1 files changed, 18 insertions, 5 deletions
diff --git a/impl/EquationSystem.hpp b/impl/EquationSystem.hpp
index 00916d0..ac0b3b2 100644
--- a/impl/EquationSystem.hpp
+++ b/impl/EquationSystem.hpp
@@ -1,6 +1,8 @@
 #ifndef EQUATION_SYSTEM_HPP
 #define EQUATION_SYSTEM_HPP
 
+#include <map>
+
 #include "Expression.hpp"
 template<typename T>
 struct MaxStrategy;
@@ -8,16 +10,26 @@ struct MaxStrategy;
 template<typename T>
 struct EquationSystem {
   virtual ~EquationSystem() {
+    for (int i = 0, size = _expressions.size(); i < size; ++i) {
+      delete _expressions[i];
+    }
     for (int i = 0, size = _vars.size(); i < size; ++i) {
       delete _vars[i];
     }
-    for (int i = 0, size = _expressions.size(); i < size; ++i) {
-      delete _expressions[i];
+  }
+  Variable<T>* newVariable(const std::string& name) {
+    typename std::map<const std::string, Variable<T>*>::iterator it = _var_names.find(name);
+    if (it == _var_names.end()) {
+      Variable<T>* newVar = new Variable<T>(_vars.size(), name);
+      _vars.push_back(newVar);
+      _var_names[name] = newVar;
+      return _vars[_vars.size()-1];
+    } else {
+      return it->second;
     }
   }
-  Variable<T>* newVariable(const std::string&) {
-    _vars.push_back(new Variable<T>(_vars.size()));
-    return _vars[_vars.size()-1];
+  const std::vector<Variable<T>*> vars() const {
+    return _vars;
   }
   unsigned int varCount() const {
     return _vars.size();
@@ -119,6 +131,7 @@ struct EquationSystem {
     return rho;
   }
   private:
+  std::map<const std::string, Variable<T>*> _var_names;
   std::vector<Variable<T>*> _vars;
   std::vector<MaxExpression<T>*> _max_expressions;
   std::vector<Expression<T>*> _expressions;