Implement finite_sets_decl_plugin with all specified operations

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

src/ast/CMakeLists.txt

@@ -28,6 +28,7 @@ z3_add_component(ast
     expr_map.cpp
     expr_stat.cpp
     expr_substitution.cpp
+    finite_sets_decl_plugin.cpp
     for_each_ast.cpp
     for_each_expr.cpp
     format.cpp

src/ast/finite_sets_decl_plugin.cpp

@@ -0,0 +1,366 @@
+/*++
+Copyright (c) 2025 Microsoft Corporation
+
+Module Name:
+
+    finite_sets_decl_plugin.cpp
+
+Abstract:
+
+    Declaration plugin for finite sets
+
+Author:
+
+    GitHub Copilot Agent 2025
+
+Revision History:
+
+--*/
+#include<sstream>
+#include "ast/finite_sets_decl_plugin.h"
+#include "ast/arith_decl_plugin.h"
+#include "util/warning.h"
+
+finite_sets_decl_plugin::finite_sets_decl_plugin():
+    m_empty_sym("set.empty"),
+    m_union_sym("set.union"),
+    m_intersect_sym("set.intersect"),
+    m_difference_sym("set.difference"),
+    m_in_sym("set.in"),
+    m_size_sym("set.size"),
+    m_subset_sym("set.subset"),
+    m_map_sym("set.map"),
+    m_filter_sym("set.filter"),
+    m_range_sym("set.range") {
+}
+
+sort * finite_sets_decl_plugin::mk_sort(decl_kind k, unsigned num_parameters, parameter const * parameters) {
+    if (k == FINITE_SET_SORT) {
+        if (num_parameters != 1) {
+            m_manager->raise_exception("FiniteSet sort expects exactly one parameter (element sort)");
+            return nullptr;
+        }
+        if (!parameters[0].is_ast() || !is_sort(parameters[0].get_ast())) {
+            m_manager->raise_exception("FiniteSet sort parameter must be a sort");
+            return nullptr;
+        }
+        sort * element_sort = to_sort(parameters[0].get_ast());
+        sort_size sz = sort_size::mk_very_big();
+        sort_info info(m_family_id, FINITE_SET_SORT, sz, num_parameters, parameters);
+        return m_manager->mk_sort(symbol("FiniteSet"), info);
+    }
+    m_manager->raise_exception("unknown finite set sort");
+    return nullptr;
+}
+
+sort * finite_sets_decl_plugin::get_element_sort(sort* finite_set_sort) const {
+    if (finite_set_sort->get_family_id() != m_family_id ||
+        finite_set_sort->get_decl_kind() != FINITE_SET_SORT) {
+        return nullptr;
+    }
+    parameter const* params = finite_set_sort->get_parameters();
+    if (!params[0].is_ast() || !is_sort(params[0].get_ast())) {
+        return nullptr;
+    }
+    return to_sort(params[0].get_ast());
+}
+
+bool finite_sets_decl_plugin::check_finite_set_arguments(unsigned arity, sort * const * domain) {
+    if (arity == 0) {
+        return true;
+    }
+    
+    sort* first_sort = domain[0];
+    if (first_sort->get_family_id() != m_family_id || 
+        first_sort->get_decl_kind() != FINITE_SET_SORT) {
+        m_manager->raise_exception("argument is not of FiniteSet sort");
+        return false;
+    }
+    
+    for (unsigned i = 1; i < arity; ++i) {
+        if (domain[i] != first_sort) {
+            std::ostringstream buffer;
+            buffer << "arguments " << 1 << " and " << (i+1) << " have different sorts";
+            m_manager->raise_exception(buffer.str());
+            return false;
+        }
+    }
+    return true;
+}
+
+func_decl * finite_sets_decl_plugin::mk_empty(sort* element_sort) {
+    parameter param(element_sort);
+    sort * finite_set_sort = m_manager->mk_sort(m_family_id, FINITE_SET_SORT, 1, &param);
+    sort * const * no_domain = nullptr;
+    return m_manager->mk_func_decl(m_empty_sym, 0u, no_domain, finite_set_sort,
+                                   func_decl_info(m_family_id, OP_FINITE_SET_EMPTY, 1, &param));
+}
+
+func_decl * finite_sets_decl_plugin::mk_union(unsigned arity, sort * const * domain) {
+    if (arity != 2) {
+        m_manager->raise_exception("set.union takes exactly two arguments");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    return m_manager->mk_func_decl(m_union_sym, arity, domain, domain[0],
+                                   func_decl_info(m_family_id, OP_FINITE_SET_UNION));
+}
+
+func_decl * finite_sets_decl_plugin::mk_intersect(unsigned arity, sort * const * domain) {
+    if (arity != 2) {
+        m_manager->raise_exception("set.intersect takes exactly two arguments");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    return m_manager->mk_func_decl(m_intersect_sym, arity, domain, domain[0],
+                                   func_decl_info(m_family_id, OP_FINITE_SET_INTERSECT));
+}
+
+func_decl * finite_sets_decl_plugin::mk_difference(unsigned arity, sort * const * domain) {
+    if (arity != 2) {
+        m_manager->raise_exception("set.difference takes exactly two arguments");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    return m_manager->mk_func_decl(m_difference_sym, arity, domain, domain[0],
