lean2/src/frontends/lean/pp.h
Leonardo de Moura f97c260b0b refactor(kernel/environment): add ro_environment
The environment object is a "smart-pointer".
Before this commit, the use of "const &" for environment objects was broken.
For example, suppose we have a function f that should not modify the input environment.
Before this commit, its signature would be
       void f(environment const & env)
This is broken, f's implementation can easilty convert it to a read-write pointer by using
the copy constructor.
       environment rw_env(env);
Now, f can use rw_env to update env.

To fix this issue, we now have ro_environment. It is a shared *const* pointer.
We can convert an environment into a ro_environment, but not the other way around.

ro_environment can also be seen as a form of documentation.
For example, now it is clear that type_inferer is not updating the environment, since its constructor takes a ro_environment.

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2013-12-12 16:48:34 -08:00

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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 "util/sexpr/options.h"
#include "kernel/context.h"
#include "kernel/formatter.h"
namespace lean {
class frontend;
class environment;
formatter mk_pp_formatter(ro_environment const & env);
std::ostream & operator<<(std::ostream & out, frontend const & fe);
}