Merge pull request #4542 from akohlmey/add-json-lib

Integrate header-only JSON library

src/info.cpp

@@ -34,6 +34,7 @@
 #include "group.h"
 #include "improper.h"
 #include "input.h"
+#include "json.h"
 #include "lmpfftsettings.h"
 #include "modify.h"
 #include "neighbor.h"
@@ -291,6 +292,7 @@ void Info::command(int narg, char **arg)
     utils::print(out,"\nCompiler: {} with {}\nC++ standard: {}\n",
                platform::compiler_info(),platform::openmp_standard(),platform::cxx_standard());
     fputs(get_fmt_info().c_str(), out);
+    fputs(get_json_info().c_str(), out);
 
     fputs("\nActive compile time flags:\n\n",out);
     if (has_gzip_support()) fputs("-DLAMMPS_GZIP\n",out);
@@ -1320,6 +1322,16 @@ std::string Info::get_fmt_info()
 
 /* ---------------------------------------------------------------------- */
 
+std::string Info::get_json_info()
+{
+  return fmt::format("Embedded JSON class version: {}.{}.{}\n",
+                     NLOHMANN_JSON_VERSION_MAJOR,
+                     NLOHMANN_JSON_VERSION_MINOR,
+                     NLOHMANN_JSON_VERSION_PATCH);
+}
+
+/* ---------------------------------------------------------------------- */
+
 void Info::get_memory_info(double *meminfo)
 {
   double bytes = 0;

src/info.h

@@ -50,6 +50,7 @@ class Info : public Command {
                                       const std::string &);
   static std::string get_fft_info();
   static std::string get_fmt_info();
+  static std::string get_json_info();
   static bool has_gpu_device();
   static std::string get_gpu_device_info();
   static std::string get_accelerator_info(const std::string &pkg = "");

src/json.h

@@ -0,0 +1,25 @@
+/* -*- c++ -*- ----------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://www.lammps.org/, Sandia National Laboratories
+   LAMMPS development team: developers@lammps.org
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#ifndef LMP_JSON_H
+#define LMP_JSON_H
+
+// wrapper around including the JSON parsing and writing class
+// Do NOT include in any header file
+
+#include "../third_party/nlohmann/json.hpp"
+
+namespace LAMMPS_NS {
+using json = ::nlohmann_lmp::json;
+}
+#endif

src/lammps.cpp

@@ -1456,6 +1456,7 @@ void LAMMPS::print_config(FILE *fp)
              platform::compiler_info(),platform::openmp_standard(),
              platform::cxx_standard());
   fputs(Info::get_fmt_info().c_str(),fp);
+  fputs(Info::get_json_info().c_str(),fp);
 
   int major,minor;
   std::string infobuf = platform::mpi_info(major,minor);

src/main.cpp

@@ -17,6 +17,8 @@
 #include "input.h"
 #include "library.h"
 
+#include "json.h"
+
 #include <cstdlib>
 #include <mpi.h>
 #include <new>
@@ -75,6 +77,11 @@ int main(int argc, char **argv)
     finalize();
     MPI_Abort(MPI_COMM_WORLD, 1);
     exit(1);
+  } catch (json::exception &je) {
+    fprintf(stderr, "\nJSON library error %d: %s\n", je.id, je.what());
+    finalize();
+    MPI_Abort(MPI_COMM_WORLD, 1);
+    exit(1);
   } catch (std::bad_alloc &ae) {
     fprintf(stderr, "C++ memory allocation failed: %s\n", ae.what());
     finalize();

third_party/README

@@ -0,0 +1 @@
+This folder contains copies of third-party software

unittest/utils/CMakeLists.txt

@@ -49,6 +49,10 @@ add_executable(test_fmtlib test_fmtlib.cpp)
 target_link_libraries(test_fmtlib PRIVATE lammps GTest::GMockMain)
 add_test(NAME FmtLib COMMAND test_fmtlib)
 
+add_executable(test_json test_json.cpp)
+target_link_libraries(test_json PRIVATE lammps GTest::GMockMain)
+add_test(NAME JSON COMMAND test_json)
+
 add_executable(test_math_eigen_impl test_math_eigen_impl.cpp)
 target_include_directories(test_math_eigen_impl PRIVATE ${LAMMPS_SOURCE_DIR})
 add_test(NAME MathEigen COMMAND test_math_eigen_impl 10 5)

unittest/utils/test_json.cpp

@@ -0,0 +1,78 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   https://www.lammps.org/, Sandia National Laboratories
+   LAMMPS Development team: developers@lammps.org
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#include "lmptype.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include <exception>
+#include <string>
+
+#include "json.h"
+
+using namespace LAMMPS_NS;
+using ::testing::Eq;
+
+#define STRINGIFY(val) XSTR(val)
+#define XSTR(val) #val
+
+// this tests a subset of the JSON class that is most relevant to LAMMPS
+
+TEST(JSON, namespace)
+{
+    std::string expected = "nlohmann_lmp::json_abi";
+    expected += "_v" STRINGIFY(NLOHMANN_JSON_VERSION_MAJOR);
+    expected += "_" STRINGIFY(NLOHMANN_JSON_VERSION_MINOR);
+    expected += "_" STRINGIFY(NLOHMANN_JSON_VERSION_PATCH);
+
+    const std::string ns{STRINGIFY(NLOHMANN_JSON_NAMESPACE)};
+    ASSERT_THAT(expected, Eq(ns));
+}
+
+TEST(JSON, serialize_deserialize)
+{
+    json j1;
+    j1["pi"]      = 3.141;
+    j1["happy"]   = true;
+    j1["name"]    = "Niels";
+    j1["nothing"] = nullptr;
+
+    std::string expected = "{\"happy\":true,\"name\":\"Niels\",\"nothing\":null,\"pi\":3.141}";
+    std::string dumped   = j1.dump();
+    ASSERT_THAT(expected, Eq(dumped));
+
+    json j2 = json::parse(expected);
+    ASSERT_TRUE(j1 == j2);
+}
+
+TEST(JSON, init_vs_incremental)
+{
+    json j1;
+    j1["pi"]                   = 3.141;
+    j1["happy"]                = true;
+    j1["name"]                 = "Niels";
+    j1["nothing"]              = nullptr;
+    j1["answer"]["everything"] = 42;
+    j1["list"]                 = {1, 0, 2};
+    j1["object"]               = {{"currency", "USD"}, {"value", 42.99}};
+
+    json j2 = {{"pi", 3.141},
+               {"happy", true},
+               {"name", "Niels"},
+               {"nothing", nullptr},
+               {"answer", {{"everything", 42}}},
+               {"list", {1, 0, 2}},
+               {"object", {{"currency", "USD"}, {"value", 42.99}}}};
+
+    ASSERT_TRUE(j1 == j2);
+}