Rust第二次综合练习

啊，啊，啊

原来我一直用的linux rust1.1的老版本，

很多书上的写法都不行，得调试。

今天早上，换成了win rust1.3版本，

于是，可以按书上标准的语法来弄了。

一，main.rs

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

use minigrep;
use minigrep::Config;

fn main() {
    let args: Vec<String> = env::args().collect();
    let config = Config::new(&args).unwrap_or_else(|err| {
        eprintln!("Problem parsing arguments: {}", err);
        process::exit(1);
    });

    if let Err(e) = minigrep::run(config) {
        eprintln!("Application error: {}", e);
        process::exit(1);
    };    
}

二，lib.rs

use std::env;
//use std::io::Read;
use std::fs;
use std::error::Error;

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

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();

        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
        //let case_sensitive = false;

        Ok(Config { query, filename, case_sensitive })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;

    let results = if config.case_sensitive {
        search(&config.query, &contents)
    } else {
        search_case_insensitive(&config.query, &contents)
    };

    for line in results {
        println!("{}", line);
    }

    Ok(())

}

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
}

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

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

    results
}

#[cfg(test)]
mod tests {
    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)
        );
    }

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

三，输出