1 files changed, 61 insertions, 0 deletions
diff --git a/Source/Utils/WarpXConst.cpp b/Source/Utils/WarpXConst.cpp
new file mode 100644
index 000000000..bd3ebc3ef
--- /dev/null
+++ b/Source/Utils/WarpXConst.cpp
@@ -0,0 +1,61 @@
+#include <limits>
+#include <cmath>
+#include <algorithm>
+#include <numeric>
+#include <sstream>
+
+#include <AMReX_ParmParse.H>
+#include <WarpX.H>
+#include <WarpXConst.H>
+#include <WarpX_f.H>
+#include <MultiParticleContainer.H>
+
+std::string UserConstants::replaceStringValue(std::string math_expr){
+    std::string pattern, value_str;
+    std::string patternexp = "e+";
+    std::size_t found;
+    amrex::Real value;
+    for (int i=0; i<nb_constants; i++){
+        pattern    = constant_names[i];
+        value      = constant_values[i];
+
+        // Convert value to string, with scientific notation
+        std::ostringstream streamObj;
+        streamObj << value;
+        value_str = streamObj.str();
+        
+        // Replace "e+" by "e" in scientific notation for Fortran compatibility
+        found = value_str.find(patternexp);
+        if (found != std::string::npos){
+            value_str.replace(found,patternexp.length(),"e");
+        }
+
+        // Replace all occurences of variable pattern by a string with its value value_str
+        found = math_expr.find(pattern);
+        while (found != std::string::npos){
+            if ((found==0               
+                        && !isalnum(math_expr[pattern.length()      ])) ||
+               (!isalnum(math_expr[found-1])  
+                        && !isalnum(math_expr[found+pattern.length()]))){ 
+                math_expr.replace(found,pattern.length(),value_str);
+             }
+            found = math_expr.find(pattern, found + pattern.length());
+        }
+    }
+    return math_expr;
+}
+
+void UserConstants::ReadParameters()
+{
+    if (!initialized){
+	    amrex::ParmParse pp("constants");
+        pp.query("use_my_constants", use_my_constants);
+        if (use_my_constants){
+            pp.getarr("constant_names", constant_names);
+            nb_constants = constant_names.size();
+            pp.getarr("constant_values", constant_values);
+            BL_ASSERT(constant_values.size() == nb_constants);
+        }
+	initialized = true;
+    }
+}