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https://github.com/Z3Prover/z3
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105 lines
3.2 KiB
C++
105 lines
3.2 KiB
C++
/*++
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Copyright (c) 2006 Microsoft Corporation
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Module Name:
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arith_solver_plugin.cpp
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Abstract:
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<abstract>
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Author:
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Leonardo de Moura (leonardo) 2008-06-30.
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Revision History:
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--*/
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#include"arith_solver_plugin.h"
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#include"ast_pp.h"
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arith_solver_plugin::arith_solver_plugin(arith_simplifier_plugin & simp):
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solver_plugin(symbol("arith"), simp.get_manager()),
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m_simplifier(simp) {
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}
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bool arith_solver_plugin::solve(expr * lhs, expr * rhs, expr_mark const & forbidden, app_ref & var, expr_ref & subst) {
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rational k;
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if (!m_simplifier.is_numeral(rhs, k))
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return false;
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bool _is_int = m_simplifier.is_int(lhs);
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ptr_buffer<expr> monomials;
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ptr_buffer<expr> todo;
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bool already_found = false;
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rational c;
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todo.push_back(lhs);
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while (!todo.empty()) {
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expr * curr = todo.back();
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todo.pop_back();
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rational coeff;
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if (m_simplifier.is_add(curr)) {
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SASSERT(to_app(curr)->get_num_args() == 2);
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todo.push_back(to_app(curr)->get_arg(1));
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todo.push_back(to_app(curr)->get_arg(0));
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}
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else {
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if (!already_found) {
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if (m_simplifier.is_mul(curr) &&
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m_simplifier.is_numeral(to_app(curr)->get_arg(0), coeff) && !coeff.is_zero() && (!_is_int || coeff.is_minus_one()) &&
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is_uninterp_const(to_app(curr)->get_arg(1)) &&
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!forbidden.is_marked(to_app(curr)->get_arg(1))) {
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c = coeff;
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var = to_app(to_app(curr)->get_arg(1));
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already_found = true;
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}
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else if (is_uninterp_const(curr) && !forbidden.is_marked(curr)) {
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c = rational::one();
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var = to_app(curr);
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already_found = true;
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}
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else {
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monomials.push_back(curr);
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}
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}
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else {
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monomials.push_back(curr);
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}
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}
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}
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if (!already_found)
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return false;
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SASSERT(!c.is_zero());
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k /= c;
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expr_ref_vector new_monomials(m_manager);
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if (!k.is_zero())
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new_monomials.push_back(m_simplifier.mk_numeral(k, _is_int));
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c.neg();
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expr_ref inv_c(m_manager);
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if (!c.is_one()) {
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rational inv(1);
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inv /= c;
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inv_c = m_simplifier.mk_numeral(inv, _is_int);
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}
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// divide monomials by c
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unsigned sz = monomials.size();
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for (unsigned i = 0; i < sz; i++) {
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expr * m = monomials[i];
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expr_ref new_m(m_manager);
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if (!c.is_one())
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m_simplifier.mk_mul(inv_c, m, new_m);
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else
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new_m = m;
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new_monomials.push_back(new_m);
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}
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if (new_monomials.empty())
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subst = m_simplifier.mk_numeral(rational(0), _is_int);
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else
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m_simplifier.mk_add(new_monomials.size(), new_monomials.c_ptr(), subst);
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TRACE("arith_solver", tout << "solving:\n" << mk_pp(lhs, m_manager) << "\n" << mk_pp(rhs, m_manager)
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<< "\nresult:\n" << mk_pp(var, m_manager) << "\n" << mk_pp(subst, m_manager) << "\n";);
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return true;
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}
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