lean2/src/kernel/for_each.h

81 lines
2.5 KiB
C
Raw Normal View History

/*
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 "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) {
if (!CacheAtomic) {
switch (e.kind()) {
case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value:
case expr_kind::Var: case expr_kind::MetaVar:
m_f(e, offset);
return;
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())
return;
m_visited->insert(p);
}
if (!m_f(e, offset))
return;
switch (e.kind()) {
case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value:
case expr_kind::Var: case expr_kind::MetaVar:
return;
case expr_kind::App:
std::for_each(begin_args(e), end_args(e), [=](expr const & arg){ return apply(arg, offset); });
return;
case expr_kind::Eq:
apply(eq_lhs(e), offset);
apply(eq_rhs(e), offset);
return;
case expr_kind::Lambda:
case expr_kind::Pi:
apply(abst_domain(e), offset);
apply(abst_body(e), offset + 1);
return;
case expr_kind::Let:
if (let_type(e))
apply(let_type(e), offset);
apply(let_value(e), offset);
apply(let_body(e), offset + 1);
return;
}
}
public:
for_each_fn(F const & f):m_f(f) {}
void operator()(expr const & e) { apply(e, 0); }
};
}