Add finite_set_value_factory implementation

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

src/model/CMakeLists.txt

@@ -2,6 +2,7 @@ z3_add_component(model
   SOURCES
     array_factory.cpp
     datatype_factory.cpp
+    finite_set_value_factory.cpp
     func_interp.cpp
     model2expr.cpp
     model_core.cpp

src/model/finite_set_value_factory.cpp

@@ -0,0 +1,62 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    finite_set_value_factory.cpp
+
+Abstract:
+
+    Factory for creating finite set values
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-11-06.
+
+Revision History:
+
+--*/
+#include "model/finite_set_value_factory.h"
+#include "model/model_core.h"
+
+finite_set_value_factory::finite_set_value_factory(ast_manager & m, family_id fid, model_core & md):
+    struct_factory(m, fid, md) {
+}
+
+expr * finite_set_value_factory::get_some_value(sort * s) {
+    // Check if we already have a value for this sort
+    value_set * set = nullptr;
+    if (m_sort2value_set.find(s, set) && !set->empty()) {
+        return *(set->begin());
+    }
+    
+    // For finite sets, we can start with an empty set representation
+    // This is a placeholder - the actual implementation would depend on
+    // how finite sets are represented in the specific theory
+    expr * r = m_model.get_some_value(s);
+    if (r != nullptr) {
+        register_value(r);
+    }
+    return r;
+}
+
+expr * finite_set_value_factory::get_fresh_value(sort * s) {
+    // Get a fresh value for a finite set sort
+    value_set * set = get_value_set(s);
+    
+    // If no values have been generated yet, use get_some_value
+    if (set->empty()) {
+        return get_some_value(s);
+    }
+    
+    // Try to generate a fresh value using the model's get_fresh_value
+    expr * fresh = m_model.get_fresh_value(s);
+    if (fresh != nullptr) {
+        register_value(fresh);
+        return fresh;
+    }
+    
+    // For finite domains, we may not be able to generate fresh values
+    // if all values have been exhausted
+    return nullptr;
+}

src/model/finite_set_value_factory.h

@@ -0,0 +1,34 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    finite_set_value_factory.h
+
+Abstract:
+
+    Factory for creating finite set values
+
+Author:
+
+    Leonardo de Moura (leonardo) 2008-11-06.
+
+Revision History:
+
+--*/
+#pragma once
+
+#include "model/struct_factory.h"
+
+/**
+   \brief Factory for finite set values.
+*/
+class finite_set_value_factory : public struct_factory {
+public:
+    finite_set_value_factory(ast_manager & m, family_id fid, model_core & md);
+    
+    expr * get_some_value(sort * s) override;
+    
+    expr * get_fresh_value(sort * s) override;
+};
+

src/model/model.cpp

@@ -26,6 +26,7 @@ Revision History:
 #include "ast/array_decl_plugin.h"
 #include "ast/bv_decl_plugin.h"
 #include "ast/recfun_decl_plugin.h"
+#include "ast/dl_decl_plugin.h"
 #include "ast/well_sorted.h"
 #include "ast/used_symbols.h"
 #include "ast/for_each_expr.h"
@@ -40,6 +41,7 @@ Revision History:
 #include "model/numeral_factory.h"
 #include "model/fpa_factory.h"
 #include "model/char_factory.h"
+#include "model/finite_set_value_factory.h"
 
 
 model::model(ast_manager & m):
@@ -104,6 +106,7 @@ value_factory* model::get_factory(sort* s) {
     if (m_factories.plugins().empty()) {
         seq_util su(m);
         fpa_util fu(m);
+        datalog::dl_decl_plugin dl_plugin;
         m_factories.register_plugin(alloc(basic_factory, m, 0));
         m_factories.register_plugin(alloc(array_factory, m, *this));
         m_factories.register_plugin(alloc(datatype_factory, m, *this));
@@ -111,6 +114,7 @@ value_factory* model::get_factory(sort* s) {
         m_factories.register_plugin(alloc(arith_factory, m));
         m_factories.register_plugin(alloc(seq_factory, m, su.get_family_id(), *this));
         m_factories.register_plugin(alloc(fpa_value_factory, m, fu.get_family_id()));
+        m_factories.register_plugin(alloc(finite_set_value_factory, m, m.mk_family_id("datalog"), *this));
         //m_factories.register_plugin(alloc(char_factory, m, char_decl_plugin(m).get_family_id());
     }
     family_id fid = s->get_family_id();