<double> V(N);
 
-  // automatic assignment of vector and use of lazy math function
+  // automatic assignment of vector 
-  triqs::clef::placeholder <0> k_; 
+  placeholder <0> k_; 
-  triqs::clef::lazy(V) [k_] << cos( (2* pi* k_)/ N );
+  std::vector<double> V(N);
+  make_expr(V) [k_] << cos( (2* pi* k_)/ N );
+
+  // chaining them ...
+  placeholder <1> i_; 
+  std::vector<std::vector<double>> W(3, std::vector<double>(N));
+  make_expr(W)[i_] [k_] << i_ + cos( (2* pi* k_)/ N );
 
   // check result... 
-  for (size_t u=0; u<V.size(); ++u) std::cout<< u << " "<<V[u]<< "  "<< cos((2*pi*u)/N)<<std::endl;
+  for (size_t u=0; u<V.size(); ++u) if (std::abs(V[u] -cos((2*pi*u)/N))> 1.e-10) throw "error!";
+  for (size_t w=0; w<W.size(); ++w) 
+   for (size_t u=0; u<W[w].size(); ++u) 
+   if (std::abs( W[w][u] - (w+cos((2*pi*u)/N)))> 1.e-10) throw "error!";
   }
 
-Implementing automatic assign for an object 
+**Details**
-------------------------------------------------------------
 
-It is sufficient to add a function ::
+The synopsis of the `triqs_clef_auto_assign` functions is ::
 
    template<typename Fnt> void triqs_clef_auto_assign (Obj & x, Fnt f);
 
-The compiler will rewrite ::
+The compiler will then rewrite ::
 
    obj(x_,y_, ...) = expression
 
@@ -60,7 +72,7 @@ into ::
 
    triqs_clef_auto_assign (obj, make_function( expression, x_, y_, ....)) 
 
-The function is found by ADL. It is therefore useful to implement it e.g. as a friend function.
+The function must be found by ADL. It is therefore useful to implement it e.g. as a friend function.
 
 Similarly, for [ ], adding a function ::
 
@@ -82,33 +94,22 @@ A complete example :
 
     #include <triqs/clef.hpp>
     #include <iostream>
+    using namespace triqs::clef;
 
     struct Obj{ 
      double v; 
-    Obj(double v_): v(v_){}
+     TRIQS_CLEF_IMPLEMENT_LAZY_CALL();
-
+     // 
-    // lazy call : cf ...
-    template< typename... Args>
-    typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const Obj>,Args...>::type
-    operator()( Args&&... args ) const { return make_expr_call (std::ref(* this),args...);}
-
-    // The non const version (which then stores a non-const reference ....)
-    template< typename... Args>
-    typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<Obj>,Args...>::type
-    operator()( Args&&... args ) { return  make_expr_call (std::ref(* this),args...);}
-
      template<typename Fnt> friend void triqs_clef_auto_assign (Obj & x, Fnt f) { 
-    x.v++; std::cout<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;
+       std::cout<< " called triqs_clef_auto_assign "<< f(x.v++)<<std::endl;
      }
-    friend std::ostream & triqs_clef_formal_print(std::ostream & out, Obj const & x) {return out<<"Obj";}
     };
 
     int main() {
-    Obj f(2);
+     Obj f{2};
-    triqs::clef::placeholder<3> x_;
+     placeholder<3> x_;
      std::cout<< f.v << std::endl;
      f(x_ ) << 8*x_ ;
-    //f(x_ + y_) = 8*x_; // leads to a compile error as expected
      std::cout<< f.v << std::endl;
     }
 

doc/reference/c++/clef/contents.rst

@@ -1,25 +1,27 @@
-Clef expressions library
+Clef 
 *************************************
 
 .. highlight:: c
 
 .. warning::
 
-    This library is still a prototype, of alpha quality. 
+    This library is still a prototype. Its basic features are used in our codes, but 
+    there are probably still some dark corners ...
     
-    Documentation is not fully up to date : work in progress. 
+    Documentation in progress.
+
+The CLEF library (**C**\ompile time **L**\azy **E**\xpressions and **F**\unctions) is a little
+library to manipulate simple expressions at compile-time and use them e.g. 
+to automatically fill containers.
 
-The little CLEF library (Compile time Lazy Expression and Function)
-is a simple lambda library for C++11, to store and code formal expressions
-using placeholders. 
 
 .. toctree::
-   :maxdepth: 1
+   :maxdepth: 2
 
+   introduction
    expressions_form
    expressions_eval
-   function
-   lazy_call
    assign
-   lazy_function_cls
+   overload
+   function
    examples/contents

doc/reference/c++/clef/copy_policy.rst

@@ -1,40 +0,0 @@
-
-Copy policy in building expressions [Advanced]
-====================================================
-
-When building expressions, a problem can appear for the object at the leaves of the expressions tree
-(scalar, placeholders, various callable objects, etc...).
-
-The question is whether they should be captured by value or by reference.
-
-In the lazy library, the choice has been made to capture them **by value**.
-
-This means that, by default, *all objects appearing in a lazy expression are copied, rather than captured by reference*.
-
-This is necessary to store expressions (with auto like above) for future reuse, transform them into new expressions
-(e.g. make partial evaluation). Expressions are objects. 
-Capturing the leaves by reference easily produces dangling references.
-[Basically, an expression is a function of its placeholder. The leaves are the parameters of the function, 
-they must leave as long as the expression live. In other words, we need to have a closure of the function].
-
-The drawback of this approach is that it can generate unless copies of large objects.
-There are several solutions to this issue : 
-
-* The object is very small (like a double), hence making a copy in not a problem.
-* You *know* that the object `A` will survive the expression, so using a reference is not a problem.
-  You can use the `lazy(A)` expression that will wrap the reference to the object.
-* The object has a compagnon view object (like array, array_view). In this case, 
-  one wishes to put a view of the object rather than a copy in the expression.
-  There are two cases.
-
-  * TRIQS objects like array, matrix, vector will do it automatically.
-
-  * For another object, if the object defines the tag `has_view_type_tag` as ::
-
-     typedef void has_view_type_tag;
-     typedef MY_VIEW_TYPE view_type;
-  
-    the instance of the object will be replaced by an instance of its view_type in building the expression.
-
-For an illustration, Cf....
-

doc/reference/c++/clef/examples/contents.rst

@@ -1,12 +1,14 @@
 .. highlight:: c
 
-Examples
+More complex examples
 =======================
 
+.. warning::
+   
+   To be written.
+
 .. toctree::
    :maxdepth: 1
 
-   vector_and_math
    lazy_sum
-   lazy_function
 

doc/reference/c++/clef/examples/lazy_function.rst

@@ -1,16 +0,0 @@
-
-.. highlight:: c
-
-.. _lazy_function_ex:
-
-Using clef::function 
------------------------------
-
-The following code :
-
-.. literalinclude:: src/lazyfunction.cpp
-
-will print :  
-  
-.. literalinclude:: src/lazyfunction2.output
-

doc/reference/c++/clef/examples/lazy_sum.rst

@@ -3,18 +3,13 @@
 A lazy sum
 --------------
  
-Problem : we want
+Here is a little functional `sum` that sums a function f over various domains
-
+and accepts lazy expressions as arguments.
-* a functional `sum` that sums a function f over various domains, with various methods.
-
-* that this functionnal accepts lazy expressions as arguments.
-
-This is done by the little code: 
 
 .. literalinclude:: src/sum_functional.cpp
 
-which will print :
+Compiling and running this code reads : 
   
-.. literalinclude:: src/sum_functional2.output
+.. literalinclude:: src/sum_functional.output
  
  

doc/reference/c++/clef/examples/src

@@ -0,0 +1 @@
+../../../../../test/triqs/clef_examples/

doc/reference/c++/clef/examples/vector_and_math.rst

@@ -1,25 +0,0 @@
-
-.. highlight:: c
-
-std::vector and math
----------------------------------
-
-A simple example using std::vector.
-
-.. compileblock::
-
-   #include "triqs/clef.hpp"
-
-   int main() {
-   // init some variables  
-   int N = 10; double pi = std::acos(-1); std::vector<double> V(N);
-
-   // Filling the vector automatically from an expression of k_
-   triqs::clef::placeholder<0> k_; 
-   triqs::clef::lazy(V) [k_]  << cos( (2* pi* k_)/ N );
-
-   // check result... 
-   for (size_t u=0; u<V.size(); ++u)
-   std::cout<< u << " "<<V[u]<< "  "<< cos((2*pi*u)/N)<<std::endl;
-   }
-

doc/reference/c++/clef/expressions.rst

@@ -1,113 +0,0 @@
-.. highlight:: c
-
-Forming lazy expressions
-===========================
-
-Expressions are composed from :
-
-* Placeholders
-* Binary operations on expressions `(+, -, *, /, >, <, >=, <=, ==)`
-* Callable objects (see below) called on expressions
-* Conditional if_else expressions
- 
-Placeholders
-----------------
-
-Placeholders are only defined by their type, they contain no data ::
-
-  triqs::lazy_expressions::placeholder <DOM,1> x_; 
-  triqs::lazy_expressions::placeholder <DOM,2> y_; 
-
-.. warning:: 
-   As a consequence, if you define::
-  
-     triqs::clef::placeholder <DOM,2> y_; 
-
-  then `x_` is the same as `y_` : `x_` == `y_` will be always true.
-
-
-Callable objects
---------------------
-
-* The header `math.hpp` contains the declaration to make 
-  the basic function of std `math.h` accept lazy_expressions.
-  Example ::
- 
-   #include <triqs/clef/math.hpp>
-   cos(2*x_+1) (x_=2) ;
-   abs(2*x_-1) (x_=2) ;
-   floor(2*x_-1) (x_=2.3) ;
-   pow(2*x_+1,2) (x_=2) ;
-
-
-* To make your object callable, or to overload a function to accept lazy argument,  see :ref:`callable_object`.
-
-
-Copy policy
---------------------
-
-.. warning:: All objects appearing in a lazy expressions are copied, rather than captured by reference.
-
-This is necessary to store expressions, make partial evaluation.
-In order to avoid unncessary copies for large objects, it is necessary to use view type objects ( or shared_ptr).
-
-**NB** : for array, matrix, vector of the triqs::arrays library, this is automatic : triqs::clef 
-takes a *view* of the objects when building the expression tree.
-
-Evaluating lazy expressions
-===============================
-
-Complete evaluation
---------------------
-
-Expressions are evaluated used named arguments, following the pattern ::
-
- expression ( placeholder_1 = value_1, placeholder_2 = value_2, ...)
-
-Example ::
-
-  (x_  + 2*y_) ( x_=1, y_ = 2)
-
-  // or (in C++11)
-  auto e = x_  + 2*y_;
-  auto r = e ( x_=1, y_ = 2);
-
-Note that : 
-
-* The order of placeholder does not matter
-* It is an error to put the same placeholder twice.
-
-Partial evaluation
---------------------
-
-The evaluation can also be partial, in which case the compiler replaces the placeholder whose value is provided
-and rebuild a new expression tree.
-
-Example ::
-
- auto expr = x_  + 2*y_;
- expr (x_ =1); // ---> 1 + (2 * y_)
- expr (x_ =x_ + y_); // ---> ((x_ + y_) + (2 * y_))
- expr(x_ =x_ + y_)( x_ = 1, y_ = 2)); //---> 7
-
-During the partial evaluation, all subtrees that can evaluated are evaluated.
-For example ::
-
- (x_ + f(y_)) (y_=1); // --> x + f(1)
-
-Assignment 
-------------
-
-Some objects are `lazy-assignable`, which means that calling them on placeholders is a possible LHS.
-Expressions like ::
-
- F(x_,y_) = an_expression_of(x_,y_);
-
-are rewritten by the compiler into ::
-
- F.set_from( make_function( an_expression_of(x_,y_), x_, y_) );
-
-
-
-
-

doc/reference/c++/clef/expressions_eval.rst

@@ -1,7 +1,7 @@
 
 .. highlight:: c
 
-Evaluating clef expressions
+Evaluating CLEF expressions
 ===============================
 
 Forming expressions is nice, but completely useless unless one can *evaluate* them 
@@ -22,19 +22,21 @@ The evaluation can be :
 Complete evaluation
 --------------------
 
-Example ::
+.. compileblock::
  
-  eval (x_  + 2*y_ , x_=1, y_ = 2)
+   #include <triqs/clef.hpp>
-
+   using namespace triqs::clef;
-  auto e = x_  + 2*y_;
+   int main () { 
-  auto r = eval( e , x_=1, y_ = 2);
+    placeholder<1> x_; placeholder<2> y_;
+    std::cout << eval (x_  + 2*y_ , x_=1, y_ =2) << std::endl;
+    std::cout << eval (x_  + 2*y_ , y_=2, x_ =1) << std::endl;
+   }
 
 Note that : 
 
 * The order of placeholder does not matter in calling eval.
 * It is an error to put the same placeholder twice.
-* The correct version of eval is found by ADL (Argument Dependent Lookup).
+* The correct version of eval is found by ADL (Argument Dependent Lookup) in the triqs::clef namespace.
-  (It if the clef::eval since arguments are defined in the clef namespace)
 
 Partial evaluation
 --------------------

doc/reference/c++/clef/expressions_form.rst

@@ -1,28 +1,25 @@
 .. highlight:: c
 
-Introduction
+Forming CLEF expressions
 ===========================
 
-The first step consists in forming lazy expressions, before evaluating them.
+In this section, we describe how to form CLEF expressions.
  
