From 6e0566a1a251ebdf4001df60fc77300693227ac6 Mon Sep 17 00:00:00 2001
From: Thomas Hahn <thomas.hahn01@gmail.com>
Date: Sun, 29 Sep 2024 12:09:11 -0400
Subject: [PATCH] Restrict type of MCSignType to double or complex

---
 c++/triqs/mc_tools/mc_concepts.hpp    |  8 ++++++++
 c++/triqs/mc_tools/mc_generic.cpp     | 27 ++++++++++++++-------------
 c++/triqs/mc_tools/mc_generic.hpp     |  5 +++--
 c++/triqs/mc_tools/mc_measure.cpp     | 11 ++++++-----
 c++/triqs/mc_tools/mc_measure.hpp     |  6 +++---
 c++/triqs/mc_tools/mc_measure_set.cpp |  9 +++++----
 c++/triqs/mc_tools/mc_measure_set.hpp |  5 +++--
 c++/triqs/mc_tools/mc_move.cpp        |  7 ++++---
 c++/triqs/mc_tools/mc_move.hpp        |  6 +++---
 c++/triqs/mc_tools/mc_move_set.cpp    | 17 +++++++++--------
 c++/triqs/mc_tools/mc_move_set.hpp    |  5 +++--
 11 files changed, 61 insertions(+), 45 deletions(-)

diff --git a/c++/triqs/mc_tools/mc_concepts.hpp b/c++/triqs/mc_tools/mc_concepts.hpp
index 452f1e71e..57d0fd048 100644
--- a/c++/triqs/mc_tools/mc_concepts.hpp
+++ b/c++/triqs/mc_tools/mc_concepts.hpp
@@ -21,6 +21,7 @@
 
 #include <h5/group.hpp>
 #include <mpi/communicator.hpp>
+#include <nda/concepts.hpp>
 
 #include <concepts>
 #include <string>
@@ -28,6 +29,13 @@
 
 namespace triqs::mc_tools {
 
+  /**
+   * @brief Check if a type is either a double or a std::complex<double>.
+   * @tparam T Type to check.
+   */
+  template <typename T>
+  concept DoubleOrComplex = std::same_as<T, double> || std::same_as<T, std::complex<double>>;
+
   /**
    * @brief Check if a type can be used as a MC move.
    * @details It checks if the given type has `attempt()` and `accept()` methods that return a value which is
diff --git a/c++/triqs/mc_tools/mc_generic.cpp b/c++/triqs/mc_tools/mc_generic.cpp
index 00c66b9cc..6af5cf076 100644
--- a/c++/triqs/mc_tools/mc_generic.cpp
+++ b/c++/triqs/mc_tools/mc_generic.cpp
@@ -18,6 +18,7 @@
 //
 // Authors: Michel Ferrero, Henri Menke, Olivier Parcollet, Priyanka Seth, Hugo U. R. Strand, Nils Wentzell, Thomas Ayral
 
+#include "./mc_concepts.hpp"
 #include "./mc_generic.hpp"
 #include "../utility/signal_handler.hpp"
 #include "../utility/timestamp.hpp"
@@ -39,7 +40,7 @@
 
 namespace triqs::mc_tools {
 
-  template <typename MCSignType> int mc_generic<MCSignType>::run(run_param_t const &params) {
+  template <DoubleOrComplex MCSignType> int mc_generic<MCSignType>::run(run_param_t const &params) {
     EXPECTS(params.cycle_length > 0);
     EXPECTS(params.stop_callback);
     EXPECTS(params.after_cycle_duty);
@@ -167,7 +168,7 @@ namespace triqs::mc_tools {
     return status;
   }
 
-  template <typename MCSignType> int mc_generic<MCSignType>::warmup(run_param_t const &params) {
+  template <DoubleOrComplex MCSignType> int mc_generic<MCSignType>::warmup(run_param_t const &params) {
     report_(3) << fmt::format("[Rank {}] Performing warum up phase...\n", params.comm.rank());
     auto p            = params;
     p.enable_measures = false;
@@ -176,7 +177,7 @@ namespace triqs::mc_tools {
     return status;
   }
 
