updated notes, fixes to dual solver

src/util/lim_vector.h

@@ -0,0 +1,42 @@
+/*++
+Copyright (c) 2020 Microsoft Corporation
+
+Module Name:
+
+    lim_vector.h
+
+Abstract:
+
+    Vector that restores during backtracking.
+
+Author:
+
+    Nikolaj Bjorner (nbjorner) 2020-29-09
+
+--*/
+#pragma once
+
+#include "util/vector.h"
+
+template<typename T>
+class lim_svector : public svector<T> {
+    unsigned_vector  m_lim;
+public:
+    lim_svector() {}
+
+    void push_scope() {
+        m_lim.push_back(size());
+    }
+
+    void pop_scope(unsigned num_scopes) {
+        SASSERT(num_scopes > 0);
+        unsigned old_sz = m_lim.size() - num_scopes;
+        shrink(m_lim[old_sz]);
+        m_lim.shrink(old_sz);
+    }
+
+    unsigned num_scopes() const { return m_lim.size(); }
+
+    unsigned old_size(unsigned n) const { return m_lim[m_lim.size() - n]; }
+};
+