Changed opMap construction

opMap is now constructed in a single statement. This avoids
problems possibly arising with multiple threads accessing for the first time
to this method simultaneously.

opMap is then made const for clarity.

(cherry picked from commit 10cbe7e8)

src/lepton/Parser.cpp

@@ -332,37 +332,36 @@ Operation* Parser::getOperatorOperation(const std::string& name) {
 
 Operation* Parser::getFunctionOperation(const std::string& name, const map<string, CustomFunction*>& customFunctions) {
 
-    static map<string, Operation::Id> opMap;
-    if (opMap.size() == 0) {
-        opMap["sqrt"] = Operation::SQRT;
-        opMap["exp"] = Operation::EXP;
-        opMap["log"] = Operation::LOG;
-        opMap["sin"] = Operation::SIN;
-        opMap["cos"] = Operation::COS;
-        opMap["sec"] = Operation::SEC;
-        opMap["csc"] = Operation::CSC;
-        opMap["tan"] = Operation::TAN;
-        opMap["cot"] = Operation::COT;
-        opMap["asin"] = Operation::ASIN;
-        opMap["acos"] = Operation::ACOS;
-        opMap["atan"] = Operation::ATAN;
-        opMap["sinh"] = Operation::SINH;
-        opMap["cosh"] = Operation::COSH;
-        opMap["tanh"] = Operation::TANH;
-        opMap["erf"] = Operation::ERF;
-        opMap["erfc"] = Operation::ERFC;
-        opMap["step"] = Operation::STEP;
-        opMap["delta"] = Operation::DELTA;
-        opMap["square"] = Operation::SQUARE;
-        opMap["cube"] = Operation::CUBE;
-        opMap["recip"] = Operation::RECIPROCAL;
-        opMap["min"] = Operation::MIN;
-        opMap["max"] = Operation::MAX;
-        opMap["abs"] = Operation::ABS;
-        opMap["floor"] = Operation::FLOOR;
-        opMap["ceil"] = Operation::CEIL;
-        opMap["select"] = Operation::SELECT;
-    }
+    const static map<string, Operation::Id> opMap ={
+        { "sqrt" , Operation::SQRT },
+        { "exp" , Operation::EXP },
+        { "log" , Operation::LOG },
+        { "sin" , Operation::SIN },
+        { "cos" , Operation::COS },
+        { "sec" , Operation::SEC },
+        { "csc" , Operation::CSC },
+        { "tan" , Operation::TAN },
+        { "cot" , Operation::COT },
+        { "asin" , Operation::ASIN },
+        { "acos" , Operation::ACOS },
+        { "atan" , Operation::ATAN },
+        { "sinh" , Operation::SINH },
+        { "cosh" , Operation::COSH },
+        { "tanh" , Operation::TANH },
+        { "erf" , Operation::ERF },
+        { "erfc" , Operation::ERFC },
+        { "step" , Operation::STEP },
+        { "delta" , Operation::DELTA },
+        { "square" , Operation::SQUARE },
+        { "cube", Operation::CUBE },
+        { "recip" , Operation::RECIPROCAL },
+        { "min" , Operation::MIN },
+        { "max" , Operation::MAX },
+        { "abs" , Operation::ABS },
+        { "floor" , Operation::FLOOR },
+        { "ceil" , Operation::CEIL },
+        { "select" , Operation::SELECT },
+    };
     string trimmed = name.substr(0, name.size()-1);
 
     // First check custom functions.