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// Copyright 2017-2020 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/>.
//! Substrate Client and associated logic.
//!
//! The [`Client`] is one of the most important components of Substrate. It mainly comprises two
//! parts:
//!
//! - A database containing the blocks and chain state, generally referred to as
//! the [`Backend`](sc_client_api::backend::Backend).
//! - A runtime environment, generally referred to as the [`Executor`](CallExecutor).
//!
//! # Initialization
//!
//! Creating a [`Client`] is done by calling the `new` method and passing to it a
//! [`Backend`](sc_client_api::backend::Backend) and an [`Executor`](CallExecutor).
//!
//! The former is typically provided by the `sc-client-db` crate.
//!
//! The latter typically requires passing one of:
//!
//! - A [`LocalCallExecutor`] running the runtime locally.
//! - A [`RemoteCallExecutor`](light::call_executor::RemoteCallRequest) that will ask a
//! third-party to perform the executions.
//! - A [`RemoteOrLocalCallExecutor`](light::call_executor::RemoteOrLocalCallExecutor), combination
//! of the two.
//!
//! Additionally, the fourth generic parameter of the `Client` is a marker type representing
//! the ways in which the runtime can interface with the outside. Any code that builds a `Client`
//! is responsible for putting the right marker.
//!
//! ## Example
//!
//! ```
//! use std::sync::Arc;
//! use sc_client::{Client, in_mem::Backend, LocalCallExecutor};
//! use sp_runtime::Storage;
//! use sc_executor::{NativeExecutor, WasmExecutionMethod};
//!
//! // In this example, we're using the `Block` and `RuntimeApi` types from the
//! // `substrate-test-runtime-client` crate. These types are automatically generated when
//! // compiling a runtime. In a typical use-case, these types would have been to be generated
//! // from your runtime.
//! use substrate_test_runtime_client::{LocalExecutor, runtime::Block, runtime::RuntimeApi};
//!
//! let backend = Arc::new(Backend::<Block>::new());
//! let client = Client::<_, _, _, RuntimeApi>::new(
//! backend.clone(),
//! LocalCallExecutor::new(
//! backend.clone(),
//! NativeExecutor::<LocalExecutor>::new(WasmExecutionMethod::Interpreted, None, 8),
//! sp_core::tasks::executor(),
//! ),
//! // This parameter provides the storage for the chain genesis.
//! &<Storage>::default(),
//! Default::default(),
//! Default::default(),
//! Default::default(),
//! None,
//! );
//! ```
//!
pub use ;
pub use crate::;
pub use ;