65 lines
2 KiB
C++
65 lines
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.h"
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#include "kernel/expr_sets.h"
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namespace lean {
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/**
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\brief Template for implementing expression visitors.
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The argument \c F must be a function object containing the method
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<code>
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void operator()(expr const & e, unsigned offset)
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</code>
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The \c offset is the number of binders under which \c e occurs.
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*/
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template<typename F>
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class for_each_fn {
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expr_cell_offset_set m_visited;
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F m_f;
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static_assert(std::is_same<typename std::result_of<F(expr const &, unsigned)>::type, void>::value,
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"for_each_fn: return type of m_f is not void");
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void apply(expr const & e, unsigned offset) {
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if (is_shared(e)) {
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expr_cell_offset p(e.raw(), offset);
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if (m_visited.find(p) != m_visited.end())
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return;
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m_visited.insert(p);
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}
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m_f(e, offset);
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switch (e.kind()) {
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case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value:
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case expr_kind::Var: case expr_kind::MetaVar:
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return;
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case expr_kind::App:
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std::for_each(begin_args(e), end_args(e), [=](expr const & arg){ return apply(arg, offset); });
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return;
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case expr_kind::Eq:
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apply(eq_lhs(e), offset);
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apply(eq_rhs(e), offset);
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return;
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case expr_kind::Lambda:
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case expr_kind::Pi:
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apply(abst_domain(e), offset);
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apply(abst_body(e), offset + 1);
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return;
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case expr_kind::Let:
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if (let_type(e))
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apply(let_type(e), offset);
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apply(let_value(e), offset);
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apply(let_body(e), offset + 1);
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return;
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}
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}
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public:
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for_each_fn(F const & f):m_f(f) {}
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void operator()(expr const & e) { apply(e, 0); }
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};
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}
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