Expression parser tolerates a + in front of an exponent

libraries/lepton/src/Parser.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2009-2011 Stanford University and the Authors.      *
+ * Portions copyright (c) 2009-2013 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -112,7 +112,7 @@ ParseToken Parser::getNextToken(const string& expression, int start) {
             }
             if ((c == 'e' || c == 'E') && !foundExp) {
                 foundExp = true;
-                if (pos < (int) expression.size()-1 && expression[pos+1] == '-')
+                if (pos < (int) expression.size()-1 && (expression[pos+1] == '-' || expression[pos+1] == '+'))
                     pos++;
                 continue;
             }

tests/TestParser.cpp

@@ -175,6 +175,7 @@ int main() {
         verifyEvaluation("5*2", 10.0);
         verifyEvaluation("2*3+4*5", 26.0);
         verifyEvaluation("2^-3", 0.125);
+        verifyEvaluation("1e+2", 100.0);
         verifyEvaluation("-x", 2.0, 3.0, -2.0);
         verifyEvaluation("y^-x", 3.0, 2.0, 0.125);
         verifyEvaluation("1/-x", 3.0, 2.0, -1.0/3.0);