115 lines
3.8 KiB
C++
115 lines
3.8 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 <memory>
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#include <utility>
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#include "util/buffer.h"
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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, bool CacheAtomic = false>
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class for_each_fn {
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std::unique_ptr<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, bool>::value,
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"for_each_fn: return type of m_f is not bool");
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void apply(expr const & e, unsigned offset) {
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buffer<std::pair<expr const &, unsigned>> todo;
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todo.emplace_back(e, offset);
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while (true) {
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begin_loop:
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if (todo.empty())
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break;
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auto p = todo.back();
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todo.pop_back();
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expr const & e = p.first;
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unsigned offset = p.second;
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if (!CacheAtomic) {
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switch (e.kind()) {
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case expr_kind::Constant:
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if (!const_type(e)) {
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// only constants without cached types are considered atomic
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m_f(e, offset);
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goto begin_loop;
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}
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break;
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case expr_kind::Type: case expr_kind::Value:
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case expr_kind::Var: case expr_kind::MetaVar:
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m_f(e, offset);
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goto begin_loop;
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default:
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break;
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}
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}
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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)
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m_visited.reset(new expr_cell_offset_set());
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if (m_visited->find(p) != m_visited->end())
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goto begin_loop;
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m_visited->insert(p);
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}
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if (!m_f(e, offset))
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goto begin_loop;
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switch (e.kind()) {
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case expr_kind::Constant:
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if (const_type(e))
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todo.emplace_back(*const_type(e), offset);
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goto begin_loop;
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case expr_kind::Type: case expr_kind::Value:
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case expr_kind::Var: case expr_kind::MetaVar:
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goto begin_loop;
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case expr_kind::App: {
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auto it = end_args(e);
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auto begin = begin_args(e);
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while (it != begin) {
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--it;
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todo.emplace_back(*it, offset);
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}
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goto begin_loop;
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}
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case expr_kind::HEq:
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todo.emplace_back(heq_rhs(e), offset);
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todo.emplace_back(heq_lhs(e), offset);
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goto begin_loop;
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case expr_kind::Lambda:
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case expr_kind::Pi:
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todo.emplace_back(abst_body(e), offset + 1);
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todo.emplace_back(abst_domain(e), offset);
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goto begin_loop;
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case expr_kind::Let:
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todo.emplace_back(let_body(e), offset + 1);
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todo.emplace_back(let_value(e), offset);
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if (let_type(e))
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todo.emplace_back(*let_type(e), offset);
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goto begin_loop;
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}
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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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template<typename F>
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void for_each(expr const & e, F f) {
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return for_each_fn<F>(f)(e);
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}
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}
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