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// Copyright 2019-2020 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Substrate is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.

//! Stores the externalities in an `environmental` value to make it scope limited available.

use crate::Externalities;

environmental::environmental!(ext: trait Externalities);

/// Set the given externalities while executing the given closure. To get access to the externalities
/// while executing the given closure [`with_externalities`] grants access to them. The externalities
/// are only set for the same thread this function was called from.
pub fn set_and_run_with_externalities<F, R>(ext: &mut dyn Externalities, f: F) -> R
	where F: FnOnce() -> R
{
	ext::using(ext, f)
}

/// Execute the given closure with the currently set externalities.
///
/// Returns `None` if no externalities are set or `Some(_)` with the result of the closure.
pub fn with_externalities<F: FnOnce(&mut dyn Externalities) -> R, R>(f: F) -> Option<R> {
	ext::with(f)
}