105 lines
4.3 KiB
C++
105 lines
4.3 KiB
C++
/*
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Copyright (c) 2014 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#pragma once
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#include <algorithm>
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#include "util/lazy_list.h"
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#include "util/list.h"
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#include "util/name_generator.h"
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#include "kernel/expr.h"
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#include "kernel/justification.h"
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#include "kernel/metavar.h"
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namespace lean {
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/**
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\brief The lean kernel type checker produces two kinds of constraints:
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- Equality constraint: t ≈ s
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The terms t and s must be definitionally equal.
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- Universe level constaint: l = m
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The universe level l must be less than or equal to m.
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\remark The constraints are only generated if the input term contains
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metavariables or level metavariables.
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Each constraint is associated with a justification object.
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\remark We also have choice constraints that are used by elaborator to specify
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the possible solutions for a metavariable. The choice constraints are not used by
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the kernel.
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*/
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enum class constraint_kind { Eq, LevelEq, Choice };
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class constraint;
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typedef list<constraint> constraints;
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/**
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\brief A choice_fn is used to enumerate the possible solutions for a metavariable.
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The input arguments are:
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- metavariable that should be inferred
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- the metavariable type
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- substitution map (metavar -> value)
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- name generator
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The result is a lazy_list of constraints
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One application of choice constraints is overloaded notation.
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*/
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typedef std::function<lazy_list<constraints>(expr const &, expr const &, substitution const &, name_generator const &)> choice_fn;
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struct constraint_cell;
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class constraint {
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constraint_cell * m_ptr;
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constraint(constraint_cell * ptr);
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public:
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constraint(constraint const & c);
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constraint(constraint && s);
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~constraint();
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constraint_kind kind() const;
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justification const & get_justification() const;
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constraint & operator=(constraint const & c);
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constraint & operator=(constraint && c);
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friend bool is_eqp(constraint const & c1, constraint const & c2) { return c1.m_ptr == c2.m_ptr; }
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friend void swap(constraint & l1, constraint & l2) { std::swap(l1, l2); }
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friend constraint mk_eq_cnstr(expr const & lhs, expr const & rhs, justification const & j);
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friend constraint mk_level_eq_cnstr(level const & lhs, level const & rhs, justification const & j);
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friend constraint mk_choice_cnstr(expr const & m, choice_fn const & fn, unsigned delay_factor, justification const & j);
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constraint_cell * raw() const { return m_ptr; }
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};
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inline bool operator==(constraint const & c1, constraint const & c2) { return c1.raw() == c2.raw(); }
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inline bool operator!=(constraint const & c1, constraint const & c2) { return !(c1 == c2); }
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constraint mk_eq_cnstr(expr const & lhs, expr const & rhs, justification const & j);
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constraint mk_level_eq_cnstr(level const & lhs, level const & rhs, justification const & j);
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constraint mk_choice_cnstr(expr const & m, choice_fn const & fn, unsigned delay_factor, justification const & j);
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inline bool is_eq_cnstr(constraint const & c) { return c.kind() == constraint_kind::Eq; }
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inline bool is_level_eq_cnstr(constraint const & c) { return c.kind() == constraint_kind::LevelEq; }
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inline bool is_choice_cnstr(constraint const & c) { return c.kind() == constraint_kind::Choice; }
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constraint update_justification(constraint const & c, justification const & j);
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/** \brief Return the lhs of an equality constraint. */
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expr const & cnstr_lhs_expr(constraint const & c);
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/** \brief Return the rhs of an equality constraint. */
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expr const & cnstr_rhs_expr(constraint const & c);
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/** \brief Return the lhs of an level constraint. */
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level const & cnstr_lhs_level(constraint const & c);
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/** \brief Return the rhs of an level constraint. */
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level const & cnstr_rhs_level(constraint const & c);
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/** \brief Return the expression associated with a choice constraint */
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expr const & cnstr_expr(constraint const & c);
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/** \brief Return the choice_fn associated with a choice constraint. */
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choice_fn const & cnstr_choice_fn(constraint const & c);
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/** \brief Return the choice constraint delay factor */
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unsigned cnstr_delay_factor(constraint const & c);
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/** \brief Printer for debugging purposes */
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std::ostream & operator<<(std::ostream & out, constraint const & c);
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}
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