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https://github.com/Z3Prover/z3
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939bf1c725
An initial update to support polymorphism from SMTLIB3 and the API (so far C, Python). The WIP SMTLIB3 format is assumed to be supporting the following declaration ``` (declare-type-var A) ``` Whenever A is used in a type signature of a function/constant or bound quantified variable, it is taken to mean that all instantiations of A are included in the signature and assertions. For example, if the function f is declared with signature A -> A, then there is a version of f for all instances of A. The semantics of polymorphism appears to follow previous proposals: the instances are effectively different functions. This may clash with some other notions, such as the type signature forall 'a . 'a -> 'a would be inhabited by a unique function (the identity), while this is not enforced in this version (and hopefully never because it is more busy work). The C API has the function 'Z3_mk_type_variable' to create a type variable and applying functions modulo polymorphic type signatures is possible. The kind Z3_TYPE_VAR is added to sort discriminators. This version is considered as early alpha. It passes a first rudimentary unit test involving quantified axioms, declare-fun, define-fun, and define-fun-rec.
140 lines
3 KiB
C++
140 lines
3 KiB
C++
/*++
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Copyright (c) 2006 Microsoft Corporation
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Module Name:
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occurs.cpp
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Abstract:
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<abstract>
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Author:
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Leonardo de Moura (leonardo) 2007-06-07.
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Revision History:
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--*/
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#include "ast/occurs.h"
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#include "ast/for_each_expr.h"
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#include "ast/for_each_ast.h"
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// -----------------------------------
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//
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// Occurs check
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//
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// -----------------------------------
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namespace {
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struct found {};
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struct proc {
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expr * m_n;
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#define CHECK() { if (n == m_n) throw found(); }
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proc(expr * n):m_n(n) {}
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void operator()(var const * n) { CHECK(); }
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void operator()(app const * n) { CHECK(); }
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void operator()(quantifier const * n) { CHECK(); }
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};
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struct decl_proc {
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func_decl * m_d;
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decl_proc(func_decl * d):m_d(d) {}
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void operator()(var const * n) { }
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void operator()(app const * n) { if (n->get_decl() == m_d) throw found(); }
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void operator()(quantifier const * n) { }
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};
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struct sort_proc {
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sort* m_s;
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sort_proc(sort* s) :m_s(s) {}
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void operator()(sort const* s2) { if (m_s == s2) throw found(); }
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void operator()(ast*) {}
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};
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}
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// Return true if n1 occurs in n2
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bool occurs(expr * n1, expr * n2) {
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proc p(n1);
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try {
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quick_for_each_expr(p, n2);
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}
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catch (const found &) {
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return true;
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}
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return false;
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}
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bool occurs(func_decl * d, expr * n) {
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decl_proc p(d);
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try {
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quick_for_each_expr(p, n);
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}
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catch (const found &) {
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return true;
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}
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return false;
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}
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bool occurs(sort* s1, sort* s2) {
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sort_proc p(s1);
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try {
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for_each_ast(p, s2, true);
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}
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catch (const found&) {
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return true;
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}
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return false;
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}
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void mark_occurs(ptr_vector<expr>& to_check, expr* v, expr_mark& occ) {
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expr_fast_mark2 visited;
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occ.mark(v, true);
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visited.mark(v, true);
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while (!to_check.empty()) {
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expr* e = to_check.back();
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if (visited.is_marked(e)) {
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to_check.pop_back();
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continue;
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}
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if (is_app(e)) {
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bool does_occur = false;
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bool all_visited = true;
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for (expr* arg : *to_app(e)) {
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if (!visited.is_marked(arg)) {
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to_check.push_back(arg);
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all_visited = false;
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}
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else
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does_occur |= occ.is_marked(arg);
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}
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if (all_visited) {
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occ.mark(e, does_occur);
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visited.mark(e, true);
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to_check.pop_back();
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}
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}
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else if (is_quantifier(e)) {
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expr* body = to_quantifier(e)->get_expr();
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if (visited.is_marked(body)) {
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visited.mark(e, true);
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occ.mark(e, occ.is_marked(body));
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to_check.pop_back();
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}
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else
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to_check.push_back(body);
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}
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else {
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visited.mark(e, true);
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to_check.pop_back();
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}
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}
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}
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