semtor_rust_grep 0.1.0

A rust implemention of grep
Documentation 
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use std::env;
use std::error::Error;
use std::fs;
use std::process;

struct Config {
    pub query: String,
    pub filename: String,
    pub file_content: String,
    pub case_sensitive: bool,
}

impl Config {
    pub fn setup() -> Result<Config, String> {
        let mut args = env::args();
        if args.len() != 3 {
            return Err(std::format!(
                "用法：\n{} {} {}",
                args.next().unwrap(),
                "[regx]",
                "[file]"
            ));
        }
        args.next();
        let case_sensitive = std::env::var("CASE_INSENSITIVE").is_err();
        let config: Config = Config {
            query: args.next().unwrap(),
            filename: args.next().unwrap(),
            file_content: String::new(),
            case_sensitive,
        };
        Ok(config)
    }

    pub fn read_file(&mut self) -> Result<(), Box<dyn Error>> {
        self.file_content = fs::read_to_string(&self.filename)?;
        Ok(())
    }
}

pub fn start() {
    let mut config = Config::setup().unwrap_or_else(|err| {
        eprintln!("错误：{}", err);
        process::exit(1);
    });
    if let Err(e) = config.read_file() {
        eprintln!("错误: {}", e);
        process::exit(1);
    }
    let results = if config.case_sensitive {
        search(&config.query, &config.file_content)
    } else {
        search_case_insensitive(&config.query, &config.file_content)
    };
    for line in results {
        println!("{}", line);
    }
}

fn search<'a>(query: &str, content: &'a str) -> Vec<&'a str> {
    // let mut res = Vec::new();
    // for line in content.lines() {
    //     if line.contains(query) {
    //         res.push(line);
    //     }
    // }
    // res
    content
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}

fn search_case_insensitive<'a>(query: &str, content: &'a str) -> Vec<&'a str> {
    // let mut res = Vec::new();
    // let query = query.to_lowercase();
    // for line in content.lines() {
    //     if line.to_lowercase().contains(&query) {
    //         res.push(line);
    //     }
    // }
    // res
    content
        .lines()
        .filter(|line| line.to_lowercase().contains(&query.to_lowercase()))
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn case_sensitive() {
        let query = "duct";
        let conetent = "\
Rust:
safe,fast,productive.
Pick three.
Duct tape";

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

    #[test]
    fn case_insensitive() {
        let query = "rUsT";
        let contents = "\
Rust:
safe,fase,productive.
Pick three.
Trust me.";
        assert_eq!(
            vec!["Rust:", "Trust me."],
            search_case_insensitive(query, contents)
        );
    }
}