 Placeholders
-----------------
+-------------------
 
 Loosely speaking, a placeholder is a "variable name" used to build an expression.
-Technically, it is a trivial object, with a type but containing no data.
 Placeholders are declared as ::
 
   placeholder<Number> Name;
 
-This declares a placeholder called Name (an empty object for C++). 
-
 Example ::
 
   placeholder <1> x_; 
   placeholder <2> y_; 
 
-Note that the only thing of significance in a placeholder is its type, since it contains no data.
+Note that the only thing of significance in a placeholder is its type (i.e. Number).
-In other words, a placeholder is **empty**. It contains **no value** at runtime. 
+A placeholder is **empty** : it contains **no value** at runtime. 
    
   .. warning:: 
     
@@ -33,18 +30,62 @@ In other words, a placeholder is **empty**. It contains **no value** at runtime.
       would imply that `x_` is the same as `y_` : `x_` == `y_` will be always true.
 
 Forming an expression
--------------------------
+------------------------
 
-Using simple operators, one can form a more complex expression, e.g.::
+CLEF expressions are made of : 
 
+* Placeholders
+* Binary operations on expressions `(+, -, *, /, >, <, >=, <=, ==)`
+* Ternary conditional if_else expressions
+* Callable objects which overload the operator () for CLEF expressions, See :ref:`callable_object`.
+* Functions overloaded for CLEF expressions. For example, the header `math.hpp` contains the declaration to make 
+  the basic function of std `math.h` accept CLEF_expressions.
+* In fact, almost anything : the *make_expr* function can be called on any object to make it lazy. 
+
+Examples : 
+
+.. compileblock::
+ 
+   #include <triqs/clef.hpp>
+   #include <vector>
+   using namespace triqs::clef;
+   int main () { 
+    placeholder<0> i_; placeholder<1> x_; placeholder<2> y_;
+    std::vector<int> V;
+
+    // arithmetic
     auto e = x_ + 2* y_;
     
-e has a complicated type (it is an expression template), which encodes the structure of the expression.
+    // simple math function
-Typically here something like ::
+    auto e1 = cos(2*x_+1);
+    auto e2 = abs(2*x_-1);
     
+    // making V lazy 
+    auto e0 = make_expr(V)[i_];
+   }
+
+Note that : 
+
+* Expressions do not compute anything, they just store the expression tree.
+* There is no check of correctness here in general : an expression can be well formed, 
+  but meaningless, e.g. ::
+
+    auto e = cos(2*x_, 8); // !
+
+
+.. highlight:: c
+
+Storage of expressions [advanced]
+-----------------------------------
+
+CLEF expressions have a complicated (expression template) type encoding the structure of the expression
+at compile time::
+
+  auto e = x_ + 2* y_;
+  // the type of e is something like   
   expr<tags::plus, placeholder<1>, expr<tags::multiplies, int, placeholder<2> >
 
-It is worth noting that : 
+Note that : 
 
 * As a user, one *never* has to write such a type
   One always use expression "on the fly", or use auto.
@@ -52,81 +93,27 @@ It is worth noting that :
 * Having the whole structure of the expression at compile time allows
   efficient evaluation (it is the principle of expression template : add a ref here).
 
-* Declaring an expression does not do any computation, hence the name of the library (lazy ...).
+* Declaring an expression does not do any computation.
   It just stores the expression tree (its structure in the type, and the leaves of the tree).
 
-What is allowed in clef expressions ? 
+* Every object in the expression tree is captured by :
-==========================================
 
-Expressions are composed of :
+   * reference it is an lvalue.
 
-* Placeholders
+   * value it is an rvalue : an rvalue (i.e. a temporary) is *moved* into the tree, using 
-* Binary operations on expressions `(+, -, *, /, >, <, >=, <=, ==)`
+     move semantics.
-* Conditional if_else expressions
-* Callable objects (see below) called on expressions
  
-Callable objects
+   Exceptions : the following objects are always copied : placeholders, expression themselves.
---------------------
 
-* Objects can overload the operator () for lazy expressions in order to build more complex
+   Example :: 
-  expressions.
 
-* For example, the header `math.hpp` contains the declaration to make 
+     double a = 3;
-  the basic function of std `math.h` accept lazy_expressions.
+     auto e = a + 2* x_ ;  // a is stored by reference (double &), but 2 is stored by value
 
- .. compileblock::
+   The rational is as follows : 
- 
-   #include <triqs/clef.hpp>
-   int main () { 
-    triqs::clef::placeholder <1> x_; 
-
-    auto e1 = cos(2*x_+1);
-    auto e2 = abs(2*x_-1);
-    auto e3 = floor(2*x_-1);
-    auto e4 = pow(2*x_+1,2);
-   }
-
-* To make your object callable, or to overload a function to accept lazy argument,  see :ref:`callable_object`.
-
-*lazy* function
--------------------
-
-The *lazy* function can be called on any object to make it lazy, e.g. 
-
-.. compileblock::
- 
-   #include <triqs/clef.hpp>
-   #include <vector>
-   namespace tql = triqs::clef;
-   int main () { 
-    std::vector<int> V;
-    tql::placeholder<1> i_;
-    auto e1 = tql::lazy(V)[i_];
-   }
-
-Copy policy in building expressions
----------------------------------------------------
-
-A central question when forming expressions is whether the object at the leaves of the expressions tree
-(scalar, placeholders, various callable objects, etc...) should be captured by value or by reference.
-
-In the clef library, the choice has been made to capture them **by value**, i.e. : 
-
-  *By default, all objects appearing in a clef expression are* **copied**, *rather than captured by reference*.
-
-This is necessary to store expressions (with auto like above) for future reuse, transform them into new expressions
-(e.g. make partial evaluation). Expressions are ordinary objects. 
-If the leaves of the expression tree were captured by reference, a guarantee would have to be made that 
-they will live at least as long as the expression itself, or one gets dangling references.
-
-The drawback of this approach is that it can generate useless copies of large objects.
-There are two simple solutions to this issue : 
-
-* If you *know* that the object `A` will survive the expression, so using a reference is not a problem
-  and use std::reference_wrapper<A> instead of A in the tree.
-
-* If the object has a compagnon view object (like array, array_view). In this case, 
-  one wishes to put a view of the object rather than a copy in the expression.
 
+   * rvalue must be moved, otherwise we would keep (dangling) reference to temporaries.
+   * for lvalue, keeping a reference is quicker. Of course, in the previous example, 
+     it is mandatory that a live longer than e ...
     
 

doc/reference/c++/clef/function.rst

@@ -1,8 +1,8 @@
 
 .. highlight:: c
 
-Clef expressions vs functions
+Transform CLEF expressions into functions
-=====================================================================
+===============================================
 
 Clef expressions are **NOT** functions. In short, 
 
@@ -14,22 +14,12 @@ Clef expressions are **NOT** functions. In short,
 
    f(1,2)
 
-It is however possible to transform expressions into functions, *as soon as you specify the order of the placeholders*,
+It is however possible to transform expressions into functions, *as soon as you specify the order of the placeholders*.
-and back.
+(the opposite is true, if the function accept lazy arguments, cf :ref:`overload_function`).
 
-Function to clef expressions
--------------------------------------
-
-This is immediate, if the function accept lazy arguments, cf :ref:`callable_object`::
-
-  auto e1 = f(x_);
-
-
-Transforming clef expressions into functions
-----------------------------------------------------
 
 make_function 
-.....................
+---------------
 
 Given any expression with placeholder `x_`, `y_`, `z_`, ..., `make_function`
 transform them into a regular function. If we say ::
@@ -38,41 +28,13 @@ transform them into a regular function. If we say ::
 
 then f is :: 
   
-  a function (placeholder_1, placeholder_2, placeholder_3, ...) --> RESULT
+  a function (x1,x2,x3) --> RESULT
 
 where RESULT is : 
 
 * the result of the complete evaluation of the expression if the list of placeholder exhausts the placeholders of the expression.
 * otherwise a clef_expression of the remaining placeholders, returning a **function**.
 
-Examples :
-
-* With one variable::
-
-   auto e1 = 2*x_ + 1;
-   auto f = make_function( e1, x_);
-   f(3) == 7; // ok
-   std::function<double(double)> F(f); // ok
-
-* With two variables ::
-  
-   auto e2 = 2*x_ + y_ + 1;
-   auto f = make_function( e2, x_, y_);
-   f(3,4) == 11; // ok
-   std::function<double(double,double)> F(f); // ok
-
-* Make a function partially ::
-
-   auto f = make_function( 2*x_ + y_ + 1, x_);
-   // f is a lazy expression expression with placeholder y_, returning a function...  
-   auto f1 = eval (f, y_=1); // f1 is a function x-> 2*x + 2
-   f1 (10) == 22; 
-
-* Currifying a function ::
-   auto f = make_function ( make_function( 2*x\_ + y\_ + 1, x\_), y\_);
-   // f a function y-> x-> 2x+y+1
-   // f(y) returns a function x-> 2x+y+1
-
 
 Short notation with >> operator
 .....................................
@@ -95,4 +57,67 @@ For function of *one* variable, the make_function notation can be simplified int
    is banned because it conflicts with the standard priority of >>. 
    Use parenthesis.
 
+clef::function
+--------------------------
+
+The class triqs::clef::function stored a function of a given signature 
+It is similar to std::function but 
+it can be constructed from an expression and an ordered list of placeholders.
+
+clef::function can be assigned with the = operator, Cf example below.
+
+.. note::
+  Like std::function, it stores the expression polymorphically, by erasing its type. 
+  This might lead to some performance penalty in some case, even though tests do not show that at present...
+
+
+Examples
+---------
+
+  .. compileblock::
+
+     #include <triqs/clef.hpp>
+     #include <iostream>
+     using namespace triqs::clef;
+     
+     int main() {
+      placeholder<0> x_; placeholder<1> y_;      
+      { // with one variable
+       auto f = make_function(2*x_ + 1, x_);
+       std::cout << f(3) << std::endl; 
+       std::function<double(double)> F(f); 
+      }
+      { //with two variables
+       auto f = make_function(2*x_ + y_ + 1, x_, y_);
+       std::cout << f(3,4) << std::endl; 
+       std::function<double(double,double)> F(f); 
+      }
+      { // Make a function partially 
+       auto f = make_function( 2*x_ + y_ + 1, x_);
+       // f is a lazy expression expression with placeholder y_, returning a function...  
+       auto f1 = eval (f, y_=1); // f1 is a function x-> 2*x + 2
+       std::cout << f1 (10) << std::endl; 
+      }
+      { // Currying a function 
+        //auto f = make_function ( make_function( 2*x_ + y_ + 1, x_), y_);
+        auto f = y_ >> ( x_ >>  2*x_ + y_ + 1);
+        // f a function y-> x-> 2x+y+1
+        // f(y) returns a function x-> 2x+y+1
+        auto g = f(3);
+        std::cout << g (10) << std::endl; 
+      }
+      { // playing with clef::function and std::function
+        triqs::clef::function<double(double,double)>  f2,g2;
+        f2(x_,y_) = x_ + y_;
+        std::cout << f2(2,3) << std::endl; 
+          
+        std::function<double(double,double)> sf2 = f2;
+        std::cout << sf2(2,3) << std::endl; 
+
+        g2(x_,y_) = x_ - y_ + f2(x_,2*y_);
+
+        std::function<double(double)>  sf = x_>> 2*x_ + 1;
+        std::cout << sf(3) << std::endl; 
+      }
+     }
          

doc/reference/c++/clef/introduction.rst

@@ -1,15 +1,72 @@
 .. highlight:: c
 
 
-Motivation
+Motivation : a little tour of CLEF 
-=======================
+=====================================
+
+A usual, the best is to start with a few examples, to show the library in action.
 
