From 023d42b5bb90a289c16fbcfefba9dd42063f7635 Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Thu, 18 Mar 2021 18:03:12 -0400
Subject: [PATCH] add support for region style plugins

---
 src/PLUGIN/plugin.cpp | 23 ++++++++++++++++++++++-
 src/domain.cpp        | 24 +++++++++++++++++++++++-
 src/domain.h          |  2 ++
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/PLUGIN/plugin.cpp b/src/PLUGIN/plugin.cpp
index 255202b86b..b52e1a1959 100644
--- a/src/PLUGIN/plugin.cpp
+++ b/src/PLUGIN/plugin.cpp
@@ -14,6 +14,7 @@
 #include "plugin.h"
 
 #include "comm.h"
+#include "domain.h"
 #include "error.h"
 #include "input.h"
 #include "force.h"
@@ -238,6 +239,16 @@ namespace LAMMPS_NS
       }
       (*fix_map)[plugin->name] = (Modify::FixCreator)plugin->creator.v2;
 
+    } else if (pstyle == "region") {
+      auto region_map = lmp->domain->region_map;
+      if (region_map->find(plugin->name) != region_map->end()) {
+        if (lmp->comm->me == 0)
+          lmp->error->warning(FLERR,fmt::format("Overriding built-in region "
+                                                "style {} from plugin",
+                                                plugin->name));
+      }
+      (*region_map)[plugin->name] = (Domain::RegionCreator)plugin->creator.v2;
+
     } else if (pstyle == "command") {
       auto command_map = lmp->input->command_map;
       if (command_map->find(plugin->name) != command_map->end()) {
@@ -271,7 +282,7 @@ namespace LAMMPS_NS
     if ((strcmp(style,"pair") != 0) && (strcmp(style,"bond") != 0)
         && (strcmp(style,"angle") != 0) && (strcmp(style,"dihedral") != 0)
         && (strcmp(style,"improper") != 0) && (strcmp(style,"compute") != 0)
-        && (strcmp(style,"fix") != 0)
+        && (strcmp(style,"fix") != 0) && (strcmp(style,"region") != 0)
         && (strcmp(style,"command") != 0)) {
       if (me == 0)
         utils::logmesg(lmp,fmt::format("Ignoring unload: {} is not a "
@@ -388,6 +399,16 @@ namespace LAMMPS_NS
            ifix >= 0; ifix = lmp->modify->find_fix_by_style(name))
         lmp->modify->delete_fix(ifix);
 
+    } else if (pstyle == "region") {
+
+      auto region_map = lmp->domain->region_map;
+      auto found = region_map->find(name);
+      if (found != region_map->end()) region_map->erase(name);
+
+      for (int iregion = lmp->domain->find_region_by_style(name);
+           iregion >= 0; iregion = lmp->domain->find_region_by_style(name))
+        lmp->domain->delete_region(iregion);
+
     } else if (pstyle == "command") {
 
       auto command_map = lmp->input->command_map;
diff --git a/src/domain.cpp b/src/domain.cpp
index c6dee63221..abf0d70079 100644
--- a/src/domain.cpp
+++ b/src/domain.cpp
@@ -1816,8 +1816,18 @@ void Domain::delete_region(int narg, char **arg)
   int iregion = find_region(arg[0]);
   if (iregion == -1) error->all(FLERR,"Delete region ID does not exist");
 
+  delete_region(iregion);
+}
+
+void Domain::delete_region(int iregion)
+{
+  if ((iregion < 0) || (iregion >= nregion)) return;
+
+  // delete and move other Regions down in list one slot
+
   delete regions[iregion];
-  regions[iregion] = regions[nregion-1];
+  for (int i = iregion+1; iregion < nregion; ++i)
+    regions[i-1] = regions[i];
   nregion--;
 }
 
@@ -1833,6 +1843,18 @@ int Domain::find_region(const std::string &name)
   return -1;
 }
 
+/* ----------------------------------------------------------------------
+   return region index if name matches existing region style
+   return -1 if no such region
+------------------------------------------------------------------------- */
+
+int Domain::find_region_by_style(const std::string &name)
+{
+  for (int iregion = 0; iregion < nregion; iregion++)
+    if (name == regions[iregion]->style) return iregion;
+  return -1;
+}
+
 /* ----------------------------------------------------------------------
    (re)set boundary settings
    flag = 0, called from the input script
diff --git a/src/domain.h b/src/domain.h
index 99349edb5d..5009a67d28 100644
--- a/src/domain.h
+++ b/src/domain.h
@@ -130,7 +130,9 @@ class Domain : protected Pointers {
   void set_lattice(int, char **);
   void add_region(int, char **);
   void delete_region(int, char **);
+  void delete_region(int);
   int find_region(const std::string &);
+  int find_region_by_style(const std::string &);
   void set_boundary(int, char **, int);
   void set_box(int, char **);
   void print_box(const std::string &);