1 files changed, 80 insertions, 0 deletions
diff --git a/impl/Expression.hpp b/impl/Expression.hpp
new file mode 100644
index 0000000..7d2d956
--- /dev/null
+++ b/impl/Expression.hpp
@@ -0,0 +1,80 @@
+#ifndef EXPRESSION_H
+#define EXPRESSION_H
+
+#include <map>
+#include <string>
+#include <vector>
+template<typename T>
+struct Expression;
+#include "Operator.hpp"
+
+template<typename T>
+struct Maximum : public Operator<T> {
+  const T eval(const std::vector<Expression<T> >& v, const std::map<std::string, T>& m) const {
+    //assert(v.size() == 1);
+    T value = -INFINITY;
+    for (typename std::vector<Expression<T> >::const_iterator it = v.begin();
+         it != v.end();
+         ++it) {
+      const T result = it->eval(m);
+      value = (value < result ? result : value);
+    }
+    return value;
+  }
+};
+
+template<typename T>
+struct Minimum : public Operator<T> {
+  const T eval(const std::vector<Expression<T> >& v, const std::map<std::string, T>& m) const {
+    //assert(v.size() == 1);
+    T value = INFINITY;
+    for (typename std::vector<Expression<T> >::const_iterator it = v.begin();
+         it != v.end();
+         ++it) {
+      const T result = it->eval(m);
+      value = (value < result ? value : result);
+    }
+    return value;
+  }
+};
+
+
+template<typename T>
+struct Expression {
+  Expression(Operator<T>* o, const std::vector< Expression<T> >& a)
+    : _operator(o), _arguments(a) { }
+  virtual const T eval(std::map<std::string, T> m) const {
+    return _operator->eval(_arguments, m);
+  }
+
+  virtual Expression<T> maxStrategyEager(const std::map<std::string, T> assignment) const {
+    if (dynamic_cast<Maximum<T>*>(_operator) != NULL) {
+      T bestVal;
+      const Expression<T>* best;
+      for (typename std::vector<Expression<T> >::const_iterator it = _arguments.begin();
+           it != _arguments.end();
+           ++it) {
+        T nextVal = it->eval(assignment);
+        if (best == NULL || nextVal > bestVal) {
+          best = &(*it);
+          bestVal = nextVal;
+        }
+      }
+      return best->maxStrategyEager(assignment);
+    }
+    std::vector<Expression<T> > newArgs;
+    for (typename std::vector<Expression<T> >::const_iterator it = _arguments.begin();
+         it != _arguments.end();
+         ++it) {
+      newArgs.push_back(it->maxStrategyEager(assignment));
+    }
+    return Expression(_operator, newArgs);
+  }
+
+  virtual ~Expression() {}
+  private:
+  Operator<T>* _operator;
+  std::vector< Expression<T> > _arguments;
+};
+
+#endif