 
-The purpose of the Named Parameter Lambda (nplambda) library is to help
+.. compileblock::
-the manipulation of formal expressions.
+
+  #include <triqs/clef.hpp>
+  #include <triqs/arrays.hpp>
+  #include <iostream> 
+  #include <algorithm> 
+  int main() { 
+   // Declaring some placeholders (i.e. dummy variables). 
+   triqs::clef::placeholder <0> i_; 
+   triqs::clef::placeholder <1> j_; 
+
+   // Declaring a 3x3 matrix
+   triqs::arrays::matrix<double> A (3,3);
+
+   // Automatically filling the matrix 
+   // -> forget about the bounds, it is automatic
+   // -> forget about the best order to order the for loops for performance, it is also automatic
+   A(i_,j_) << i_ + 2*j_;
+
+   // Cheking the result
+   std::cout<< A<< std::endl;
+
+   // It also works for std container: we just have to add a call clef::make_expr function
+   std::vector<double> V(10); 
+   double pi = std::acos(-1);
+
+   // Automatically filling the vector with the evaluation of the expression in i_
+   triqs::clef::make_expr(V) [i_] << cos( 2* pi / 5.0 * i_ );
+  
+   // -> by the way, the constant calculation is precomputed
+   // (expressions are partially evaluated as soon as possible)
+   // illustration : 
+   // the time_consuming_function will be called only once in the loop, while cos is called 10 times
+   auto time_consuming_function=[](double x){std::cout<<"call time_consuming_function"<<std::endl;return 2*x;};  
+   triqs::clef::make_expr(V) [i_] << cos( time_consuming_function(10) * i_ );
+
+   // If you insist using on more complex container ....
+   std::vector<std::vector<double>> W(3, std::vector<double>(5));
+   triqs::clef::make_expr(W)[i_] [j_] << i_ + cos( time_consuming_function(10) * j_  + i_);
+
+   // You can also put a CLEF expression in a std::function
+   // a function i -> 2*i +1 
+   std::function<int(int)>        f =   i_ >>  2*i_ +1;
+   // a function (i,j)  -> 2*i +j
+   std::function<double(int,int)> g =  var(i_,j_) >> 2*i_ +j_; 
+   // checking ...
+   std::cout<< "f(10) =" << f(10)<< "  g(1,2) =" << g(1,2)<< std::endl;   
+   
+   // You can also use a Curry form : h is a function i-> j -> 2*i+ j
+   auto h = i_ >> (j_ >> 2*i_ +j_);
+   std::cout<< "h(1)(2) = " << h(1)(2) << std::endl;
+
+   // You an also use this to quickly write some lambda, as an alternative syntax to the C++ lambda
+   // with e.g. STL algorithms (with the advantage that the function is polymorphic !).
+   std::vector<int> v = {0,-1,2,-3,4,5,-6};
+   // replace all negative elements (i.e. those for which i -> (i<0) return true), by 0
+   std::replace_if(begin(v), end(v), i_ >> (i_<0), 0);
+   // for non believer, it really worked ... 
+   for (auto const & x : v) std::cout <<x <<" "; std::cout << std::endl; 
+   }
 
-Functional programming techniques are now widely used. For example, boost::phoenix library
-provides simple lambda techniques.
 
-NPL is 
 

doc/reference/c++/clef/lazy_call.rst

@@ -1,226 +0,0 @@
-
-.. highlight:: c
-
-.. _callable_object:
-
-Overloading functions and callable objects for clef expression arguments 
-=============================================================================
-
-Given a callable object or a function, it is possible to overload it for clef expression arguments, returning a clef expression.
-In all  cases:
-
-   *Overloads that are activated iif at least one argument is a clef expression*.
-
-Functions
-------------
-
-std math functions
-^^^^^^^^^^^^^^^^^^^^^^^^
-
-The overload is defined by clef automatically for usual functions : 
-
-.. compileblock::
-
-    #include <triqs/clef.hpp>
-    #include <iostream>
-    int main() { 
-      triqs::clef::placeholder<3> x_;
-      std::cout << 2.0 + std::cos(2.0) << std::endl;  
-      std::cout << eval( x_ + cos(x_), x_ = 2) << std::endl; // NB : note the absence of std::
-    }
-  
-Overloading a function for clef expressions arguments
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The `TRIQS_CLEF_MAKE_FNT_LAZY` macro defines the overload for clef expressions arguments of a function. Synopsis is ::
-
- namespace triqs { namespace clef { 
- TRIQS_CLEF_MAKE_FNT_LAZY (function_to_make_lazy);
- }}
-
-For example:
-
-.. compileblock::
-
-    #include <triqs/clef.hpp>
-    #include <iostream>
- 
-    double foo(double x) { return x/2;}
-    int foo(int x) { return x*2;}
-
-    namespace triqs { namespace clef { TRIQS_CLEF_MAKE_FNT_LAZY (foo) ; }}
-
-    int main() { 
-      triqs::clef::placeholder<3> x_;
-      std::cout << foo(2.0) << std::endl;  
-      std::cout << eval( x_ + foo(x_), x_ = 3) << std::endl;  
-      std::cout << eval( x_ + foo(x_), x_ = 3.5) << std::endl;  
-    }
-  
-Note that : 
- 
- * This overload **must** be defined in the triqs::clef namespace, since it is found by ADL.
- * The function `foo` can have many overloads.
- * The function foo can be a template, BUT then the template must be disabled for lazy expressions, as in ::
-
-.. compileblock::
-
-    #include <triqs/clef.hpp>
-    #include <iostream>
-       
-    template<typename T> 
-    typename std::enable_if<!triqs::clef::is_any_lazy<T>::value,T>::type 
-    foo (T const & x) { return x+1;}
-      
-    namespace triqs { namespace clef { TRIQS_CLEF_MAKE_FNT_LAZY (foo) ; }}
-
-    int main() { 
-      triqs::clef::placeholder<3> x_;
-      std::cout << foo(2.0) << std::endl;  
-      std::cout << eval( x_ + foo(x_), x_ = 3) << std::endl;  
-      std::cout << eval( x_ + foo(x_), x_ = 3.5) << std::endl;  
-    }
-
-Callable objects
---------------------
-
-Similarly to functions, classes can define an `operator()` for lazy expressions arguments.
-It is an ordinary operator() that must : 
-
-* Be enabled only when one argument is a clef expression
-
-* Return a clef expression.
-
-The function make_expr_call helps.
-
-Object stored by copy (default)
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-The default behaviour is to store the object by copy in the expression tree...
-
-.. compileblock::
-
-    #include <triqs/clef.hpp>
-
-    struct Obj { 
-    double v;                      // put something in it
-    Obj(double v_): v(v_){}        // constructor
-
-    // The "normal", non lazy call operator ....
-    double operator() (double x) const { return 10*x;}
-
-    // Call operator for const object
-    // make_expr_call creates a clef expression with a "call" node at the top
-    // calling this object on the arguments.
-    // Obj is stored by making a copy in the expression tree.
-    // NB : the make_expr_call trait enabled only if one of the arguments is lazy
-    // hence if none of the Args are clef expression, the template is disabled by SFINAE.
-    template< typename... Args>
-    typename triqs::clef::result_of::make_expr_call<Obj,Args...>::type
-    operator()( Args&&... args ) const { return make_expr_call(* this,args...);}
-
-    // Just to print itself nicely in the expressions
-    friend std::ostream & operator<<(std::ostream & out, Obj const & x) { return out<<"Obj";}
-    };
-
-    int main() { 
-    Obj f(7);
-    triqs::clef::placeholder<3> x_;
-    triqs::clef::placeholder<4> y_;
-    std::cout << "Clef expression     : "<<  f(y_) + 2*x_ << std::endl ; 
-    std::cout << "Complete evaluation : "<< eval(f(x_) + 2*x_, x_=1) << std::endl ; 
-    std::cout << "Partial evaluation  : "<< eval(f(y_) + 2*x_, y_=1) << std::endl ; 
-    std::cout << "Complete evalution  : "<< eval(f(y_) + 2*x_, x_=3, y_=1) << std::endl ; 
-    }
- 
-Object stored by reference 
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Sometimes, one want to escape the copy of the object in the tree.
-In that case, just use a std::reference_wrapper in place of the object.
-You have then to guarantee that the object will live longer that the expression 
-that you form.
-
-.. compileblock::
-
-   #include <triqs/clef.hpp>
-
-   struct Obj { 
-   double v;                       // put something in it
-   Obj(double v_): v(v_){}        // constructor
-   Obj(Obj const &) = delete;    // a non copyable object 
-
-   // The "normal", non lazy call operator ....
-   double operator() (double x) const { return 10*x;}
-
-   // Same as above, but now we stored a ref to the object and not a copy of the object.
-   // Reference are encapsulated in std::reference_wrapper (Cf C++ documentation).
-   template< typename... Args>
-   typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const Obj>,Args...>::type
-   operator()( Args&&... args ) const { return make_expr_call (std::ref(* this),args...);}
-
-   // The non const version (which then stores a non-const reference ....)
-   template< typename... Args>
-   typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<Obj>,Args...>::type
-   operator()( Args&&... args ) { return  make_expr_call (std::ref(* this),args...);}
-
-   // Just to print itself nicely in the expressions
-   friend std::ostream & operator<<(std::ostream & out, Obj const & x) { return out<<"Obj";}
-   };
-
-   int main() { 
-   Obj f(7);
-   triqs::clef::placeholder<3> x_;
-   triqs::clef::placeholder<4> y_;
-   std::cout << "Clef expression     : "<<  f(y_) + 2*x_ << std::endl ; 
-   std::cout << "Complete evaluation : "<< eval(f(x_) + 2*x_, x_=1) << std::endl ; 
-   std::cout << "Partial evaluation  : "<< eval(f(y_) + 2*x_, y_=1) << std::endl ; 
-   std::cout << "Complete evalution  : "<< eval(f(y_) + 2*x_, x_=3, y_=1) << std::endl ; 
-   }
-
-.. note : one can of course replace the reference_wrapper by a view of the object, e.g....
-
-
-NB: When non lazy operator() is already a template ?
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Then it must be disabled for clef expression argument, using the trait ::
-
-   clef::is_any_lazy<T...> :: value // true iif one of the T is a clef expression
-
-Example, derived from the previous one : 
-
-.. compileblock::
-
-    #include <triqs/clef.hpp>
-    #include <iostream>
-
-    struct Obj { 
-    double v;                       // put something in it
-    Obj(double v_): v(v_){}        // constructor
-
-    // The "normal", non lazy call operator is now a template 
-    template <typename T>
-    typename std::enable_if<!triqs::clef::is_any_lazy<T>::value, T>::type   // correct 
-    // T operator() (T const & x) const { return 10*x;}  would be ambiguous !
-    operator() (T const & x) const { return 10*x;}
-
-    // lazy expression
-    template< typename... Args>
-    typename triqs::clef::result_of::make_expr_call<Obj,Args...>::type
-    operator()( Args&&... args ) const { return make_expr_call(* this,args...);}
-
-    // Just to print itself nicely in the expressions
-    friend std::ostream & operator<<(std::ostream & out, Obj const & x) { return out<<"Obj";}
-    };
-
-    int main() { 
-    Obj f(7); 
-    triqs::clef::placeholder<3> x_;
-    triqs::clef::placeholder<4> y_;
-    std::cout << "Clef expression     : "<<  f(y_) + 2*x_ << std::endl ; 
-    std::cout << "Partial evaluation  : "<< eval(f(y_) + 2*x_, y_=1) << std::endl ; 
-    std::cout << "Complete evalution  : "<< eval(f(y_) + 2*x_, x_=3, y_=1) << std::endl ; 
-    }
-
-

doc/reference/c++/clef/lazy_function_cls.rst

@@ -1,16 +0,0 @@
-.. highlight:: c
- 
-clef::function class 
-==========================
-
-The class triqs::clef::function is similar to boost::function (std::function),
-except that :
-
-* it can be constructed from an expression and an ordered list of placeholders.
-* it is `lazy-callable` and `lazy-assignable`
-
-.. note::
-  It stores the expression polymorphically, by erasing its type. (You can put various expressions into it, cf below).
-  This might lead to some performance penalty in some case, even though tests do not show that at present...
-
-Example of usage is given in :ref:`lazy_function_ex`. 

doc/reference/c++/clef/overload.rst

@@ -0,0 +1,129 @@
+.. highlight:: c
+
+Overloading functions and methods for CLEF arguments
+=====================================================
+
+.. _overload_function:
+
+Overloading functions 
+----------------------------
+
+Given a function, it is possible to overload it for CLEF expression arguments, returning a CLEF expression
+using the `TRIQS_CLEF_MAKE_FNT_LAZY` macro.
+
+**Synopsis** ::
+
+ namespace triqs { namespace clef { 
+ TRIQS_CLEF_MAKE_FNT_LAZY (function_to_make_lazy);
+ }}
+
+For example:
+
+.. compileblock::
+
+    #include <triqs/clef.hpp>
+    #include <iostream>
+
+    // a simple foo function 
+    double foo(double x) { return x/2;}
+    int foo(int x) { return x*2;}
+
+    // a more complex case : bar is already a template
+    // we have to disable it for CLEF expression to avoid ambiguity
+
+    // C++14 clean syntax will be (using concepts)
+    // template<NotClefExpression T>
+    // T bar (T const & x) { return x+1;} 
+
+    // C++11 workaround
+    template<typename T> 
+    typename std::enable_if<!triqs::clef::is_clef_expression<T>::value,T>::type 
+    bar (T const & x) { return x+1;} 
+ 
+    namespace triqs { namespace clef { TRIQS_CLEF_MAKE_FNT_LAZY (foo) ; TRIQS_CLEF_MAKE_FNT_LAZY (bar) ; }}
+
+    int main() { 
+      triqs::clef::placeholder<3> x_;
+      std::cout << foo(2.0)<<" "<<eval(x_ + foo(x_), x_ = 3)<<" "<<eval(x_ + foo(x_), x_ = 3.5) << std::endl;  
+      std::cout << bar(2.0)<<" "<<eval(x_ + bar(x_), x_ = 3)<<" "<<eval(x_ + bar(x_), x_ = 3.5) << std::endl;  
+     }
+  
+Note that : 
+ 
+* This overload **must** be defined in the triqs::clef namespace, since it is found by ADL.
+* The function `foo` can have many overloads.
+* The function `bar` can be a template, BUT then the template must be disabled for lazy expressions.
+* The overload is already defined by clef for usual functions : 
+
+.. compileblock::
+
+    #include <triqs/clef.hpp>
+    #include <iostream>
+    int main() { 
+      triqs::clef::placeholder<3> x_;
+      std::cout << 2.0 + std::cos(2.0) << std::endl;  
+      std::cout << eval( x_ + cos(x_), x_ = 2) << std::endl; // NB : note the absence of std::
+    }
+  
+.. _callable_object:
+
+Overloading operator() and other methods 
+---------------------------------------------------
+
+
+Similarly to functions, classes can define an `operator()` for CLEF expressions arguments (or any other method).
+It is an ordinary operator() that must : 
+
+* Be enabled only when one argument is a CLEF expression
+* Return a CLEF expression.
+
+Example : 
+
+.. compileblock::
+       
+    #include <triqs/clef.hpp>
+        
+    struct Obj { 
+    double v;                      // put something in it
+    Obj(double v_): v(v_){}        // constructor
+    Obj(Obj const &) = delete;    // a non copyable object, to illustrate that we do NOT copy...
+
+    // The "normal", non CLEF call operator ....
+    double operator() (double x) const { return 10*x;}
+
+    // This macro implements properly an overload of the operator ()
+    TRIQS_CLEF_IMPLEMENT_LAZY_CALL();
+
+    // a method
+    double my_method(double x) { return 2*x;}
+   
+    // CLEF overload
+    TRIQS_CLEF_IMPLEMENT_LAZY_METHOD(Obj,my_method);
+     
+    // Just to print itself nicely in the expressions
+    friend std::ostream & operator<<(std::ostream & out, Obj const & x) { return out<<"Obj";}
+    };
+
+    int main() { 
+    Obj f(7);
+    triqs::clef::placeholder<1> x_; triqs::clef::placeholder<2> y_;
+
+    std::cout << "Clef expression     : "<<  f(y_) + 2*x_ << std::endl ; 
+    std::cout << "Complete evaluation : "<< eval(f(x_) + 2*x_, x_=1) << std::endl ; 
+    std::cout << "Partial evaluation  : "<< eval(f(y_) + 2*x_, y_=1) << std::endl ; 
+    std::cout << "Complete evalution  : "<< eval(f(y_) + 2*x_, x_=3, y_=1) << std::endl<<std::endl ; 
+
+    std::cout << "Clef expression     : "<<  f.my_method(y_) + 2*x_ << std::endl ; 
+    std::cout << "Complete evaluation : "<< eval(f.my_method(x_) + 2*x_, x_=1) << std::endl ; 
+    std::cout << "Partial evaluation  : "<< eval(f.my_method(y_) + 2*x_, y_=1) << std::endl ; 
+    std::cout << "Complete evalution  : "<< eval(f.my_method(y_) + 2*x_, x_=3, y_=1) << std::endl ; 
+     }
+ 
+**NB**  When the method or the non CLEF operator() is already a template, 
+        it must be disabled for clef expression argument, using the trait ::
+
+           clef::is_clef_expression<T...> // true iif one of the T is a clef expression
+
+        as the `bar` function above.
+
+

