lean2/src/kernel/replace_fn.h

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/*
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
2013-10-26 18:07:06 +00:00
#include <tuple>
#include "util/buffer.h"
#include "util/interrupt.h"
#include "kernel/expr.h"
#include "kernel/expr_maps.h"
namespace lean {
/**
\brief Default replace_fn postprocessor functional object. It is a
do-nothing object.
*/
class default_replace_postprocessor {
public:
void operator()(expr const &, expr const &) {}
};
/**
\brief Functional for applying <tt>F</tt> to the subexpressions of a given expression.
The signature of \c F is
expr const &, unsigned -> optional(expr)
F is invoked for each subexpression \c s of the input expression e.
In a call <tt>F(s, n)</tt>, n is the scope level, i.e., the number of
bindings operators that enclosing \c s. The replaces only visits children of \c e
if F return none_expr
P is a "post-processing" functional object that is applied to each
pair (old, new)
*/
class replace_fn {
struct frame {
expr m_expr;
unsigned m_offset;
bool m_shared;
unsigned m_index;
frame(expr const & e, unsigned o, bool s):m_expr(e), m_offset(o), m_shared(s), m_index(0) {}
};
typedef buffer<frame> frame_stack;
typedef buffer<expr> result_stack;
expr_cell_offset_map<expr> m_cache;
std::function<optional<expr>(expr const &, unsigned)> m_f;
std::function<void(expr const &, expr const &)> m_post;
frame_stack m_fs;
result_stack m_rs;
void save_result(expr const & e, expr const & r, unsigned offset, bool shared);
bool visit(expr const & e, unsigned offset);
bool check_index(frame & f, unsigned idx);
expr const & rs(int i);
void pop_rs(unsigned num);
public:
template<typename F, typename P = default_replace_postprocessor>
replace_fn(F const & f, P const & p = P()):
m_f(f), m_post(p) {}
expr operator()(expr const & e);
void clear();
};
template<typename F> expr replace(expr const & e, F const & f) {
return replace_fn(f)(e);
}
template<typename F, typename P> expr replace(expr const & e, F const & f, P const & p) {
return replace_fn(f, p)(e);
}
}