238 lines
10 KiB
C++
238 lines
10 KiB
C++
/*
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Copyright (c) 2013-2014 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 <utility>
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#include <memory>
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#include <vector>
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#include "util/rc.h"
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#include "util/optional.h"
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#include "util/list.h"
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#include "util/rb_map.h"
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#include "util/name_set.h"
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#include "util/name_map.h"
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#include "kernel/expr.h"
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#include "kernel/constraint.h"
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#include "kernel/declaration.h"
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#include "kernel/normalizer_extension.h"
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#ifndef LEAN_BELIEVER_TRUST_LEVEL
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// If an environment E is created with a trust level > LEAN_BELIEVER_TRUST_LEVEL, then
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// we can add declarations to E without type checking them.
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#define LEAN_BELIEVER_TRUST_LEVEL 1024
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#endif
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namespace lean {
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class type_checker;
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class environment;
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class certified_declaration;
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typedef std::function<bool(name const &)> extra_opaque_pred; // NOLINT
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extra_opaque_pred const & no_extra_opaque();
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/**
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\brief The header of an environment is created when we create the empty environment.
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Moreover if environment B is an extension of environment A, then A and B share the same header.
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*/
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class environment_header {
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/* In the following field, 0 means untrusted mode (i.e., check everything),
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higher level allow us to trust the implementation of macros, and even
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allow us to add declarations without type checking them (e.g., m_trust_lvl > LEAN_BELIEVER_TRUST_LEVEL)
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*/
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unsigned m_trust_lvl;
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bool m_prop_proof_irrel; //!< true if the kernel assumes proof irrelevance for Prop (aka Type.{0})
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bool m_eta; //!< true if the kernel uses eta-reduction in convertability checks
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bool m_impredicative; //!< true if the kernel should treat (universe level 0) as a impredicative Prop.
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std::unique_ptr<normalizer_extension const> m_norm_ext;
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void dealloc();
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public:
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environment_header(unsigned trust_lvl, bool prop_proof_irrel, bool eta, bool impredicative,
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std::unique_ptr<normalizer_extension const> ext);
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unsigned trust_lvl() const { return m_trust_lvl; }
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bool prop_proof_irrel() const { return m_prop_proof_irrel; }
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bool eta() const { return m_eta; }
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bool impredicative() const { return m_impredicative; }
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normalizer_extension const & norm_ext() const { return *(m_norm_ext.get()); }
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};
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class environment_extension {
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public:
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virtual ~environment_extension();
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};
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typedef std::vector<std::shared_ptr<environment_extension const>> environment_extensions;
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/** \brief environment identifier for tracking descendants of a given environment. */
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class environment_id {
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friend class environment_id_tester;
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friend class environment; // Only the environment class can create object of this type.
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struct path;
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path * m_ptr;
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unsigned m_depth;
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/**
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\brief Create an identifier for an environment that is a direct descendant of the given one.
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The bool field is just to make sure this constructor is not confused with a copy constructor
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*/
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environment_id(environment_id const & ancestor, bool);
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/** \brief Create an identifier for an environment without ancestors (e.g., empty environment) */
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environment_id();
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/** Create an identifier for an environment that is a direct descendant of the given one. */
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static environment_id mk_descendant(environment_id const & ancestor) { return environment_id(ancestor, true); }
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public:
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environment_id(environment_id const & id);
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environment_id(environment_id && id);
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~environment_id();
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environment_id & operator=(environment_id const & s);
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environment_id & operator=(environment_id && s);
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/** \brief Return true iff this object is a descendant of the given one. */
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bool is_descendant(environment_id const & id) const;
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};
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/**
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\brief Lean core environment. An environment object can be extended/customized in different ways:
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1- By providing a normalizer_extension when creating an empty environment.
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2- By setting the proof_irrel and eta flags when creating an empty environment.
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3- By attaching additional data as environment::extensions. The additional data can be added
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at any time. They contain information used by the automation (e.g., rewriting sets, unification hints, etc).
