From bb6a1180067e6de2639120ff5742ff9dfb492f96 Mon Sep 17 00:00:00 2001
From: Axel Kohlmeyer <akohlmey@gmail.com>
Date: Mon, 3 Oct 2022 16:31:23 -0400
Subject: [PATCH] refactor for simpler flow of control. apply clang-format.

---
 src/pair_zero.cpp | 33 ++++++++++++++++-----------------
 src/pair_zero.h   |  4 +---
 2 files changed, 17 insertions(+), 20 deletions(-)

diff --git a/src/pair_zero.cpp b/src/pair_zero.cpp
index e4d98ad66e..b554f78b7f 100644
--- a/src/pair_zero.cpp
+++ b/src/pair_zero.cpp
@@ -88,25 +88,24 @@ void PairZero::allocate()
 
 void PairZero::settings(int narg, char **arg)
 {
-  if ((narg != 1) && (narg != 2) && (narg != 3)) error->all(FLERR, "Illegal pair_style command");
+  if (narg < 1) utils::missing_cmd_args(FLERR, "pair_style zero", error);
 
   cut_global = utils::numeric(FLERR, arg[0], false, lmp);
 
-  if (narg == 2){
-    if (strcmp("nocoeff", arg[1]) == 0)
+  // reset to defaults
+  coeffflag = 1;
+  fullneighflag = 0;
+
+  int iarg = 1;
+  while (iarg < narg) {
+    if (strcmp("nocoeff", arg[iarg]) == 0) {
       coeffflag = 0;
-    else if(strcmp("full", arg[1]) == 0)
+      ++iarg;
+    } else if (strcmp("full", arg[iarg]) == 0) {
       fullneighflag = 1;
-    else
-      error->all(FLERR, "Illegal pair_style command");
-  }
-  else if (narg == 3) {
-    if (strcmp("nocoeff", arg[1]) == 0 || strcmp("nocoeff", arg[2]) == 0)
-      coeffflag = 0;
-    else if(strcmp("full", arg[1]) == 0 || strcmp("full", arg[2]) == 0)
-      fullneighflag = 1;
-    else
-      error->all(FLERR, "Illegal pair_style command");
+      ++iarg;
+    } else
+      error->all(FLERR, "Unknown pair style zero option {}", arg[iarg]);
   }
 
   // reset cutoffs that have been explicitly set
@@ -154,10 +153,10 @@ void PairZero::coeff(int narg, char **arg)
 
 void PairZero::init_style()
 {
-  if (fullneighflag == 0)
-    neighbor->add_request(this, NeighConst::REQ_DEFAULT);
-  else
+  if (fullneighflag)
     neighbor->add_request(this, NeighConst::REQ_FULL);
+  else
+    neighbor->add_request(this, NeighConst::REQ_DEFAULT);
 }
 
 /* ----------------------------------------------------------------------
diff --git a/src/pair_zero.h b/src/pair_zero.h
index 10102f1cad..06d7b2ab72 100644
--- a/src/pair_zero.h
+++ b/src/pair_zero.h
@@ -56,12 +56,10 @@ class PairZero : public Pair {
   double cut_global;
   double **cut;
   int coeffflag;
-  int fullneighflag; // 0 for half list, 1 for full list
+  int fullneighflag;    // 0 for half list, 1 for full list
 
   virtual void allocate();
 };
-
 }    // namespace LAMMPS_NS
-
 #endif
 #endif