From 10d07302179b83de4d574c437ac0428c9ba18f85 Mon Sep 17 00:00:00 2001
From: Daniel Burrows <dburrows@debian.org>
Date: Fri, 22 May 2009 07:29:53 -0700
Subject: Add support for dumping incremental expression trees. Current values
 aren't dumped at the moment.

---
 .../problemresolver/incremental_expression.cc      | 15 ++++++++
 .../problemresolver/incremental_expression.h       | 40 ++++++++++++++++++++++
 2 files changed, 55 insertions(+)

(limited to 'src')

diff --git a/src/generic/problemresolver/incremental_expression.cc b/src/generic/problemresolver/incremental_expression.cc
index 619d84ba..1a3d16a4 100644
--- a/src/generic/problemresolver/incremental_expression.cc
+++ b/src/generic/problemresolver/incremental_expression.cc
@@ -91,11 +91,21 @@ bool and_e::get_value()
   return get_num_true() == get_children().size();
 }
 
+std::string and_e::get_name()
+{
+  return "and";
+}
+
 bool or_e::get_value()
 {
   return get_num_true() > 0;
 }
 
+std::string or_e::get_name()
+{
+  return "or";
+}
+
 void not_e::child_modified(const cwidget::util::ref_ptr<expression<bool> > &child,
 			   bool old_value,
 			   bool new_value)
@@ -107,3 +117,8 @@ bool not_e::get_value()
 {
   return !child->get_value();
 }
+
+void not_e::dump(std::ostream &out)
+{
+  out << "~" << child;
+}
diff --git a/src/generic/problemresolver/incremental_expression.h b/src/generic/problemresolver/incremental_expression.h
index c0bbf03a..0456b95e 100644
--- a/src/generic/problemresolver/incremental_expression.h
+++ b/src/generic/problemresolver/incremental_expression.h
@@ -29,6 +29,8 @@
 #include <algorithm>
 #include <set>
 
+#include <ostream>
+
 // A system of incrementally computed expressions stored as a DAG.
 // NOT THREADSAFE (the weak-reference system would utterly break in
 // the presence of threads without a lot of expensive locking, and
@@ -187,6 +189,7 @@ public:
   }
 
   virtual T get_value() = 0;
+  virtual void dump(std::ostream &out) = 0;
 };
 
 /** \brief Base class for expressions that can contain other
@@ -242,6 +245,22 @@ public:
 
     children.erase(new_end, children.end());
   }
+
+  virtual std::string get_name() = 0;
+
+  virtual void dump(std::ostream &out)
+  {
+    out << get_name() << "(";
+    for(std::vector<cwidget::util::ref_ptr<expression<bool> > >::const_iterator
+	  it = get_children().begin(); it != get_children().end(); ++it)
+      {
+	if(it != get_children().begin())
+	  out << ", ";
+
+	(*it)->dump(out);
+      }
+    out << ")";
+  }
 };
 
 template<typename T>
@@ -285,6 +304,9 @@ expression_weak_ref<T>::~expression_weak_ref()
  *
  *  Variables can be modified arbitrarily; changes are immediately
  *  propagated to parent expressions.
+ *
+ *  It would be nice if the user could attach names for better
+ *  printing of expressions, but that would take a lot of memory.
  */
 template<typename T>
 class var_e : public expression<T>
@@ -318,6 +340,11 @@ public:
 	signal_value_changed(old_value, new_value);
       }
   }
+
+  void dump(std::ostream &out)
+  {
+    out << "v" << this;
+  }
 };
 
 /** \brief Boolean-specific expressions. */
@@ -383,6 +410,8 @@ public:
   }
 
   bool get_value();
+  std::string get_name();
+  void dump(std::ostream &out);
 };
 
 class or_e : public counting_bool_e
@@ -413,6 +442,8 @@ public:
   }
 
   bool get_value();
+  std::string get_name();
+  void dump(std::ostream &out);
 };
 
 class not_e : public expression_container<bool>
@@ -435,8 +466,17 @@ public:
 		      bool old_value,
 		      bool new_value);
   bool get_value();
+  void dump(std::ostream &out);
 };
 
+template<typename T>
+std::ostream &operator<<(std::ostream &out,
+			 const cwidget::util::ref_ptr<expression<T> > &o)
+{
+  o->dump(out);
+  return out;
+}
+
 // @}
 
 #endif
-- 
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