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|
//! A very partial unfaithful implementation of cargo's command line.
//!
//! This showcases some hairier patterns, like subcommands and custom value parsing.
use std::{path::PathBuf, str::FromStr};
const HELP: &str = "cargo [+toolchain] [OPTIONS] [SUBCOMMAND]";
fn main() -> Result<(), lexopt::Error> {
use lexopt::prelude::*;
let mut settings = GlobalSettings {
toolchain: "stable".to_owned(),
color: Color::Auto,
offline: false,
quiet: false,
verbose: false,
};
let mut parser = lexopt::Parser::from_env();
while let Some(arg) = parser.next()? {
match arg {
Long("color") => {
settings.color = parser.value()?.parse()?;
}
Long("offline") => {
settings.offline = true;
}
Long("quiet") => {
settings.quiet = true;
settings.verbose = false;
}
Long("verbose") => {
settings.verbose = true;
settings.quiet = false;
}
Long("help") => {
println!("{}", HELP);
std::process::exit(0);
}
Value(value) => {
let value = value.string()?;
match value.as_str() {
value if value.starts_with('+') => {
settings.toolchain = value[1..].to_owned();
}
"install" => {
return install(settings, parser);
}
value => {
return Err(format!("unknown subcommand '{}'", value).into());
}
}
}
_ => return Err(arg.unexpected()),
}
}
println!("{}", HELP);
Ok(())
}
#[derive(Debug)]
struct GlobalSettings {
toolchain: String,
color: Color,
offline: bool,
quiet: bool,
verbose: bool,
}
fn install(settings: GlobalSettings, mut parser: lexopt::Parser) -> Result<(), lexopt::Error> {
use lexopt::prelude::*;
let mut package: Option<String> = None;
let mut root: Option<PathBuf> = None;
let mut jobs: u16 = get_no_of_cpus();
while let Some(arg) = parser.next()? {
match arg {
Value(value) if package.is_none() => {
package = Some(value.string()?);
}
Long("root") => {
root = Some(parser.value()?.into());
}
Short('j') | Long("jobs") => {
jobs = parser.value()?.parse()?;
}
Long("help") => {
println!("cargo install [OPTIONS] CRATE");
std::process::exit(0);
}
_ => return Err(arg.unexpected()),
}
}
println!("Settings: {:#?}", settings);
println!(
"Installing {} into {:?} with {} jobs",
package.ok_or("missing CRATE argument")?,
root,
jobs
);
Ok(())
}
#[derive(Debug)]
enum Color {
Auto,
Always,
Never,
}
// clap has a macro for this: https://docs.rs/clap/2.33.3/clap/macro.arg_enum.html
// We have to do it manually.
impl FromStr for Color {
type Err = String;
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.to_lowercase().as_str() {
"auto" => Ok(Color::Auto),
"always" => Ok(Color::Always),
"never" => Ok(Color::Never),
_ => Err(format!(
"Invalid style '{}' [pick from: auto, always, never]",
s
)),
}
}
}
fn get_no_of_cpus() -> u16 {
4
}
|