+                                   func_decl_info(m_family_id, OP_FINITE_SET_DIFFERENCE));
+}
+
+func_decl * finite_sets_decl_plugin::mk_in(unsigned arity, sort * const * domain) {
+    if (arity != 2) {
+        m_manager->raise_exception("set.in takes exactly two arguments");
+        return nullptr;
+    }
+    if (domain[1]->get_family_id() != m_family_id ||
+        domain[1]->get_decl_kind() != FINITE_SET_SORT) {
+        m_manager->raise_exception("second argument of set.in must be a FiniteSet");
+        return nullptr;
+    }
+    
+    sort* element_sort = get_element_sort(domain[1]);
+    if (!element_sort) {
+        m_manager->raise_exception("invalid FiniteSet sort");
+        return nullptr;
+    }
+    
+    if (domain[0] != element_sort) {
+        m_manager->raise_exception("element type does not match set element type");
+        return nullptr;
+    }
+    
+    sort* bool_sort = m_manager->mk_bool_sort();
+    return m_manager->mk_func_decl(m_in_sym, arity, domain, bool_sort,
+                                   func_decl_info(m_family_id, OP_FINITE_SET_IN));
+}
+
+func_decl * finite_sets_decl_plugin::mk_size(unsigned arity, sort * const * domain) {
+    if (arity != 1) {
+        m_manager->raise_exception("set.size takes exactly one argument");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    
+    arith_util arith(*m_manager);
+    sort * int_sort = arith.mk_int();
+    return m_manager->mk_func_decl(m_size_sym, arity, domain, int_sort,
+                                   func_decl_info(m_family_id, OP_FINITE_SET_SIZE));
+}
+
+func_decl * finite_sets_decl_plugin::mk_subset(unsigned arity, sort * const * domain) {
+    if (arity != 2) {
+        m_manager->raise_exception("set.subset takes exactly two arguments");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    
+    sort* bool_sort = m_manager->mk_bool_sort();
+    return m_manager->mk_func_decl(m_subset_sym, arity, domain, bool_sort,
+                                   func_decl_info(m_family_id, OP_FINITE_SET_SUBSET));
+}
+
+func_decl * finite_sets_decl_plugin::mk_map(func_decl* f, unsigned arity, sort* const* domain) {
+    if (arity != 1) {
+        m_manager->raise_exception("set.map takes exactly one set argument");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    
+    // Get the element sort of the input set
+    sort* input_element_sort = get_element_sort(domain[0]);
+    if (!input_element_sort) {
+        m_manager->raise_exception("invalid FiniteSet sort");
+        return nullptr;
+    }
+    
+    // Check that the function has correct signature
+    if (f->get_arity() != 1) {
+        m_manager->raise_exception("set.map function must take exactly one argument");
+        return nullptr;
+    }
+    if (f->get_domain(0) != input_element_sort) {
+        m_manager->raise_exception("set.map function domain must match set element type");
+        return nullptr;
+    }
+    
+    // Create output set sort with the function's range as element type
+    sort* output_element_sort = f->get_range();
+    parameter param(output_element_sort);
+    sort* output_set_sort = m_manager->mk_sort(m_family_id, FINITE_SET_SORT, 1, &param);
+    
+    parameter func_param(f);
+    return m_manager->mk_func_decl(m_map_sym, arity, domain, output_set_sort,
+                                   func_decl_info(m_family_id, OP_FINITE_SET_MAP, 1, &func_param));
+}
+
+func_decl * finite_sets_decl_plugin::mk_filter(func_decl* f, unsigned arity, sort* const* domain) {
+    if (arity != 1) {
+        m_manager->raise_exception("set.filter takes exactly one set argument");
+        return nullptr;
+    }
+    if (!check_finite_set_arguments(arity, domain)) {
+        return nullptr;
+    }
+    
+    // Get the element sort of the set
+    sort* element_sort = get_element_sort(domain[0]);
+    if (!element_sort) {
+        m_manager->raise_exception("invalid FiniteSet sort");
+        return nullptr;
+    }
+    
+    // Check that the function has correct signature (S -> Bool)
+    if (f->get_arity() != 1) {
+        m_manager->raise_exception("set.filter function must take exactly one argument");
+        return nullptr;
+    }
+    if (f->get_domain(0) != element_sort) {
+        m_manager->raise_exception("set.filter function domain must match set element type");
+        return nullptr;
+    }
+    if (!m_manager->is_bool(f->get_range())) {
+        m_manager->raise_exception("set.filter function must return Bool");
+        return nullptr;
+    }
+    
+    parameter func_param(f);
+    return m_manager->mk_func_decl(m_filter_sym, arity, domain, domain[0],