-  template <typename MCSignType> int mc_generic<MCSignType>::accumulate(run_param_t const &params) {
+  template <DoubleOrComplex MCSignType> int mc_generic<MCSignType>::accumulate(run_param_t const &params) {
     report_(3) << fmt::format("[Rank {}] Performing accumulation up phase...\n", params.comm.rank());
     auto p               = params;
     p.enable_measures    = true;
@@ -186,7 +187,7 @@ namespace triqs::mc_tools {
     return status;
   }
 
-  template <typename MCSignType>
+  template <DoubleOrComplex MCSignType>
   int mc_generic<MCSignType>::run(std::int64_t ncycles, std::int64_t cycle_length, std::function<bool()> stop_callback, bool enable_measures,
                                   mpi::communicator c, bool enable_calibration) {
     return run({.ncycles            = ncycles,
@@ -197,23 +198,23 @@ namespace triqs::mc_tools {
                 .enable_calibration = enable_calibration});
   }
 
-  template <typename MCSignType>
+  template <DoubleOrComplex MCSignType>
   int mc_generic<MCSignType>::warmup(std::int64_t ncycles, std::int64_t cycle_length, std::function<bool()> stop_callback, MCSignType initial_sign,
                                      mpi::communicator c) {
     return warmup({.ncycles = ncycles, .cycle_length = cycle_length, .stop_callback = stop_callback, .initial_sign = initial_sign, .comm = c});
   }
 
-  template <typename MCSignType>
+  template <DoubleOrComplex MCSignType>
   int mc_generic<MCSignType>::warmup(std::int64_t ncycles, std::int64_t cycle_length, std::function<bool()> stop_callback, mpi::communicator c) {
     return warmup({.ncycles = ncycles, .cycle_length = cycle_length, .stop_callback = stop_callback, .comm = c});
   }
 
-  template <typename MCSignType>
+  template <DoubleOrComplex MCSignType>
   int mc_generic<MCSignType>::accumulate(std::int64_t ncycles, std::int64_t cycle_length, std::function<bool()> stop_callback, mpi::communicator c) {
     return accumulate({.ncycles = ncycles, .cycle_length = cycle_length, .stop_callback = stop_callback, .comm = c});
   }
 
-  template <typename MCSignType>
+  template <DoubleOrComplex MCSignType>
   int mc_generic<MCSignType>::warmup_and_accumulate(std::int64_t ncycles_warmup, std::int64_t ncycles_acc, std::int64_t cycle_length,
                                                     std::function<bool()> stop_callback, MCSignType initial_sign, mpi::communicator c) {
     auto status =
@@ -222,13 +223,13 @@ namespace triqs::mc_tools {
     return status;
   }
 
-  template <typename MCSignType>
+  template <DoubleOrComplex MCSignType>
   int mc_generic<MCSignType>::warmup_and_accumulate(std::int64_t ncycles_warmup, std::int64_t ncycles_acc, std::int64_t cycle_length,
                                                     std::function<bool()> stop_callback, mpi::communicator c) {
     return warmup_and_accumulate(ncycles_warmup, ncycles_acc, cycle_length, stop_callback, default_initial_sign, c);
   }
 
-  template <typename MCSignType> void mc_generic<MCSignType>::collect_results(mpi::communicator const &c) {
+  template <DoubleOrComplex MCSignType> void mc_generic<MCSignType>::collect_results(mpi::communicator const &c) {
     report_(3) << fmt::format("[Rank {}] Collect results: Waiting for all MPI processes to finish accumulating...\n", c.rank());
 
     // collect results from all MPI processes
@@ -258,7 +259,7 @@ namespace triqs::mc_tools {
     }
   }
 
-  template <typename MCSignType> void mc_generic<MCSignType>::print_sim_info(run_param_t const &params, std::int64_t cycle_counter) {
+  template <DoubleOrComplex MCSignType> void mc_generic<MCSignType>::print_sim_info(run_param_t const &params, std::int64_t cycle_counter) {
     // current simulation parameters
     auto const rank           = params.comm.rank();
     double const runtime      = run_timer_;
@@ -275,7 +276,7 @@ namespace triqs::mc_tools {
     if (params.enable_measures) report_(3) << measures_.report();
   }
 