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*/
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class environment {
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typedef std::shared_ptr<environment_header const> header;
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typedef name_map<declaration> declarations;
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typedef std::shared_ptr<environment_extensions const> extensions;
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header m_header;
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environment_id m_id;
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declarations m_declarations;
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name_set m_global_levels;
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extensions m_extensions;
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environment(header const & h, environment_id const & id, declarations const & d, name_set const & global_levels, extensions const & ext);
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public:
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environment(unsigned trust_lvl = 0, bool prop_proof_irrel = true, bool eta = true, bool impredicative = true);
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environment(unsigned trust_lvl, bool prop_proof_irrel, bool eta, bool impredicative,
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std::unique_ptr<normalizer_extension> ext);
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~environment();
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/** \brief Return the environment unique identifier. */
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environment_id const & get_id() const { return m_id; }
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/** \brief Return true iff this environment is a descendant of \c env. */
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bool is_descendant(environment const & env) const { return m_id.is_descendant(env.m_id); }
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/** \brief Return the trust level of this environment. */
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unsigned trust_lvl() const { return m_header->trust_lvl(); }
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/** \brief Return true iff the environment assumes proof irrelevance for Type.{0} (i.e., Prop) */
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bool prop_proof_irrel() const { return m_header->prop_proof_irrel(); }
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/** \brief Return true iff the environment assumes Eta-reduction */
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bool eta() const { return m_header->eta(); }
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/** \brief Return true iff the environment treats universe level 0 as an impredicative Prop */
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bool impredicative() const { return m_header->impredicative(); }
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/** \brief Return reference to the normalizer extension associatied with this environment. */
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normalizer_extension const & norm_ext() const { return m_header->norm_ext(); }
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/** \brief Return declaration with name \c n (if it is defined in this environment). */
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optional<declaration> find(name const & n) const;
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/** \brief Return declaration with name \c n. Throws and exception if declaration does not exist in this environment. */
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declaration get(name const & n) const;
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/**
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\brief Add a new global universe level with name \c n
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This method throws an exception if the environment already contains a level named \c n.
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*/
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environment add_universe(name const & n) const;
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/** \brief Return true iff the environment has a universe level named \c n. */
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bool is_universe(name const & n) const;
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/**
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\brief Extends the current environment with the given (certified) declaration
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This method throws an exception if:
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- The declaration was certified in an environment which is not an ancestor of this one.
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- The environment already contains a declaration with the given name.
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*/
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environment add(certified_declaration const & d) const;
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/**
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\brief Adds a declaration that was not type checked. This method throws an excetion if
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trust_lvl() <= LEAN_BELIEVER_TRUST_LEVEL.
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It is mainly when importing pre-compiled .olean files, and trust_lvl() > LEAN_BELIEVER_TRUST_LEVEL.
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\remark If trust_lvl() == 0, then this method will always throw an exception. No matter what is
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the value of LEAN_BELIEVER_TRUST_LEVEL used to compile Lean.
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*/
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environment add(declaration const & d) const;
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/**
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\brief Replace the axiom with name <tt>t.get_declaration().get_name()</tt> with the theorem t.get_declaration().
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This method throws an exception if:
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- The theorem was certified in an environment which is not an ancestor of this one.
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- The environment does not contain an axiom named <tt>t.get_declaration().get_name()</tt>
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*/
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environment replace(certified_declaration const & t) const;
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/**
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\brief Register an environment extension. Every environment
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object may contain this extension. The argument \c initial is
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the initial value for the new extensions. The extension object
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can be retrieved using the given token (unsigned integer) returned
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by this method.
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\remark The extension objects are created on demand.
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\see get_extension
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*/
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static unsigned register_extension(std::shared_ptr<environment_extension const> const & initial);
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/** \brief Return the extension with the given id. */
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environment_extension const & get_extension(unsigned extid) const;
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/** \brief Update the environment extension with the given id. */
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environment update(unsigned extid, std::shared_ptr<environment_extension const> const & ext) const;
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/**
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\brief Return a new environment, where its "history" has been truncated/forgotten.
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That is, <tt>is_descendant(e)</tt> will return false for any environment \c e that
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is not pointer equal to the result.
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*/
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environment forget() const;
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/** \brief Apply the function \c f to each declaration */
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void for_each_declaration(std::function<void(declaration const & d)> const & f) const;
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/** \brief Apply the function \c f to each universe */
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void for_each_universe(std::function<void(name const & u)> const & f) const;
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};
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void initialize_environment();
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void finalize_environment();
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class name_generator;
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/**
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\brief A certified declaration is one that has been type checked.
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Only the type_checker class can create certified declarations.
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*/
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class certified_declaration {
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friend certified_declaration check(environment const & env, declaration const & d,
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name_generator const & g, extra_opaque_pred const & extra_opaque);
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environment_id m_id;
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declaration m_declaration;
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certified_declaration(environment_id const & id, declaration const & d):m_id(id), m_declaration(d) {}
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public:
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/** \brief Return the id of the environment that was used to type check this declaration. */
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environment_id const & get_id() const { return m_id; }
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declaration const & get_declaration() const { return m_declaration; }
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};
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}
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