+                                   func_decl_info(m_family_id, OP_FINITE_SET_FILTER, 1, &func_param));
+}
+
+func_decl * finite_sets_decl_plugin::mk_range(unsigned arity, sort * const * domain) {
+    if (arity != 2) {
+        m_manager->raise_exception("set.range takes exactly two arguments");
+        return nullptr;
+    }
+    
+    arith_util arith(*m_manager);
+    sort * int_sort = arith.mk_int();
+    
+    if (domain[0] != int_sort || domain[1] != int_sort) {
+        m_manager->raise_exception("set.range arguments must be Int");
+        return nullptr;
+    }
+    
+    parameter param(int_sort);
+    sort* output_set_sort = m_manager->mk_sort(m_family_id, FINITE_SET_SORT, 1, &param);
+    
+    return m_manager->mk_func_decl(m_range_sym, arity, domain, output_set_sort,
+                                   func_decl_info(m_family_id, OP_FINITE_SET_RANGE));
+}
+
+func_decl * finite_sets_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters, 
+                                                   parameter const * parameters,
+                                                   unsigned arity, sort * const * domain, 
+                                                   sort * range) {
+    switch (k) {
+    case OP_FINITE_SET_EMPTY:
+        if (num_parameters != 1 || !parameters[0].is_ast() || !is_sort(parameters[0].get_ast())) {
+            m_manager->raise_exception("set.empty requires one sort parameter");
+            return nullptr;
+        }
+        return mk_empty(to_sort(parameters[0].get_ast()));
+    case OP_FINITE_SET_UNION:
+        return mk_union(arity, domain);
+    case OP_FINITE_SET_INTERSECT:
+        return mk_intersect(arity, domain);
+    case OP_FINITE_SET_DIFFERENCE:
+        return mk_difference(arity, domain);
+    case OP_FINITE_SET_IN:
+        return mk_in(arity, domain);
+    case OP_FINITE_SET_SIZE:
+        return mk_size(arity, domain);
+    case OP_FINITE_SET_SUBSET:
+        return mk_subset(arity, domain);
+    case OP_FINITE_SET_MAP:
+        if (num_parameters != 1 || !parameters[0].is_ast() || !is_func_decl(parameters[0].get_ast())) {
+            m_manager->raise_exception("set.map requires one function parameter");
+            return nullptr;
+        }
+        return mk_map(to_func_decl(parameters[0].get_ast()), arity, domain);
+    case OP_FINITE_SET_FILTER:
+        if (num_parameters != 1 || !parameters[0].is_ast() || !is_func_decl(parameters[0].get_ast())) {
+            m_manager->raise_exception("set.filter requires one function parameter");
+            return nullptr;
+        }
+        return mk_filter(to_func_decl(parameters[0].get_ast()), arity, domain);
+    case OP_FINITE_SET_RANGE:
+        return mk_range(arity, domain);
+    default:
+        return nullptr;
+    }
+}
+
+void finite_sets_decl_plugin::get_op_names(svector<builtin_name>& op_names, symbol const & logic) {
+    op_names.push_back(builtin_name("set.empty", OP_FINITE_SET_EMPTY));
+    op_names.push_back(builtin_name("set.union", OP_FINITE_SET_UNION));
+    op_names.push_back(builtin_name("set.intersect", OP_FINITE_SET_INTERSECT));
+    op_names.push_back(builtin_name("set.difference", OP_FINITE_SET_DIFFERENCE));
+    op_names.push_back(builtin_name("set.in", OP_FINITE_SET_IN));
+    op_names.push_back(builtin_name("set.size", OP_FINITE_SET_SIZE));
+    op_names.push_back(builtin_name("set.subset", OP_FINITE_SET_SUBSET));
+    op_names.push_back(builtin_name("set.map", OP_FINITE_SET_MAP));
+    op_names.push_back(builtin_name("set.filter", OP_FINITE_SET_FILTER));
+    op_names.push_back(builtin_name("set.range", OP_FINITE_SET_RANGE));
+}
+
+void finite_sets_decl_plugin::get_sort_names(svector<builtin_name>& sort_names, symbol const & logic) {
+    sort_names.push_back(builtin_name("FiniteSet", FINITE_SET_SORT));
+}
+
+expr * finite_sets_decl_plugin::get_some_value(sort * s) {
+    if (s->get_family_id() == m_family_id && s->get_decl_kind() == FINITE_SET_SORT) {
+        // Return empty set for the given sort
+        sort* element_sort = get_element_sort(s);
+        if (element_sort) {
+            parameter param(element_sort);
+            return m_manager->mk_app(m_family_id, OP_FINITE_SET_EMPTY, 1, &param, 0, nullptr);
+        }
+    }
+    return nullptr;
+}
+
+bool finite_sets_decl_plugin::is_fully_interp(sort * s) const {
+    return s->get_family_id() == m_family_id && s->get_decl_kind() == FINITE_SET_SORT;
+}
+
+bool finite_sets_decl_plugin::is_value(app * e) const {
+    // Empty set is a value
+    return is_app_of(e, m_family_id, OP_FINITE_SET_EMPTY);
+}
+
+bool finite_sets_decl_plugin::is_unique_value(app* e) const {
+    // Empty set is a unique value for its sort
+    return is_value(e);
+}

