language = "C++"

# The "\u0065" in the header is simply the letter 'e'. This trick is to prevent
# our tools from marking this file as generated file.
header = """/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This software may be used and distributed according to the terms of the
 * GNU General Public License version 2.
 *
 * This file is generated with cbindgen. Please run `./tools/cbindgen.sh` to
 * update this file.
 *
 * @gen\u0065rated <<SignedSource::*O*zOeWoEQle#+L!plEphiEmie@IsG>>
 *
 */

// The generated functions are exported from this Rust library
// @dep=:backingstore

#pragma once

#include <memory>
#include <functional>
#include <folly/Range.h>

extern "C" void rust_cfallible_free_error(char *ptr);

// MSVC toolchain dislikes having template in `extern "C"` functions. So we will
// have to use void pointer here. Cbindgen does not support generating code like
// this since it's kinda a special case so we manually generate this struct.
struct RustCFallibleBase {
 void *value;
 char *error;
};

// Some Rust functions will have the return type `RustCFallibleBase`, and we
// have this convenient struct to help C++ code to consume the returned
// struct. This is the only way to use the returned `RustCFallibleBase` from
// Rust, and the user must provide a `Deleter` to correctly free the pointer
// returned from Rust.
template <typename T, typename Deleter = std::function<void(T*)>>
class RustCFallible {
private:
  std::unique_ptr<T, std::function<void(T*)>> ptr_;
  char* error_;

public:
  RustCFallible(RustCFallibleBase&& base, Deleter deleter)
      : ptr_(reinterpret_cast<T*>(base.value), deleter), error_(base.error) {}

  bool isError() const {
    return error_ != nullptr;
  }

  char* getError() {
    return error_;
  }

  T* get() {
    return ptr_.get();
  }

  std::unique_ptr<T, Deleter> unwrap() {
    return std::move(ptr_);
  }

  ~RustCFallible() {
    if (error_ != nullptr) {
      rust_cfallible_free_error(error_);
    }

    unwrap();
  }
};
"""

[export]
prefix= "Rust"
exclude = ["CFallible"]
include = ["Tree", "TreeEntry", "TreeEntryType"]

[export.rename]
"CFallible" = "CFallibleBase"

[export.body]
"CBytes" = """
folly::ByteRange asByteRange() const {
  return folly::ByteRange(ptr, len);
}

operator folly::ByteRange() const {
  return asByteRange();
}
"""