3 files changed, 42 insertions, 10 deletions
diff --git a/Source/Initialization/PlasmaInjector.cpp b/Source/Initialization/PlasmaInjector.cpp
index 69aefc47e..2fbc7ad19 100644
--- a/Source/Initialization/PlasmaInjector.cpp
+++ b/Source/Initialization/PlasmaInjector.cpp
@@ -120,15 +120,15 @@ PlasmaInjector::PlasmaInjector (int ispecies, const std::string& name)
     }
 #   endif
 
-    pp.query("xmin", xmin);
-    pp.query("ymin", ymin);
-    pp.query("zmin", zmin);
-    pp.query("xmax", xmax);
-    pp.query("ymax", ymax);
-    pp.query("zmax", zmax);
-
-    pp.query("density_min", density_min);
-    pp.query("density_max", density_max);
+    queryWithParser(pp, "xmin", xmin);
+    queryWithParser(pp, "ymin", ymin);
+    queryWithParser(pp, "zmin", zmin);
+    queryWithParser(pp, "xmax", xmax);
+    queryWithParser(pp, "ymax", ymax);
+    queryWithParser(pp, "zmax", zmax);
+
+    queryWithParser(pp, "density_min", density_min);
+    queryWithParser(pp, "density_max", density_max);
 
     std::string physical_species_s;
     bool species_is_specified = pp.query("species_type", physical_species_s);
diff --git a/Source/Utils/WarpXUtil.H b/Source/Utils/WarpXUtil.H
index d3682be2f..e5a01a44a 100644
--- a/Source/Utils/WarpXUtil.H
+++ b/Source/Utils/WarpXUtil.H
@@ -161,6 +161,20 @@ T trilinear_interp(T x0, T x1,T y0, T y1, T z0, T z1,
 */
 WarpXParser makeParser (std::string const& parse_function, std::vector<std::string> const& varnames);
 
+/**
+ * \brief Similar to amrex::ParmParse::query, but also supports math expressions for the value.
+ *
+ * amrex::ParmParse::query reads a name and a value from the input file. This function does the
+ * same, and applies the WarpXParser to the value, so the user has the choice to specify a value or
+ * a math expression (including user-defined constants).
+ * Only works for amrex::Real numbers, one would need another version for integers etc.
+ *
+ * \param[in] a_pp amrex::ParmParse object
+ * \param[in] str name of the parameter to read
+ * \param[out] val where the value queried and parsed is stored
+ */
+int queryWithParser (amrex::ParmParse& a_pp, char const * const str, amrex::Real& val);
+
 namespace WarpXUtilMsg{
 
 /** \brief If is_expression_true is false, this function prints msg and calls amrex::abort()
diff --git a/Source/Utils/WarpXUtil.cpp b/Source/Utils/WarpXUtil.cpp
index 7a584f6e1..4372c132e 100644
--- a/Source/Utils/WarpXUtil.cpp
+++ b/Source/Utils/WarpXUtil.cpp
@@ -190,7 +190,6 @@ void Store_parserString(amrex::ParmParse& pp, std::string query_string,
     f.clear();
 }
 
-
 WarpXParser makeParser (std::string const& parse_function, std::vector<std::string> const& varnames)
 {
     WarpXParser parser(parse_function);
@@ -213,6 +212,25 @@ WarpXParser makeParser (std::string const& parse_function, std::vector<std::stri
     return parser;
 }
 
+int
+queryWithParser (amrex::ParmParse& a_pp, char const * const str, amrex::Real& val)
+{
+    // call amrex::ParmParse::query, check if the user specified str.
+    std::string tmp_str;
+    int is_specified = a_pp.query(str, tmp_str);
+    if (is_specified)
+    {
+        // If so, create a parser object and apply it to the value provided by the user.
+        std::string str_val;
+        Store_parserString(a_pp, str, str_val);
+
+        auto parser = makeParser(str_val, {});
+        val = parser.eval();
+    }
+    // return the same output as amrex::ParmParse::query
+    return is_specified;
+}
+
 /**
  * \brief Ensures that the blocks are setup correctly for the RZ spectral solver
  * When using the RZ spectral solver, the Hankel transform cannot be