From 42e729d20000eb141b2907ad83630af34f4afea3 Mon Sep 17 00:00:00 2001
From: Carlo Zancanaro <carlo@carlo-laptop>
Date: Mon, 6 Aug 2012 22:58:29 +1000
Subject: New variation on the equation system solver.

Much simpler to understand. Basically have a variable assignment which
is dynamic and updates with the strategy changes. Similarly have
strategy changes easily invalidate the variable assignment.

This makes them strongly inter-dependent, but simplifies the
implementation considerably. Proving it should be easier like this, too.
---
 impl/Expression.hpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'impl/Expression.hpp')

diff --git a/impl/Expression.hpp b/impl/Expression.hpp
index 01921b6..63f732d 100644
--- a/impl/Expression.hpp
+++ b/impl/Expression.hpp
@@ -13,6 +13,12 @@ struct VariableAssignment;
 template<typename Domain>
 struct MaxStrategy;
 
+template<typename Domain>
+struct Variable;
+
+template<typename Domain>
+struct MaxExpression;
+
 template<typename Domain>
 struct Expression {
   virtual ~Expression() { }
@@ -23,6 +29,9 @@ struct Expression {
     return eval(rho);
   }
 
+  virtual void mapTo(Variable<Domain>&, IdMap<MaxExpression<Domain>, Variable<Domain>*>&) const {
+  }
+
   virtual void print(std::ostream&) const = 0;
 };
 
@@ -101,6 +110,14 @@ struct OperatorExpression : public Expression<Domain> {
     return _operator;
   }
 
+  virtual void mapTo(Variable<Domain>& v, IdMap<MaxExpression<Domain>, Variable<Domain>*>& m) const {
+    for (unsigned int i = 0, length = _arguments.size();
+         i < length;
+         ++i) {
+      _arguments[i]->mapTo(v, m);
+    }
+  }
+
   void print(std::ostream& cout) const {
     cout << _operator << "(";
     for (unsigned int i = 0, length = _arguments.size();
@@ -144,6 +161,15 @@ struct MaxExpression : public OperatorExpression<Domain> {
     return bestIndex;
   }
 
+  virtual void mapTo(Variable<Domain>& v, IdMap<MaxExpression<Domain>, Variable<Domain>*>& m) const {
+    m[*this] = &v;
+    for (unsigned int i = 0, length = this->_arguments.size();
+         i < length;
+         ++i) {
+      this->_arguments[i]->mapTo(v, m);
+    }
+  }
+
   unsigned int id() const {
     return _id;
   }
-- 
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