85092412c7
@Kha @dselsam: This hack was preventing us from making `Expr` a "real" Lean type. This was bad for a few reasons: - It was hard to extend/modify `Expr` in Lean since we would also have to modify the C++ code that creates the `Expr` objects with the hidden fields. - `Expr.lam` and `Expr.forallE` were not following the Lean layout standard where we sort fields by size. @Kha: recall we used that to avoid a UB. The issue with `Expr.lam` and `Expr.forallE` is that they have a "visible" field (`BinderInfo`), which is smaller than hidden fields such as hash code. - `Expr.fvar` had only one field at `Expr.lean,` but four behind the scenes. I added a new constructor `Local` that is only accessible from C++. It is only used in legacy code we inherited from Lean2. We will eventually delete it. This refactoring was quite painful since many parts of the codebase were mixing the new `Expr.fvar` with the old `Expr.local`. I doubt I would be able to do it without the new staging framework @Kha built. BTW, some of the patches are horrible. I didn't care much since we are going to deleted the super ugly files. That being said, you should expect new weird bevaior due to `Expr.fvar` vs `Expr.local`. Next step: use the new `ExprCachedData` to make all `Expr` hidden visibles accessible from Lean. checkpoint
40 lines
1.3 KiB
C++
40 lines
1.3 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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class replace_visitor {
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protected:
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typedef expr_bi_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_constant(expr const &);
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virtual expr visit_var(expr const &);
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virtual expr visit_meta(expr const &);
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virtual expr visit_fvar(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_let(expr const & e);
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virtual expr visit_lit(expr const & e);
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virtual expr visit_mdata(expr const & e);
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virtual expr visit_proj(expr const & e);
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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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