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|
use winnow::prelude::*;
mod parser;
mod parser_ast;
fn main() -> Result<(), lexopt::Error> {
let args = Args::parse()?;
let input = args.input.as_deref().unwrap_or("1 + 1");
println!("{} =", input);
match args.implementation {
Impl::Eval => match parser::expr.parse(input) {
Ok(result) => {
println!(" {}", result);
}
Err(err) => {
println!(" {}", err);
}
},
Impl::Ast => match parser_ast::expr.parse(input) {
Ok(result) => {
println!(" {:#?}", result);
}
Err(err) => {
println!(" {}", err);
}
},
}
Ok(())
}
#[derive(Default)]
struct Args {
input: Option<String>,
implementation: Impl,
}
enum Impl {
Eval,
Ast,
}
impl Default for Impl {
fn default() -> Self {
Self::Eval
}
}
impl Args {
fn parse() -> Result<Self, lexopt::Error> {
use lexopt::prelude::*;
let mut res = Args::default();
let mut args = lexopt::Parser::from_env();
while let Some(arg) = args.next()? {
match arg {
Long("impl") => {
res.implementation = args.value()?.parse_with(|s| match s {
"eval" => Ok(Impl::Eval),
"ast" => Ok(Impl::Ast),
_ => Err("expected `eval`, `ast`"),
})?;
}
Value(input) => {
res.input = Some(input.string()?);
}
_ => return Err(arg.unexpected()),
}
}
Ok(res)
}
}
|
