add support for command plugins with example

examples/plugins/Makefile

@@ -2,7 +2,10 @@ CXX=mpicxx
 CXXFLAGS=-I../../src -Wall -Wextra -O3 -fPIC -I../../src/USER-OMP -fopenmp
 LD=$(CXX) -shared -rdynamic -fopenmp
 
-default: morse2plugin.so nve2plugin.so
+default: morse2plugin.so nve2plugin.so helloplugin.so
+
+helloplugin.so: helloplugin.o
+	$(LD) -o $@ $^
 
 morse2plugin.so: morse2plugin.o pair_morse2.o pair_morse2_omp.o
 	$(LD) -o $@ $^
@@ -13,6 +16,8 @@ nve2plugin.so: nve2plugin.o fix_nve2.o
 .cpp.o:
 	$(CXX) -o $@ $(CXXFLAGS) -c $<
 
+helloplugin.o: helloplugin.cpp
+
 pair_morse2.o: pair_morse2.cpp pair_morse2.h
 pair_morse2_omp.o: pair_morse2_omp.cpp pair_morse2_omp.h pair_morse2.h
 morse2plugin.o: morse2plugin.cpp pair_morse2.h pair_morse2_omp.h
@@ -23,4 +28,3 @@ nve2plugin.o: nve2plugin.cpp fix_nve2.h
 clean:
 	rm -f *~ *.so *.o log.lammps
 
-

examples/plugins/helloplugin.cpp

@@ -0,0 +1,49 @@
+
+#include "lammpsplugin.h"
+
+#include "comm.h"
+#include "error.h"
+#include "pointers.h"
+#include "version.h"
+
+#include <cstring>
+
+namespace LAMMPS_NS {
+  class Hello : protected Pointers {
+    public:
+      Hello(class LAMMPS *lmp) : Pointers(lmp) {};
+      void command(int, char **);
+  };
+}
+
+using namespace LAMMPS_NS;
+
+void Hello::command(int argc, char **argv)
+{
+   if (argc != 1) error->all(FLERR,"Illegal hello command");
+   if (comm->me == 0)
+     utils::logmesg(lmp,fmt::format("Hello, {}!\n",argv[0]));
+}
+
+static void hellocreator(LAMMPS *lmp, int argc, char **argv)
+{
+    Hello hello(lmp);
+    hello.command(argc,argv);
+}
+
+extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
+{
+  lammpsplugin_t plugin;
+  lammpsplugin_regfunc register_plugin = (lammpsplugin_regfunc) regfunc;
+
+  plugin.version = LAMMPS_VERSION;
+  plugin.style   = "command";
+  plugin.name    = "hello";
+  plugin.info    = "Hello world command v1.0";
+  plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
+  plugin.creator1 = nullptr;
+  plugin.creator2 = nullptr;
+  plugin.creator3 = (lammpsplugin_factory3 *) &hellocreator;
+  plugin.handle  = handle;
+  (*register_plugin)(&plugin,lmp);
+}

examples/plugins/morse2plugin.cpp

@@ -33,6 +33,7 @@ extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
   plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
   plugin.creator1 = (lammpsplugin_factory1 *) &morse2creator;
   plugin.creator2 = nullptr;
+  plugin.creator3 = nullptr;
   plugin.handle  = handle;
   (*register_plugin)(&plugin,lmp);
 

examples/plugins/nve2plugin.cpp

@@ -24,7 +24,9 @@ extern "C" void lammpsplugin_init(void *lmp, void *handle, void *regfunc)
   plugin.name    = "nve2";
   plugin.info    = "NVE2 variant fix style v1.0";
   plugin.author  = "Axel Kohlmeyer (akohlmey@gmail.com)";
+  plugin.creator1 = nullptr;
   plugin.creator2 = (lammpsplugin_factory2 *) &nve2creator;
+  plugin.creator3 = nullptr;
   plugin.handle  = handle;
   (*register_plugin)(&plugin,lmp);
 }

src/lammpsplugin.h

@@ -20,6 +20,7 @@ extern "C" {
 
   typedef void *(lammpsplugin_factory1)(void *);
   typedef void *(lammpsplugin_factory2)(void *, int, char **);
+  typedef void (lammpsplugin_factory3)(void *, int, char **);
 
   typedef struct {
     const char *version;
@@ -29,6 +30,7 @@ extern "C" {
     const char *author;
     lammpsplugin_factory1 *creator1;
     lammpsplugin_factory2 *creator2;
+    lammpsplugin_factory3 *creator3;
     void *handle;
   } lammpsplugin_t;
 

src/plugin.cpp

@@ -15,6 +15,7 @@
 
 #include "comm.h"
 #include "error.h"
+#include "input.h"
 #include "force.h"
 #include "lammps.h"
 #include "modify.h"
@@ -128,8 +129,8 @@ namespace LAMMPS_NS
                                                 "style {} from plugin",
                                                 plugin->name));
       }
-
       (*pair_map)[plugin->name] = (Force::PairCreator)plugin->creator1;
+
     } else if (pstyle == "fix") {
       auto fix_map = lmp->modify->fix_map;
       if (fix_map->find(plugin->name) != fix_map->end()) {
@@ -138,8 +139,18 @@ namespace LAMMPS_NS
                                                 "style {} from plugin",
                                                 plugin->name));
       }
-
       (*fix_map)[plugin->name] = (Modify::FixCreator)plugin->creator2;
+
+    } else if (pstyle == "command") {
+      auto command_map = lmp->input->command_map;
+      if (command_map->find(plugin->name) != command_map->end()) {
+        if (lmp->comm->me == 0)
+          lmp->error->warning(FLERR,fmt::format("Overriding built-in fix "
+                                                "style {} from plugin",
+                                                plugin->name));
+      }
+      (*command_map)[plugin->name] = (Input::CommandCreator)plugin->creator3;
+
     } else {
       utils::logmesg(lmp,fmt::format("Loading plugin for {} styles not "
                                      "yet implemented\n",pstyle));