relational.cpp

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/*
 *  GiNaC Copyright (C) 1999-2026 Johannes Gutenberg University Mainz, Germany
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#include "relational.h"
#include "operators.h"
#include "numeric.h"
#include "archive.h"
#include "utils.h"
#include "hash_seed.h"
 
#include <stdexcept>
 
namespace GiNaC {
 
GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(relational, basic,
  print_func<print_context>(&relational::do_print).
  print_func<print_tree>(&relational::do_print_tree).
  print_func<print_python_repr>(&relational::do_print_python_repr))
 

// default constructor
 
relational::relational() { }

// other constructors
 
// public
 
relational::relational(const ex & lhs, const ex & rhs, operators oper) :
    lh(lhs), rh(rhs), o(oper) { }

// archiving
 
void relational::read_archive(const archive_node& n, lst& sym_lst)
{
    inherited::read_archive(n, sym_lst);
    unsigned int opi;
    if (!(n.find_unsigned("op", opi)))
        throw (std::runtime_error("unknown relational operator in archive"));
    o = (operators)opi;
    n.find_ex("lh", lh, sym_lst);
    n.find_ex("rh", rh, sym_lst);
}
GINAC_BIND_UNARCHIVER(relational);
 
void relational::archive(archive_node &n) const
{
    inherited::archive(n);
    n.add_ex("lh", lh);
    n.add_ex("rh", rh);
    n.add_unsigned("op", o);
}

// functions overriding virtual functions from base classes
 
// public
 
static void print_operator(const print_context & c, relational::operators o)
{
    switch (o) {
    case relational::equal:
        c.s << "==";
        break;
    case relational::not_equal:
        c.s << "!=";
        break;
    case relational::less:
        c.s << "<";
        break;
    case relational::less_or_equal:
        c.s << "<=";
        break;
    case relational::greater:
        c.s << ">";
        break;
    case relational::greater_or_equal:
        c.s << ">=";
        break;
    default:
        c.s << "(INVALID RELATIONAL OPERATOR)";
        break;
    }
}
 
void relational::do_print(const print_context & c, unsigned level) const
{
    if (precedence() <= level)
        c.s << "(";
    lh.print(c, precedence());
    print_operator(c, o);
    rh.print(c, precedence());
    if (precedence() <= level)
        c.s << ")";
}
 
void relational::do_print_python_repr(const print_python_repr & c, unsigned level) const
{
    c.s << class_name() << '(';
    lh.print(c);
    c.s << ',';
    rh.print(c);
    c.s << ",'";
    print_operator(c, o);
    c.s << "')";
}
 
bool relational::info(unsigned inf) const
{
    switch (inf) {
        case info_flags::relation:
            return 1;
        case info_flags::relation_equal:
            return o==equal;
        case info_flags::relation_not_equal:
            return o==not_equal;
        case info_flags::relation_less:
            return o==less;
        case info_flags::relation_less_or_equal:
            return o==less_or_equal;
        case info_flags::relation_greater:
            return o==greater;
        case info_flags::relation_greater_or_equal:
            return o==greater_or_equal;
    }
    return 0;
}
 
size_t relational::nops() const
{
    return 2;
}
 
ex relational::op(size_t i) const
{
    GINAC_ASSERT(i<2);
 
    return i==0 ? lh : rh;
}
 
ex relational::map(map_function & f) const
{
    const ex &mapped_lh = f(lh);
    const ex &mapped_rh = f(rh);
 
    if (!are_ex_trivially_equal(lh, mapped_lh)
     || !are_ex_trivially_equal(rh, mapped_rh))
        return dynallocate<relational>(mapped_lh, mapped_rh, o);
    else
        return *this;
}
 
ex relational::subs(const exmap & m, unsigned options) const
{
    const ex & subsed_lh = lh.subs(m, options);
    const ex & subsed_rh = rh.subs(m, options);
 
    if (!are_ex_trivially_equal(lh, subsed_lh) || !are_ex_trivially_equal(rh, subsed_rh))
        return relational(subsed_lh, subsed_rh, o).subs_one_level(m, options);
    else
        return subs_one_level(m, options);
}
 
ex relational::eval_ncmul(const exvector & v) const
{
    return lh.eval_ncmul(v);
}
 