src/ast/finite_sets_decl_plugin.h

@@ -24,3 +24,157 @@ Operators:
     set.range : Int Int -> (FiniteSet Int)
    
 --*/
+#pragma once
+
+#include "ast/ast.h"
+
+enum finite_sets_sort_kind {
+    FINITE_SET_SORT
+};
+
+enum finite_sets_op_kind {
+    OP_FINITE_SET_EMPTY,
+    OP_FINITE_SET_UNION,
+    OP_FINITE_SET_INTERSECT,
+    OP_FINITE_SET_DIFFERENCE,
+    OP_FINITE_SET_IN,
+    OP_FINITE_SET_SIZE,
+    OP_FINITE_SET_SUBSET,
+    OP_FINITE_SET_MAP,
+    OP_FINITE_SET_FILTER,
+    OP_FINITE_SET_RANGE,
+    LAST_FINITE_SET_OP
+};
+
+class finite_sets_decl_plugin : public decl_plugin {
+    symbol m_empty_sym;
+    symbol m_union_sym;
+    symbol m_intersect_sym;
+    symbol m_difference_sym;
+    symbol m_in_sym;
+    symbol m_size_sym;
+    symbol m_subset_sym;
+    symbol m_map_sym;
+    symbol m_filter_sym;
+    symbol m_range_sym;
+
+    func_decl * mk_empty(sort* element_sort);
+    func_decl * mk_union(unsigned arity, sort * const * domain);
+    func_decl * mk_intersect(unsigned arity, sort * const * domain);
+    func_decl * mk_difference(unsigned arity, sort * const * domain);
+    func_decl * mk_in(unsigned arity, sort * const * domain);
+    func_decl * mk_size(unsigned arity, sort * const * domain);
+    func_decl * mk_subset(unsigned arity, sort * const * domain);
+    func_decl * mk_map(func_decl* f, unsigned arity, sort* const* domain);
+    func_decl * mk_filter(func_decl* f, unsigned arity, sort* const* domain);
+    func_decl * mk_range(unsigned arity, sort * const * domain);
+
+    bool check_finite_set_arguments(unsigned arity, sort * const * domain);
+    sort * get_element_sort(sort* finite_set_sort) const;
+
+public:
+    finite_sets_decl_plugin();
+
+    decl_plugin * mk_fresh() override {
+        return alloc(finite_sets_decl_plugin);
+    }
+
+    //
+    // Contract for sort:
+    //   parameters[0]     - element sort
+    //
+    sort * mk_sort(decl_kind k, unsigned num_parameters, parameter const * parameters) override;
+
+    //
+    // Contract for func_decl:
+    //   For OP_FINITE_SET_MAP and OP_FINITE_SET_FILTER:
+    //     parameters[0]     - function declaration
+    //   For others:
+    //     no parameters
+    func_decl * mk_func_decl(decl_kind k, unsigned num_parameters, parameter const * parameters,
+                             unsigned arity, sort * const * domain, sort * range) override;
+
+    void get_op_names(svector<builtin_name> & op_names, symbol const & logic) override;
+
+    void get_sort_names(svector<builtin_name> & sort_names, symbol const & logic) override;
+
+    expr * get_some_value(sort * s) override;
+
+    bool is_fully_interp(sort * s) const override;
+
+    bool is_value(app * e) const override;
+
+    bool is_unique_value(app* e) const override;
+};
+
+class finite_sets_recognizers {
+protected:
+    family_id m_fid;
+public:
+    finite_sets_recognizers(family_id fid):m_fid(fid) {}
+    family_id get_family_id() const { return m_fid; }
+    bool is_finite_set(sort* s) const { return is_sort_of(s, m_fid, FINITE_SET_SORT); }
+    bool is_finite_set(expr* n) const { return is_finite_set(n->get_sort()); }
