frame-support 2.0.1

Support code for the runtime.
Documentation 
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// This file is part of Substrate.

// Copyright (C) 2019-2020 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Operation on unhashed runtime storage.

use sp_std::prelude::*;
use codec::{Encode, Decode};

/// Return the value of the item in storage under `key`, or `None` if there is no explicit entry.
pub fn get<T: Decode + Sized>(key: &[u8]) -> Option<T> {
	sp_io::storage::get(key).and_then(|val| {
		Decode::decode(&mut &val[..]).map(Some).unwrap_or_else(|_| {
			// TODO #3700: error should be handleable.
			runtime_print!("ERROR: Corrupted state at {:?}", key);
			None
		})
	})
}

/// Return the value of the item in storage under `key`, or the type's default if there is no
/// explicit entry.
pub fn get_or_default<T: Decode + Sized + Default>(key: &[u8]) -> T {
	get(key).unwrap_or_else(Default::default)
}

/// Return the value of the item in storage under `key`, or `default_value` if there is no
/// explicit entry.
pub fn get_or<T: Decode + Sized>(key: &[u8], default_value: T) -> T {
	get(key).unwrap_or(default_value)
}

/// Return the value of the item in storage under `key`, or `default_value()` if there is no
/// explicit entry.
pub fn get_or_else<T: Decode + Sized, F: FnOnce() -> T>(key: &[u8], default_value: F) -> T {
	get(key).unwrap_or_else(default_value)
}

/// Put `value` in storage under `key`.
pub fn put<T: Encode + ?Sized>(key: &[u8], value: &T) {
	value.using_encoded(|slice| sp_io::storage::set(key, slice));
}

/// Remove `key` from storage, returning its value if it had an explicit entry or `None` otherwise.
pub fn take<T: Decode + Sized>(key: &[u8]) -> Option<T> {
	let r = get(key);
	if r.is_some() {
		kill(key);
	}
	r
}

/// Remove `key` from storage, returning its value, or, if there was no explicit entry in storage,
/// the default for its type.
pub fn take_or_default<T: Decode + Sized + Default>(key: &[u8]) -> T {
	take(key).unwrap_or_else(Default::default)
}

/// Return the value of the item in storage under `key`, or `default_value` if there is no
/// explicit entry. Ensure there is no explicit entry on return.
pub fn take_or<T: Decode + Sized>(key: &[u8], default_value: T) -> T {
	take(key).unwrap_or(default_value)
}

/// Return the value of the item in storage under `key`, or `default_value()` if there is no
/// explicit entry. Ensure there is no explicit entry on return.
pub fn take_or_else<T: Decode + Sized, F: FnOnce() -> T>(key: &[u8], default_value: F) -> T {
	take(key).unwrap_or_else(default_value)
}

/// Check to see if `key` has an explicit entry in storage.
pub fn exists(key: &[u8]) -> bool {
	sp_io::storage::read(key, &mut [0;0][..], 0).is_some()
}

/// Ensure `key` has no explicit entry in storage.
pub fn kill(key: &[u8]) {
	sp_io::storage::clear(key);
}

/// Ensure keys with the given `prefix` have no entries in storage.
pub fn kill_prefix(prefix: &[u8]) {
	sp_io::storage::clear_prefix(prefix);
}

/// Get a Vec of bytes from storage.
pub fn get_raw(key: &[u8]) -> Option<Vec<u8>> {
	sp_io::storage::get(key)
}

/// Put a raw byte slice into storage.
///
/// **WARNING**: If you set the storage of the Substrate Wasm (`well_known_keys::CODE`),
/// you should also call `frame_system::RuntimeUpgraded::put(true)` to trigger the
/// `on_runtime_upgrade` logic.
pub fn put_raw(key: &[u8], value: &[u8]) {
	sp_io::storage::set(key, value)
}