Reorganizing source code. Created util dir

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/list.h

@@ -0,0 +1,96 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    list.h
+
+Abstract:
+
+    Simple list data structure. It is meant to be used with region allocators.
+
+Author:
+
+    Leonardo de Moura (leonardo) 2007-07-10.
+
+Revision History:
+
+--*/
+#ifndef _LIST_H_
+#define _LIST_H_
+
+#include"buffer.h"
+#include"region.h"
+
+template<typename T>
+class list {
+    T      m_head;
+    list * m_tail;
+
+public:
+    list(T const & h, list * t = 0):
+        m_head(h),
+        m_tail(t) {
+    }
+
+    T const & head() const { return m_head; }
+    list * tail() const { return m_tail; }
+    T & head() { return m_head; }
+    list * & tail() { return m_tail; }
+
+    class iterator {
+        list const * m_curr;
+    public:
+        iterator(list const * c = 0):m_curr(c) {}
+        T const & operator*() const { return m_curr->head(); }
+        iterator & operator++() { m_curr = m_curr->tail(); return *this; }
+        iterator operator++(int) { iterator tmp = *this; ++*this; return tmp; }
+        bool operator==(iterator const & it) { return m_curr == it.m_curr; }
+        bool operator!=(iterator const & it) { return m_curr != it.m_curr; }
+    };        
+
+    typedef iterator const_iterator;
+    iterator begin() const { return iterator(this); }
+    iterator end() const { return iterator(0); }
+};
+
+/**
+   \brief Return the list length.
+*/
+template<typename T>
+unsigned length(list<T> * l) {
+    unsigned r = 0;
+    while(l) {
+        l = l->tail();
+        r++;
+    }
+    return r;
+}
+
+/**
+   \brief Non destructive apppend operation.  The new nodes are allocated
+   using the given region allocator.
+*/
+template<typename T>
+list<T> * append(region & r, list<T> * l1, list<T> * l2) {
+    if (l2 == 0) {
+        return l1;
+    }
+    ptr_buffer<list<T> > buffer;
+    while (l1) {
+        buffer.push_back(l1);
+        l1 = l1->tail();
+    }
+    list<T> * result = l2;
+    typename ptr_buffer<list<T> >::const_iterator it    = buffer.end();
+    typename ptr_buffer<list<T> >::const_iterator begin = buffer.begin();
+    while (it != begin) {
+        --it;
+        list<T> * curr = *it;
+        result = new (r) list<T>(curr->head(), result);
+    }
+    return result;
+}
+
+#endif /* _LIST_H_ */
+