New class for sparse vectors in util

Sparse vectors represent a 2^64 sized space while
allocating only space that is used.

Author: romainbrenguier

src/util/sparse_vector.h

@@ -0,0 +1,60 @@
+/*******************************************************************\
+
+Module: Sparse Vectors
+
+Author: Romain Brenguier
+
+\*******************************************************************/
+
+#ifndef CPROVER_UTIL_SPARSE_VECTOR_H
+#define CPROVER_UTIL_SPARSE_VECTOR_H
+
+#include<cstdint>
+
+template<class T> class sparse_vectort
+{
+protected:
+  typedef std::map<uint64_t, T> underlyingt;
+  underlyingt underlying;
+  uint64_t _size;
+
+public:
+  sparse_vectort() :
+    _size(0) {}
+
+  const T &operator[](uint64_t idx) const
+  {
+    assert(idx<_size && "index out of range");
+    return underlying[idx];
+  }
+
+  T &operator[](uint64_t idx)
+  {
+    assert(idx<_size && "index out of range");
+    return underlying[idx];
+  }
+
+  uint64_t size() const
+  {
+    return _size;
+  }
+
+  void resize(uint64_t new_size)
+  {
+    assert(new_size>=_size && "sparse vector can't be shrunk (yet)");
+    _size=new_size;
+  }
+
+  typedef typename underlyingt::iterator iteratort;
+  typedef typename underlyingt::const_iterator const_iteratort;
+
+  iteratort begin() { return underlying.begin(); }
+  const_iteratort begin() const { return underlying.begin(); }
+
+  iteratort end() { return underlying.end(); }
+  const_iteratort end() const { return underlying.end(); }
+
+  const_iteratort find(uint64_t idx) { return underlying.find(idx); }
+};
+
+#endif // CPROVER_UTIL_SPARSE_VECTOR_H