+    bool is_empty(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_EMPTY); }
+    bool is_union(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_UNION); }
+    bool is_intersect(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_INTERSECT); }
+    bool is_difference(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_DIFFERENCE); }
+    bool is_in(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_IN); }
+    bool is_size(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_SIZE); }
+    bool is_subset(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_SUBSET); }
+    bool is_map(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_MAP); }
+    bool is_filter(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_FILTER); }
+    bool is_range(expr* n) const { return is_app_of(n, m_fid, OP_FINITE_SET_RANGE); }
+};
+
+class finite_sets_util : public finite_sets_recognizers {
+    ast_manager& m_manager;
+public:
+    finite_sets_util(ast_manager& m):
+        finite_sets_recognizers(m.mk_family_id("finite_sets")), m_manager(m) {}
+    
+    ast_manager& get_manager() const { return m_manager; }
+
+    app * mk_empty(sort* element_sort) {
+        parameter param(element_sort);
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_EMPTY, 1, &param, 0, nullptr);
+    }
+
+    app * mk_union(expr* s1, expr* s2) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_UNION, s1, s2);
+    }
+
+    app * mk_intersect(expr* s1, expr* s2) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_INTERSECT, s1, s2);
+    }
+
+    app * mk_difference(expr* s1, expr* s2) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_DIFFERENCE, s1, s2);
+    }
+
+    app * mk_in(expr* elem, expr* set) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_IN, elem, set);
+    }
+
+    app * mk_size(expr* set) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_SIZE, set);
+    }
+
+    app * mk_subset(expr* s1, expr* s2) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_SUBSET, s1, s2);
+    }
+
+    app * mk_map(func_decl* f, expr* set) {
+        parameter param(f);
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_MAP, 1, &param, 1, &set);
+    }
+
+    app * mk_filter(func_decl* f, expr* set) {
+        parameter param(f);
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_FILTER, 1, &param, 1, &set);
+    }
+
+    app * mk_range(expr* low, expr* high) {
+        return m_manager.mk_app(m_fid, OP_FINITE_SET_RANGE, low, high);
+    }
+};

src/ast/reg_decl_plugins.cpp

@@ -29,6 +29,7 @@ Revision History:
 #include "ast/pb_decl_plugin.h"
 #include "ast/fpa_decl_plugin.h"
 #include "ast/special_relations_decl_plugin.h"
+#include "ast/finite_sets_decl_plugin.h"
 
 void reg_decl_plugins(ast_manager & m) {
     if (!m.get_plugin(m.mk_family_id(symbol("arith")))) {
@@ -64,4 +65,7 @@ void reg_decl_plugins(ast_manager & m) {
     if (!m.get_plugin(m.mk_family_id(symbol("specrels")))) {
         m.register_plugin(symbol("specrels"), alloc(special_relations_decl_plugin));
     }
+    if (!m.get_plugin(m.mk_family_id(symbol("finite_sets")))) {
+        m.register_plugin(symbol("finite_sets"), alloc(finite_sets_decl_plugin));
+    }
 }