lean4-htt/src/library/vm/vm_string.h
Leonardo de Moura 9399ce8346 feat(library/vm/vm_string): provide native implementation of type string in the VM
closes #1175

The types `string_imp` and `string.iterator_imp` were supposed to be
marked private, but we cannot do it because we need to provide
`string_imp.mk`, `string_imp.cases_on`, `string.iterator_imp.mk` and
`string.iterator_imp.cases_on` in the VM since we use a different
internal representation. Note that marking them as private does not
work since users can still access `string_imp.cases_on` using
meta-programming.
So, we need better support for private declarations.

Missing feature, char literals do not support non ASCII values.
That is, in the current implementation, we cannot write 'α'.
This will be implemented in the future.

The VM native implementation does not behave correctly for huge
strings (i.e., strings with more than 4G characters).
The problem is that the current implementation relies on
```
size_t force_to_size_t(vm_obj const & o, size_t def)
```
We may also have overflow problems in the string.iterator implementation
code. This is not a big deal right now, since I doubt we will try
to process string with more than 2^32 characters.

@Kha the `core_lib` and tests seem to be working correctly, but
we need more tests.
2017-10-23 10:55:26 -07:00

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/*
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
#pragma once
#include <string>
#include "library/vm/vm.h"
namespace lean {
std::string to_string(vm_obj const & o);
vm_obj to_obj(std::string const & str);
void initialize_vm_string();
void finalize_vm_string();
}