-  template <typename MCSignType> void mc_generic<MCSignType>::metropolis_step() {
+  template <DoubleOrComplex MCSignType> void mc_generic<MCSignType>::metropolis_step() {
     double r = moves_.attempt();
     if (rng_() < std::min(1.0, r)) {
       sign_ *= moves_.accept();
@@ -284,7 +285,7 @@ namespace triqs::mc_tools {
     }
   }
 
-  template <typename MCSignType> void mc_generic<MCSignType>::after_cycle_duties(run_param_t const &params) {
+  template <DoubleOrComplex MCSignType> void mc_generic<MCSignType>::after_cycle_duties(run_param_t const &params) {
     params.after_cycle_duty();
     if (params.enable_calibration) moves_.calibrate(params.comm);
     if (params.enable_measures) {
diff --git a/c++/triqs/mc_tools/mc_generic.hpp b/c++/triqs/mc_tools/mc_generic.hpp
index c7a9dfa82..4821804e7 100644
--- a/c++/triqs/mc_tools/mc_generic.hpp
+++ b/c++/triqs/mc_tools/mc_generic.hpp
@@ -20,6 +20,7 @@
 
 #pragma once
 
+#include "./mc_concepts.hpp"
 #include "./mc_measure_aux_set.hpp"
 #include "./mc_measure_set.hpp"
 #include "./mc_move_set.hpp"
@@ -73,9 +74,9 @@ namespace triqs::mc_tools {
    * - A signal is caught by the triqs::utility::signal_handler.
    * - An exception is caught.
    *
-   * @tparam MCSignType Type of the sign/weight of a MC configuration.
+   * @tparam MCSignType triqs::mc_tools::DoubleOrComplex type of the sign/weight of a MC configuration.
    */
-  template <typename MCSignType> class mc_generic {
+  template <DoubleOrComplex MCSignType> class mc_generic {
     private:
     // Value to indicate that the initial sign of the user-provided parameters should not be used.
     static constexpr MCSignType default_initial_sign = std::numeric_limits<double>::infinity();
diff --git a/c++/triqs/mc_tools/mc_measure.cpp b/c++/triqs/mc_tools/mc_measure.cpp
index 004e7026f..ecd71e476 100644
--- a/c++/triqs/mc_tools/mc_measure.cpp
+++ b/c++/triqs/mc_tools/mc_measure.cpp
@@ -17,6 +17,7 @@
 //
 // Authors: Michel Ferrero, Olivier Parcollet, Nils Wentzell
 
+#include "./mc_concepts.hpp"
 #include "./mc_measure.hpp"
 
 #include <fmt/format.h>
@@ -27,18 +28,18 @@
 
 namespace triqs::mc_tools {
 
-  template <typename MCSignType> void measure<MCSignType>::collect_results(mpi::communicator const &c) {
+  template <DoubleOrComplex MCSignType> void measure<MCSignType>::collect_results(mpi::communicator const &c) {
     if (enable_timer_) timer_.start();
     ptr_->collect_results(c);
     if (enable_timer_) timer_.stop();
   }
 
-  template <typename MCSignType> std::string measure<MCSignType>::report() const {
+  template <DoubleOrComplex MCSignType> std::string measure<MCSignType>::report() const {
     if (enable_report_) return ptr_->report();
     return {};
   }
 
-  template <typename MCSignType> std::string measure<MCSignType>::get_timings(std::string const &name, std::string const &prefix) const {
+  template <DoubleOrComplex MCSignType> std::string measure<MCSignType>::get_timings(std::string const &name, std::string const &prefix) const {
     if (is_measure_set_) {
       auto str = fmt::format("{}Measure set {}: Duration = {:.4f}\n", prefix, name, duration());
       return str + ptr_->ms_get_timings(prefix + "  ");
@@ -47,12 +48,12 @@ namespace triqs::mc_tools {
     }
   }
 
-  template <typename MCSignType> std::vector<std::string> measure<MCSignType>::names() const {
+  template <DoubleOrComplex MCSignType> std::vector<std::string> measure<MCSignType>::names() const {
     if (is_measure_set_) return ptr_->ms_names();
     return {};
   }
 
