[Rust] Command Line Program 제작 (28일차)

 

<예제 코드_1>

// Cargo.toml 과 동일한 위치의 최상단 경로에 poem.txt 생성

I'm nobody! Who are you?
Are you nobody, too?
Then there's a pair of us — don't tell!
They'd banish us, you know.

How dreary to be somebody!
How public, like a frog
To tell your name the livelong day
To an admiring bog!

 

// $cargo run the poem.txt 명령어를 입력하여 실행

use std::env;
use std::fs::File;
use std::io::prelude::*;

fn main() {
    let args: Vec<String> = env::args().collect();

    let config = parse_config(&args);

    println!("Searching for {}", config.query);
    println!("In file {}", config.filename);

    let mut f = File::open(config.filename).expect("file not found");

    let mut contents = String::new();
    f.read_to_string(&mut contents).expect("Something went wrong reading the file");

    println!("With text:\n{}", contents);
}

struct Config {
    query: String,
    filename: String,
}

fn parse_config(args: &[String]) -> Config {
    let query = args[1].clone();
    let filename = args[2].clone();

    Config { query, filename }
}

 

---

 

<예제 코드_2>

// src/main.rs 파일

extern crate greprs;

use std::env;
use std::process;

use greprs::Config;

fn main() {
    let args: Vec<String> = env::args().collect();

    let config = Config::new(&args).unwrap_or_else(|err| {
        print!("Problem parsing arguments: {}\n", err);
        process::exit(1);
    });

    println!("Searching for {}", config.query);
    println!("In file {}", config.filename);

    if let Err(e) = greprs::run(config) {
        println!("Application error: {}", e);

        process::exit(1);
    }
}

 

// src/lib.rs 파일

use std::error::Error;
use std::fs::File;
use std::io::prelude::*;

pub struct Config {
    pub query: String,
    pub filename: String,
}

impl Config {
    pub fn new(args: &[String]) -> Result<Config, &'static str> {
        if args.len() < 3 {
            return Err("not enough arguments");
        }

        let query = args[1].clone();
        let filename = args[2].clone();

        Ok(Config { query, filename })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let mut f = File::open(config.filename)?;

    let mut contents = String::new();
    f.read_to_string(&mut contents)?;

    println!("With text:\n{}", contents);

    Ok(())
}

 

---

 

<예제 코드_3>

// lib.rs 를 아래 코드로 수정. 다음 명령어를 입력해보자

// $cargo run frog poem.txt

// $ cargo run body poem.txt

use std::error::Error;
use std::fs::File;
use std::io::prelude::*;

pub struct Config {
    pub query: String,
    pub filename: String,
}

impl Config {
    pub fn new(args: &[String]) -> Result<Config, &'static str> {
        if args.len() < 3 {
            return Err("not enough arguments");
        }

        let query = args[1].clone();
        let filename = args[2].clone();

        Ok(Config { query, filename })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let mut f = File::open(config.filename)?;

    let mut contents = String::new();
    f.read_to_string(&mut contents)?;

    for line in search(&config.query, &contents) {
        println!("{}", line);
    }

    Ok(())
}

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let mut results = Vec::new();

    for line in contents.lines() {
        if line.contains(query) {
            results.push(line);
        }
    }

    results
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn one_result() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";

        assert_eq!(
            vec!["safe, fast, productive."],
            search(query, contents)
        );
    }
}

 

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<참조 1> https://rinthel.github.io/rust-lang-book-ko/ch12-03-improving-error-handling-and-modularity.html

<참조 2> https://rinthel.github.io/rust-lang-book-ko/ch12-04-testing-the-librarys-functionality.html