test/speed/clef_common.hpp

@@ -1,67 +0,0 @@
-#include <triqs/clef/clef.hpp>
-#include <triqs/clef/io.hpp>
-#define TEST(X) std::cout << BOOST_PP_STRINGIZE((X)) << " ---> "<< (X) <<std::endl;
-
-struct F1{ 
- double v; 
- F1(double v_): v(v_){} 
- F1(F1 const &) = delete; // non copyable
- double operator() (double x) const { return 10*x;}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const F1>,Args...>::type
-  operator()( Args&&... args ) const { return make_expr_call (std::ref(*this),args...);}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<F1>,Args...>::type
-  operator()( Args&&... args ) { return  make_expr_call (std::ref(*this),args...);}
-
-  template<typename Fnt> friend void triqs_clef_auto_assign (F1 & x, Fnt f) { x.v++; std::cerr<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;}
- friend std::ostream & operator<<(std::ostream & out, F1 const & x) { return out<<"F1";}
-};
-
-struct F1b {
- double v; std::shared_ptr<double> v_ptr;
-
- F1b(double v_): v_ptr (new double(v_)) {v=v_;} // on purpose, I avoid adding a default constructor !  
- F1b (F1b const & x)  { v_ptr  = x.v_ptr; v = x.v; std::cerr<< " F1 COPY "<<std::endl;}
- //F1b (F1b && x)  { v_ptr  = x.v_ptr; v = x.v; std::cerr<< " F1 COPY "<<std::endl;}
-
- double operator() (double x) const { return 10*x;}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<F1b,Args...>::type
-  operator()( Args&&... args ) { return  triqs::clef::make_expr_call (*this,args...);}
-
-  template<typename Fnt> friend void triqs_clef_auto_assign (F1b & x, Fnt f) { (*(x.v_ptr))++; std::cerr<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;}
- friend std::ostream & operator<<(std::ostream & out, F1b const & x) { return out<<"F1b";}
-
-};
-
-struct F2 {
-
- double v; 
- F2() {v=0;}
-
- double operator()(double x, double y) const { return 10*x + y;}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const F2>,Args...>::type
-  operator()( Args&&... args ) const { return  make_expr_call (std::ref(*this),args...);}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<F2>,Args...>::type
-  operator()( Args&&... args ) { return  make_expr_call (std::ref(*this),args...);}
-
- template<typename Fnt> friend void triqs_clef_auto_assign (F2 const & x, Fnt f) { std::cerr<< " called F2 triqs_clef_auto_assign "<< f(10,20)<<std::endl;}
- friend std::ostream & operator<<(std::ostream & out, F2 const & x) { return out<<"F2";}
-};
-
-
-using namespace triqs::clef;
-
-triqs::clef::placeholder <1> x_; 
-triqs::clef::placeholder <2> y_; 
-triqs::clef::placeholder <3> z_; 
-namespace tql= triqs::clef;
-

test/speed/clef_common.hpp

@@ -0,0 +1 @@
+../triqs/clef/common.hpp

test/triqs/clef/F7.cpp

@@ -5,13 +5,7 @@ struct F7 {
  F7(double v_): v(v_){} 
  double operator() (int i1, int i2, int i3, int i4, int i5, int i6, int i7 ) const { return 10*i1;}
  
- template< typename... Args>
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(F7);
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const F7>,Args...>::type
-  operator()( Args&&... args ) const { return  make_expr_call (std::ref(*this),args...);}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<F7>,Args...>::type
-  operator()( Args&&... args ) { return  make_expr_call (std::ref(*this),args...);}
 
  template<typename Fnt> friend void triqs_clef_auto_assign (F7 & x, Fnt f) { x.v++; std::cerr<< " called triqs_clef_auto_assign "<< f(1,2,3,4,5,6,7)<<std::endl;}
  friend std::ostream & operator<<(std::ostream & out, F7 const & x) { return out<<"F7";}

test/triqs/clef/chain_call.cpp

@@ -9,13 +9,12 @@ struct F2_vec {
  
  F2 const & operator()(size_t i) const { return vec[i];}
 
- template< typename... Args>
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(F2_vec);
-  typename triqs::clef::result_of::make_expr_call<F2_vec,Args...>::type
-  operator()( Args&&... args ) const { return  triqs::clef::make_expr_call (*this,args...);}
 
  template<typename Fnt>
   friend void triqs_clef_auto_assign (F2_vec const & x, Fnt f) { 
-   for (size_t i=0; i< x.vec.size(); ++i) triqs_clef_auto_assign(x.vec[i],  f(i)); } 
+   for (size_t i=0; i< x.vec.size(); ++i) triqs_clef_auto_assign(x.vec[i],  f(i)); 
+  } 
 
  friend std::ostream & operator<<(std::ostream & out, F2_vec const & x) { return out<<"F2_vec";}
 };

test/triqs/clef/common.hpp

@@ -6,37 +6,17 @@ struct F1{
  double v; 
  F1(double v_): v(v_){} 
  F1(F1 const &) = delete; // non copyable
+ F1(F1 &&x) : v(x.v) { std::cerr << "Moving F1 "<< v<<std::endl;}
+
  double operator() (double x) const { return 10*x;}
 
- template< typename... Args>
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(F1);
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const F1>,Args...>::type
-  operator()( Args&&... args ) const { return make_expr_call (std::ref(*this),args...);}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<F1>,Args...>::type
-  operator()( Args&&... args ) { return  make_expr_call (std::ref(*this),args...);}
 
  template<typename Fnt> friend void triqs_clef_auto_assign (F1 & x, Fnt f) { x.v++; std::cerr<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;}
+ 
  friend std::ostream & operator<<(std::ostream & out, F1 const & x) { return out<<"F1";}
 };
 
-struct F1b {
- double v; std::shared_ptr<double> v_ptr;
-
- F1b(double v_): v_ptr (new double(v_)) {v=v_;} // on purpose, I avoid adding a default constructor !  
- F1b (F1b const & x)  { v_ptr  = x.v_ptr; v = x.v; std::cerr<< " F1 COPY "<<std::endl;}
- //F1b (F1b && x)  { v_ptr  = x.v_ptr; v = x.v; std::cerr<< " F1 COPY "<<std::endl;}
-
- double operator() (double x) const { return 10*x;}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<F1b,Args...>::type
-  operator()( Args&&... args ) { return  triqs::clef::make_expr_call (*this,args...);}
-
-  template<typename Fnt> friend void triqs_clef_auto_assign (F1b & x, Fnt f) { (*(x.v_ptr))++; std::cerr<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;}
- friend std::ostream & operator<<(std::ostream & out, F1b const & x) { return out<<"F1b";}
-
-};
 
 struct F2 {
 
@@ -45,15 +25,10 @@ struct F2 {
 
  double operator()(double x, double y) const { return 10*x + y;}
 
- template< typename... Args>
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(F2);
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const F2>,Args...>::type
-  operator()( Args&&... args ) const { return  make_expr_call (std::ref(*this),args...);}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<F2>,Args...>::type
-  operator()( Args&&... args ) { return  make_expr_call (std::ref(*this),args...);}
 
  template<typename Fnt> friend void triqs_clef_auto_assign (F2 const & x, Fnt f) { std::cerr<< " called F2 triqs_clef_auto_assign "<< f(10,20)<<std::endl;}
+
  friend std::ostream & operator<<(std::ostream & out, F2 const & x) { return out<<"F2";}
 };
 

test/triqs/clef/function.cpp

@@ -34,5 +34,8 @@ int main() {
  TEST(tql::eval( h, y_=1) (10)); 
  TEST(h); 
 
+ auto hh = var(x_, y_) >> 2*x_ + y_;
+ std::cout  << hh (3,1) << std::endl; 
+
 }
 

test/triqs/clef/function.output

@@ -9,3 +9,4 @@
 lazy function : (_1) --> (((2 * _1) + 1) + 1)
 (tql::eval( h, y_=1) (10)) ---> 22
 (h) ---> lazy function : (_1) --> (((2 * _1) + _2) + 1)
+7

test/triqs/clef/general.cpp

@@ -59,30 +59,24 @@ int main() {
  { 
   // testing the LHS wrting on an object caught by ref
   F1 f(7);
+  std::cerr  << " operator(double) still ok "<< f(2) << std::endl; 
   std::cout<< " f.v before assign "<<f.v<<" "<<  std::endl;
   f(x_ ) << 8*x_ ;
-  //f(x_ + y_) = 8*x_ ;// leads to a compile error as expected
+  //f(x_ + y_) << 8*x_ ;// leads to a compile error as expected
   // test.cpp:129:14: error: no viable overloaded '='
-  // f(x_ + y_) = 8*x_ ;
+  // f(x_ + y_) << 8*x_ ;
   // ~~~~~~~~~~ ^ ~~~~
   std::cout<< " f.v after assign "<<f.v<<" "<<  std::endl;
   std::cout<<"-------------"<<std::endl;
+  std::cerr  <<F1{9}(2,x_, F1{2})<<std::endl;
+  auto expr = F1{9}(x_);
+  expr << 7*x_;
+  std::cerr  << expr << std::endl ;
+  F1{9}(x_ ) << 8*x_ ;
+  std::cerr<<"-------------"<<std::endl;
 
  }
 
-{ 
-  // testing the LHS wrting on object caught by copy
-  F1b fb(7); 
-  std::cout<< " fb.v before assign "<<fb.v<<" "<< *fb.v_ptr<< std::endl;
-  fb(x_ ) << 8*x_ ; 
-  //f(x_ + y_) = 8*x_ ;// leads to a compile error as expected
-  // test.cpp:129:14: error: no viable overloaded '='
-  // f(x_ + y_) = 8*x_ ;
-  // ~~~~~~~~~~ ^ ~~~~
-  std::cout<< " fb.v after assign "<<fb.v<<" "<< *fb.v_ptr<< std::endl;
-  std::cout<<"-------------"<<std::endl;
-
- }
  { 
   // testing fnt of 2 variables
   F2 ff;

test/triqs/clef/general.output

@@ -45,9 +45,6 @@
 -------------
  f.v before assign 7 
  f.v after assign 8 
--------------
- fb.v before assign 7 7
- fb.v after assign 7 8
 -------------
 expr = (F2(_1, _2) + (2 * _2))
 eval(expr,x_ =1, y_ =2) =  16 and it should be 16

test/triqs/clef/lazy.cpp

@@ -12,19 +12,19 @@ int main() {
  V[0]=14; V[1]=2; V[2]=3;
  std::cout<< "V = "<< V[0]<<" "<<V[1]<<" "<<V[2]<<std::endl;
 
- TEST( tql::eval(lazy(V) [i_],  i_=0));
+ TEST( tql::eval(make_expr(V) [i_],  i_=0));
   
