3 * Interface to relations between expressions. */
6 * GiNaC Copyright (C) 1999-2007 Johannes Gutenberg University Mainz, Germany
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
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13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
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23 #ifndef __GINAC_RELATIONAL_H__
24 #define __GINAC_RELATIONAL_H__
31 /** This class holds a relation consisting of two expressions and a logical
32 * relation between them. */
33 class relational : public basic
35 GINAC_DECLARE_REGISTERED_CLASS(relational, basic)
50 relational(const ex & lhs, const ex & rhs, operators oper=equal);
52 // functions overriding virtual functions from base classes
54 unsigned precedence() const {return 20;}
55 bool info(unsigned inf) const;
57 ex op(size_t i) const;
58 ex map(map_function & f) const;
59 ex subs(const exmap & m, unsigned options = 0) const;
60 ex eval(int level=0) const;
63 ex eval_ncmul(const exvector & v) const;
64 bool match_same_type(const basic & other) const;
65 unsigned return_type() const;
66 tinfo_t return_type_tinfo() const;
67 unsigned calchash() const;
69 // new virtual functions which can be overridden by derived classes
71 void do_print(const print_context & c, unsigned level) const;
72 void do_print_python_repr(const print_python_repr & c, unsigned level) const;
75 virtual ex lhs() const;
76 virtual ex rhs() const;
78 // non-virtual functions in this class
80 // For conversions to boolean, as would be used in an if conditional,
81 // implicit conversions from bool to int have a large number of
82 // undesirable side effects. The following safe_bool type enables
83 // use of relational objects in conditionals without those side effects
84 struct safe_bool_helper {
88 typedef void (safe_bool_helper::*safe_bool)();
90 safe_bool make_safe_bool(bool) const;
93 operator safe_bool() const;
94 safe_bool operator!() const;
106 // inlined functions for efficiency
107 inline relational::safe_bool relational::operator!() const
109 return make_safe_bool(!static_cast<bool>(*this));
114 #endif // ndef __GINAC_RELATIONAL_H__