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>
After this commit, a value of type 'expr' cannot be a reference to nullptr.
This commit also fixes several bugs due to the use of 'null' expressions.
TODO: do the same for kernel objects, sexprs, etc.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
copy_values is not a big if-then-else anymore.
Before this change, whenever we added a new kind of userdata, we would have to update copy_values.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
The directory bindings/lua was getting too big and had too many dependencies.
Moreover, it was getting too painful to edit/maintain two different places.
Now, the bindings for module X are in the directory that defines X.
For example, the bindings for util/name.cpp are located at util/name.cpp.
The only exception is the kernel. We do not want to inflate the kernel
with Lua bindings. The bindings for the kernel classes are located
at bindings/kernel_bindings.
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
