603dafbaf7
We simulate it in the following way:
1- An opaque 'let'-expressions (let x : t := v in b) is encoded as
((fun (x : t), b) v)
We also use a macro (let-macro) to mark this pattern.
Thus, the pretty-printer knows how to display it correctly.
2- Transparent 'let'-expressions are eagerly expanded by the parser.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
38 lines
1.2 KiB
C++
38 lines
1.2 KiB
C++
/*
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Copyright (c) 2013 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_maps.h"
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namespace lean {
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/**
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\brief Base class for implementing operations that apply modifications
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on expressions.
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The default behavior is a NOOP, users must create subclasses and
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redefine the visit_* methods.
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*/
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class replace_visitor {
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protected:
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typedef expr_map<expr> cache;
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cache m_cache;
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expr save_result(expr const & e, expr && r, bool shared);
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virtual expr visit_sort(expr const &);
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virtual expr visit_macro(expr const &);
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virtual expr visit_constant(expr const &);
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virtual expr visit_var(expr const &);
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virtual expr visit_mlocal(expr const &);
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virtual expr visit_meta(expr const &);
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virtual expr visit_local(expr const &);
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virtual expr visit_app(expr const &);
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virtual expr visit_binding(expr const &);
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virtual expr visit_lambda(expr const &);
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virtual expr visit_pi(expr const &);
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virtual expr visit(expr const &);
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public:
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expr operator()(expr const & e) { return visit(e); }
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void clear() { m_cache.clear(); }
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};
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}
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