Adopt std::optional for try_get_value and try_get_size functions (#8268)

* Initial plan

* Convert try_get_value and try_get_size to use std::optional

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

* Add unit tests for std::optional conversions and fix compilation error

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

* Address code review comments - improve readability and reduce code duplication

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>

src/muz/base/dl_context.cpp

@@ -50,7 +50,10 @@ namespace datalog {
 
         sort_domain(sort_kind k, context & ctx, sort * s)
             : m_kind(k), m_sort(s, ctx.get_manager()) {
-                m_limited_size = ctx.get_decl_util().try_get_size(s, m_size);
+                auto opt_size = ctx.get_decl_util().try_get_size(s);
+                m_limited_size = opt_size.has_value();
+                if (m_limited_size)
+                    m_size = *opt_size;
         }
     public:
         virtual ~sort_domain() = default;

src/muz/fp/datalog_parser.cpp

@@ -1125,13 +1125,12 @@ protected:
        \brief Make a constant for DK_SYMBOL sort out of an integer
      */
     app* mk_symbol_const(uint64_t el, sort* s) {
-        uint64_t sz = 0;
         if (m_arith.is_int(s)) 
             return m_arith.mk_numeral(rational(el, rational::ui64()), s);
-        else if (m_decl_util.try_get_size(s, sz)) {
-            if (el >= sz) {
+        else if (auto sz = m_decl_util.try_get_size(s)) {
+            if (el >= *sz) {
                 std::ostringstream ous;
-                ous << "numeric value " << el << " is out of bounds of domain size " << sz;
+                ous << "numeric value " << el << " is out of bounds of domain size " << *sz;
                 throw default_exception(ous.str());
             }
             return m_decl_util.mk_numeral(el, s);

src/muz/rel/dl_relation_manager.cpp

@@ -400,7 +400,11 @@ namespace datalog {
     }
 
     bool relation_manager::relation_sort_to_table(const relation_sort & from, table_sort & to) {
-        return get_context().get_decl_util().try_get_size(from, to);
+        if (auto size = get_context().get_decl_util().try_get_size(from)) {
+            to = *size;
+            return true;
+        }
+        return false;
     }
 
     void relation_manager::from_predicate(func_decl * pred, unsigned arg_index, relation_sort & result) {

src/muz/rel/udoc_relation.cpp

@@ -248,6 +248,17 @@ namespace datalog {
         SASSERT(dl.is_finite_sort(s));
         return dl.mk_numeral(r.get_uint64(), s);
     }
+
+    // Helper function to count bits needed to represent a size
+    unsigned udoc_plugin::count_bits_for_size(uint64_t size) const {
+        unsigned num_bits = 0;
+        while (size > 0) {
+            ++num_bits;
+            size /= 2;
+        }
+        return num_bits;
+    }
+
     bool udoc_plugin::is_numeral(expr* e, rational& r, unsigned& num_bits) {
         if (bv.is_numeral(e, r, num_bits)) return true;
         if (m.is_true(e)) {
@@ -260,12 +271,13 @@ namespace datalog {
             num_bits = 1;
             return true;
         }
-        uint64_t n, sz;
-        if (dl.is_numeral(e, n) && dl.try_get_size(e->get_sort(), sz)) {
-            num_bits = 0;
-            while (sz > 0) ++num_bits, sz = sz/2;
-            r = rational(n, rational::ui64());
-            return true;
+        uint64_t n;
+        if (dl.is_numeral(e, n)) {
+            if (auto sz = dl.try_get_size(e->get_sort())) {
+                num_bits = count_bits_for_size(*sz);
+                r = rational(n, rational::ui64());
+                return true;
+            }
         }
         return false;
     }
@@ -275,10 +287,8 @@ namespace datalog {
             return bv.get_bv_size(s);
         if (m.is_bool(s)) 
             return 1;
-        uint64_t sz;
-        if (dl.try_get_size(s, sz)) {
-            while (sz > 0) ++num_bits, sz /= 2;
-            return num_bits;
+        if (auto sz = dl.try_get_size(s)) {
+            return count_bits_for_size(*sz);
         }
         UNREACHABLE();
         return 0;

src/muz/rel/udoc_relation.h

@@ -105,6 +105,7 @@ namespace datalog {
         static udoc_relation const & get(relation_base const& r);   
         void mk_union(doc_manager& dm, udoc& dst, udoc const& src, udoc* delta);
         bool is_numeral(expr* e, rational& r, unsigned& num_bits);
+        unsigned count_bits_for_size(uint64_t size) const;
         unsigned num_sort_bits(expr* e) const { return num_sort_bits(e->get_sort()); }
         unsigned num_sort_bits(sort* s) const;
         bool     is_finite_sort(sort* s) const;