- lazy(V) [i_]  << i_ + 2;
+ make_expr(V) [i_]  << i_ + 2;
   
  std::cout<< "V = "<< V[0]<<" "<<V[1]<<" "<<V[2]<<std::endl;
  
- lazy(W) [i_]  << i_ + lazy(V)[i_];
+ make_expr(W) [i_]  << i_ + make_expr(V)[i_];
 
  std::cout<< "W = "<< W[0]<<" "<<W[1]<<" "<<W[2]<<std::endl;
 
  std::vector< std::vector< int> > v2 (3, std::vector<int>(2));
 
- lazy(v2)[i_][j_] << (i_ + j_ + 1);
+ make_expr(v2)[i_][j_] << (i_ + j_ + 1);
 
  for (size_t u=0; u<v2.size(); ++u)
  for (size_t up=0; up<v2[0].size(); ++up)

test/triqs/clef/lazy.output

@@ -1,5 +1,5 @@
 V = 14 2 3
-(tql::eval(lazy(V) [i_], i_=0)) ---> 14
+(tql::eval(make_expr(V) [i_], i_=0)) ---> 14
 V = 2 3 4
 W = 2 4 6
 11

test/triqs/clef/lazy_method.cpp

@@ -0,0 +1,37 @@
+#include "./common.hpp"
+
+struct AA{ 
+ double v; 
+ AA(double v_): v(v_){} 
+ AA(AA const &) = delete; // non copyable
+ AA(AA &&x) : v(x.v) { std::cerr << "Moving AA "<< std::endl;}
+
+ double operator() (double x) const { return 10*x;}
+
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(AA);
+
+ template<typename Fnt> friend void triqs_clef_auto_assign (AA & x, Fnt f) { x.v++; std::cerr<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;}
+ 
+ friend std::ostream & operator<<(std::ostream & out, AA const & x) { return out<<"AA";}
+
+ double my_method(double x) { return 2*x;}
+
+#ifndef TRIQS_COMPILER_OBSOLETE_GCC
+ TRIQS_CLEF_IMPLEMENT_LAZY_METHOD(AA,my_method);
+#else
+ TRIQS_CLEF_IMPLEMENT_LAZY_METHOD(AA,my_method,double);
+#endif
+
+};
+
+
+
+int main() { 
+
+ AA f{8};
+
+ TEST(eval( f.my_method(x_), x_ = 10));
+
+
+};
+

test/triqs/clef/lazy_method.output

@@ -0,0 +1 @@
+(eval( f.my_method(x_), x_ = 10)) ---> 20

test/triqs/clef/test1.cpp

@@ -13,15 +13,10 @@ struct F1{
  F1(F1 const &) = delete; // non copyable
  double operator() (double x) const { return 10*x;}
 
- template< typename... Args>
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(F1);
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<const F1>,Args...>::type
-  operator()( Args&&... args ) const { return  make_expr_call (std::ref(*this),args...);}
-
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<std::reference_wrapper<F1>,Args...>::type
-  operator()( Args&&... args ) { return  make_expr_call (std::ref(*this),args...);}
 
  template<typename Fnt> friend void triqs_clef_auto_assign (F1 & x, Fnt f) { x.v++; std::cerr<< " called triqs_clef_auto_assign "<< f(100)<<std::endl;}
+ 
  friend std::ostream & operator<<(std::ostream & out, F1 const & x) { return out<<"F1";}
 };
 

test/triqs/clef_examples/sum_functional.cpp

@@ -1,56 +1,39 @@
 #include <triqs/clef.hpp>
-#include <triqs/clef/io.hpp>
-// a general implementation type for all domain and summation methods
-template<typename Domain, typename Options> struct sum_impl;
-struct Riemann{}; // one sum method
 
-template<typename Domain> struct sum_impl<Domain, Riemann> {
+template<typename Domain> struct sum_impl { 
  Domain d;
- sum_impl(Domain const &d_):d(d_) {}
 
- // Disabled when F is a lazy_expression
+ // C++14 
+ // double operator() (NotClefExpression const & f) const { double s=0; for (int u=0; u<10; ++u) s += f(u/10.0); return s;}
+
+ // C++11 form 
  template <typename F>
-  typename std::enable_if< !triqs::clef::is_any_lazy <F>::value, double >::type 
+  typename std::enable_if< !triqs::clef::is_clef_expression <F>::value, double >::type 
   operator() (F const & f) const { double s=0; for (int u=0; u<10; ++u) s += f(u/10.0); return s;}
 
- // Defines operator(). Enabled iff one argument is a clef expression.
+ TRIQS_CLEF_IMPLEMENT_LAZY_CALL(sum_impl);
- template< typename... Args>
-  typename triqs::clef::result_of::make_expr_call<sum_impl,Args...>::type
-  operator()( Args&&... args ) const { return  triqs::clef::make_expr_call (*this,args...);}
 
- // How to print this object in the printing of clef expression
  friend std::ostream & operator<<(std::ostream & out, sum_impl const & x) { return out<<"sum";}
 };
 
-template<typename Domain, typename Option> 
+// a little factory ...
-sum_impl<Domain,Option> sum_functional (Domain && d, Option) {return d;}
+template<typename Domain> sum_impl<Domain> sum_functional (Domain d) {return {d};}
-
-//---------    MAIN   ---------------------------------------
 
 struct DOM{};
 
 int main() { 
- // two placeholders
+ triqs::clef::placeholder <1> x_; triqs::clef::placeholder <2> y_; 
- triqs::clef::placeholder <1> x_; 
+ DOM d; 
- triqs::clef::placeholder <2> y_; 
 
- DOM d; // a domain
+ // integrate_on_d is the integration functional 
- 
+ auto integrate_on_d = sum_functional(d); 
- // integrate_on_d is the integration (!) over d with Riemann method
- auto integrate_on_d = sum_functional( d, Riemann()); 
 
  // This is a simple application of the sum to a function 
  std::cout<< integrate_on_d( x_ >> 2*x_ + 1 )  << std::endl;
 
- // This creates a clef expression of placeholder y_, waiting to make the sum
+ // A function y -> y_ + integrate (x -> 2*x + y) 
- // Indeed the argument is a clef expression of y_ returning a function
+ auto e1 = y_ + integrate_on_d( x_ >> 2*x_  + y_ );
- // composed by integrate_on_d, it is a clef expression of y_ returning a double
+ std::cout<< e1 << std::endl;
- std::cout<< integrate_on_d( x_ >> 2*x_ + 1 + y_ )  << std::endl;
+ std::cout<< eval (e1 ,y_ =0)  << std::endl;
-
- // Of course this expression can be mixed with others...
- std::cout<< y_ + 2* integrate_on_d( x_ >> 2*x_ + 1 + y_ )  << std::endl;
-
- // and it can be evaluated 
- std::cout<< eval (y_ + 2* integrate_on_d( x_ >> 2*x_ + 1 + y_ ) ,y_ =0)  << std::endl;
 }
 

test/triqs/clef_examples/sum_functional.output

@@ -0,0 +1,3 @@
+19
+(_2 + sum(lazy function : (_1) --> ((2 * _1) + _2)))
+9

test/triqs/clef_examples/sum_functional2.output

@@ -1,4 +0,0 @@
-19
-sum(lazy function : (_1) --> (((2 * _1) + 1) + _2))
-(_2 + (2 * sum(lazy function : (_1) --> (((2 * _1) + 1) + _2))))
-38

test/triqs/clef_examples/vector_and_math.cpp

@@ -10,9 +10,9 @@ int main() {
  double pi = std::acos(-1);
  std::vector<double> V(N);
 
- // automatic assignment of vector and use of lazy math function
+ // automatic assignment of vector and use of make_expr math function
  tql::placeholder <0> k_; 
- tql::lazy(V) [k_]  << cos( (2* pi* k_)/ N );
+ tql::make_expr(V) [k_]  << cos( (2* pi* k_)/ N );
 
  // check result... 
  for (size_t u=0; u<V.size(); ++u)

triqs/arrays/impl/indexmap_storage_pair.hpp

@@ -232,6 +232,31 @@ namespace triqs { namespace arrays {
     typename ISPViewType<value_type,domain_type::rank, OptionFlags, TraversalOrder, ViewTag, StorageType::is_weak >::type
      operator()() && { return *this; }
 
+    // Interaction with the CLEF library : calling with any clef expression as argument build a new clef expression
+    // NB : this is ok because indexmap_storage_pair has a shallow copy constructor ...
+    // Correction : no copy, just a ref...
+    // so A(i_) if A is an array will NOT copy the data....
+    template< typename... Args>
+     typename clef::_result_of::make_expr_call<indexmap_storage_pair const &,Args...>::type
+     operator()( Args&&... args ) const & {
+      static_assert(sizeof...(Args) <= indexmap_type::rank, "Incorrect number of variable in call");// not perfect : ellipsis ...
+      return make_expr_call(*this,args...);
+     }
+
+    template< typename... Args>
+     typename clef::_result_of::make_expr_call<indexmap_storage_pair &,Args...>::type
+     operator()( Args&&... args ) & {
+      static_assert(sizeof...(Args) <= indexmap_type::rank, "Incorrect number of variable in call");// not perfect : ellipsis ...
+      return make_expr_call(*this,args...);
+     }
+
+    template< typename... Args>
+     typename clef::_result_of::make_expr_call<indexmap_storage_pair,Args...>::type
+     operator()( Args&&... args ) && {
+      static_assert(sizeof...(Args) <= indexmap_type::rank, "Incorrect number of variable in call");// not perfect : ellipsis ...
+      return make_expr_call(std::move(*this),args...);
+     }
+
 #else
 
     template<typename... Args>   // non const version
@@ -258,18 +283,25 @@ namespace triqs { namespace arrays {
     typename ISPViewType<value_type,domain_type::rank, OptionFlags, TraversalOrder, ViewTag, false >::type
      operator()() { return *this; }
 
-#endif
     // Interaction with the CLEF library : calling with any clef expression as argument build a new clef expression
     // NB : this is ok because indexmap_storage_pair has a shallow copy constructor ...
+    // Correction : no copy, just a ref...
     // so A(i_) if A is an array will NOT copy the data....
     template< typename... Args>
-     typename clef::result_of::make_expr_call<indexmap_storage_pair,Args...>::type
+     typename clef::_result_of::make_expr_call<indexmap_storage_pair const &,Args...>::type
      operator()( Args&&... args ) const {
       static_assert(sizeof...(Args) <= indexmap_type::rank, "Incorrect number of variable in call");// not perfect : ellipsis ...
       return make_expr_call(*this,args...);
-      //return make_expr_call( view_type(*this),args...);
      }
 
+    template< typename... Args>
+     typename clef::_result_of::make_expr_call<indexmap_storage_pair &,Args...>::type
+     operator()( Args&&... args ) {
+      static_assert(sizeof...(Args) <= indexmap_type::rank, "Incorrect number of variable in call");// not perfect : ellipsis ...
+      return make_expr_call(*this,args...);
+     }
+
+#endif
     template<typename Fnt> friend void triqs_clef_auto_assign (indexmap_storage_pair & x, Fnt f) { assign_foreach(x,f);}
 
     // ------------------------------- Iterators --------------------------------------------

triqs/arrays/make_immutable_array.hpp

@@ -30,7 +30,7 @@ namespace triqs { namespace arrays {
    template<int I> struct _si { typedef size_t type;};
    public : 
     immutable_array_expr_impl(Expr e_, clef::pair<ph,range> ... p): 
-     f(clef::make_function(e_, clef::placeholder<ph>()...)), dom_(make_shape(p.rhs().size()...)) {};
+     f(clef::make_function(e_, clef::placeholder<ph>()...)), dom_(make_shape(p.rhs.size()...)) {};
     typedef typename triqs::clef::result_of::make_function<Expr,clef::placeholder<ph>... >::type function_type;
     typedef typename std::result_of<function_type(typename _si<ph>::type...)>::type value_type;
     typedef indexmaps::cuboid::domain_t<sizeof...(ph)> domain_type;

triqs/clef/adapters/math.hpp

@@ -23,6 +23,7 @@
 #include "../clef.hpp"
 #include <math.h>
 #include <boost/preprocessor/seq/for_each.hpp>
+#include <complex>
 
 #define TRIQS_CLEF_STD_MATH_FNT_TO_MAKE_LAZY (cos)(sin)(tan)(cosh)(sinh)(tanh)(acos)(asin)(atan)(exp)(log)(sqrt)(abs)(floor)(pow)
 

triqs/clef/clef.hpp

@@ -2,7 +2,7 @@
  *
  * TRIQS: a Toolbox for Research in Interacting Quantum Systems
  *
- * Copyright (C) 2012 by O. Parcollet
+ * Copyright (C) 2012-2013 by O. Parcollet
  *
  * TRIQS is free software: you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
@@ -21,12 +21,13 @@
 #ifndef TRIQS_CLEF_CORE_H
 #define TRIQS_CLEF_CORE_H
 #include <triqs/utility/first_include.hpp>
+#include <triqs/utility/macros.hpp>
+#include <triqs/utility/compiler_details.hpp>
 #include <tuple>
 #include <type_traits>
 #include <functional>
 #include <memory>
 #include <complex>
-#include <assert.h>
 #include <boost/preprocessor/stringize.hpp>
 #include <boost/preprocessor/repetition/repeat_from_to.hpp>
 #include <boost/preprocessor/repetition/enum.hpp>
@@ -36,38 +37,49 @@
 
 namespace triqs { namespace clef { 
  typedef unsigned long long ull_t;
- template<typename T> struct remove_cv_ref : std::remove_cv< typename std::remove_reference<T>::type> {};
  namespace tags { struct function_class{}; struct function{}; struct subscript{}; struct terminal{}; struct if_else{}; struct unary_op{}; struct binary_op{}; }
 