-  template <typename MCSignType> double measure<MCSignType>::duration() const {
+  template <DoubleOrComplex MCSignType> double measure<MCSignType>::duration() const {
     if (enable_timer_) return static_cast<double>(timer_);
     return 0.0;
   }
diff --git a/c++/triqs/mc_tools/mc_measure.hpp b/c++/triqs/mc_tools/mc_measure.hpp
index dcaf4ff8a..ce77a7f39 100644
--- a/c++/triqs/mc_tools/mc_measure.hpp
+++ b/c++/triqs/mc_tools/mc_measure.hpp
@@ -37,7 +37,7 @@
 namespace triqs::mc_tools {
 
   // Forward declaration.
-  template <typename MCSignType> class measure_set;
+  template <DoubleOrComplex MCSignType> class measure_set;
 
   /**
    * @brief Type erasure class for MC measures.
@@ -56,9 +56,9 @@ namespace triqs::mc_tools {
    * - `void h5_write(h5::group, std::string const &, T const &) const`: Writes the measure object of type `T` to HDF5.
    * - `void h5_read(h5::group, std::string const &, T &)`: Reads the measure object of type `T` from HDF5.
    *
-   * @tparam MCSignType Type of the sign/weight of a MC configuration.
+   * @tparam MCSignType triqs::mc_tools::DoubleOrComplex type of the sign/weight of a MC configuration.
    */
-  template <typename MCSignType> class measure {
+  template <DoubleOrComplex MCSignType> class measure {
     private:
     // MC measure concept defines the interface for MC measures.
     struct measure_concept {
diff --git a/c++/triqs/mc_tools/mc_measure_set.cpp b/c++/triqs/mc_tools/mc_measure_set.cpp
index 9617dfd3e..11a4fcf2a 100644
--- a/c++/triqs/mc_tools/mc_measure_set.cpp
+++ b/c++/triqs/mc_tools/mc_measure_set.cpp
@@ -17,6 +17,7 @@
 //
 // Authors: Michel Ferrero, Olivier Parcollet, Nils Wentzell
 
+#include "./mc_concepts.hpp"
 #include "./mc_measure_set.hpp"
 
 #include <fmt/format.h>
@@ -28,7 +29,7 @@
 
 namespace triqs::mc_tools {
 
-  template <typename MCSignType> std::vector<std::string> measure_set<MCSignType>::names() const {
+  template <DoubleOrComplex MCSignType> std::vector<std::string> measure_set<MCSignType>::names() const {
     std::vector<std::string> res;
     for (auto &[name, m] : measures_) {
       res.push_back(name);
@@ -38,11 +39,11 @@ namespace triqs::mc_tools {
     return res;
   }
 
-  template <typename MCSignType> void measure_set<MCSignType>::collect_results(const mpi::communicator &c) {
+  template <DoubleOrComplex MCSignType> void measure_set<MCSignType>::collect_results(const mpi::communicator &c) {
     for (auto &[name, m] : measures_) m.collect_results(c);
   }
 
-  template <typename MCSignType> std::string measure_set<MCSignType>::report() const {
+  template <DoubleOrComplex MCSignType> std::string measure_set<MCSignType>::report() const {
     std::string res;
     for (auto &[name, m] : measures_) {
       auto str = m.report();
@@ -51,7 +52,7 @@ namespace triqs::mc_tools {
     return res;
   }
 
-  template <typename MCSignType> std::string measure_set<MCSignType>::get_timings(std::string const &prefix) const {
+  template <DoubleOrComplex MCSignType> std::string measure_set<MCSignType>::get_timings(std::string const &prefix) const {
     std::string res;
     for (auto const &[name, m] : measures_) { res += m.get_timings(name, prefix); }
     return res;
diff --git a/c++/triqs/mc_tools/mc_measure_set.hpp b/c++/triqs/mc_tools/mc_measure_set.hpp
index 6139b7053..bc219d77b 100644
--- a/c++/triqs/mc_tools/mc_measure_set.hpp
+++ b/c++/triqs/mc_tools/mc_measure_set.hpp
@@ -19,6 +19,7 @@
 
 #pragma once
 
+#include "./mc_concepts.hpp"
 #include "./mc_measure.hpp"
 
