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use std::error::Error;
use std::process;
use std::fs;
use std::io::{self, BufReader, BufRead};
use clap::Parser;
#[derive(Parser)]
#[command(author, version, about, long_about = None)] // Read from `Cargo.toml`
struct Config {
/// The pattern to look for
pattern: String,
/// The path to files to read. A path of "-" stands for standard input.
///
/// If no FILE is given, read standard input.
files: Vec<String>,
}
fn main() {
let mut config = Config::parse();
if config.files.is_empty() {
config.files.push(String::from("-"));
}
if let Err(e) = run(config) {
eprintln!("Error: {e}");
process::exit(1);
}
}
fn run(config: Config) -> Result<(), Box<dyn Error>> {
for file in config.files {
// On-Stack Dynamic Dispatch
let (mut stdin_read, mut file_read);
// We need to ascribe the type to get dynamic dispatch.
let reader: &mut dyn BufRead = if file == "-" {
stdin_read = BufReader::new(io::stdin());
&mut stdin_read
} else {
file_read = BufReader::new(fs::File::open(&file)?);
&mut file_read
};
let mut contents = String::new();
reader.read_to_string(&mut contents)?;
for line in trgrep::search(&config.pattern, &contents) {
println!("{line}");
}
}
Ok(())
}
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