+ // Compute the type to put in the expression tree.
+ // If T is a lvalue reference, pack it into a reference_wrapper, unless force_copy_in_expr<T>::value == true
+ // If T is an rvalue reference, we store it as the type (using move semantics).
+ template<typename T> struct force_copy_in_expr : std::false_type{};
+ template<typename T> struct force_copy_in_expr<T const> : force_copy_in_expr<T>{};
+
+ template< class T > struct expr_storage_t      {typedef T type;};
+ template< class T > struct expr_storage_t<T&>  : std::conditional<force_copy_in_expr<T>::value, T ,std::reference_wrapper<T>>{};
+ template< class T > struct expr_storage_t<T&&> {typedef T type;};
+ 
  /* ---------------------------------------------------------------------------------------------------
   *  Placeholder and corresponding traits
   *  --------------------------------------------------------------------------------------------------- */
- template<int i, typename T> struct pair { 
+ template<int i, typename T> class pair; // forward
-  static constexpr int p = i; 
-  typedef typename remove_cv_ref <T>::type value_type; 
-  value_type const & r;
-  value_type const & rhs() const { return r;} 
-  pair (T const & t) : r(t){}
- };
 
+  // a placeholder is an empty struct, labelled by an int.
  template<int N> struct placeholder {
   static_assert( (N>=0) && (N<64) , "Placeholder number limited to [0,63]");
   static constexpr int index = N;
-  template <typename RHS> pair<N,RHS> operator = (RHS const & rhs) { return pair<N,RHS>(rhs);} 
+  template <typename RHS> pair<N,RHS> operator = (RHS && rhs) { return {std::forward<RHS>(rhs)};} 
  };
  
- template<typename T> struct is_placeholder : std::false_type  {}; 
+ // placeholder will always be copied (they are empty anyway).
- template<int N> struct is_placeholder <placeholder <N> > : std::true_type  {}; 
+ template< int N > struct force_copy_in_expr<placeholder<N>> : std::true_type{};
 
+ // represent a couple (placeholder, value). 
+ template<int N, typename U> struct pair {
+  U rhs;
+  static constexpr int p = N;
+  typedef typename remove_cv_ref <U>::type value_type; 
+ };
+
+ // ph_set is a trait that given a pack of type, returns the set of placeholders they contain
+ // it returns a int in binary coding : bit N in the int is 1 iif at least one T is lazy and contains placeholder<N>
  template<typename... T> struct ph_set;
  template<typename T0, typename... T> struct ph_set<T0,T...>{static constexpr ull_t value= ph_set<T0>::value| ph_set<T...>::value;};
  template<typename T> struct ph_set<T>                      {static constexpr ull_t value= 0;};
  template<int N>      struct ph_set<placeholder<N>>         {static constexpr ull_t value= 1ull<<N;};
  template<int i, typename T> struct ph_set<pair<i,T> > : ph_set<placeholder<i>>{};
 
- /* ---------------------------------------------------------------------------------------------------
+ // in_any_lazy : trait to detect if any of Args is a lazy expression
-  *  Detect if an object is a lazy expression
-  *  --------------------------------------------------------------------------------------------------- */
  template<typename... Args>             struct is_any_lazy                     :  std::false_type {};
  template<int N>                        struct is_any_lazy <placeholder <N> >  :  std::true_type  {};
  template <typename T>                  struct is_any_lazy< T >                :  std::false_type {};
@@ -77,68 +89,78 @@ namespace triqs { namespace clef {
  template<typename T, typename... Args> struct is_any_lazy<T, Args...>         :
   std::integral_constant<bool, is_any_lazy<T>::value || is_any_lazy<Args...>::value> {}; 
 
- // a trait that checks the type are value i.e. no &, &&
+ template<typename T>
- template<typename... T> struct has_no_ref : std::true_type {};
+ constexpr bool ClefExpression() { return is_any_lazy<T>::value;}
- template<typename T0, typename... T> struct has_no_ref<T0,T...> : std::integral_constant<bool, !(std::is_reference<T0>::value)&& has_no_ref<T...>::value> {};
+
+ template<typename T> struct is_clef_expression : is_any_lazy<T>{};
 
 /* ---------------------------------------------------------------------------------------------------
   * Node of the expression tree
   *  --------------------------------------------------------------------------------------------------- */
  template<typename Tag, typename... T> struct expr {
-  static_assert( has_no_ref<T...>::value , "Internal error : expr childs can not be reference "); 
+  // T can be U, U & (a reference or a value).
   typedef std::tuple<T...> childs_t; 
   childs_t childs; 
   expr(expr const & x) = default; 
-  expr(expr && x) : childs(std::move(x.childs)) {}
+  expr(expr && x) noexcept : childs(std::move(x.childs)) {}
-  template<typename... Args> explicit expr(Tag, Args&&...args) : childs(std::forward<Args>(args)...) {} 
+  // a constructor with the Tag make it unambiguous with other constructors...
+  template<typename... Args> expr(Tag, Args&&...args) : childs(std::forward<Args>(args)...) {} 
+  // [] returns a new lazy expression, with one more layer
   template<typename Args> 
-   expr<tags::subscript, expr, typename remove_cv_ref<Args>::type > operator[](Args && args) const 
+   expr<tags::subscript, expr, typename expr_storage_t<Args>::type > operator[](Args && args) const 
-   { return expr<tags::subscript, expr, typename remove_cv_ref<Args>::type> (tags::subscript(), *this,std::forward<Args>(args));}
+   { return {tags::subscript(), *this,std::forward<Args>(args)};}
+  // () also ...
   template< typename... Args > 
-   expr<tags::function, expr, typename remove_cv_ref<Args>::type...> operator()(Args && ... args) const 
+   expr<tags::function, expr, typename expr_storage_t<Args>::type...> operator()(Args && ... args) const 
-   { return expr<tags::function, expr, typename remove_cv_ref<Args>::type...>(tags::function(), *this,std::forward<Args>(args)...);}
+   { return {tags::function(), *this,std::forward<Args>(args)...};}
-  // only f(i,j) = expr is allowed, in case where f is a clef::function
+  // assignement is in general deleted
-  // otherwise use the << operator
+  expr & operator= (expr const &)  = delete; // no ordinary assignment
+  expr & operator= (expr &&)  = default; // move assign ok 
+  // however, this is ok in the case f(i,j) = expr, where f is a clef::function
   template<typename RHS, typename CH = childs_t> 
-   typename std::enable_if<std::is_base_of<tags::function_class, typename std::tuple_element<0,CH>::type>::value>::type
+   ENABLE_IF(std::is_base_of<tags::function_class, typename std::tuple_element<0,CH>::type>)
    operator= (RHS const & rhs) { *this << rhs;}
   template<typename RHS, typename CH = childs_t> 
-   typename std::enable_if<!std::is_base_of<tags::function_class, typename std::tuple_element<0,CH>::type>::value>::type
+   DISABLE_IF(std::is_base_of<tags::function_class, typename std::tuple_element<0,CH>::type>)
    operator= (RHS const & rhs) = delete; 
-  expr & operator= (expr const & )  = delete; // no ordinary copy
  };
+ // set some traits
  template<typename Tag, typename... T> struct ph_set< expr<Tag,T... > > : ph_set<T...> {};
  template<typename Tag, typename... T> struct is_any_lazy< expr<Tag,T... > >: std::true_type {};
+ // if we want that subexpression are copied ?
+ template<typename Tag, typename... T> struct force_copy_in_expr< expr<Tag,T... > > : std::true_type{};
 
  /* ---------------------------------------------------------------------------------------------------
   * The basic operations put in a template.... 
   *  --------------------------------------------------------------------------------------------------- */
  template<typename Tag> struct operation;
 
+ // a little function to clean the reference_wrapper
+ template<typename U> U & _cl(U & x) { return x;}
+ template<typename U> U & _cl(std::reference_wrapper<U> x) { return x.get();}
+
  /// Terminal 
  template<> struct operation<tags::terminal> { template<typename L> L operator()(L&& l) const { return std::forward<L>(l);} };
 
  /// Function call 
  template<> struct operation<tags::function> { 
-  template<typename F, typename... Args> auto operator()(F const & f, Args const & ... args) const -> decltype(f(args...)) { return f(args...);} 
+  template<typename F, typename... Args> auto operator()(F const & f, Args const & ... args) const DECL_AND_RETURN(_cl(f)(_cl(args)...));
-  template<typename F, typename... Args> auto operator()(std::reference_wrapper<F> const &f, Args const & ... args) const -> decltype(f.get()(args...)) { return f.get()(args...);} 
  };
 
  /// [ ] Call
  template<> struct operation<tags::subscript> { 
-  template<typename F, typename Args> auto operator()(F const & f, Args const & args) const -> decltype(f[args]) { return f[args];} 
+  template<typename F, typename Args> auto operator()(F const & f, Args const & args) const DECL_AND_RETURN(_cl(f)[_cl(args)]);
-  template<typename F, typename Args> auto operator()(std::reference_wrapper<F> const &f, Args const & args) const -> decltype(f.get()[args]) { return f.get()[args];} 
  };
 
  // all binary operators....
 #define TRIQS_CLEF_OPERATION(TAG,OP)\
  namespace tags { struct TAG : binary_op { static const char * name() { return BOOST_PP_STRINGIZE(OP);} };}\
  template<> struct operation<tags::TAG> {\
-  template<typename L, typename R> auto operator()(L  const & l, R  const & r) const -> decltype(l OP r) { return l OP r;}\
+  template<typename L, typename R> auto operator()(L  const & l, R  const & r) const DECL_AND_RETURN ( _cl(l) OP _cl(r));\
  };\
  template<typename L, typename R>\
- typename std::enable_if<is_any_lazy<L,R>::value, expr<tags::TAG,typename remove_cv_ref<L>::type,typename remove_cv_ref<R>::type> >::type \
+ typename std::enable_if<is_any_lazy<L,R>::value, expr<tags::TAG,typename expr_storage_t<L>::type,typename expr_storage_t<R>::type> >::type \
- operator OP (L && l, R && r) { return expr<tags::TAG,typename remove_cv_ref<L>::type,typename remove_cv_ref<R>::type> (tags::TAG(),std::forward<L>(l),std::forward<R>(r));}\
+ operator OP (L && l, R && r) { return {tags::TAG(),std::forward<L>(l),std::forward<R>(r)};}\
 
  TRIQS_CLEF_OPERATION(plus,       +);
  TRIQS_CLEF_OPERATION(minus,      -);
@@ -155,11 +177,11 @@ namespace triqs { namespace clef {
 #define TRIQS_CLEF_OPERATION(TAG,OP)\
  namespace tags { struct TAG : unary_op { static const char * name() { return BOOST_PP_STRINGIZE(OP);} };}\
  template<> struct operation<tags::TAG> {\
-  template<typename L> auto operator()(L const & l) const -> decltype(OP l) { return OP l;}\
+  template<typename L> auto operator()(L const & l) const DECL_AND_RETURN (OP _cl(l));\
  };\
  template<typename L>\
- typename std::enable_if<is_any_lazy<L>::value, expr<tags::TAG,typename remove_cv_ref<L>::type> >::type \
+ typename std::enable_if<is_any_lazy<L>::value, expr<tags::TAG,typename expr_storage_t<L>::type> >::type \
- operator OP (L && l) { return expr<tags::TAG,typename remove_cv_ref<L>::type> (tags::TAG(),std::forward<L>(l));}\
+ operator OP (L && l) { return {tags::TAG(),std::forward<L>(l)};}\
 
  TRIQS_CLEF_OPERATION(negate,      -);
  TRIQS_CLEF_OPERATION(loginot,     !);
@@ -167,17 +189,12 @@ namespace triqs { namespace clef {
 
  /// the only ternary node :  expression if
  template<> struct operation<tags::if_else> { 
-  template<typename C, typename A, typename B> auto operator()(C const & c, A const & a, B const & b) const -> decltype((c?a:b)) {
+  template<typename C, typename A, typename B> auto operator()(C const & c, A const & a, B const & b) const DECL_AND_RETURN (_cl(c) ? _cl(a): _cl(b));
-   //static_assert(std::is_same<typename remove_cv_ref<A>::type,typename remove_cv_ref<B>::type>::value, "Expression if : evaluation type must be the same");
-   return (c ? a: b);
-  } 
  };
  // operator is : if_else( Condition, A, B)
  template<typename C, typename A, typename B> 
-  expr<tags::if_else,typename remove_cv_ref<C>::type,typename remove_cv_ref<A>::type,typename remove_cv_ref<B>::type>
+  expr<tags::if_else,typename expr_storage_t<C>::type,typename expr_storage_t<A>::type,typename expr_storage_t<B>::type>
-  if_else(C && c, A && a, B && b) { 
+  if_else(C && c, A && a, B && b) { return {tags::if_else(),std::forward<C>(c),std::forward<A>(a),std::forward<B>(b)};}
-   return  expr<tags::if_else,typename remove_cv_ref<C>::type,typename remove_cv_ref<A>::type,typename remove_cv_ref<B>::type>
-    (tags::if_else(),std::forward<C>(c),std::forward<A>(a),std::forward<B>(b));}
 
