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z3/src/ast/rewriter/char_rewriter.cpp
Nikolaj Bjorner 004139b320 rewrites for characters
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
2022-07-02 11:37:21 -07:00

109 lines
2.6 KiB
C++

/*++
Copyright (c) 2015 Microsoft Corporation
Module Name:
char_rewriter.cpp
Abstract:
Basic rewriting rules for character constraints
Author:
Nikolaj Bjorner (nbjorner) 2015-12-5
--*/
#include "util/debug.h"
#include "ast/rewriter/char_rewriter.h"
#include "ast/bv_decl_plugin.h"
#include "ast/arith_decl_plugin.h"
char_rewriter::char_rewriter(ast_manager& m):
m(m) {
m_char = static_cast<char_decl_plugin*>(m.get_plugin(m.mk_family_id("char")));
}
family_id char_rewriter::get_fid() {
return m_char->get_family_id();
}
br_status char_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result) {
SASSERT(f->get_family_id() == get_fid());
br_status st = BR_FAILED;
switch (f->get_decl_kind()) {
case OP_CHAR_CONST:
break;
case OP_CHAR_LE:
st = mk_char_le(args[0], args[1], result);
break;
case OP_CHAR_TO_INT:
st = mk_char_to_int(args[0], result);
break;
case OP_CHAR_TO_BV:
st = mk_char_to_bv(args[0], result);
break;
case OP_CHAR_FROM_BV:
st = mk_char_from_bv(args[0], result);
break;
case OP_CHAR_IS_DIGIT:
st = mk_char_is_digit(args[0], result);
break;
}
return st;
}
br_status char_rewriter::mk_char_is_digit(expr* a, expr_ref& result) {
unsigned n;
if (!m_char->is_const_char(a, n))
return BR_FAILED;
result = m.mk_bool_val('0' <= n && n <= '9');
return BR_DONE;
}
br_status char_rewriter::mk_char_to_bv(expr* a, expr_ref& result) {
return BR_FAILED;
}
br_status char_rewriter::mk_char_le(expr* a, expr* b, expr_ref& result) {
unsigned na = 0, nb = 0;
if (m_char->is_const_char(a, na)) {
if (na == 0) {
result = m.mk_true();
return BR_DONE;
}
}
if (m_char->is_const_char(b, nb)) {
if (na != 0) {
result = m.mk_bool_val(na <= nb);
return BR_DONE;
}
if (nb == m_char->max_char()) {
result = m.mk_true();
return BR_DONE;
}
}
return BR_FAILED;
}
br_status char_rewriter::mk_char_from_bv(expr* e, expr_ref& result) {
bv_util bv(m);
rational n;
if (bv.is_numeral(e, n) && n.is_unsigned() && n <= m_char->max_char()) {
result = m_char->mk_char(n.get_unsigned());
return BR_DONE;
}
return BR_FAILED;
}
br_status char_rewriter::mk_char_to_int(expr* e, expr_ref& result) {
unsigned n = 0;
if (m_char->is_const_char(e, n)) {
arith_util arith(m);
result = arith.mk_int(n);
return BR_DONE;
}
return BR_FAILED;
}