f97c260b0b
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>
45 lines
1.5 KiB
C++
45 lines
1.5 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 "util/shared_mutex.h"
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#include "kernel/environment.h"
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namespace lean {
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/**
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\brief The environment object is not thread safe.
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The helper classes \c read_only_shared_environment and \c read_write_shared_environment
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provides thread safe access to the environment object.
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\remark We do not use these classes internally.
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They are only used for implementing external APIs.
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*/
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class read_only_shared_environment {
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ro_environment m_env;
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shared_lock m_lock;
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public:
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read_only_shared_environment(ro_environment const & env);
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~read_only_shared_environment();
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operator ro_environment const &() const { return m_env; }
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environment_cell const * operator->() const { return m_env.m_ptr.get(); }
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environment_cell const & operator*() const { return *(m_env.m_ptr.get()); }
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};
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/**
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\brief See \c read_only_shared_environment
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*/
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class read_write_shared_environment {
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environment m_env;
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exclusive_lock m_lock;
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public:
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read_write_shared_environment(environment const & env);
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~read_write_shared_environment();
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operator environment const &() const { return m_env; }
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operator ro_environment() const { return ro_environment(m_env); }
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environment_cell * operator->() const { return m_env.m_ptr.get(); }
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environment_cell & operator*() const { return *(m_env.m_ptr.get()); }
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};
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}
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