  /* ---------------------------------------------------------------------------------------------------
   * Evaluation of the expression tree.
@@ -186,7 +203,7 @@ namespace triqs { namespace clef {
  template<typename Tag, bool IsLazy,  typename... Args> struct operation2;
  template<typename Tag, typename... Args> struct operation2<Tag, true, Args...> { 
   typedef expr<Tag,typename remove_cv_ref<Args>::type ...> rtype;
-  rtype operator()(Args && ...  args) const  {return rtype (Tag(), std::forward<Args>(args)...);} 
+  rtype operator()(Args const & ...  args) const  {return rtype {Tag(), args...};} 
  };
  template<typename Tag, typename... Args> struct operation2<Tag, false, Args...> { 
   typedef typename std::remove_reference<typename std::result_of<operation<Tag>(Args...)>::type>::type rtype;
@@ -207,40 +224,53 @@ namespace triqs { namespace clef {
   rtype operator()(placeholder<N>, pair<i,T> const &, Pairs const& ... pairs) { return eval_t()(placeholder<N>(), pairs...);} 
  };
  template<int N, typename T, typename... Pairs> struct evaluator< placeholder<N>, pair<N,T>, Pairs... > {
-  typedef typename pair<N,T>::value_type const & rtype;
+  typedef T const & rtype;
-  rtype operator()(placeholder<N>, pair<N,T> const & p, Pairs const& ...) { return p.r;}
+  //typedef typename pair<N,T>::value_type const & rtype;
+  rtype operator()(placeholder<N>, pair<N,T> const & p, Pairs const& ...) { return p.rhs;}
  };
 
  // general expr node
  template<typename Tag, typename... Childs, typename... Pairs> struct evaluator<expr<Tag, Childs...>, Pairs...> {
   typedef operation2<Tag, is_any_lazy<typename evaluator<Childs, Pairs...>::rtype... >::value, typename evaluator<Childs, Pairs...>::rtype... > OPTYPE;
   typedef typename OPTYPE::rtype rtype;
+
+  // first done manually for clearer error messages ... 
+  template< int arity = sizeof...(Childs)>
+  typename std::enable_if< arity==1, rtype>::type
+  operator()(expr<Tag, Childs...> const & ex, Pairs const & ... pairs) const
+  { return OPTYPE()(eval(std::get<0>(ex.childs),pairs...) );}
+ 
+  template< int arity = sizeof...(Childs)>
+  typename std::enable_if< arity==2, rtype>::type
+  operator()(expr<Tag, Childs...> const & ex, Pairs const & ... pairs) const
+  { return OPTYPE()(eval(std::get<0>(ex.childs),pairs...),eval(std::get<1>(ex.childs),pairs...) );}
+ 
 #define AUX(z,p,unused)  eval(std::get<p>(ex.childs),pairs...) 
 #define IMPL(z, NN, unused)  \
   template< int arity = sizeof...(Childs)>\
   typename std::enable_if< arity==NN, rtype>::type\
   operator()(expr<Tag, Childs...> const & ex, Pairs const & ... pairs) const\
   { return OPTYPE()(BOOST_PP_ENUM(NN,AUX,nil));}
-  BOOST_PP_REPEAT_FROM_TO(1,BOOST_PP_INC(TRIQS_CLEF_MAXNARGS), IMPL, nil);
+  BOOST_PP_REPEAT_FROM_TO(3,BOOST_PP_INC(TRIQS_CLEF_MAXNARGS), IMPL, nil);
 #undef AUX
 #undef IMPL 
  }; 
 
+#ifdef TRIQS_CLEF_EVAL_SHORT_CIRCUIT
+ // A short circuit if intersection of ph and is 0, no need to evaluate the whole tree......
+ // Seems useless, && the second eval is not correct if hte expression is a terminal. 
+ template<typename T, typename... Pairs> 
+  typename std::enable_if< (ph_set<T>::value & ph_set<Pairs...>::value) !=0, typename evaluator<T,Pairs...>::rtype > ::type
+  eval (T const & ex, Pairs const &... pairs) { return evaluator<T, Pairs...>()(ex, pairs...); }
+
+ template<typename T, typename... Pairs> 
+  typename std::enable_if< (ph_set<T>::value & ph_set<Pairs...>::value) ==0, T const &> ::type
+  eval (T const & ex, Pairs const &... pairs) { return ex;}
+#else
  // The general eval function for expressions
  template<typename T, typename... Pairs> 
   typename evaluator<T,Pairs...>::rtype 
   eval (T const & ex, Pairs const &... pairs) { return evaluator<T, Pairs...>()(ex, pairs...); }
-
-#ifdef TRIQS_SHORT_CIRCUIT_NOT_IMPLEMENTED
- // A short circuit if intersection of ph and is 0, no need to evaluate the whole tree......
- template<typename T, typename... Pairs> 
-  template<typename Tag, typename... Childs, typename... Pairs> 
-  typename std::enable_if< (ph_set<Childs...>::value & ph_set<Pairs...>::value) !=0, typename evaluator<expr<Tag,Childs...>,Pairs...>::rtype > ::type
-  eval (expr<Tag,Childs...> const & ex, Pairs const &... pairs) { return evaluator<expr<Tag,Childs...>, Pairs...>()(ex, pairs...); }
-
- template<typename Tag, typename... Childs, typename... Pairs> 
-  typename std::enable_if< (ph_set<Childs...>::value & ph_set<Pairs...>::value) ==0, expr<Tag,Childs...> > ::type
-  eval (expr<Tag,Childs...> const & ex, Pairs const &... pairs) { return ex; }
 #endif
 
  /* ---------------------------------------------------------------------------------------------------
@@ -252,29 +282,30 @@ namespace triqs { namespace clef {
   make_fun_impl(Expr const & ex_) : ex(ex_) {} 
 
   // gcc 4.6 crashes (!!!) on the first variant
-#define TRIQS_WORKAROUND_GCC46BUG
+#ifndef TRIQS_COMPILER_OBSOLETE_GCC
-#ifndef TRIQS_WORKAROUND_GCC46BUG
   template<typename... Args> 
    typename evaluator<Expr,pair<Is,Args>...>::rtype 
-   operator()(Args const &... args) const 
+   operator()(Args &&... args) const 
-   { return evaluator<Expr,pair<Is,Args>...>() ( ex, pair<Is,Args>(args)...); }
+   { return evaluator<Expr,pair<Is,Args>...>() ( ex, pair<Is,Args>{std::forward<Args>(args)}...); }
 #else
   template<typename... Args> struct __eval { 
    typedef evaluator<Expr,pair<Is,Args>...> eval_t;
    typedef typename eval_t::rtype rtype;
-   rtype operator()(Expr const &ex , Args const &... args) const { return eval_t() ( ex, pair<Is,Args>(args)...); }
+   rtype operator()(Expr const &ex , Args &&... args) const { return eval_t() ( ex, pair<Is,Args>{std::forward<Args>(args)}...); }
   };
   template<typename... Args> 
-   typename __eval<Args...>::rtype operator()(Args const &... args) const { return __eval<Args...>() ( ex, args...); } 
+   typename __eval<Args...>::rtype operator()(Args &&... args) const { return __eval<Args...>() ( ex, std::forward<Args>(args)...); } 
 #endif
  };
 
+ // values of the ph, excluding the Is ...
  template<ull_t x, int... Is> struct ph_filter;
  template<ull_t x, int I0, int... Is> struct ph_filter<x,I0,Is...> { static constexpr ull_t value =  ph_filter<x,Is...>::value & (~ (1ull<<I0));};
  template<ull_t x> struct ph_filter<x> { static constexpr ull_t value = x; }; 
 
  template< typename Expr, int... Is> struct ph_set<make_fun_impl<Expr,Is...> >  { static constexpr ull_t value = ph_filter <ph_set<Expr>::value, Is...>::value;};
  template< typename Expr, int... Is> struct is_any_lazy<make_fun_impl<Expr,Is...> > : std::integral_constant<bool,ph_set<make_fun_impl<Expr,Is...>>::value !=0>{};
+ template< typename Expr, int... Is> struct force_copy_in_expr<make_fun_impl<Expr,Is...> > : std::true_type{};
 
  template< typename Expr, int... Is,typename... Pairs> struct evaluator<make_fun_impl<Expr,Is...>, Pairs...> {
   typedef evaluator<Expr,Pairs...> e_t;
@@ -283,15 +314,21 @@ namespace triqs { namespace clef {
  };
 
  template< typename Expr, typename ... Phs> 
-  make_fun_impl<typename std::remove_cv<typename std::remove_reference<Expr>::type>::type,Phs::index...> 
+  make_fun_impl<typename remove_cv_ref <Expr>::type,Phs::index...> 
   make_function(Expr && ex, Phs...) { return {ex}; }
 
  namespace result_of {
   template< typename Expr, typename ... Phs> struct make_function { 
-   typedef make_fun_impl<typename std::remove_cv<typename std::remove_reference<Expr>::type>::type,Phs::index...> type;
+   typedef make_fun_impl<typename remove_cv_ref<Expr>::type,Phs::index...> type;
   };
  }
 
+  template<int ... N> 
+  std::tuple<placeholder<N>...> var( placeholder<N> ...) { return std::make_tuple(placeholder<N>()...);} 
+
+  template<typename Expr, int ... N> 
+  auto operator >> (std::tuple<placeholder<N>...>, Expr const & ex) DECL_AND_RETURN( make_function(ex, placeholder<N>()...));
+
  /* --------------------------------------------------------------------------------------------------
   *  make_function
   *  x_ >> expression  is the same as make_function(expression,x)
@@ -327,6 +364,10 @@ namespace triqs { namespace clef {
   void operator<<(expr<tags::function, F, placeholder<Is>...> const & ex, RHS && rhs) { 
    triqs_clef_auto_assign(std::get<0>(ex.childs), make_function(std::forward<RHS>(rhs), placeholder<Is>()...));
   }
+ template<typename F, typename RHS, int... Is> 
+  void operator<<(expr<tags::function, F, placeholder<Is>...> & ex, RHS && rhs) { 
+   triqs_clef_auto_assign(std::get<0>(ex.childs), make_function(std::forward<RHS>(rhs), placeholder<Is>()...));
+  }
 
  // any other case e.g. f(x_+y_) = RHS etc .... which makes no sense : compiler will stop
  template<typename F, typename RHS, typename... T> 
@@ -348,6 +389,9 @@ namespace triqs { namespace clef {
  { triqs_clef_auto_assign_subscript(std::get<0>(t.childs),std::forward<F>(f));}
 
  // auto assign of an expr ? (for chain calls) : just reuse the same operator
+ template<typename Tag, typename... Childs, typename RHS> 
+  void triqs_clef_auto_assign_subscript (expr<Tag,Childs...> && ex, RHS const & rhs) { ex << rhs;}
+
  template<typename Tag, typename... Childs, typename RHS> 
   void triqs_clef_auto_assign_subscript (expr<Tag,Childs...> const & ex, RHS const & rhs) { ex << rhs;}
 
@@ -356,45 +400,58 @@ namespace triqs { namespace clef {
   void operator<<(expr<tags::subscript, F, placeholder<Is>...> const & ex, RHS && rhs) { 
    triqs_clef_auto_assign_subscript(std::get<0>(ex.childs), make_function(std::forward<RHS>(rhs), placeholder<Is>()...));
   }
+  template<typename F, typename RHS, int... Is> 
+  void operator<<(expr<tags::subscript, F, placeholder<Is>...> && ex, RHS && rhs) { 
+   triqs_clef_auto_assign_subscript(std::get<0>(ex.childs), make_function(std::forward<RHS>(rhs), placeholder<Is>()...));
+  }
+
+  template<typename F, typename RHS, typename... T> 
+  void operator<<(expr<tags::subscript, F, T...> && ex, RHS && rhs) = delete;
+
   template<typename F, typename RHS, typename... T> 
   void operator<<(expr<tags::subscript, F, T...> const & ex, RHS && rhs) = delete;
 
  /* --------------------------------------------------------------------------------------------------
-  * Create a terminal node of an object. The reference is wrapped in a reference_wrapper... 
+  * Create a terminal node of an object. the from clone version force copying the object  
   * --------------------------------------------------------------------------------------------------- */
 
- template<typename T> expr<tags::terminal,typename remove_cv_ref<T>::type >
+ // make a node with the ref, unless it is an rvalue (which is moved).
-  make_expr(T && x){ return expr<tags::terminal,typename remove_cv_ref<T>::type >(tags::terminal(), std::forward<T>(x));}
+ template<typename T> expr<tags::terminal,typename expr_storage_t<T>::type >
+  make_expr(T && x){ return {tags::terminal(), std::forward<T>(x)};}
 
- template<typename T> auto lazy (T && x) -> decltype (make_expr(std::ref(x))) { return make_expr(std::ref(x)); }
+ // make a node from a copy of the object
+ template<typename T> expr<tags::terminal,typename remove_cv_ref<T>::type >
+  make_expr_from_clone(T && x){ return {tags::terminal(), std::forward<T>(x)};}
 
  /* --------------------------------------------------------------------------------------------------
   * Create a call node of an object
   * The object can be kept as a : a ref, a copy, a view
   * --------------------------------------------------------------------------------------------------- */
 
