[PPL-devel] [GIT] ppl/ppl(master): Method PIP_Tree_Node::solve() now checks context feasibility when needed.

[Enea Zaffanella]

Module: ppl/ppl
Branch: master
Commit: 802e03131e75ff1962b42a6b071afca7cdf65b85
URL:    http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=802e03131e75ff1962b42a6b071afca7cdf65b85

Author: Enea Zaffanella <zaffanella at cs.unipr.it>
Date:   Mon Mar  1 23:58:07 2010 +0100

Method PIP_Tree_Node::solve() now checks context feasibility when needed.

---

 src/PIP_Problem.cc   |    1 +
 src/PIP_Tree.cc      |   24 ++++++++++++++++++++----
 src/PIP_Tree.defs.hh |    7 +++++++
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/PIP_Problem.cc b/src/PIP_Problem.cc
index 953ed23..1acb759 100644
--- a/src/PIP_Problem.cc
+++ b/src/PIP_Problem.cc
@@ -207,6 +207,7 @@ PPL::PIP_Problem::solve() const {
 
       // Actually solve problem.
       x.current_solution = x.current_solution->solve(*this,
+                                                     check_feasible_context,
                                                      initial_context,
                                                      parameters,
                                                      external_space_dim);
diff --git a/src/PIP_Tree.cc b/src/PIP_Tree.cc
index 5a0aafd..45427ae 100644
--- a/src/PIP_Tree.cc
+++ b/src/PIP_Tree.cc
@@ -678,6 +678,7 @@ PIP_Decision_Node::update_tableau(const PIP_Problem& pip,
 
 PIP_Tree_Node*
 PIP_Decision_Node::solve(const PIP_Problem& pip,
+                         const bool check_feasible_context,
                          const Matrix& context,
                          const Variables_Set& params,
                          dimension_type space_dim) {
@@ -688,7 +689,8 @@ PIP_Decision_Node::solve(const PIP_Problem& pip,
   add_artificial_parameters(context_true, all_params, space_dim,
                             num_art_params);
   merge_assign(context_true, constraints_, all_params);
-  true_child = true_child->solve(pip, context_true, all_params, space_dim);
+  true_child = true_child->solve(pip, check_feasible_context,
+                                 context_true, all_params, space_dim);
 
   if (false_child) {
     // Decision nodes with false child must have exactly one constraint
@@ -697,7 +699,8 @@ PIP_Decision_Node::solve(const PIP_Problem& pip,
     Matrix& context_false = context_true;
     Row& last = context_false[context_false.num_rows()-1];
     complement_assign(last, last, 1);
-    false_child = false_child->solve(pip, context_false, all_params, space_dim);
+    false_child = false_child->solve(pip, check_feasible_context,
+                                     context_false, all_params, space_dim);
   }
 
   if (true_child != 0 || false_child != 0) {
@@ -1603,6 +1606,7 @@ PIP_Solution_Node::update_tableau(const PIP_Problem& pip,
 
 PIP_Tree_Node*
 PIP_Solution_Node::solve(const PIP_Problem& pip,
+                         const bool check_feasible_context,
                          const Matrix& ctx,
                          const Variables_Set& params,
                          dimension_type space_dim) {
@@ -1614,6 +1618,16 @@ PIP_Solution_Node::solve(const PIP_Problem& pip,
   const dimension_type num_art_params = artificial_parameters.size();
   add_artificial_parameters(context, all_params, space_dim, num_art_params);
   merge_assign(context, constraints_, all_params);
+
+  // If needed, (re-)check feasibility of context.
+  if (check_feasible_context) {
+    Matrix ctx_copy(context);
+    if (!compatibility_check(ctx_copy)) {
+      delete this;
+      return 0;
+    }
+  }
+
   const dimension_type not_a_dim = not_a_dimension();
 
   // Main loop of the simplex algorithm.
@@ -2001,7 +2015,8 @@ PIP_Solution_Node::solve(const PIP_Problem& pip,
       // Add parametric constraint to context.
       context.add_row(t_test);
       // Recusively solve true node wrt updated context.
-      t_node = t_node->solve(pip, context, all_params, space_dim);
+      t_node = t_node->solve(pip, check_feasible_context,
+                             context, all_params, space_dim);
 
       // Modify *this in place to become the "false" version of current node.
       PIP_Tree_Node* f_node = this;
@@ -2016,7 +2031,8 @@ PIP_Solution_Node::solve(const PIP_Problem& pip,
       complement_assign(f_test, t_test, 1);
 
       // Recusively solve false node wrt updated context.
-      f_node = f_node->solve(pip, context, all_params, space_dim);
+      f_node = f_node->solve(pip, check_feasible_context,
+                             context, all_params, space_dim);
 
       // Case analysis on recursive resolution calls outcome.
       if (t_node == 0) {
diff --git a/src/PIP_Tree.defs.hh b/src/PIP_Tree.defs.hh
index 54fcde9..ef6e23a 100644
--- a/src/PIP_Tree.defs.hh
+++ b/src/PIP_Tree.defs.hh
@@ -190,6 +190,10 @@ protected:
     \param pip
     The PIP_Problem object containing this node.
 
+    \param check_feasible_context
+    Whether the resolution process should (re-)check feasibility of
+    context (since the initial context may have been modified).
+
     \param context
     The context, being a set of constraints on the parameters.
 
@@ -200,6 +204,7 @@ protected:
     The space dimension of parent, including artificial parameters.
   */
   virtual PIP_Tree_Node* solve(const PIP_Problem& pip,
+                               bool check_feasible_context,
                                const Matrix& context,
                                const Variables_Set& params,
                                dimension_type space_dim) = 0;
@@ -632,6 +637,7 @@ protected:
 
   //! Implements pure virtual method PIP_Tree_Node::solve.
   virtual PIP_Tree_Node* solve(const PIP_Problem& pip,
+                               bool check_feasible_context,
                                const Matrix& context,
                                const Variables_Set& params,
                                dimension_type space_dim);
@@ -765,6 +771,7 @@ protected:
 
   //! Implements pure virtual method PIP_Tree_Node::solve.
   virtual PIP_Tree_Node* solve(const PIP_Problem& pip,
+                               bool check_feasible_context,
                                const Matrix& context,
                                const Variables_Set& params,
                                dimension_type space_dim);