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src/util/var_queue.h

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+/*++
+Copyright (c) 2011 Microsoft Corporation
+
+Module Name:
+
+    var_queue.h
+
+Abstract:
+
+    SAT variable priority queue.
+
+Author:
+
+    Leonardo de Moura (leonardo) 2011-05-21.
+
+Revision History:
+
+--*/
+#pragma once
+
+#include "util/heap.h"
+
+
+    
+class var_queue {
+    typedef unsigned var;
+
+    struct lt {
+        svector<unsigned> & m_activity;
+    lt(svector<unsigned> & act):m_activity(act) {}
+        bool operator()(var v1, var v2) const { return m_activity[v1] > m_activity[v2]; }
+    };
+    heap<lt>  m_queue;
+public:
+
+    
+    var_queue(svector<unsigned> & act):m_queue(128, lt(act)) {}
+    
+    void activity_increased_eh(var v) {
+        if (m_queue.contains(v))
+            m_queue.decreased(v);
+    }
+    
+    void activity_changed_eh(var v, bool up) {
+        if (m_queue.contains(v)) {
+            if (up) 
+                m_queue.decreased(v);
+            else 
+                m_queue.increased(v);
+        }
+    }
+    
+    void mk_var_eh(var v) {
+        m_queue.reserve(v+1);
+        m_queue.insert(v);
+    }
+    
+    void del_var_eh(var v) {
+        if (m_queue.contains(v))
+            m_queue.erase(v);
+    }
+    
+    void unassign_var_eh(var v) {
+        if (!m_queue.contains(v))
+            m_queue.insert(v);
+    }
+    
+    void reset() {
+        m_queue.reset();
+    }
+    
+    bool empty() const { return m_queue.empty(); }
+    
+    var next_var() { SASSERT(!empty()); return m_queue.erase_min(); }
+    
+    var min_var() { SASSERT(!empty()); return m_queue.min_value(); }
+    
+    bool more_active(var v1, var v2) const { return m_queue.less_than(v1, v2); }
+};
+