- namespace result_of { 
+ template<typename T> struct arity { static constexpr int value =-1;};
+
+ namespace _result_of { 
   template< typename Obj, typename... Args > struct make_expr_call : 
-   std::enable_if< is_any_lazy<Args...>::value, expr<tags::function,typename remove_cv_ref<Obj>::type, typename remove_cv_ref<Args>::type ...> > {};
+   std::enable_if< is_any_lazy<Args...>::value, expr<tags::function,typename expr_storage_t<Obj>::type, typename expr_storage_t<Args>::type ...> > {
+   static_assert (((arity<Obj>::value==-1) || (arity<Obj>::value == sizeof...(Args))), "Object called with a wrong number of arguments"); 
+   };
  }
  template< typename Obj, typename... Args >
-  typename result_of::make_expr_call<Obj,Args...>::type 
+  typename _result_of::make_expr_call<Obj,Args...>::type 
-  make_expr_call(Obj&& obj, Args &&... args) 
+  make_expr_call(Obj&& obj, Args &&... args) { return {tags::function(),std::forward<Obj>(obj), std::forward<Args>(args)...};}
-  { return typename result_of::make_expr_call<Obj,Args...>::type (tags::function(),std::forward<Obj>(obj), std::forward<Args>(args)...);}
 
  /* --------------------------------------------------------------------------------------------------
   * Create a [] call (subscript) node of an object
   * The object can be kept as a : a ref, a copy, a view
   * --------------------------------------------------------------------------------------------------- */
 
- namespace result_of { 
+ namespace _result_of { 
   template< typename Obj, typename Arg> struct make_expr_subscript : 
-   std::enable_if< is_any_lazy<Arg>::value, expr<tags::subscript,typename remove_cv_ref<Obj>::type, typename remove_cv_ref<Arg>::type> > {};
+   std::enable_if< is_any_lazy<Arg>::value, expr<tags::subscript,typename expr_storage_t<Obj>::type, typename expr_storage_t<Arg>::type> > {};
  }
  template< typename Obj, typename Arg>
-  typename result_of::make_expr_subscript<Obj,Arg>::type 
+  typename _result_of::make_expr_subscript<Obj,Arg>::type 
-  make_expr_subscript(Obj&& obj, Arg && arg) 
+  make_expr_subscript(Obj&& obj, Arg && arg) { return {tags::subscript(),std::forward<Obj>(obj), std::forward<Arg>(arg)};}
-  { return typename result_of::make_expr_subscript<Obj,Arg>::type (tags::subscript(),std::forward<Obj>(obj), std::forward<Arg>(arg));}
 
  /* --------------------------------------------------------------------------------------------------
   *  function class : stores any expression polymorphically
@@ -408,16 +465,21 @@ namespace triqs { namespace clef {
   mutable std::shared_ptr <void>  _exp; // CLEAN THIS MUTABLE ?
   mutable std::shared_ptr < std_function_type > _fnt_ptr;
   public:
-  function():_fnt_ptr(new std_function_type ()){}
+  function():_fnt_ptr{std::make_shared<std_function_type> ()}{}
 
   template<typename Expr, typename...  X>
    explicit function(Expr const & _e, X... x) : _exp(new Expr(_e)),_fnt_ptr(new std_function_type(make_function(_e, x...))){} 
 
   ReturnType operator()(T const &... t) const { return (*_fnt_ptr)(t...);}
 
+#ifndef TRIQS_COMPILER_OBSOLETE_GCC
   template< typename... Args>
-   typename triqs::clef::result_of::make_expr_call<function,Args...>::type
+   auto operator()( Args&&... args ) const DECL_AND_RETURN(make_expr_call (*this,std::forward<Args>(args)...));
-   operator()( Args&&... args ) const { return  triqs::clef::make_expr_call (*this,args...);}
+#else
+  template< typename... Args>
+  typename _result_of::make_expr_call<function const & ,Args...>::type
+   operator()( Args&&... args ) const { return make_expr_call (*this,args...);}
+#endif
 
   template<typename RHS> friend void triqs_clef_auto_assign (function const & x, RHS rhs) {
    * (x._fnt_ptr) =  std_function_type (rhs);
@@ -425,6 +487,8 @@ namespace triqs { namespace clef {
   }
 
  };
+ template<typename F> struct force_copy_in_expr <function<F>> : std::true_type{};
+  
  /* --------------------------------------------------------------------------------------------------
   *  The macro to make any function lazy
   *  TRIQS_CLEF_MAKE_FNT_LAZY (Arity,FunctionName ) : creates a new function in the triqs::lazy namespace 
@@ -433,11 +497,54 @@ namespace triqs { namespace clef {
   * --------------------------------------------------------------------------------------------------- */
 #define TRIQS_CLEF_MAKE_FNT_LAZY(name)\
  struct name##_lazy_impl { \
-  template<typename... A> auto operator()(A&&... a) const -> decltype (name(std::forward<A>(a)...)) { return name(std::forward<A>(a)...); }\
+  template<typename... A> auto operator()(A&&... a) const DECL_AND_RETURN (name(std::forward<A>(a)...));\
  };\
  template< typename... A> \
- typename triqs::clef::result_of::make_expr_call<name##_lazy_impl,A...>::type name( A&& ... a) { return make_expr_call(name##_lazy_impl(),a...);}
+ auto name( A&& ... a) DECL_AND_RETURN(make_expr_call(name##_lazy_impl(),std::forward<A>(a)...));
 
-}} //  namespace triqs::clef
+#ifndef TRIQS_COMPILER_OBSOLETE_GCC
+
+ #define TRIQS_CLEF_IMPLEMENT_LAZY_METHOD(TY,name)\
+ struct __clef_lazy_method_impl_##name { \
+  TY * _x;\
+  template<typename... A> auto operator()(A&&... a) const DECL_AND_RETURN ((*_x).name(std::forward<A>(a)...));\
+  friend std::ostream & operator<<(std::ostream & out, __clef_lazy_method_impl_##name  const & x) { return out<<BOOST_PP_STRINGIZE(TY)<<"."<<BOOST_PP_STRINGIZE(name);}\
+ };\
+ template< typename... A> \
+ auto name( A&& ... a) DECL_AND_RETURN (make_expr_call(__clef_lazy_method_impl_##name{this},std::forward<A>(a)...));
+
+#define TRIQS_CLEF_IMPLEMENT_LAZY_CALL(...)\
+ template< typename... Args>\
+ auto operator()(Args&&... args ) const & DECL_AND_RETURN(make_expr_call (*this,std::forward<Args>(args)...));\
+ \
+ template< typename... Args>\
+ auto operator()(Args&&... args ) & DECL_AND_RETURN(make_expr_call (*this,std::forward<Args>(args)...));\
+ \
+ template< typename... Args>\
+ auto operator()(Args&&... args ) && DECL_AND_RETURN(make_expr_call (std::move(*this),std::forward<Args>(args)...));\
+
+#else
+
+#define TRIQS_CLEF_IMPLEMENT_LAZY_METHOD(TY,name,RETURN_TYPE)\
+ struct __clef_lazy_method_impl_##name { \
+  TY * _x;\
+  template<typename... A> RETURN_TYPE operator()(A&&... a) const {return ((*_x).name(std::forward<A>(a)...));}\
+  friend std::ostream & operator<<(std::ostream & out, __clef_lazy_method_impl_##name  const & x) { return out<<BOOST_PP_STRINGIZE(TY)<<"."<<BOOST_PP_STRINGIZE(name);}\
+ };\
+ template< typename... A> \
+ typename _result_of::make_expr_call<__clef_lazy_method_impl_##name, A...>::type\
+ name( A&& ... a) {return make_expr_call(__clef_lazy_method_impl_##name{this},std::forward<A>(a)...);}
+
+#define TRIQS_CLEF_IMPLEMENT_LAZY_CALL(TY)\
+ template< typename... Args>\
+ typename triqs::clef::_result_of::make_expr_call<TY const &,Args...>::type\
+ operator()(Args&&... args ) const {return make_expr_call (*this,std::forward<Args>(args)...);}\
+ \
+ template< typename... Args>\
+ typename triqs::clef::_result_of::make_expr_call<TY &,Args...>::type\
+ operator()(Args&&... args ) {return make_expr_call (*this,std::forward<Args>(args)...);}
 
 #endif
+
+}} //  namespace triqs::clef
+#endif 

triqs/clef/io.hpp

@@ -31,6 +31,7 @@ namespace triqs { namespace clef {
 
  template<int N>       std::ostream &operator <<(std::ostream &sout, placeholder<N> ){return sout << "_"<<N ; }
  template<typename T> std::ostream & operator<<(std::ostream & out, std::reference_wrapper<T> const & x) { return out<< x.get(); }
+ //template<typename T> std::ostream & operator<<(std::ostream & out, std::reference_wrapper<T> const & x) { return out<< "["<<x.get()<<"]"; }
 
  inline std::ostream & variadic_print(std::ostream& out) { return out; }
  template<typename T0, typename... T> std::ostream & variadic_print(std::ostream& out, T0&& t0, T&&... t) 

triqs/gfs/gf.hpp

@@ -186,9 +186,14 @@ namespace triqs { namespace gfs {
       operator() (Arg0&& arg0, Args&&... args) const { return _evaluator(this,std::forward<Arg0>( arg0), std::forward<Args>(args)...); }
 
     // Interaction with the CLEF library : calling the gf with any clef expression as argument build a new clef expression
+    //template<typename Arg0, typename ...Args>
+    // auto operator()(Arg0 arg0, Args... args) const DECL_AND_RETURN( clef::make_expr_call(view_type(*this),arg0, args...));
+ 
+    //template<typename Arg0, typename ...Args>
+    // auto operator()(Arg0 arg0, Args... args) DECL_AND_RETURN( clef::make_expr_call(view_type(*this),arg0, args...));
+
     template<typename Arg0, typename ...Args>
-     typename clef::result_of::make_expr_call<view_type,Arg0, Args...>::type
+     typename clef::_result_of::make_expr_call<view_type,Arg0, Args...>::type
-     //typename clef::result_of::make_expr_call<gf_impl,Arg0, Args...>::type
      operator()(Arg0 arg0, Args... args) const {
       return clef::make_expr_call(view_type(*this),arg0, args...);
      }
@@ -223,14 +228,29 @@ namespace triqs { namespace gfs {
      cr_type operator[] (closest_pt_wrap<U...> const & p) const { return _data_proxy(_data, _mesh.index_to_linear( gfs_implementation::get_closest_point<Variable,Target,Opt>::invoke(this,p)));}
 
     // Interaction with the CLEF library : calling the gf with any clef expression as argument build a new clef expression
-    template<typename Arg>
+    /* template<typename Arg>
        typename boost::lazy_enable_if<    // enable the template if
        clef::is_any_lazy<Arg>,  // One of Args is a lazy expression
-     clef::result_of::make_expr_subscript<view_type,Arg>
+       clef::_result_of::make_expr_subscript<view_type,Arg>
        >::type     // end of lazy_enable_if
        operator[](Arg && arg) const { return clef::make_expr_subscript(view_type(*this),std::forward<Arg>(arg));}
+       */
+
+    /*template<typename Arg>
+    //auto operator[](Arg && arg) const DECL_AND_RETURN(clef::make_expr_subscript((*this)(),std::forward<Arg>(arg)));
+    auto operator[](Arg && arg) const DECL_AND_RETURN(clef::make_expr_subscript(view_type(*this),std::forward<Arg>(arg)));
+
+    template<typename Arg>
+    //auto operator[](Arg && arg) DECL_AND_RETURN(clef::make_expr_subscript((*this)(),std::forward<Arg>(arg)));
+    auto operator[](Arg && arg) DECL_AND_RETURN(clef::make_expr_subscript(view_type(*this),std::forward<Arg>(arg)));
+    */ 
+
+    template<typename Arg>
+     typename clef::_result_of::make_expr_subscript<view_type,Arg>::type
+      operator[](Arg && arg) const { return clef::make_expr_subscript(view_type(*this),std::forward<Arg>(arg));}
 
     /// A direct access to the grid point
+ 
     template<typename... Args>
      r_type on_mesh (Args&&... args) { return _data_proxy(_data,_mesh.index_to_linear(mesh_index_t(std::forward<Args>(args)...)));}
 

triqs/utility/compiler_details.hpp

@@ -32,20 +32,11 @@
 #if GCC_VERSION < 40801
 //#warning "gcc compiler" GCC_VERSION
 #define TRIQS_COMPILER_IS_OBSOLETE
+#define TRIQS_COMPILER_OBSOLETE_GCC
 // we still accept gcc 4.6 and 4.7, but only the 4.8.1 and higher is a compliant c++11
 #endif
 #endif
 
 
-#ifdef __GXX_EXPERIMENTAL_CXX0X__
-#define TRIQS_USE_STATIC_ASSERT
-//#define USE_VARIADIC_TEMPLATES
-#endif
-
-#ifndef TRIQS_USE_STATIC_ASSERT
-#include "boost/static_assert.hpp"
-#define static_assert(X,MESS) BOOST_STATIC_ASSERT((X)) 
-#endif
-
 #endif
 

triqs/utility/macros.hpp

@@ -36,5 +36,9 @@
 
 #define DECL_AND_RETURN(...)  -> decltype(__VA_ARGS__) { return __VA_ARGS__;}
 
+namespace triqs { 
+ template<typename T> struct remove_cv_ref : std::remove_cv< typename std::remove_reference<T>::type> {};
+};
+
 #endif