38 lines
1.7 KiB
C++
38 lines
1.7 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 "kernel/expr.h"
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namespace lean {
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/**
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\brief The Lean kernel can be instantiated with different normalization extensions.
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Each extension is part of the trusted code base. The extensions allow us to support
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different flavors of the core type theory. We will use these extensions to implement
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inductive datatype (ala Coq), HIT, record types, etc.
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*/
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class normalizer_extension {
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public:
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virtual ~normalizer_extension() {}
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virtual optional<pair<expr, constraint_seq>> operator()(expr const & e, extension_context & ctx) const = 0;
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/** \brief Return true if the extension may reduce \c e after metavariables are instantiated. */
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virtual bool may_reduce_later(expr const & e, extension_context & ctx) const = 0;
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/** \brief Return true iff the extension supports a feature with the given name,
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this method is only used for sanity checking. */
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virtual bool supports(name const & feature) const = 0;
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};
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inline optional<pair<expr, constraint_seq>> none_ecs() { return optional<pair<expr, constraint_seq>>(); }
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inline optional<pair<expr, constraint_seq>> some_ecs(expr const & e, constraint_seq const & cs) {
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return optional<pair<expr, constraint_seq>>(e, cs);
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}
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/** \brief Create the do-nothing normalizer extension */
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std::unique_ptr<normalizer_extension> mk_id_normalizer_extension();
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/** \brief Create the composition of two normalizer extensions */
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std::unique_ptr<normalizer_extension> compose(std::unique_ptr<normalizer_extension> && ext1, std::unique_ptr<normalizer_extension> && ext2);
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}
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