lean2/src/kernel/for_each_fn.h
2013-11-19 13:03:46 -08:00

115 lines
3.8 KiB
C++

/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#pragma once
#include <memory>
#include <utility>
#include "util/buffer.h"
#include "kernel/expr.h"
#include "kernel/expr_sets.h"
namespace lean {
/**
\brief Template for implementing expression visitors.
The argument \c F must be a function object containing the method
<code>
void operator()(expr const & e, unsigned offset)
</code>
The \c offset is the number of binders under which \c e occurs.
*/
template<typename F, bool CacheAtomic = false>
class for_each_fn {
std::unique_ptr<expr_cell_offset_set> m_visited;
F m_f;
static_assert(std::is_same<typename std::result_of<F(expr const &, unsigned)>::type, bool>::value,
"for_each_fn: return type of m_f is not bool");
void apply(expr const & e, unsigned offset) {
buffer<std::pair<expr const &, unsigned>> todo;
todo.emplace_back(e, offset);
while (true) {
begin_loop:
if (todo.empty())
break;
auto p = todo.back();
todo.pop_back();
expr const & e = p.first;
unsigned offset = p.second;
if (!CacheAtomic) {
switch (e.kind()) {
case expr_kind::Constant:
if (!const_type(e)) {
// only constants without cached types are considered atomic
m_f(e, offset);
goto begin_loop;
}
break;
case expr_kind::Type: case expr_kind::Value:
case expr_kind::Var: case expr_kind::MetaVar:
m_f(e, offset);
goto begin_loop;
default:
break;
}
}
if (is_shared(e)) {
expr_cell_offset p(e.raw(), offset);
if (!m_visited)
m_visited.reset(new expr_cell_offset_set());
if (m_visited->find(p) != m_visited->end())
goto begin_loop;
m_visited->insert(p);
}
if (!m_f(e, offset))
goto begin_loop;
switch (e.kind()) {
case expr_kind::Constant:
if (const_type(e))
todo.emplace_back(const_type(e), offset);
goto begin_loop;
case expr_kind::Type: case expr_kind::Value:
case expr_kind::Var: case expr_kind::MetaVar:
goto begin_loop;
case expr_kind::App: {
auto it = end_args(e);
auto begin = begin_args(e);
while (it != begin) {
--it;
todo.emplace_back(*it, offset);
}
goto begin_loop;
}
case expr_kind::Eq:
todo.emplace_back(eq_rhs(e), offset);
todo.emplace_back(eq_lhs(e), offset);
goto begin_loop;
case expr_kind::Lambda:
case expr_kind::Pi:
todo.emplace_back(abst_body(e), offset + 1);
todo.emplace_back(abst_domain(e), offset);
goto begin_loop;
case expr_kind::Let:
todo.emplace_back(let_body(e), offset + 1);
todo.emplace_back(let_value(e), offset);
if (let_type(e))
todo.emplace_back(let_type(e), offset);
goto begin_loop;
}
}
}
public:
for_each_fn(F const & f):m_f(f) {}
void operator()(expr const & e) { apply(e, 0); }
};
template<typename F>
void for_each(expr const & e, F f) {
return for_each_fn<F>(f)(e);
}
}