// protected
 
int relational::compare_same_type(const basic & other) const
{
    GINAC_ASSERT(is_exactly_a<relational>(other));
    const relational &oth = static_cast<const relational &>(other);
    if (o==oth.o && lh.is_equal(oth.lh) && rh.is_equal(oth.rh))
        return 0;
    switch (o) {
        case equal:
        case not_equal:
            if (oth.o!=o)
                return (o < oth.o) ? -1 : 1;
            break;
        case less:
            if (oth.o!=greater)
                return (o < oth.o) ? -1 : 1;
            break;
        case less_or_equal:
            if (oth.o!=greater_or_equal)
                return (o < oth.o) ? -1 : 1;
            break;
        case greater:
            if (oth.o!=less)
                return (o < oth.o) ? -1 : 1;
            break;
        case greater_or_equal:
            if (oth.o!=less_or_equal)
                return (o < oth.o) ? -1 : 1;
            break;
    }
    const int lcmpval = lh.compare(oth.lh);
    return (lcmpval!=0) ? lcmpval : rh.compare(oth.rh);
}
 
bool relational::match_same_type(const basic & other) const
{
    GINAC_ASSERT(is_exactly_a<relational>(other));
    const relational &oth = static_cast<const relational &>(other);
 
    return o == oth.o;
}
 
unsigned relational::return_type() const
{
    GINAC_ASSERT(lh.return_type()==rh.return_type());
    return lh.return_type();
}
 
return_type_t relational::return_type_tinfo() const
{
    GINAC_ASSERT(lh.return_type_tinfo()==rh.return_type_tinfo());
    return lh.return_type_tinfo();
}
 
unsigned relational::calchash() const
{
    unsigned v = make_hash_seed(typeid(*this));
    unsigned lhash = lh.gethash();
    unsigned rhash = rh.gethash();
 
    v = rotate_left(v);
    switch(o) {
        case equal:
        case not_equal:
            if (lhash>rhash) {
                v ^= lhash;
                lhash = rhash;
            } else {
                v ^= rhash;
            }
            break;
        case less:
        case less_or_equal:
            v ^= rhash;
            break;
        case greater:
        case greater_or_equal:
            v ^= lhash;
            lhash = rhash;
            break;
    }
    v = rotate_left(v);
    v ^= lhash;
 
    // store calculated hash value only if object is already evaluated
    if (flags & status_flags::evaluated) {
        setflag(status_flags::hash_calculated);
        hashvalue = v;
    }
 
    return v;
}

// new virtual functions which can be overridden by derived classes
 
// none

// non-virtual functions in this class
 
relational::safe_bool relational::make_safe_bool(bool cond) const
{
    return cond? &safe_bool_helper::nonnull : nullptr;
}

relational::operator relational::safe_bool() const
{
    const ex df = lh-rh;  // like ::canonical() method
    // We treat numeric and symbolic expression differently
    if (is_exactly_a<numeric>(df)) {
        switch (o) {
            case equal:
                return make_safe_bool(ex_to<numeric>(df).is_zero());
            case not_equal:
                return make_safe_bool(!ex_to<numeric>(df).is_zero());
            case less:
                return make_safe_bool(ex_to<numeric>(df)<(*_num0_p));
            case less_or_equal:
                return make_safe_bool(ex_to<numeric>(df)<=(*_num0_p));
            case greater:
                return make_safe_bool(ex_to<numeric>(df)>(*_num0_p));
            case greater_or_equal:
                return make_safe_bool(ex_to<numeric>(df)>=(*_num0_p));
            default:
                throw(std::logic_error("invalid relational operator"));
        }
    } else {
        // The conversion for symbolic expressions is based on the info flags
        switch (o) {
            case equal:
                return make_safe_bool(df.is_zero());
            case not_equal:
                return make_safe_bool(! df.is_zero());
            case less:
                return make_safe_bool(df.info(info_flags::negative));
            case less_or_equal:
                return make_safe_bool((-df).info(info_flags::nonnegative));
            case greater:
                return make_safe_bool(df.info(info_flags::positive));
            case greater_or_equal:
                return make_safe_bool(df.info(info_flags::nonnegative));
            default:
                throw(std::logic_error("invalid relational operator"));
        }
    }
}

ex relational::canonical() const
{
    return relational(lh-rh, _ex0, o);
}
 
} // namespace GiNaC