38 lines
1.6 KiB
C++
38 lines
1.6 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 "util/lazy_list.h"
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#include "kernel/environment.h"
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#include "kernel/constraint.h"
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#include "kernel/type_checker.h"
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namespace lean {
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/**
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\brief A unifier_plugin provides a simple way to extend the \c unify procedures.
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Whenever, the default implementation does not know how to solve a constraint, it invokes the plugin.
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The plugin return a lazy_list (stream) of possible solutions. Each "solution" is represented as
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a new list of constraints.
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The method \c delay_constraint is invoked to decide whether the particular constraint should
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be delayed. This is useful when implementing unification plugins
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*/
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class unifier_plugin_cell {
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public:
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virtual ~unifier_plugin_cell() {}
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virtual lazy_list<constraints> solve(type_checker &, constraint const &, name_generator const &) const = 0;
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virtual bool delay_constraint(type_checker &, constraint const &) const = 0;
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};
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typedef std::shared_ptr<unifier_plugin_cell> unifier_plugin;
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/** \brief Combine two plugins by appending their solutions. */
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unifier_plugin append(unifier_plugin const & p1, unifier_plugin const & p2);
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/** \brief Combine two plugins by taking the solutions of p1, if it is empty, then return solutions of p2 */
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unifier_plugin orelse(unifier_plugin const & p1, unifier_plugin const & p2);
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environment set_unifier_plugin(environment const & env, unifier_plugin const & p);
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unifier_plugin const & get_unifier_plugin(environment const & env);
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}
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