ccc

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/util/queue.h

@@ -0,0 +1,61 @@
+/*++
+Copyright (c) 2017 Microsoft Corporation
+
+Module Name:
+
+    queue.h
+
+Abstract:
+   
+    Generic queue.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2017-4-17
+
+Notes:
+
+--*/
+#ifndef _QUEUE_H_
+#define _QUEUE_H_
+
+#include "vector.h"
+
+template<class T>
+class queue {
+    vector<T> m_elems;
+    unsigned  m_head;
+    unsigned  m_capacity;
+    
+public:
+    
+    queue(): m_head(0), m_capacity(0) {}
+
+    void push(T const& t) { m_elems.push_back(t); }
+
+    bool empty() const { 
+        return m_head == m_elems.size(); 
+    }
+
+    T top() const {
+        return m_elems[m_head];
+    }
+
+    T pop() { 
+        SASSERT(!empty());
+        m_capacity = std::max(m_capacity, m_elems.size());
+        SASSERT(m_head < m_elems.size()); 
+        if (2 * m_head > m_capacity && m_capacity > 10) {
+            for (unsigned i = 0; i < m_elems.size() - m_head; ++i) {
+                m_elems[i] = m_elems[i + m_head];
+            }
+            m_elems.shrink(m_elems.size() - m_head);
+            m_head = 0;
+        } 
+        return m_elems[m_head++];        
+    }
+
+};
+
+#endif
+