 #include <fmt/format.h>
@@ -46,9 +47,9 @@ namespace triqs::mc_tools {
    * - measure_set::collect_results: Calls the measure::collect_results method for all registered MC measures.
    * - measure_set::report: Concatenates the reports from all measurements by calling their measure::report method.
    *
-   * @tparam MCSignType Type of the sign/weight of a MC configuration.
+   * @tparam MCSignType triqs::mc_tools::DoubleOrComplex type of the sign/weight of a MC configuration.
    */
-  template <typename MCSignType> class measure_set {
+  template <DoubleOrComplex MCSignType> class measure_set {
     public:
     /// Map type used for storing the measures.
     using measure_map_t = std::map<std::string, measure<MCSignType>>;
diff --git a/c++/triqs/mc_tools/mc_move.cpp b/c++/triqs/mc_tools/mc_move.cpp
index 874f7808a..37932de5d 100644
--- a/c++/triqs/mc_tools/mc_move.cpp
+++ b/c++/triqs/mc_tools/mc_move.cpp
@@ -17,6 +17,7 @@
 //
 // Authors: Michel Ferrero, Olivier Parcollet, Nils Wentzell
 
+#include "./mc_concepts.hpp"
 #include "./mc_move.hpp"
 
 #include <fmt/format.h>
@@ -28,21 +29,21 @@
 
 namespace triqs::mc_tools {
 
-  template <typename MCSignType> void move<MCSignType>::collect_statistics(mpi::communicator const &c) {
+  template <DoubleOrComplex MCSignType> void move<MCSignType>::collect_statistics(mpi::communicator const &c) {
     std::uint64_t nacc_tot  = mpi::all_reduce(nacc_, c);
     std::uint64_t nprop_tot = mpi::all_reduce(nprop_, c);
     acc_rate_               = nacc_tot / static_cast<double>(nprop_tot);
     ptr_->collect_statistics(c);
   }
 
-  template <typename MCSignType> void move<MCSignType>::clear_statistics() {
+  template <DoubleOrComplex MCSignType> void move<MCSignType>::clear_statistics() {
     nacc_     = 0;
     nprop_    = 0;
     acc_rate_ = -1;
     ptr_->ms_clear_statistics();
   }
 
-  template <typename MCSignType> std::string move<MCSignType>::get_statistics(std::string const &name, std::string const &prefix) const {
+  template <DoubleOrComplex MCSignType> std::string move<MCSignType>::get_statistics(std::string const &name, std::string const &prefix) const {
     if (is_move_set_) {
       auto str = fmt::format("{}Move set {}: Proposed = {}, Accepted = {}, Rate = {:.4f}\n", prefix, name, nprop_, nacc_, acc_rate_);
       return str + ptr_->ms_get_statistics(prefix + "  ");
diff --git a/c++/triqs/mc_tools/mc_move.hpp b/c++/triqs/mc_tools/mc_move.hpp
index 2600a9f82..3c2092475 100644
--- a/c++/triqs/mc_tools/mc_move.hpp
+++ b/c++/triqs/mc_tools/mc_move.hpp
@@ -35,7 +35,7 @@
 namespace triqs::mc_tools {
 
   // Forward declaration.
-  template <typename MCSignType> class move_set;
+  template <DoubleOrComplex MCSignType> class move_set;
 
   /**
    * @brief Type erasure class for MC moves.
@@ -59,9 +59,9 @@ namespace triqs::mc_tools {
    * - `void h5_write(h5::group, std::string const &, T const &) const`: Writes the move object of type `T` to HDF5.
    * - `void h5_read(h5::group, std::string const &, T &)`: Reads the move object of type `T` from HDF5.
    *
-   * @tparam MCSignType Type of the sign/weight of a MC configuration.
+   * @tparam MCSignType triqs::mc_tools::DoubleOrComplex type of the sign/weight of a MC configuration.
    */
-  template <typename MCSignType> class move {
+  template <DoubleOrComplex MCSignType> class move {
     private:
     // MC move concept defines the interface for MC moves.
     struct move_concept {
diff --git a/c++/triqs/mc_tools/mc_move_set.cpp b/c++/triqs/mc_tools/mc_move_set.cpp
index 8d5e823a9..72a064cc8 100644
--- a/c++/triqs/mc_tools/mc_move_set.cpp
+++ b/c++/triqs/mc_tools/mc_move_set.cpp
@@ -17,6 +17,7 @@
 //
 // Authors: Michel Ferrero, Olivier Parcollet, Nils Wentzell
 
+#include "./mc_concepts.hpp"
 #include "./mc_move_set.hpp"
 
