TRIQS/nda 1.3.0
Multi-dimensional array library for C++
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nda::clef::placeholder< N >
Compile-time lazy expressions and functions » Placeholders

#include <nda/clef/placeholder.hpp>

Detailed Description

template<int N>
struct nda::clef::placeholder< N >

A placeholder is an empty struct, labelled by an int.

It is used in lazy expressions. For example:

nda::clef::placeholder<0> i_;
nda::clef::placeholder<1> j_;
auto expr = i_ + j_;
auto res = nda::clef::eval(expr, i_ = 1.0, j_ = 2.0); // double res = 3.0;
nda::clef::eval
__inline__ decltype(auto) eval(T const &obj, Pairs &&...pairs)
Generic function to evaluate expressions and other types.
Definition eval.hpp:186
nda::clef::expr
Single node of the expression tree.
Definition expression.hpp:65
nda::clef::placeholder
A placeholder is an empty struct, labelled by an int.
Definition placeholder.hpp:50

Here expr is a lazy binary nda::clef::expr with the nda::clef::tags::plus tag, which can be evaluated later on with the nda::clef::eval function and by assigning values to the placeholders (see nda::clef::pair).

Template Parameters
NInteger label (must be < 64).

Definition at line 50 of file placeholder.hpp.

Public Member Functions

template<typename... Args>
auto operator() (Args &&...args) const
 Function call operator.
template<typename RHS>
pair< N, RHS > operator= (RHS &&rhs) const
 Assign a value to the placeholder.
template<typename T>
auto operator[] (T &&t) const
 Subscript operator.

Static Public Attributes

static constexpr int index = N
 Integer label.

Member Function Documentation

◆ operator()()

template<int N>
template<typename... Args>
auto nda::clef::placeholder< N >::operator() ( Args &&... args) const
inline

Function call operator.

Template Parameters
ArgsTypes of the function call arguments.
Parameters
argsFunction call arguments.
Returns
An nda::clef::expr object with the nda::clef::tags::function tag containing the placeholder (for the callable) and the given arguments.

Definition at line 77 of file placeholder.hpp.

◆ operator=()

template<int N>
template<typename RHS>
pair< N, RHS > nda::clef::placeholder< N >::operator= ( RHS && rhs) const
inline

Assign a value to the placeholder.

Template Parameters
RHSType of the right-hand side.
Parameters
rhsRight-hand side of the assignment.
Returns
An nda::clef::pair object, containing the integer label of the placeholder and the value assigned to it.

Definition at line 64 of file placeholder.hpp.

◆ operator[]()

template<int N>
template<typename T>
auto nda::clef::placeholder< N >::operator[] ( T && t) const
inline

Subscript operator.

Template Parameters
TType of the subscript argument.
Parameters
tSubscript argument.
Returns
An nda::clef::expr object with the nda::clef::tags::subscript tag containing the placeholder (for the object to be accessed) and the given argument.

Definition at line 90 of file placeholder.hpp.

The documentation for this struct was generated from the following file: