From 8c7de1fc64e2ef1994b558f223e0e77fb1395539 Mon Sep 17 00:00:00 2001
From: Carlo Zancanaro <carlo@pc-4w14-0.cs.usyd.edu.au>
Date: Fri, 2 Nov 2012 16:11:39 +1100
Subject: Change to using "touched" sets, and some writing.

---
 impl/MaxStrategy.hpp        | 18 +++++++++++++++---
 impl/VariableAssignment.hpp | 31 ++++++++++++++++++++++++++++---
 2 files changed, 43 insertions(+), 6 deletions(-)

(limited to 'impl')

diff --git a/impl/MaxStrategy.hpp b/impl/MaxStrategy.hpp
index 6fee921..1b471e0 100644
--- a/impl/MaxStrategy.hpp
+++ b/impl/MaxStrategy.hpp
@@ -132,7 +132,7 @@ private:
 
   struct DependencyAssignment : public VariableAssignment<Domain>{
     DependencyAssignment(DynamicMaxStrategy& strat,
-                         VariableAssignment<Domain>& rho,
+                         DynamicVariableAssignment<Domain>& rho,
                          const MaxExpression<Domain>& expr)
       : _strat(strat),
         _rho(rho),
@@ -144,11 +144,23 @@ private:
       // recursive magic!
       _strat.solve(*_strat._system[var]);
       _strat._influence[*_strat._system[var]].insert(_expr);
-      return _rho[var];
+
+      // force evaluation to get touched variables
+      Domain value = _rho[var];
+      // invalidate touched variables
+      IdSet<Variable<Domain> > changed = _rho.get_changed();
+      for (typename IdSet<Variable<Domain> >::iterator
+             it = changed.begin(),
+             ei = changed.end();
+           it != ei;
+           ++it) {
+        _strat.invalidate(_strat._system.variable(*it));
+      }
+      return value;
     }
   private:
     DynamicMaxStrategy& _strat;
-    VariableAssignment<Domain>& _rho;
+    DynamicVariableAssignment<Domain>& _rho;
     const MaxExpression<Domain>& _expr;
     IdSet<Variable<Domain> > _current;
   };
diff --git a/impl/VariableAssignment.hpp b/impl/VariableAssignment.hpp
index e575d60..fff00b5 100644
--- a/impl/VariableAssignment.hpp
+++ b/impl/VariableAssignment.hpp
@@ -24,9 +24,11 @@ struct DynamicVariableAssignment : public VariableAssignment<Domain> {
   ) : _system(system),
       _strategy(strat),
       _values(system.variableCount(), value),
+      _old_values(system.variableCount(), value),
       _unstable(system.variableCount()),
       _influence(system.variableCount(),
-                 IdSet<Variable<Domain> >(system.variableCount()))
+                 IdSet<Variable<Domain> >(system.variableCount())),
+      _touched(system.variableCount())
   { }
 
   const Domain operator[](const Variable<Domain>& var) {
@@ -39,6 +41,8 @@ struct DynamicVariableAssignment : public VariableAssignment<Domain> {
       log::fixpoint << indent() << "Invalidating " << x << std::endl;
  
       _unstable.insert(x);
+      _old_values[x] = _values[x];
+      _touched.insert(x);
       _values[x] = infinity<Domain>();
 
       IdSet<Variable<Domain> > infl = _influence[x];
@@ -54,6 +58,27 @@ struct DynamicVariableAssignment : public VariableAssignment<Domain> {
     }
   }
 
+  IdSet<Variable<Domain> > get_changed() {
+    IdSet<Variable<Domain> > changed;
+    for (typename IdSet<Variable<Domain> >::iterator
+           it = _touched.begin(),
+           ei = _touched.end();
+         it != ei;
+         ++it) {
+      Variable<Domain>& var = _system.variable(*it);
+      //if (_old_values[var] != _values[var]) {
+        changed.insert(var);
+        _touched.remove(var);
+      //}
+    }
+    //_touched.clear();
+    return changed;
+  }
+
+  const IdMap<Variable<Domain>, Domain> get_old_values() const {
+    return _old_values;
+  }
+
 private:
 
   void solve(const Variable<Domain>& x) {
@@ -72,8 +97,6 @@ private:
       if (val != _values[x]) {
         log::fixpoint << x << " = " << val << std::endl;
  
-        _strategy.invalidate(x);
-
         IdSet<Variable<Domain> > oldInfluence = _influence[x];
         _influence[x].clear();
         _values[x] = val;
@@ -111,8 +134,10 @@ private:
   const EquationSystem<Domain>& _system;
   DynamicMaxStrategy<Domain>& _strategy;
   IdMap<Variable<Domain>, Domain> _values;
+  IdMap<Variable<Domain>, Domain> _old_values;
   IdSet<Variable<Domain> > _unstable;
   IdMap<Variable<Domain>,IdSet<Variable<Domain> > > _influence;
+  IdSet<Variable<Domain> > _touched;
 };
 
 #endif
-- 
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