[client cli] generic blocknumber (#4376)

* rewrite me

* [cli]: make `BlockNumber` generic

* cleanup

substrate/client/cli/src/lib.rs

@@ -42,7 +42,7 @@ use sc_network::{
 use sp_core::H256;
 
 use std::{
-	io::{Write, Read, Seek, Cursor, stdin, stdout, ErrorKind}, iter, fs::{self, File},
+	io::{Write, Read, Seek, Cursor, stdin, stdout, ErrorKind}, iter, fmt::Debug, fs::{self, File},
 	net::{Ipv4Addr, SocketAddr}, path::{Path, PathBuf}, str::FromStr, pin::Pin, task::Poll
 };
 
@@ -64,7 +64,7 @@ use lazy_static::lazy_static;
 use futures::{Future, compat::Future01CompatExt, executor::block_on};
 use sc_telemetry::TelemetryEndpoints;
 use sp_runtime::generic::BlockId;
-use sp_runtime::traits::Block as BlockT;
+use sp_runtime::traits::{Block as BlockT, Header as HeaderT};
 
 /// default sub directory to store network config
 const DEFAULT_NETWORK_CONFIG_PATH : &'static str = "network";
@@ -373,6 +373,8 @@ impl<'a> ParseAndPrepareExport<'a> {
 	where S: FnOnce(&str) -> Result<Option<ChainSpec<G, E>>, String>,
 		F: FnOnce(Configuration<C, G, E>) -> Result<B, error::Error>,
 		B: ServiceBuilderCommand,
+		<<<<B as ServiceBuilderCommand>::Block as BlockT>::Header as HeaderT>
+			::Number as FromStr>::Err: Debug,
 		C: Default,
 		G: RuntimeGenesis,
 		E: ChainSpecExtension,
@@ -383,8 +385,9 @@ impl<'a> ParseAndPrepareExport<'a> {
 		if let DatabaseConfig::Path { ref path, .. } = &config.database {
 			info!("DB path: {}", path.display());
 		}
-		let from = self.params.from.unwrap_or(1);
-		let to = self.params.to;
+		let from = self.params.from.and_then(|f| f.parse().ok()).unwrap_or(1);
+		let to = self.params.to.and_then(|t| t.parse().ok());
+
 		let json = self.params.json;
 
 		let file: Box<dyn Write> = match self.params.output {
@@ -402,7 +405,7 @@ impl<'a> ParseAndPrepareExport<'a> {
 		});
 
 		let mut export_fut = builder(config)?
-			.export_blocks(file, from.into(), to.map(Into::into), json)
+			.export_blocks(file, from.into(), to, json)
 			.compat();
 		let fut = futures::future::poll_fn(|cx| {
 			if exit_recv.try_recv().is_ok() {
@@ -596,6 +599,8 @@ impl<'a> ParseAndPrepareRevert<'a> {
 		S: FnOnce(&str) -> Result<Option<ChainSpec<G, E>>, String>,
 		F: FnOnce(Configuration<C, G, E>) -> Result<B, error::Error>,
 		B: ServiceBuilderCommand,
+		<<<<B as ServiceBuilderCommand>::Block as BlockT>::Header as HeaderT>
+			::Number as FromStr>::Err: Debug,
 		C: Default,
 		G: RuntimeGenesis,
 		E: ChainSpecExtension,
@@ -603,8 +608,8 @@ impl<'a> ParseAndPrepareRevert<'a> {
 		let config = create_config_with_db_path(
 			spec_factory, &self.params.shared_params, self.version
 		)?;
-		let blocks = self.params.num;
-		builder(config)?.revert_chain(blocks.into())?;
+		let blocks = self.params.num.parse()?;
+		builder(config)?.revert_chain(blocks)?;
 		Ok(())
 	}
 }

substrate/client/cli/src/params.rs

@@ -16,7 +16,7 @@
 
 use crate::traits::{AugmentClap, GetLogFilter};
 
-use std::path::PathBuf;
+use std::{str::FromStr, path::PathBuf};
 use structopt::{StructOpt, clap::{arg_enum, App, AppSettings, SubCommand, Arg}};
 
 pub use crate::execution_strategy::ExecutionStrategy;
@@ -734,6 +734,41 @@ pub struct BuildSpecCmd {
 
 impl_get_log_filter!(BuildSpecCmd);
 
+/// Wrapper type of `String` which holds an arbitary sized unsigned integer formatted as decimal.
+#[derive(Debug, Clone)]
+pub struct BlockNumber(String);
+
+impl FromStr for BlockNumber {
+	type Err = String;
+
+	fn from_str(block_number: &str) -> Result<Self, Self::Err> {
+		if block_number.chars().any(|d| !d.is_digit(10)) {
+			Err(format!(
+				"Invalid block number: {}, expected decimal formatted unsigned integer",
+				block_number
+			))
+		} else {
+			Ok(Self(block_number.to_owned()))
+		}
+	}
+}
+
+impl BlockNumber {
+	/// Wrapper on top of `std::str::parse<N>` but with `Error` as a `String`
+	///
+	/// See `https://doc.rust-lang.org/std/primitive.str.html#method.parse` for more elaborate
+	/// documentation.
+	pub fn parse<N>(&self) -> Result<N, String>
+	where
+		N: FromStr,
+		N::Err: std::fmt::Debug,
+	{
+		self.0
+			.parse()
+			.map_err(|e| format!("BlockNumber: {} parsing failed because of {:?}", self.0, e))
+	}
+}
+
 /// The `export-blocks` command used to export blocks.
 #[derive(Debug, StructOpt, Clone)]
 pub struct ExportBlocksCmd {
@@ -745,13 +780,13 @@ pub struct ExportBlocksCmd {
 	///
 	/// Default is 1.
 	#[structopt(long = "from", value_name = "BLOCK")]
-	pub from: Option<u32>,
+	pub from: Option<BlockNumber>,
 
 	/// Specify last block number.
 	///
 	/// Default is best block.
 	#[structopt(long = "to", value_name = "BLOCK")]
-	pub to: Option<u32>,
+	pub to: Option<BlockNumber>,
 
 	/// Use JSON output rather than binary.
 	#[structopt(long = "json")]
@@ -817,7 +852,7 @@ impl_get_log_filter!(CheckBlockCmd);
 pub struct RevertCmd {
 	/// Number of blocks to revert.
 	#[structopt(default_value = "256")]
-	pub num: u32,
+	pub num: BlockNumber,
 
 	#[allow(missing_docs)]
 	#[structopt(flatten)]