 #include <fmt/ostream.h>
@@ -35,7 +36,7 @@
 
 namespace triqs::mc_tools {
 
-  template <typename MCSignType> double move_set<MCSignType>::attempt() {
+  template <DoubleOrComplex MCSignType> double move_set<MCSignType>::attempt() {
     assert(std::abs(acc_probs_.back() - 1.0) < 1e-13);
 
     // choose a move
@@ -46,19 +47,19 @@ namespace triqs::mc_tools {
     return check_ratio(moves_[current_].attempt());
   }
 
-  template <typename MCSignType> void move_set<MCSignType>::clear_statistics() {
+  template <DoubleOrComplex MCSignType> void move_set<MCSignType>::clear_statistics() {
     for (auto &m : moves_) m.clear_statistics();
   }
 
-  template <typename MCSignType> void move_set<MCSignType>::collect_statistics(mpi::communicator const &c) {
+  template <DoubleOrComplex MCSignType> void move_set<MCSignType>::collect_statistics(mpi::communicator const &c) {
     for (auto &m : moves_) m.collect_statistics(c);
   }
 
-  template <typename MCSignType> void move_set<MCSignType>::calibrate(mpi::communicator const &c) {
+  template <DoubleOrComplex MCSignType> void move_set<MCSignType>::calibrate(mpi::communicator const &c) {
     for (auto &m : moves_) m.calibrate(c);
   }
 
-  template <typename MCSignType> std::map<std::string, double> move_set<MCSignType>::get_acceptance_rates() const {
+  template <DoubleOrComplex MCSignType> std::map<std::string, double> move_set<MCSignType>::get_acceptance_rates() const {
     std::map<std::string, double> res;
     for (auto const &[m, name] : itertools::zip(moves_, names_)) {
       res.insert({name, m.acceptance_rate()});
@@ -68,13 +69,13 @@ namespace triqs::mc_tools {
     return res;
   }
 
-  template <typename MCSignType> std::string move_set<MCSignType>::get_statistics(std::string const &prefix) const {
+  template <DoubleOrComplex MCSignType> std::string move_set<MCSignType>::get_statistics(std::string const &prefix) const {
     std::string str;
     for (auto const &[m, name] : itertools::zip(moves_, names_)) { str += m.get_statistics(name, prefix); }
     return str;
   }
 
-  template <typename MCSignType> void move_set<MCSignType>::initialize() {
+  template <DoubleOrComplex MCSignType> void move_set<MCSignType>::initialize() {
     // initialize is called in add, so we need to resize the vectors
     probs_.resize(weights_.size());
     acc_probs_.resize(weights_.size());
@@ -87,7 +88,7 @@ namespace triqs::mc_tools {
     std::partial_sum(probs_.begin(), probs_.end(), acc_probs_.begin());
   }
 
-  template <typename MCSignType> double move_set<MCSignType>::check_ratio(MCSignType ratio) {
+  template <DoubleOrComplex MCSignType> double move_set<MCSignType>::check_ratio(MCSignType ratio) {
     // handle infinities in case of double MC weights
     if constexpr (std::is_same_v<MCSignType, double>) {
       if (std::isinf(ratio)) {
diff --git a/c++/triqs/mc_tools/mc_move_set.hpp b/c++/triqs/mc_tools/mc_move_set.hpp
index c808342e1..abaa244a4 100644
--- a/c++/triqs/mc_tools/mc_move_set.hpp
+++ b/c++/triqs/mc_tools/mc_move_set.hpp
@@ -19,6 +19,7 @@
 
 #pragma once
 
+#include "./mc_concepts.hpp"
 #include "./mc_move.hpp"
 #include "./random_generator.hpp"
 
@@ -51,9 +52,9 @@ namespace triqs::mc_tools {
    * - move_set::calibrate, move_set::collect_statistics and the HDF5 routines loop over all moves and call the
    * corresponding method for each registered move.
    *
-   * @tparam MCSignType Type of the sign/weight of a MC configuration.
+   * @tparam MCSignType triqs::mc_tools::DoubleOrComplex type of the sign/weight of a MC configuration.
    */
-  template <typename MCSignType> class move_set {
+  template <DoubleOrComplex MCSignType> class move_set {
     public:
     /**
      * @brief Construct a move set with a given random number generator (stored in a `std::reference_wrapper`).